Hot press-formed product, tailored blank, method for manufacturing a hot press-formed product, and method for manufacturing a tailored blank

Abstract

To provide a hot press molded product which suppresses breakage at a weld metal section.SOLUTION: A hot press molded product 1A includes: a first member 10A; a second member 30A which abuts the first member; and a weld metal section 50A which joins the first member and the second member, where the hot press molded product is developed in a flat shape. When a longitudinal direction X in a neighborhood part of the weld metal section is defined, at least one formed angle out of the following formed angles is 80° or less, the formed angles are: two formed angles θ11 between a longitudinal direction through a first intersection and a portion connected to the first intersection Q1 between the weld metal section and an outer edge 36d of the hot press molded product on a side opposite to a second member first ridgeline 41A of a second member first piece 36; two formed angles θ12 between a longitudinal direction through a second intersection and a portion connected to the second intersection Q2 between the weld metal section and an outer edge 37d of the hot press molded product on a side opposite to a second member first ridgeline of a second member second piece 37; and four formed angles θ21 between a longitudinal direction through a third intersection and a portion connected to the third intersection Q3 between the weld metal section and the second member first ridgeline.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] This invention relates to hot press-formed articles, tailored blanks, methods for manufacturing hot press-formed articles, and methods for manufacturing tailored blanks. [Background technology]

[0002] Conventionally, in hot-pressed products using aluminum-plated steel sheets, aluminum can become mixed into the weld metal, making it impossible to harden the weld metal during hot-press forming (see, for example, Patent Documents 1 and 2). Two countermeasures have been proposed to address this problem.

[0003] The first countermeasure is to remove the aluminum plating layer from the aluminum-plated steel sheets before welding them together, thereby suppressing the inclusion of aluminum in the weld metal. The second solution is to supply austenitic welding material during welding. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Patent No. 5237263 [Patent Document 2] International Publication No. 2013 / 045497 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the first countermeasure requires a step to remove the aluminum plating layer. In the second countermeasure, there is a risk of aluminum concentration at the weld edge (weld toe), where stirring of the molten weld metal is less likely.

[0006] This invention has been made in view of the above problems, and aims to provide a hot press-formed product, a tailored blank, a method for manufacturing a hot press-formed product, and a method for manufacturing a tailored blank that can suppress fracture at the weld metal portion. [Means for solving the problem]

[0007] To solve the aforementioned problems, this invention proposes the following means. (1) A first aspect of the present invention is a hot press-formed product comprising: a first member; a second member whose end abuts against the end of the first member; and a welded metal portion that joins the end of the first member and the end of the second member, wherein at least one of the first member and the second member is an aluminum-plated member, and the first member has a first part first piece and a first part second piece connected to the first part first piece via a first ridge of the first member, and the second member The hot press-formed product comprises a first piece of the first part and a first piece of the second part joined via the welded metal portion, a first ridge of the first part and a first ridge of the second part joined via the welded metal portion, and a second piece of the second part connected to the first piece of the second part and the first ridge of the second part, and joined to the second piece of the first part and the welded metal portion, and defines the longitudinal direction of the hot press-formed product with respect to the portion near the welded metal portion when the hot press-formed product is unfolded into a planar shape, and the hot press-formed product When the press-formed product is unfolded into a planar shape and viewed in the thickness direction of the second member, with the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the press-formed product on the opposite side of the first ridge of the second part of the first piece of the second part and the welded metal portion, the angle formed by the portion of the welded metal portion connected to the first intersection point and the longitudinal direction passing through the first intersection point, and with the second piece of the second part as the reference, the opposite side of the first ridge of the second part of the second piece of the second part At the second intersection, which is the point where the outer edge of the hot-pressed product intersects with the welded metal portion, the angle of at least one of the eight angles formed, including the two angles formed by the portion of the welded metal portion connected to the second intersection and the longitudinal direction passing through the second intersection, and at the third intersection, which is the point where the first ridge of the second portion intersects with the welded metal portion, the angle of at least one of the eight angles formed by the portion of the welded metal portion connected to the third intersection and the longitudinal direction passing through the third intersection, is 80° or less.

[0008] (12) A second aspect of the present invention is a method for manufacturing a hot press-formed product, comprising: an arrangement step of arranging the end of a first steel plate and the end of a second steel plate so as to abut; a welding step of joining the end of the first steel plate and the end of the second steel plate by welding to form a weld metal portion and manufacture a tailored blank; and a forming step of hot press forming the tailored blank to form a first part first ridge on a first member obtained from the first steel plate and a second part first ridge on a second member obtained from the second steel plate, wherein the first At least one of the member and the second member is an aluminum plated member, the first member has a first piece of the first part and a second piece of the first part connected to the first piece of the first part via the first ridge of the first part, the second member has a first piece of the second part joined to the first piece of the first part via the welded metal part, the first ridge of the second part joined to the first ridge of the first part via the welded metal part, and the second piece of the second part connected to the first piece of the second part via the first ridge of the second part and joined to the second piece of the first part via the welded metal part, and the hot press forming When the product is unfolded into a planar shape, the longitudinal direction of the hot-pressed product in the vicinity of the welded metal portion is defined, and with the second part first piece as the reference, the first intersection is the point where the outer edge of the hot-pressed product on the opposite side of the second part first edge of the second part intersects with the welded metal portion, and the angle between the portion of the welded metal portion connected to the first intersection and the longitudinal direction passing through the first intersection, and with the second part second piece as the reference, the outer edge of the hot-pressed product on the opposite side of the second part first edge of the second part and the welded metal portion. The hot press-formed product is manufactured such that, when the hot press-formed product is unfolded into a planar shape and viewed in the thickness direction of the second member, the angle of at least one of the eight angles formed, including the two angles formed at the second intersection, which is the point of intersection with the metal part, between the portion of the welded metal part connected to the second intersection and the longitudinal direction passing through the second intersection, and the four angles formed at the third intersection, which is the point of intersection between the first ridge of the second part and the welded metal part, between the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection, is 80° or less.

[0009] In these inventions, the inventors, after diligent study of hot-pressed products, found the following: For example, when a tensile force is applied to a hot-pressed product in the longitudinal direction, crack initiation points are likely to occur in the portion connected to the first intersection of the weld metal, the portion connected to the second intersection of the weld metal, and the portion connected to the third intersection of the weld metal. Therefore, by constructing (manufacturing) the hot-pressed product such that at least one of the eight angles formed by the weld metal portion at the first intersection, including the two angles between the portion of the weld metal portion at the first intersection and the longitudinal direction passing through the first intersection, the two angles between the portion of the weld metal portion at the second intersection and the longitudinal direction passing through the second intersection, and the four angles between the portion of the weld metal portion at the third intersection and the longitudinal direction passing through the third intersection, the angle of at least one of these angles is 80° or less when the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member, the external force acting in the direction of opening the weld metal portion, caused by the tensile force acting on the portion having at least one of these angles, is suppressed. Consequently, fracture of the hot-pressed product at the weld metal portion can be suppressed.

[0010] (2) In the hot press-formed product described in (1) above, the hot press-formed product has the weld metal portion, at least a part of the first member connected to the weld metal portion, and at least a part of the second member connected to the weld metal portion, and has a shaft portion extending in a predetermined direction, the longitudinal direction may correspond to the predetermined direction. (13) In the method for manufacturing a hot press-formed product described in (12) above, the hot press-formed product has the weld metal portion, at least a part of the first member connected to the weld metal portion, and at least a part of the second member connected to the weld metal portion, and has a shaft portion extending in a predetermined direction, the longitudinal direction may correspond to the predetermined direction. These inventions make it possible to prevent a hot-pressed product from fracturing at the weld metal portion when a tensile force is applied in a predetermined direction in which the shaft portion extends.

[0011] (3) The hot press-formed product described in (1) or (2) above may satisfy formula (1). T w H w <T2H2<T1H1··(1) However, T1: thickness of the first member (mm), H1: Vickers hardness of the first member (HV), T2: thickness of the second member (mm), H2: Vickers hardness of the second member (HV), T w : The thickness of the welded metal portion (the thinner of the thickness T1 and the thickness T2) (mm), H w : This is the Vickers hardness (HV) of the welded metal portion. (14) The method for manufacturing a hot press-formed product described in (12) or (13) above may satisfy formula (2). T w H w <T2H2<T1H1··(2) However, T1: thickness of the first member (mm), H1: Vickers hardness of the first member of the hot-pressed product (HV), T2: thickness of the second member (mm), H2: Vickers hardness of the second member of the hot-pressed product (HV), T w : The thickness of the welded metal portion (the thinner of the thickness T1 and the thickness T2) (mm), H w : This is the Vickers hardness (HV) of the weld metal portion of the hot-pressed product.

[0012] Note that equation (2) is identical to equation (1). In these inventions, in hot-pressed products, the product of thickness and Vickers hardness, i.e., rigidity, increases in the order of welded metal, second member, and first member. Generally, in hot-pressed products including aluminum-plated members, the rigidity of the welded metal is less than the rigidity of the member. If the left - hand - side inequality of formula (1) is satisfied and the rigidity of the welded metal part is smaller than that of the member, stress is more likely to concentrate on the welded metal part. However, by configuring (manufacturing) the hot - press - formed product such that at least one of the eight angles including the two angles formed between the part of the welded metal part connected to the first intersection and the longitudinal direction passing through the first intersection at the first intersection, the two angles formed between the part of the welded metal part connected to the second intersection and the longitudinal direction passing through the second intersection at the second intersection, and the four angles formed between the part of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection at the third intersection is 80° or less when the hot - press - formed product is developed flat and viewed in the thickness direction of the second member, the external force acting in the direction in which the welded metal part opens, which is generated by the tensile force acting on the part having at least one of the above - mentioned angles, can be suppressed. Therefore, since the effects of the present invention can be significantly manifested, it is preferable that the rigidity of the welded metal part is smaller than that of the member. Also, by satisfying the right - hand - side inequality of formula (1) and making the rigidity of the second member smaller than that of the first member, stress can be concentrated on the second member among the first member and the second member, and the second member is more likely to break. As a result, the fracture countermeasure in the hot - press - formed product can be concentrated on the second member.

[0013] (4) In the hot - press - formed product according to any one of (1) to (3) above, when the hot - press - formed product is developed flat and viewed in the thickness direction of the second member, at the third intersection, at least one of the four angles formed between the part of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection may be 60° or less. (15) In the method for manufacturing a hot - press - formed product according to any one of (12) to (14) above, at the third intersection, the hot - press - formed product may be manufactured such that at least one of the four angles formed between the part of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 60° or less when the hot - press - formed product is developed flat and viewed in the thickness direction of the second member. In these inventions, for example, when a tensile force acts in the longitudinal direction on a hot press-formed product, an external force acting in the direction in which the welded metal part opens can be further suppressed in a portion continuous with the third intersection of the welded metal part.

[0014] (5) In the hot press-formed product according to any one of (1) to (4) above, the welded metal part may have a welding start end and a welding end. (16) In the method for manufacturing a hot press-formed product according to any one of (12) to (15) above, the welded metal part may have a welding start end and a welding end. In these inventions, even when the hot press-formed product has a welding start end and a welding end, it is possible to suppress breakage at the welded metal part.

[0015] (6) In the hot press-formed product according to any one of (1) to (5) above, the concentration of aluminum contained in the welded metal part may be 0.3 mass% or more and 2.5 mass% or less. (17) In the method for manufacturing a hot press-formed product according to any one of (12) to (16) above, the concentration of aluminum contained in the welded metal part after hot press forming may be 0.3 mass% or more and 2.5 mass% or less. In these inventions, since the aluminum concentration of the welded metal part of the hot press-formed product is high, the corrosion resistance of the welded metal part can be improved.

[0016] (7) In the hot press-formed product according to any one of (1) to (6) above, when the hot press-formed product is developed in a planar shape, the welded metal part may be in a polygonal line shape or a curved line shape. (18) In the method for manufacturing a hot press-formed product according to any one of (12) to (17) above, when the hot press-formed product is developed in a planar shape, the welded metal part may be in a polygonal line shape or a curved line shape. In these inventions, compared with the case where the welded metal part is linear, it is more difficult for the welded metal part to break at once.

[0017] (8) In the hot press-formed product according to any one of (1) to (7) above, the first member has a third piece of the first part which is connected to the first piece of the first part via the first ridge of the first part and to the second piece of the first part via the second ridge of the first part, and the second member has a second ridge of the second part which is joined to the second ridge of the first part via the weld metal portion, and the first piece of the second part is connected to the first ridge of the second part, the second piece of the second part is connected to the second ridge of the second part and to the third piece of the first part which is joined to the weld metal portion The product has a piece and a part, and when the hot press-formed product is unfolded into a planar shape and viewed in the thickness direction, at the third intersection, at least one of the four angles made between the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less, and at the fourth intersection, which is the intersection of the second ridge of the second part and the welded metal part, at least one of the four angles made between the portion of the welded metal part connected to the fourth intersection and the longitudinal direction passing through the fourth intersection is 80° or less. (19) In the method for manufacturing a hot press-formed product described in any one of (12) to (18) above, the first member of the hot press-formed product has a third piece of the first part which is connected to the first piece of the first part via the first ridge of the first part and to the second piece of the first part via the second ridge of the first part, and the second member of the hot press-formed product has a second ridge of the second part which is joined to the second ridge of the first part via the weld metal portion, the first piece of the second part is connected to the first ridge of the second part, the second piece of the second part is connected to the second ridge of the second part and to the third piece of the first part via the weld metal portion The hot press-formed product may be manufactured such that, when the hot press-formed product is unfolded into a planar shape and viewed in the thickness direction, at the third intersection, at least one of the four angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less, and at the fourth intersection, which is the intersection of the second ridge of the second part and the welded metal part, at least one of the four angles formed by the portion of the welded metal part connected to the fourth intersection and the longitudinal direction passing through the fourth intersection is 80° or less. In these inventions, since the angle between the weld metal portion and the longitudinal direction is 80° or less at both the third and fourth intersections, fracture of the hot-pressed product at the weld metal portion can be further suppressed.

[0018] (9) In the hot press-formed product described in (8) above, the angle of at least one of the four angles made between the welded metal portion and the longitudinal direction over the entire length between the first ridge of the second portion and the second ridge of the second portion may be 80° or less. (20) In the method for manufacturing a hot press-formed product described in (19) above, the hot press-formed product may be manufactured such that, over the entire length between the first ridge of the second part and the second ridge of the second part, at least one of the four angles made between the welded metal part and the longitudinal direction is 80° or less. These inventions make it possible to prevent the hot-pressed product from fracturing at the weld metal portion along the entire length between the first ridge of the second part and the second ridge of the second part.

[0019] (10) The hot press-formed product described in any one of (1) to (9) above may be an automobile part. (21) In the method for manufacturing a hot press-formed product described in any one of (12) to (20) above, the hot press-formed product may be a part for an automobile. These inventions allow for the use of hot-pressed products, which are less prone to fracture at the weld metal portion, as automotive parts.

[0020] (11) A third aspect of the present invention is a tailored blank comprising a first steel plate, a second steel plate whose end abuts against the end of the first steel plate, and a welded metal portion that joins the end of the first steel plate and the end of the second steel plate, wherein at least one of the first steel plate and the second steel plate is an aluminum-plated steel plate, and the first steel plate comprises a first piece of the first part and a second piece of the first part connected to the first piece of the first part via a first ridge line portion of the first part. The tailored blank has a piece and a second steel plate, the second steel plate having a first piece of the first part joined to the first piece of the first part via the welded metal portion, a first ridge line planned portion of the second part joined to the first ridge line planned portion of the first part via the welded metal portion, and a second piece of the second part connected to the first piece of the second part via the first ridge line planned portion of the second part and joined to the second piece of the first part via the welded metal portion, and the longitudinal direction in the portion near the welded metal portion of the tailored blank is defined When the first piece of the second part is used as a reference, at the first intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the first piece and the weld metal part, the angle between the portion of the weld metal part connected to the first intersection point and the longitudinal direction passing through the first intersection point, and the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the second piece when the second piece of the second part is used as a reference point. At the second intersection, which is the intersection point of the weld metal portion, the angle of at least one of the eight angles formed, including the two angles between the portion of the weld metal portion connected to the second intersection and the longitudinal direction passing through the second intersection, and at the third intersection, which is the intersection point of the planned first ridge line portion of the second part and the weld metal portion, the angle of at least one of the angles formed, including the four angles between the portion of the weld metal portion connected to the third intersection and the longitudinal direction passing through the third intersection, is 80° or less.

[0021] (22) A fourth aspect of the present invention is a method for manufacturing a tailored blank, comprising: an arrangement step of arranging the end of a first steel plate and the end of a second steel plate so as to abut; and a welding step of joining the end of the first steel plate and the end of the second steel plate by welding to form a weld metal portion, wherein at least one of the first steel plate and the second steel plate is an aluminum-plated steel plate, and the first steel plate comprises a first piece of the first part and a first edge of the first part The tailored blank has a first part and a second piece connected via a line-planning portion, and the second steel plate has a second part and a first piece joined to the first part and the first piece via the weld metal portion, a second part and a first ridge-planning portion joined to the first part and the first ridge-planning portion, and a second part and a second piece connected to the first part and the first ridge-planning portion of the second part and joined to the first part and the weld metal portion, and the length of the portion near the weld metal portion in the tailored blank When the direction of hand is defined, with the first piece of the second part as the reference, at the first intersection which is the intersection point between the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the first piece and the weld metal part, the angle between the portion of the weld metal part connected to the first intersection and the longitudinal direction passing through the first intersection, and with the second piece of the second part as the reference, the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the second piece and the weld metal The tailored blank is manufactured such that at least one of the eight angles formed, including the two angles formed at the second intersection, which is the intersection point with the part, between the portion of the welded metal part connected to the second intersection and the longitudinal direction passing through the second intersection, and the four angles formed at the third intersection, which is the intersection point between the planned first ridge line portion of the second part and the welded metal part, between the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection, is 80° or less.

[0022] In these inventions, the inventors, after diligent study of tailored blanks, found the following: For example, when a tensile force is applied in the longitudinal direction to a hot-pressed product obtained by hot-pressing a tailored blank, crack initiation points are likely to occur in the portions connected to the first intersection of the weld metal, the second intersection of the weld metal, and the third intersection of the weld metal. Therefore, in the tailored blank, the hot-pressed product is constructed (manufactured) such that at least one of the eight angles formed by the weld metal portion at the first intersection, including the two angles between the portion of the weld metal portion at the first intersection and the longitudinal direction passing through the first intersection, the two angles between the portion of the weld metal portion at the second intersection and the longitudinal direction passing through the second intersection, and the four angles between the portion of the weld metal portion at the third intersection and the longitudinal direction passing through the third intersection, is 80° or less when the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member. Then, when this tailored blank is hot-pressed to form a hot-pressed product, the external force acting in the direction of opening the weld metal portion, caused by the tensile force acting on the portion having at least one of the angles, is suppressed. Accordingly, it is possible to suppress fracture of the hot-pressed product formed from the tailored blank at the weld metal portion. [Effects of the Invention]

[0023] The hot-pressed product, tailored blank, method for manufacturing the hot-pressed product, and method for manufacturing the tailored blank of the present invention can suppress fracture at the weld metal portion. [Brief explanation of the drawing]

[0024] [Figure 1] This is a plan view of a tailored blank according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view along the cutting line A1-A1 in Figure 1. [Figure 3] This is a plan view of a hot-pressed part according to one embodiment of the present invention. [Figure 4] This is a view taken in the direction of arrow B1 in Figure 3. [Figure 5] This figure shows the shape of the hot-pressed product when it is unfolded into a flat surface. [Figure 6] This is a flowchart showing a method for manufacturing a hot press-formed product according to one embodiment of the present invention. [Figure 7] This diagram illustrates the arrangement process in the manufacturing method of the hot-pressed product. [Figure 8] This figure shows the shape of a hot-pressed product in a first modified example of one embodiment of the present invention when it is unfolded into a planar shape. [Figure 9] This figure shows the shape of a hot-pressed product in a second modified example of one embodiment of the present invention when it is unfolded into a planar shape. [Figure 10] This photograph illustrates a tensile test using a hot-pressed product as an example of an experiment. [Figure 11] This photograph illustrates a tensile test using a hot-pressed product as an example of an experiment. [Figure 12] This photograph illustrates a tensile test using a hot-pressed product as an example of an experiment. [Figure 13] This diagram shows the relationship between stroke and load in a tensile test using a hot-pressed product as an experimental example. [Figure 14] This figure shows the shape of Sample No. 1 when it is unfolded into a flat surface. [Figure 15] This figure shows the shape of Sample No. 2 when it is unfolded into a flat surface. [Figure 16] This figure shows the shape of Sample No. 3 when it is unfolded into a flat surface. [Figure 17] This figure shows the shape of Sample No. 4 when it is unfolded into a flat surface. [Figure 18] This figure shows the shape of Sample No. 5 when it is unfolded into a flat surface. [Figure 19] This figure shows the shape of Sample No. 6 when it is unfolded into a flat surface. [Modes for carrying out the invention]

[0025] Hereinafter, an embodiment of the tailored blank and hot-pressed product according to the present invention will be described with reference to Figures 1 to 19. As shown in Figures 1 and 2, the tailored blank (butt-jointed steel plate) 1 of this embodiment comprises a first steel plate 10, a second steel plate 30, and a weld metal portion 50. The first steel plate 10 and the second steel plate 30 are each formed in a flat plate shape. At least one of the first steel plate 10 and the second steel plate 30 is an aluminum-plated steel plate. The end of the second steel plate 30 is positioned to abut against the end of the first steel plate 10. The welded metal portion 50 joins the end of the first steel plate 10 to the end of the second steel plate 30.

[0026] Figures 3 and 4 show a hot-pressed product 1A obtained by hot-pressing a tailored blank 1. The hot-pressed product 1A comprises a first member 10A, a second member 30A, and a welded metal portion 50A. At least one of the first member 10A and the second member 30A is an aluminum-plated member. The aluminum-plated member is obtained by hot-pressing an aluminum-plated steel sheet. The criterion for determining whether an aluminum-plated component has been hot-press-formed is when the martensite area ratio is 80% or more. To achieve a martensite area ratio of 80% or more in a hot-press-formed product, for example, the following hot stamping conditions can be applied to a tailored blank.

[0027] First, the tailored blank is heated to a temperature range of 850-1000°C and held at this temperature range for 0.1-30.0 minutes. After that, it is quickly transferred to a mold and press-formed (hot stamped). Subsequently, the tailored blank is pressurized, and the press-formed steel sheet is cooled to a temperature range of 250°C or lower within the mold by heat transfer between the steel sheet and the mold. The average heating rate to the 850-1000°C temperature range should be 0.1-200°C / s. The average cooling rate within the mold must be above the critical cooling rate at which martensitic transformation occurs in order to obtain a hot-press-formed product with a martensitic area ratio of 80% or more. Therefore, the average cooling rate within the mold should be 20-200°C / s. Within the 850-1000°C temperature range, the temperature may be varied or kept constant. Furthermore, in order to obtain a hot-pressed product with a martensite area ratio of 80% or more, the transport time from the heating furnace to the mold must be faster than the start of the ferrite-pearlite transformation and bainite transformation, and the product must be transported to the mold and press-formed. The time at which the ferrite-pearlite transformation and bainite transformation occur can be investigated by attaching a thermocouple to the tailored blank, measuring the temperature, and observing the heat generated during the transformation.

[0028] The area ratio of martensite can be determined by microscopic observation of the microstructure in a location unaffected by welding heat in a hot-pressed product. Specifically, samples are taken from five locations on the thickness-direction cross-section of the hot-pressed product, at positions 1 / 8, 3 / 8, 5 / 8, and 7 / 8 of the plate thickness from the surface. These samples are etched using a Repera etching solution, and a 100 μm square field of view is observed at 1000x magnification using an optical microscope. Within the observed field of view, areas appearing white to reddish-brown are identified as martensite, and the area ratio of martensite is measured. The average of the area ratios of martensite in the 20 observed fields of view can be used as the martensite area ratio of the hot-pressed product. The first member 10A is formed by hot-pressing the first steel plate 10. Similarly, the second member 30A and the welded metal part 50A are formed by hot-pressing the second steel plate 30 and the welded metal part 50, respectively. The end of the second member 30A is positioned to abut against the end of the first member 10A. The welded metal portion 50A joins the end of the first member 10A to the end of the second member 30A.

[0029] The hot-pressed product 1A has a welded metal portion 50A, a first member 10A connected to the welded metal portion 50A, and a second member 30A connected to the welded metal portion 50A, and is equipped with a shaft portion 1B extending in a predetermined direction U. Let us describe the case where the second member 30A has an extension shape 30B that extends in a direction intersecting a predetermined direction U from the end of the second member 30A opposite to the welded metal portion 50A. Note that the extension shape 30B may be an extension of a part of the second member, or it may be a separate member connected to the second member. When defining the shaft portion 1B, the shaft portion 1B extending in the predetermined direction U is determined by the welded metal portion 50A, the first member 10A, and the second member 30A, without considering the extension shape 30B of the second member 30A. In other words, the shaft portion is recognized as a member that has a welded metal portion, at least a part of a first member connected to the welded metal portion, and at least a part of a second member connected to the welded metal portion, and extends in a predetermined direction.

[0030] In the tailored blank 1 shown in Figure 1, the extension shape 30C corresponding to the extension shape 30B of the hot press-formed product 1A is not considered. In Figure 1, the longitudinal direction of the hot-pressed product 1A in the vicinity of the weld metal portion 50 is defined as the longitudinal direction X. The vicinity of the weld metal portion 50, as used here, refers to, for example, the area 20 times the width of the weld metal portion 50, centered on the widthwise center of the tailored blank 1 (hot-pressed product 1A) when viewed from above. The longitudinal direction X corresponds to the predetermined direction U (it is parallel).

[0031] Below, we will first describe the composition of the first steel plate 10 and the second steel plate 30 of the tailored blank 1.

[0032] <Aluminum-plated steel sheet> At least one of the first steel sheet 10 and the second steel sheet 30 is an aluminum-plated steel sheet. Figure 2 shows an example where both the first steel sheet 10 and the second steel sheet 30 are aluminum-plated steel sheets. As shown in Figure 2, in the first steel sheet 10, an intermetallic compound layer 12 and an aluminum plating layer 13 are provided on each surface 11a and 11b of the base steel sheet 11 in the thickness direction Z, starting from the base steel sheet 11 side. Figure 1 is a plan view of the tailored blank 1 as seen in the thickness direction Z. As shown in Figure 2, surface 11a is the surface facing the first side in the thickness direction Z of the base steel sheet 11. Surface 11b is the surface facing the second side opposite to the first side in the thickness direction Z of the base steel sheet 11. On surface 11a of the base steel sheet 11, an intermetallic compound layer 12 and an aluminum plating layer 13 are provided in order from the base steel sheet 11 side. On surface 11b of the base steel sheet 11, an intermetallic compound layer 12 and an aluminum plating layer 13 are provided in order from the base steel sheet 11 side.

[0033] The second steel sheet 30 is constructed in the same manner as the first steel sheet 10. Specifically, in the second steel sheet 30, an intermetallic compound layer 32 and an aluminum plating layer 33 are provided on each surface 31a and 31b of the base steel sheet 31 in the thickness direction Z, starting from the base steel sheet 31 side. The thickness direction of the base steel sheet 31 of the second steel sheet 30 is aligned with the thickness direction Z of the base steel sheet 11 of the first steel sheet 10.

[0034] Hot-pressed product 1A is obtained by hot-pressing a tailored blank 1. Hereinafter, the hot-press-formed first steel plate 10, second steel plate 30, and welded metal portion 50 will be referred to as the first member 10A, the second member 30A, and the welded metal portion 50A. The hot-press-formed product 1A comprises the first member 10A, the second member 30A, and the welded metal portion 50A.

[0035] <Base material steel plate> The base steel sheet is the steel sheet before the aluminum plating layer is applied. The base steel sheet can be any sheet obtained by a conventional method and is not particularly limited. The base steel sheet may be either a hot-rolled steel sheet or a cold-rolled steel sheet. The thickness of the base steel sheet can be any thickness appropriate for the purpose and is not particularly limited. For example, the thickness of the base steel sheet, as the total thickness of the steel sheet after the aluminum plating layer is applied, can be 0.8 mm to 4.0 mm, or further, 1.0 mm to 3.0 mm.

[0036] As an example of a base steel sheet, it is preferable to use a steel sheet formed to have high mechanical strength (meaning various properties related to mechanical deformation and fracture, such as tensile strength, yield point, elongation, reduction of area, hardness, impact value, fatigue strength, etc.).

[0037] Examples of preferred chemical compositions for the base steel sheet include the following: In mass %, C: 0.02%~0.58%, Mn: 0.20%~3.00%, Al: 0.005%~0.06%, Ti: 0%~0.20%, Nb: 0%~0. 20%, V:0%~1.0%, W:0%~1.0%, Cr:0%~1.0%, Mo:0%~1.0%, Cu:0%~1.0%, Ni:0%~1.0%, B: It has a chemical composition consisting of 0% to 0.0100%, Mg: 0% to 0.05%, Ca: 0% to 0.05%, REM: 0% to 0.05%, Sn: 0% to 0.5%, Bi: 0% to 0.05%, Si: 0% to 2.00%, P: 0.03% or less, S: 0.010% or less, N: 0.010% or less, and the remainder being Fe and impurities. In the following, "%" indicating the content of components (elements) means "mass%". Numerical ranges expressed using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0038] <Aluminum plating layer> The aluminum plating layer is formed on both sides of the base steel sheet. The method for forming the aluminum plating layer is not particularly limited. For example, the aluminum plating layer may be formed on each surface of the base steel sheet by a hot-dip plating method, in which the base steel sheet is immersed in a molten metal bath mainly containing aluminum to form the aluminum plating layer.

[0039] Here, the aluminum plating layer is a plating layer mainly containing aluminum, and it is sufficient if it contains 50% by mass or more of aluminum. Depending on the purpose, it may also contain elements other than aluminum (for example, Si, etc.), and may contain impurities that are introduced during the manufacturing process. Specifically, the aluminum plating layer may have a chemical composition consisting of 5% to 12% by mass of Si (silicon), with the remainder being aluminum and impurities. Alternatively, it may have a chemical composition consisting of 5% to 12% by mass of Si (silicon) and 2% to 4% by mass of Fe (iron), with the remainder being aluminum and impurities. By incorporating Si within the above range, the decrease in processability and corrosion resistance can be suppressed. Furthermore, the thickness of the intermetallic compound layer can be reduced.

[0040] The thickness of the aluminum plating layer is not particularly limited. For example, the average thickness is often in the range of 8 μm (micrometers) to 35 μm, and preferably in the range of 15 μm to 30 μm. Note that the thickness of the aluminum plating layer represents the average thickness.

[0041] The aluminum plating layer prevents corrosion of steel sheets (improves corrosion resistance). Furthermore, when steel sheets are processed by hot press forming, the aluminum plating layer prevents the formation of scale (iron compounds) due to surface oxidation, even when heated to high temperatures. Additionally, the aluminum plating layer has higher boiling and melting points than plating with organic materials or other metallic materials (e.g., zinc-based materials). Therefore, when forming steel sheets by hot press forming, the coating does not evaporate, resulting in a high level of surface protection.

[0042] Upon heating during molten plating and hot press forming, the aluminum plating layer can alloy with iron (Fe) in the steel sheet. Therefore, the aluminum plating layer is not necessarily formed as a single layer with a constant component composition, but may include a partially alloyed layer (alloy layer).

[0043] <Intermetallic compound layer> The intermetallic compound layer is a layer formed at the boundary between the base steel sheet and the aluminum plating layer when the aluminum plating layer is provided on the base steel sheet. Specifically, the intermetallic compound layer is formed by the reaction of iron (Fe) of the base steel sheet with a metal containing aluminum (Al) in a molten metal bath mainly containing aluminum. The intermetallic compound layer mainly consists of Fe x Al y (where x and y represent 1 or more) and is formed of a plurality of types of compounds. When the aluminum plating layer contains Si (silicon), it consists of Fe x Al y and Fe x Al y Si z (where x, y, and z represent 1 or more) and is formed of a plurality of types of compounds.

[0044] The thickness of the intermetallic compound layer is not particularly limited, but for example, it is often in the range of 3 μm to 10 μm in terms of average thickness, and preferably in the range of 4 μm to 8 μm. Note that the thickness of the intermetallic compound layer represents the average thickness. Note that the thickness of the intermetallic compound layer can be controlled by the temperature and immersion time of the molten metal bath mainly containing aluminum.

[0045] Here, the confirmation of the base steel sheet, the intermetallic compound layer, and the aluminum plating layer, and the measurement of the thickness of the intermetallic compound layer and the aluminum plating layer are carried out by the following methods.

[0046] The steel plate is cut so that its cross-section is exposed, and the cross-section is polished. The polished cross-section of the steel plate is then subjected to line analysis from the surface to the base steel plate using an electron probe microanalyser (FE-EPMA) to measure the aluminum and iron concentrations. The measurement conditions are an acceleration voltage of 15kV, a beam diameter of approximately 100nm, an irradiation time of 1000ms per point, a measurement pitch of 60nm, and a measurement distance that allows for measurement of the thickness of the plating layer, for example, approximately 30μm to 80μm in the thickness direction. The thickness of the base steel sheet and the aluminum-plated steel sheet are preferably measured using an optical microscope or micrometer.

[0047] As a measurement of the aluminum concentration in the cross-section of the steel plate, the region where the aluminum (Al) concentration is less than 2.0 mass% is determined to be the base steel plate, and the region where the aluminum concentration is 2.0 mass% or more is determined to be either the intermetallic compound layer or the aluminum plating layer. Furthermore, within the intermetallic compound layer and the aluminum plating layer, the region where the iron (Fe) concentration exceeds 4.0 mass% is determined to be the intermetallic compound layer, and the region where the iron concentration is 4.0 mass% or less is determined to be the aluminum plating layer. The thickness of the intermetallic compound layer is defined as the distance from the boundary of the base steel sheet to the boundary of the aluminum plating layer. Furthermore, the thickness of the aluminum plating layer is defined as the distance from the boundary between the intermetallic compound layer and the aluminum plating layer to the surface of the steel sheet where the aluminum plating layer is formed.

[0048] The thickness of the aluminum plating layer and the intermetallic compound layer are measured by line analysis from the surface of the steel sheet to the surface of the base steel sheet (the boundary between the base steel sheet and the intermetallic compound layer) as follows. The thickness of the aluminum plating layer is determined according to the aforementioned criteria by measuring the thickness from the surface of the steel sheet with the aluminum plating layer to the intermetallic compound layer at five arbitrary locations, and averaging these values. The thickness of the intermetallic compound layer is determined according to the aforementioned criteria by measuring the thickness from the boundary between the intermetallic compound layer and the aluminum plating layer to the boundary between the intermetallic compound layer and the base steel sheet at five arbitrary locations, and averaging these values ​​to determine the thickness of the intermetallic compound layer.

[0049] Next, we will explain the details of the shape and other aspects of Tailored Blank 1. As shown in Figures 1 and 2, in the following, the side of the longitudinal direction X that is on the side of the first steel plate 10 relative to the second steel plate 30 will be referred to as the first side X1. The side of the longitudinal direction X that is on the side of the second steel plate 30 relative to the first steel plate 10 will be referred to as the second side X2. The second side X2 is the side that is moving from the first steel plate 10 toward the second steel plate 30 along the longitudinal direction X. The directions perpendicular to the longitudinal direction X and the thickness direction Z are called the orthogonal directions Y. One of the orthogonal directions Y is called the first side Y1, and the other orthogonal direction Y opposite to the first side Y1 is called the second side Y2. The thickness direction Z is the thickness direction of the first steel plate 10 and the thickness direction of the second steel plate 30.

[0050] As shown in Figure 1, the first steel plate 10 has a first piece 16 of the first part, a second piece 17 of the first part, and a third piece 18 of the first part. Part 1, first piece 16, Part 1, second piece 17, and Part 1, third piece 18 are each flat. The outer edge of the second side X2 in the first piece 16 of the first part, the outer edge 16a of the first side Y1 portion, is inclined so as it approaches the first side Y1, it gradually slopes toward the first side X1. The third piece 18 of the first part is positioned on the second side Y2 relative to the first piece 16 of the first part. The third piece 18 of the first part is connected to the first piece 16 of the first part via the planned first ridge line portion 21 of the first part. Here, "connected" means directly connected without the use of other members. However, if the connection is via a member, for example, a part of the first steel plate 10, it may be indirectly connected via other pieces or ridge lines. The planned first ridge section 21 of the first part is the part where the first steel plate 10 is planned to be folded to form the first ridge 21A of the first part, which will be described later. The planned first ridge section 21 of the first part extends along the longitudinal direction X. The first steel plate 10 is not folded in the planned first ridge section 21 of the first part. Furthermore, indicators such as marking lines may be provided in the planned section 21 of the first ridge of Part 1.

[0051] The outer edge 16b of the first piece 16 of the first part, opposite to the planned first ridge line portion 21 of the first part, is inclined so as it approaches the first side Y1, it gradually slopes toward the first side X1. The outer edge 16b is more aligned with the longitudinal direction X than the outer edge 16a. The center of the longitudinal direction X at the end of the second side Y2 of the first piece 16 of the first part, and the center of the longitudinal direction X of the third piece 18 of the first part, coincide with each other.

[0052] The outer edge 17a of the second piece 17 on the second side X2, specifically the portion on the second side Y2, is inclined to gradually move towards the first side X1 as it moves towards the second side Y2. The second piece 17 of the first part is positioned on the second side Y2 than the third piece 18 of the first part. The second piece 17 of the first part is connected to the third piece 18 of the first part via the planned second ridge section 22 of the first part. The planned second ridge section 22 of the first part is the portion of the first steel plate 10 that is planned to be folded to form the second ridge 22A of the first part, which will be described later. The planned second ridge section 22 of the first part is positioned on the second side Y2 than the planned first ridge section 21 of the first part and extends along the longitudinal direction X. The first steel plate 10 is not folded at the planned second ridge section 22 of the first part.

[0053] In the second piece 17 of the first part, the outer edge 17b opposite to the planned second ridge line 22 of the first part gradually slopes toward the first side X1 as it approaches the second side Y2. The outer edge 17b is more aligned with the longitudinal direction X than the outer edge 17a. The center of the longitudinal direction X at the end of the first side Y1 of the second piece 17 of the first part, and the center of the longitudinal direction X of the third piece 18 of the first part, coincide with each other. As described above, the second piece 17 of the first part is connected to the first piece 16 of the first part via the first ridge line planned section 21 of the first part, the third piece 18 of the first part, and the second ridge line planned section 22 of the first part.

[0054] The second steel plate 30 has a second part first piece 36, a second part second piece 37, and a second part third piece 38. The first piece 36 of the second part has a main body 36a and a projection 36b. The main body 36a has a trapezoidal shape when viewed in the thickness direction Z. The projection 36b protrudes toward the first side X1 from the outer edge of the first side X1 of the main body 36a, specifically from the portion toward the first side Y1. The projection 36b has a triangular shape when viewed in the thickness direction Z. The outer edge 36c of the first side X1 on the projection 36b gradually slopes toward the first side X1 as it approaches the first side Y1. The second part first piece 36 is positioned on the second side X2 of the first steel plate 10 compared to the first part first piece 16. The second part first piece 36 is joined to the first part first piece 16 via a weld metal portion 50. The outer edge 36d of the second part first piece 36 and the outer edge 16b of the first part first piece 16 are aligned on the same straight line.

[0055] The third piece 38 of the second part has a rectangular shape when viewed in the thickness direction Z. The third piece 38 of the second part is located on the second side Y2 of the first piece 36 of the second part. The third piece 38 of the second part is connected to the main body 36a of the first piece 36 of the second part via the planned first ridge section 41 of the second part. The planned first ridge section 41 of the second part is the part of the second steel plate 30 that is planned to be folded to form the first ridge 41A of the second part, which will be described later. The planned first ridge section 41 of the second part extends along the longitudinal direction X. The second steel plate 30 is not folded at the planned first ridge section 41 of the second part. The planned first ridge section 41 of the second part is joined to the planned first ridge section 21 of the first part via the weld metal section 50. The second part third piece 38 is positioned on the second side X2 of the first steel plate 10 compared to the first part third piece 18. The second part third piece 38 is joined to the first part third piece 18 via the weld metal portion 50.

[0056] The outer edge 36d of the first piece 36 of the second part, opposite to the planned first ridge line portion 41 of the second part, is inclined to gradually move towards the first side X1 as it moves towards the first side Y1. The outer edge 36d is more aligned with the longitudinal direction X than the outer edge 36c. The center of the longitudinal direction X at the second side Y2 end of the main body 36a of the first piece 36 of the second part, and the center of the longitudinal direction X of the third piece 38 of the second part, coincide with each other. The outer edge 36d of the first piece 36 of the second part and the outer edge 16b of the first piece 16 of the first part are aligned on the same straight line. The planned first ridge line portion 41 of the second part and the planned first ridge line portion 21 of the first part of the first steel plate 10 are joined via the welded metal portion 50 and are aligned on the same straight line.

[0057] The second piece 37 of the second part has a main body 37a and a projection 37b. The main body 37a has a trapezoidal shape when viewed in the thickness direction Z. The projection 37b protrudes toward the first side X1 from the outer edge of the first side X1 of the main body 37a, from the portion of the second side Y2. The projection 37b has a triangular shape when viewed in the thickness direction Z. The outer edge 37c of the first side X1 of the projection 37b is inclined so as it approaches the second side Y2, and then gradually toward the first side X1. The outer edge 37d of the second piece 37 of the second part, opposite to the planned second ridge line section 42 (planned first ridge line section 41) of the second part, gradually slopes toward the first side X1 as it approaches the second side Y2. The outer edge 37d is more aligned with the longitudinal direction X than the outer edge 37c.

[0058] The second piece 37 of the second part is positioned second to the left Y2 than the third piece 38 of the second part. The main body 37a of the second piece 37 of the second part is connected to the third piece 38 of the second part via the planned second ridge section 42 of the second part. The planned second ridge section 42 of the second part is the portion of the second steel plate 30 that is planned to be folded to form the second ridge 42A of the second part, which will be described later. The planned second ridge section 42 of the second part is positioned second to the left Y2 than the planned first ridge section 41 of the second part and extends along the longitudinal direction X. The second steel plate 30 is not folded at the planned second ridge section 42 of the second part. The planned second ridge section 42 of the second part is joined to the planned second ridge section 22 of the first part via the welded metal section 50. The outer edge 37d of the second piece 37 of the second part, opposite to the planned second ridge line section 42 (planned first ridge line section 41) of the second part, gradually slopes toward the first side X1 as it approaches the second side Y2. The outer edge 37d is more aligned with the longitudinal direction X than the outer edge 37c. As described above, the second piece 37 of the second part is connected to the first piece 36 of the second part via the first ridge line planned section 41 of the second part, the third piece 38 of the second part, and the second ridge line planned section 42 of the second part.

[0059] The second piece 37 of the second part is joined to the second piece 17 of the first part via a welded metal portion 50. The outer edge 37d of the second piece 37 of the second part and the outer edge 17b of the second piece 17 of the first part are aligned on the same straight line. The planned second ridge line portion 42 of the second part and the planned second ridge line portion 22 of the first steel plate 10 are joined via a welded metal portion 50 and are aligned on the same straight line.

[0060] The weld metal portion 50 is bent into a line. The weld metal portion 50 has a first piece 51, a second piece 52, and a third piece 53. The weld metal portion may also be curved or straight. The first piece 51 joins the outer edge 16a of the first piece 16 of the first part and the outer edge 36c of the first piece 36 of the second part. The first piece 51 extends gradually toward the first side X1 as it moves toward the first side Y1. The end of the first piece 51 toward the first side Y1 is the portion of the weld metal 50 that is connected to the outer edge 36d of the first piece 36 of the second part. The outer edges 36d and 16b are the outer edges of the tailored blank 1 (1A of the hot-pressed product) on the side opposite to the first ridge line 41A of the second part when the first piece 36 of the second part is used as the reference. The second piece 52 joins the outer edge 17a of the second piece 17 of the first part to the outer edge 37c of the second piece 37 of the second part. The second piece 52 extends gradually toward the first side X1 as it moves toward the second side Y2. The end of the second piece 52 toward the second side Y2 is the portion of the weld metal 50 that is connected to the outer edge 37d of the second piece 37 of the second part.

[0061] The third piece 53 joins the outer edge of the second side X2 of the third piece 18 of the first part and the outer edge of the first side X1 of the third piece 38 of the second part. Furthermore, the third piece 53 joins the outer edge of the second side X2 in the first piece 16 of the first part and the portion of the second side Y2 in the outer edge of the first side X1 in the body 36a of the first piece 36 of the second part. The third piece 53 joins the outer edge of the second side X2 in the second piece 17 of the first part and the portion of the first side Y1 in the outer edge of the first side X1 in the body 37a of the second piece 37 of the second part. The first side Y1 portion of the third piece 53 is the portion that connects to the planned first ridge line portion 41 of the second part in the weld metal portion 50. The second side Y2 portion of the third piece 53 is the portion that connects to the planned second ridge line portion 42 of the second part in the weld metal portion 50.

[0062] The weld metal portion 50 has a weld start end 56 and a weld end end 57. For example, the weld start end 56 is provided at the end of the first side Y1 of the first piece 51. The weld end end 57 is provided at the end of the second side Y2 of the second piece 52. Generally, the weld start and end points may be cut off (trimmed) after hot press forming. In this embodiment, the weld start point 56 and weld end point 57 remain on the hot press formed product 1A without being cut off. Note that the weld metal portion 50 does not necessarily have a weld start point 56 and a weld end point 57. Generally, the weld is stable in areas of the weld metal other than the weld start and end points. The weld start and end points are where welding begins and ends, and for example, craters (depressions) are formed in these areas. The concentration of aluminum in the weld metal portion 50A after hot press forming is preferably 0.3% by mass or more and 2.5% by mass or less. In order to suppress thinning of the weld metal portion 50A, welding may be performed while supplying filler wire as needed.

[0063] The aluminum concentration in the weld metal part 50A is measured as follows. The hot-pressed part 1A is cut perpendicular to the weld metal part 50A, trimmed so that the cross-section of the weld metal part 50A remains, and embedded in resin. The embedded hot-pressed part 1A is polished, and the aluminum concentration is measured by mapping and analyzing the surface of the hot-pressed part 1A to the base steel plates 11 and 31 using an electron beam microanalyzer (FE-EPMA). The measurement conditions are an acceleration voltage of 15kV, a beam diameter of approximately 100nm, and an irradiation time of 1000ms. The measurement pitch is a grid pattern with a 5μm pitch. The measured aluminum concentration of the weld metal part is averaged to determine the average concentration.

[0064] In the embodiment shown in Figure 1, with the first piece 36 of the second part as the reference, at the first intersection Q1, which is the intersection point between the outer edge (36d and 16b) of the first side Y1 of the tailored blank 1 (hot press-formed product 1A) and the first piece 51, the two angles formed by the portion of the first piece 51 connected to the first intersection Q1 and the longitudinal direction X passing through the first intersection Q1 are hereinafter referred to as the first outer edge angles θ11. In this example, of the two first outer edge angles θ11, the smallest first outer edge angle θ11 (hereinafter referred to as the smallest first outer edge angle θ11) is the first outer edge angle θ11 formed between the second side X2 from the first intersection Q1 and the first piece 51 in the longitudinal direction X passing through the first intersection Q1. The smallest first outer edge angle θ11 is greater than 0° and 90° or less. In this embodiment, the smallest first outer edge angle θ11 is 80° or less. Here, the specific method for measuring the first outer edge angle θ11 is to measure the angles formed by the first piece 51 within a 20 mm range from the first intersection Q1 to the second side Y2, and the longitudinal direction passing through the first intersection Q1. If the first piece 51 is a broken line or a curve, the first outer edge angle θ11 is defined as the angle formed by the line connecting the point where the longitudinal direction X intersects the first piece 51 and the first intersection Q1, at a position 20 mm away from the first intersection Q1 to the second side Y2, and the longitudinal direction passing through the first intersection Q1.

[0065] With the second piece 37 of the second part as the reference, at the second intersection Q2, which is the intersection point between the outer edge (37d and 17b) of the second side Y2 of the tailored blank 1 and the second piece 52, the angles formed by the portion of the second piece 52 that is connected to the second intersection Q2 and the longitudinal direction X passing through the second intersection Q2 are hereinafter referred to as the second outer edge angles θ12. In this example, of the two second outer edge angles θ12, the smallest second outer edge angle θ12 (hereinafter referred to as the smallest second outer edge angle θ12) is the second outer edge angle θ12 formed between the second side X2 of the longitudinal direction X passing through the second intersection Q2 and the second piece 52, and the angle of the smallest second outer edge angle θ12 is 80° or less. The smallest second outer edge angle θ12 is greater than 0° and 90° or less. In this embodiment, the smallest second outer edge angle θ12 is 80° or less. Here, the specific method for measuring the second outer edge angle θ12 involves measuring the angles formed by the second piece 52 within a 20 mm range from the second intersection Q2 to the first side Y1, and the longitudinal direction passing through the second intersection Q2. If the second piece 52 is a broken line or a curve, the second outer edge angle θ12 is defined as the angle between the line connecting the point where the longitudinal direction X intersects the second piece 52 and the second intersection Q2, at a position 20 mm away from the second intersection Q2 to the first side Y1, and the longitudinal direction passing through the second intersection Q2.

[0066] At the third intersection Q3, which is the intersection of the third piece 53 and the extension of the first planned ridge line 21 of the first part or the first planned ridge line 41 of the second part, the four angles formed by the portion of the third piece 53 connected to the third intersection Q3 and the longitudinal direction X passing through the third intersection Q3 are hereinafter referred to as the first ridge angles θ21. In this example, the angle of the smallest first ridge angle θ21 (hereinafter referred to as the smallest first ridge angle θ21) among the four first ridge angles θ21 is 90°. Here, the specific method for measuring the first ridge angle θ21 is to measure the four angles formed by the third piece 53 and the longitudinal direction passing through the third intersection Q3 within a 20 mm range from the third intersection Q3 to the first side Y1 and the second side Y2. If the third piece 53 is a broken line or a curve, the first ridge angle θ21 is defined as the four angles formed by the line connecting the point where the longitudinal direction X intersects the third piece 53 and the third intersection Q3, and the longitudinal direction passing through the third intersection Q3, at positions 20 mm away from the third intersection Q3 to the first side Y1 and the second side Y2. The minimum first ridge angle θ21 is preferably 75° or less, and more preferably 60° or less.

[0067] At the fourth intersection Q4, which is the intersection of the third piece 53 and the extension of the planned second ridge line 22 of the first part or the planned second ridge line 42 of the second part, the four angles formed by the portion of the third piece 53 that is connected to the fourth intersection Q4 and the longitudinal direction X passing through the fourth intersection Q4 are hereafter referred to as the second ridge angles θ22. In this example, the angle of the smallest second ridge angle θ22 (hereinafter referred to as the smallest second ridge angle θ22) among the four second ridge angles θ22 is 90°. Here, the specific method for measuring the second ridge angle θ22 is to measure the four angles formed by the third piece 53 and the longitudinal direction passing through the fourth intersection Q4 within a 20 mm range from the fourth intersection Q4 to the first side Y1 and the second side Y2. If the third piece 53 is a broken line or a curve, the second ridge angle θ22 is defined as the four angles formed by the line connecting the point where the longitudinal direction X intersects with the third piece 53 and the fourth intersection Q4, at positions 20 mm away from the fourth intersection Q4 to the first side Y1 and the second side Y2, and the longitudinal direction passing through the fourth intersection Q4. The minimum second ridge angle θ22 is preferably 75° or less, and more preferably 60° or less.

[0068] In the embodiment shown in Figure 1, at least one of the twelve angles formed by the two first outer edge angles θ11, the two second outer edge angles θ12, the four first edge angles θ21, and the four second edge angles θ22 is 80° or less. More specifically, the minimum first outer edge angle θ11 is 80° or less, and the minimum second outer edge angle θ12 is 80° or less. The minimum first edge angle θ21 is 90°, and the minimum second edge angle θ22 is 90°. Furthermore, the weld metal portion 50 is a line-symmetrical folded shape with respect to the center of the Y-direction orthogonal to the tailored blank 1. The shape of the weld metal portion 50 is not limited, but from the viewpoint of stress distribution, it is preferable to have a line-symmetrical shape with respect to the center of the Y-direction orthogonal to the tailored blank 1. In the tailored blank 1 (hot press-formed product 1A), it is preferable that at least one of the four first edge angles θ21 is 60° or less, and it is preferable that at least one of the four second edge angles θ22 is 60° or less.

[0069] Next, we will describe the details of the shape and other aspects of the hot-pressed product 1A. As shown in Figure 4, the hot-pressed product 1A is U-shaped with an opening at the bottom when viewed in the longitudinal direction X. However, the shape of the hot-pressed product is not limited to a U-shape; for example, it may be a hat shape with flanges on both sides of the U-shape. As shown in Figures 3 and 4, the first member 10A has the first piece 16 of the first part, the second piece 17 of the first part, and the third piece 18 of the first part. The third piece 18 of the first part is connected to the first piece 16 of the first part via the first ridge line 21A of the first part. The second piece 17 of the first part is connected to the third piece 18 of the first part via the second ridge line 22A of the first part. That is, the third piece 18 of the first part is positioned between the first ridge line 21A of the first part and the second piece 17 of the first part. The third piece 18 of the first part is connected to the second piece 17 of the first part via the second ridge line 22A of the first part. As described above, the second piece 17 of the first part is connected to the first piece 16 of the first part via the first ridge line 21A of the first part, the third piece 18 of the first part, and the second ridge line 22A of the first part. The first ridge line 21A of the first part and the second ridge line 22A of the first part are formed in the first steel plate 10 at the positions where the planned first ridge line portion 21 and the planned second ridge line portion 22 of the first part are formed, respectively.

[0070] The second member 30A has the first piece 36 of the second part, the second piece 37 of the second part, and the third piece 38 of the second part. The first piece 36 of the second part is joined to the first piece 16 of the first part via a welded metal portion 50A. The third piece 38 of the second part is connected to the first piece 36 of the second part via the first ridge line 41A of the second part. The second piece 37 of the second part is connected to the third piece 38 of the second part via the second ridge line 42A of the second part. In other words, the third piece 38 of the second part is located between the first ridge line 41A of the second part and the second piece 37 of the second part. The third piece 38 of the second part is connected to the second piece 37 of the second part via the second ridge line 42A of the second part.

[0071] As described above, the second piece 37 of the second part is connected to the first piece 36 of the second part via the first ridge line 41A of the second part, the third piece 38 of the second part, and the second ridge line 42A of the second part. The first ridge line 41A and the second ridge line 42A of the second part are formed in the second steel plate 30 at the positions where the planned first ridge line portion 41 and the planned second ridge line portion 42 of the second part are formed, respectively. The third piece 38 of the second part is joined to the third piece 18 of the first part via a welded metal portion 50A. The second piece 37 of the second part is joined to the second piece 17 of the first part via a welded metal portion 50A. The weld metal portion 50A is bent. The weld metal portion 50A has a weld start end 56 and a weld end end 57 (not shown).

[0072] Figure 5 shows the shape of the hot-pressed product 1A when it is unfolded into a planar shape. For example, the unfolding of the hot-pressed product 1A can be performed by deforming the hot-pressed product 1A under the same conditions as the heating conditions in the molding process S16 of the hot-pressed product manufacturing method S10 described later. The unfolding of the hot-pressed product 1A can be performed without changing the shape of each of the pieces 16, 17, 18, 36, 37, and 38, for example by rotating pieces 16, 17, 36, and 37 around the edges 21A, 22A, 41A, and 42A with respect to the third pieces 18 and 38. Alternatively, the shapes of each piece 16, 17, 18, 36, 37, and 38 can be obtained by taking photographs of each piece or by scanning each piece. Then, based on the obtained shapes of each piece 16, 17, 18, 36, 37, and 38, the shape of the hot-pressed product 1A when unfolded can be estimated.

[0073] The method for determining the first outer edge angle θ11, the second outer edge angle θ12, the first edge angle θ21, the second edge angle θ22, etc., of the hot-pressed product 1A is the same as the method for determining them in the tailored blank 1 described above. When the hot-pressed product 1A is unfolded into a planar shape and viewed in the thickness direction Z, the minimum first outer edge angle θ11 is 80° or less, the minimum second outer edge angle θ12 is 80° or less, the minimum first edge angle θ21 is 90°, and the minimum second edge angle θ22 is 90°.

[0074] The Vickers hardness of the first member 10A, based on JIS Z 2244:2009 Vickers hardness test - test method (hereinafter simply referred to as Vickers hardness), is greater (harder) than the Vickers hardness of the first steel plate 10. Similarly, the Vickers hardness of the second member 30A and the weld metal part 50A are greater than the Vickers hardness of the second steel plate 30 and the weld metal part 50, respectively. The test force used to measure Vickers hardness is 2.94 N (Newtons).

[0075] Here, the hot-pressed product 1A is defined as follows. Note that Figure 2 is also a cross-sectional view of the cutting line A2-A2 in Figure 3. As shown in Figure 2, the thickness of the first member 10A is defined as T1 (mm). Here, the thickness T1 of the first member 10A is determined by measuring the thickness of the first member 10A at five arbitrary locations using a micrometer or the like, and averaging the values ​​obtained. The Vickers hardness of the first member 10A is defined as H1 (HV). Here, the Vickers hardness H1 of the first member 10A is determined at three points, each center of a region that divides the entire length of the first steel plate 10 in the butt joint direction X, at the center of the thickness direction Z of the first member 10A. The average of these determined values ​​is taken as the Vickers hardness H1. The thickness of the second member 30A is specified as T2 (mm). The Vickers hardness of the second member 30A is specified as H2 (HV). The thickness of the weld metal part 50A is specified as T w (mm) is specified, and the thickness T w This value is equal to the thinner of the two thicknesses, T1 and T2. The thickness and Vickers hardness of the second member 30A are determined in the same way as for the first member 10A. The Vickers hardness of the weld metal part 50A is H w It is defined as (HV). The thickness T1 of the first member 10A is equal to the thickness of the first steel plate 10. Similarly, the thickness T2 of the second member 30A and the thickness T of the welded metal part 50A are equal. w This is equal to the thickness of the second steel plate 30 and the thickness of the welded metal part 50, respectively.

[0076] At this time, the hot-pressed product 1A satisfies equation (1). T w H w <T2H2<T1H1··(1) Here, the product of thickness and Vickers hardness corresponds to stiffness. The concentration of aluminum contained in the weld metal part 50A is preferably 0.3% by mass or more and 2.5% by mass or less. Hot-pressed product 1A is used, for example, in automotive parts such as B-pillars. Furthermore, the shape of the tailored blank 1 shown in Figure 1 is also the shape of the hot-pressed product 1A when it is unfolded into a planar shape and viewed in the thickness direction Z.

[0077] Here, the plane passing through the center of the orthogonal direction Y in the weld metal portion 50A and perpendicular to the orthogonal direction Y is called the reference plane. As shown in Figure 2, the Vickers hardness H of the weld metal portion 50A w The measurement is taken at six locations P1 on the reference plane. Three of the six locations P1 are measured at the center of the longitudinal direction X of the weld metal portion 50A. The other three locations P1 are measured at positions closer to the thinner member (second member 30A) of members 10A and 30A than the center of the longitudinal direction X of the weld metal portion 50A. The three locations P1 are the center of each surface layer in the thickness direction Z of the weld metal 50A, and the center between each surface layer. The average of the values ​​obtained at the six locations is used to determine the Vickers hardness H. w Let's assume that.

[0078] Next, the method for manufacturing a hot press-formed product 1A, which is configured as described above, according to this embodiment will be explained. Figure 6 is a flowchart showing the method for manufacturing a hot press-formed product S10. First, the tailored blank manufacturing method of this embodiment (step S11 shown in Figure 6) is performed to manufacture the tailored blank 1. In the tailored blank manufacturing method S11, a placement step (step S12) is performed. In the placement step S12, as shown in Figure 7, the ends of the first steel plate 10 and the second steel plate 30 are placed so as to abut each other in the longitudinal direction X. In the steel plates 10 and 30, the intermetallic compound layers 12 and 32 and the aluminum plating layers 13 and 33 at the ends are not removed. Once the placement process S12 is completed, the process moves to step S13.

[0079] Next, in the welding process (step S13), as shown in Figure 1, the end of the first steel plate 10 and the end of the second steel plate 30 are joined by welding to form a weld metal portion 50 and to manufacture the tailored blank 1. Laser welding, plasma welding, etc., can be used for welding. In the tailored blank manufacturing method S11, taking the form shown in Figure 1 as an example, the tailored blank 1 is manufactured such that at least one of the twelve angles formed by the two first outer edge angles θ11, the two second outer edge angles θ12, the four first edge angles θ21, and the four second edge angles θ22 is 80° or less. More specifically, the tailored blank 1 is manufactured such that the minimum first outer edge angle θ11 is 80° or less and the minimum second outer edge angle θ12 is 80° or less. The tailored blank 1 is manufactured such that the minimum first edge angle θ21 is 90° and the minimum second edge angle θ22 is 90°. Once welding process S13 is completed, all steps of the tailored blank manufacturing method S11 are finished, and the process moves on to step S16.

[0080] Next, in the forming process (step S16), the tailored blank 1 is hot-press formed to create a first ridge line 21A and a second ridge line 22A on the first member 10A obtained from the first steel sheet 10. A second ridge line 41A and a second ridge line 42A are formed on the second member 30A obtained from the second steel sheet 30. For example, hot press forming is performed by heating a tailored blank 1 and shaping it into a predetermined form, and then quenching the tailored blank 1 that has been shaped into the predetermined form. For example, the heating conditions in the heating and forming process are such that the maximum temperature reached is 850°C to 1000°C. It is more preferable that the maximum temperature reached is 900°C to 950°C. The quenching process is performed by cooling the mold used for press forming, or by directly spraying water onto the tailored blank 1 to cool it. The first ridge line 21A and the second ridge line 22A of the first part are formed by folding the first steel plate 10 at the locations of the planned first ridge line 21 and the planned second ridge line 22 of the first part. The first ridge line 41A and the second ridge line 42A of the second part are formed by folding the second steel plate 30 at the locations of the planned first ridge line 41 and the planned second ridge line 42 of the second part.

[0081] In the hot press-formed product manufacturing method S10, taking the form shown in Figure 5 as an example, when the hot press-formed product 1A is unfolded into a planar shape and viewed in the thickness direction Z, the hot press-formed product is manufactured such that the minimum first outer edge angle θ11 is 80° or less and the minimum second outer edge angle θ12 is 80° or less. The hot press-formed product is manufactured such that the minimum first edge angle θ21 is 90° and the minimum second edge angle θ22 is 90°. Furthermore, in the manufacturing method S10 for hot-pressed products, when the hot-pressed product 1A is unfolded into a planar shape and viewed in the thickness direction Z, the hot-pressed product 1A may be manufactured such that at least one of the four first edge angles θ21 is 60° or less, or the hot-pressed product 1A may be manufactured such that at least one of the four second edge angles θ22 is 60° or less. More specifically, the hot-pressed product 1A may be manufactured such that one or both of the minimum first edge angle θ21 and the minimum second edge angle θ22 are 60° or less.

[0082] When the molding process S16 is completed, all steps of the manufacturing method S10 for the hot press-formed product are completed, and the hot press-formed product 1A is manufactured.

[0083] As described above, in the hot press-formed product 1A and the manufacturing method S10 of the hot press-formed product of this embodiment, the inventors have found the following as a result of diligent study. That is, for example, when a tensile force is applied to the hot press-formed product 1A in the longitudinal direction, crack initiation points are likely to occur in the portion of the weld metal portion 50 connected to the first intersection Q1, the portion of the weld metal portion 50 connected to the second intersection Q2, the portion of the weld metal portion 50 connected to the third intersection Q3, and the portion of the weld metal portion 50 connected to the fourth intersection Q4. Therefore, by constructing (manufacturing) the hot-pressed product such that at least one of the twelve angles formed by the two first outer edge angles θ11, the two second outer edge angles θ12, the four first ridge angles θ21, and the four second ridge angles θ22 is 80° or less when the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member, the external force acting in the direction of opening the weld metal portion, which is caused by the tensile force acting on the portion having at least one of the angles, is suppressed. Consequently, it is possible to prevent the hot-pressed product 1A from fracturing at the weld metal portion 50A.

[0084] Preferably, the hot-pressed product 1A has a welded metal portion 50A, at least a part of the first member 10A connected to the welded metal portion 50A, and at least a part of the second member 30A connected to the welded metal portion, and includes a shaft portion 1B extending in a predetermined direction. The shaft portion 1B of the hot-pressed product 1A extends in a predetermined direction U, and the longitudinal direction X corresponds to the predetermined direction U. Therefore, for example, when a tensile force is applied in the predetermined direction U to which the shaft portion 1B extends, it is possible to suppress fracture of the hot-pressed product 1A at the welded metal portion 50A.

[0085] It is preferable that the hot-pressed product 1A satisfies equation (1). In the hot-pressed product 1A, the product of thickness and Vickers hardness, i.e., stiffness, increases in the order of weld metal portion 50A, second member 30A, and first member 10A. Generally, in hot-pressed products, the stiffness of the weld metal portion is less than the stiffness of the member, satisfying the inequality on the left side of equation (1). If the rigidity of the weld metal is less than the rigidity of the member, stress tends to concentrate more easily in the weld metal. However, by constructing (manufacturing) the hot-pressed product such that at least one of the twelve angles formed by the two first outer edge angles θ11, the two second outer edge angles θ12, the four first ridge angles θ21, and the four second ridge angles θ22 is 80° or less when the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member, the external force acting in the direction of opening the weld metal, caused by the tensile force acting on the portion having at least one of the angles, is suppressed. Therefore, it is preferable that the rigidity of the weld metal is less than the rigidity of the member, as this allows the effects of the present invention to be significantly realized. Furthermore, by satisfying the inequality on the right side of equation (1) and making the rigidity of the second member less than that of the first member, stress can be concentrated in the second member 30A of the two members 30A, making the second member 30A more prone to fracture. This allows the fracture prevention measures in the hot-pressed product 1A to be concentrated on the second member 30A.

[0086] When the hot-pressed product 1A is unfolded into a planar shape and viewed in the thickness direction of the second member 30A, it is preferable that at least one of the four first edge angles θ21 (minimum first edge angle θ21) is 60° or less. For example, when a tensile force is applied to the hot-pressed product 1A in the longitudinal direction X, the external force acting in the direction of opening the weld metal portion 50A in the portion connected to the third intersection Q3 of the weld metal portion can be further suppressed. Similarly, if a second edge angle θ22 exists, it is preferable that the minimum second edge angle θ22 is 75° or less, and more preferably 60° or less. Furthermore, it is most preferable that both the minimum first edge angle θ21 and the minimum second edge angle θ22 are 60° or less.

[0087] It is preferable that the weld metal portion 50A has a weld start end 56 and a weld end end 57. Even if the hot press-formed product 1A has a weld start end 56 and a weld end end 57, fracture at the weld metal portion 50A can be suppressed, and the fracture suppression effect at the weld metal portion of this application can be more effectively realized.

[0088] It is preferable that the aluminum concentration in the weld metal part 50A is between 0.3% by mass and 2.5% by mass. When the aluminum concentration of the weld metal part 50A is within this range, the high aluminum concentration in the weld metal part improves the corrosion resistance of the weld metal part.

[0089] The weld metal portion 50A is preferably bent or curved. By making the weld metal portion 50A bent or curved, it becomes less likely to break all at once compared to when the weld metal portion is straight.

[0090] The hot-pressed product 1A is preferably used as a part for automobiles. Since reliability is required for automobile parts, the present invention, which can suppress fracture at the weld metal portion 50A, is suitable.

[0091] Furthermore, in the tailored blank 1 and the method for manufacturing the tailored blank S11 of this embodiment, the inventors have found the following as a result of diligent study. That is, for example, when a tensile force is applied in the longitudinal direction X to a hot-pressed product 1A obtained by hot-pressing the tailored blank 1, crack initiation points are likely to occur in the portion connected to the first intersection Q1 of the weld metal portion, the portion connected to the second intersection Q2 of the weld metal portion, the portion connected to the third intersection Q3 of the weld metal portion, and the portion connected to the fourth intersection Q4 of the weld metal portion 50. For this reason, in the tailored blank, the hot-pressed product is constructed (manufactured) such that at least one of the twelve angles formed by the two first outer edge angles θ11, the two second outer edge angles θ12, the four first ridge angles θ21, and the four second ridge angles θ22 is 80° or less when the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member. As a result, when the tailored blank 1 is hot-press-formed to produce a hot-press-formed product, the external force acting in the direction of opening the weld metal portion 50A, which is caused by the tensile force acting on the portion having at least one angle, is suppressed. Therefore, it is possible to suppress fracture of the hot-press-formed product 1A obtained by hot-press-forming the tailored blank 1 at the weld metal portion 50A.

[0092] The hot-pressed product 1A of this embodiment can be modified in various ways, as described below. The first modified hot-pressed product 2A shown in Figure 8 is equipped with a welded metal portion 60A instead of the welded metal portion 50A in the hot-pressed product 1A of this embodiment. The hot-pressed product 2A is obtained by hot-pressing a tailored blank 2. In the welded metal portion 60A, the minimum first outer edge angle θ11 and the minimum second outer edge angle θ12 are both 90°. The minimum first edge angle θ21 and the minimum second edge angle θ22 are both 80° or less. Furthermore, the welded metal portion 60A is a line-symmetrical folded line with respect to the center of the hot-pressed product 1A in the orthogonal direction Y.

[0093] The hot-pressed product 3A of the second modified example shown in Figure 9 has a welded metal portion 70A instead of the welded metal portion 50A in the hot-pressed product 1A of this embodiment. The hot-pressed product 3A is obtained by hot-pressing a tailored blank 3. In the welded metal portion 70A, the minimum first outer edge angle θ11 and the minimum second outer edge angle θ12 are both 90°. The minimum first edge angle θ21 and the minimum second edge angle θ22 are 80° or less. Furthermore, the welded metal portion 70A is a non-symmetrical folded line when the center of the hot-pressed product 1A in the orthogonal direction Y is taken as the reference point. When the hot-pressed product 3A is unfolded into a planar shape and viewed in the thickness direction Z, the weld metal portion 70A, over its entire length between the first ridge line 41A and the second ridge line 42A of the second part, has at least one angle of 80° or less among the four angles that the weld metal portion 70A makes with the longitudinal direction X. In the method for manufacturing a hot press-formed product 3A, during the forming process, when the hot press-formed product 3A is unfolded into a planar shape and viewed in the thickness direction Z, the weld metal portion 70A is manufactured such that, over its entire length between the first ridge line 41A and the second ridge line 42A of the second part, at least one of the four angles made between the weld metal portion 70A and the longitudinal direction X is 80° or less.

[0094] The hot-pressed products 2A and 3A of the second and third modified examples can be prevented from fracturing at the weld metal portions 60A and 70A. Furthermore, in the hot press-formed product 3A and the method for manufacturing the hot press-formed product, it is possible to suppress fracture of the hot press-formed product 3A at the weld metal portion 70A along the entire length between the first ridge line 41A and the second ridge line 42A of the second part.

[0095] (Example of experiment) Next, we will describe the results of tensile tests conducted using hot-pressed products without ridges. Both the first and second members were made of aluminum-plated material. In the hot-pressed product 4A of the experimental example shown in Figure 10, the first outer edge angle θ11 and the second outer edge angle θ12 with respect to the weld metal portion 50A are both 90°. In the hot-pressed product 5A of the experimental example shown in Figure 11, the first outer edge angle θ11 with respect to the weld metal portion 50A is 60°, and the second outer edge angle θ12 is 60°. In the hot-pressed product 6A of the experimental example shown in Figure 12, the first outer edge angle θ11 with respect to the weld metal portion 50A is 45°, and the second outer edge angle θ12 is 45°. Although hot-pressed parts 5A and 6A do not have ridges formed, they are closer to the embodiment than hot-pressed part 4A.

[0096] Tensile tests were conducted on hot-pressed products 4A, 5A, and 6A by pulling them in the longitudinal direction, and the relationship between the tensile load and the stroke (elongation) of hot-pressed products 4A, 5A, and 6A was investigated. As shown in Figures 10 to 12, three hot-pressed parts 4A, 5A, and 6A were tested. Hot-pressed parts 4A, 5A, and 6A fractured at fracture locations P4, P5, and P6, respectively. In hot-pressed part 4A, a portion fractured at the weld metal portion 50A. Hot-pressed parts 5A and 6A fractured at the second component.

[0097] The test results are shown in Figure 13. In Figure 13, the horizontal axis represents the stroke (mm) of hot-pressed products 4A, 5A, and 6A, and the vertical axis represents the tensile load (kN) applied to hot-pressed products 4A, 5A, and 6A. In Figure 13, the dashed line L4 represents the test results for hot-pressed product 4A. Similarly, the solid line L5 represents the test results for hot-pressed product 5A, and the dotted line L6 represents the test results for hot-pressed product 6A. The breaking loads of hot-pressed parts 4A, 5A, and 6A are approximately the same. Compared to hot-pressed part 4A, hot-pressed parts 5A and 6A have a larger stroke at the time of breaking. Therefore, the amount of energy absorbed before breaking is greater for hot-pressed parts 5A and 6A than for hot-pressed part 4A. Based on these test results, it is considered that in hot-pressed products, by setting at least one of the first outer edge angle θ11 and the second outer edge angle θ12 to 80° or less, the amount of energy absorbed before the hot-pressed product fractures increases compared to when both the first and second outer edge angles θ11 and θ12 are 90°.

[0098] (Examples) Next, we will explain the results of tensile tests conducted using hot-pressed products. Tensile tests were performed on hot-pressed products No. 1 to 6 of the samples shown in Table 1 and Figures 14 to 19. Both the first and second members were made of aluminum-plated material.

[0099] [Table 1]

[0100] Figures 14 to 19 show the shape of the hot-pressed product when it is unfolded into a flat surface. In the hot-pressed products of samples No. 1 to 6, the negative side (first side Y1) of the orthogonal direction Y of the hot-pressed product was set as the origin of the orthogonal direction Y. The width (length in the orthogonal direction Y) of members 10A and 30A was set to 400 mm. The position of the first ridge line 41A of the second part in the orthogonal direction Y was set to 100 mm. Figures 14 to 19 are extracted views of the vicinity of the weld metal part 50A, and the longitudinal direction of each sample is the X direction.

[0101] For samples No. 1 to 6, the thickness and Vickers hardness were set as follows. The thickness T1 of the first member 10A was set to 1.6 mm. The Vickers hardness H1 of the first member 10A was set to 500 HV. The thickness T2 of the second member 30A was set to 1.2 mm. The Vickers hardness H2 of the second member 30A was set to 400 HV. Thickness T of the weld metal part 50A w The thickness was set to 1.2 mm. The Vickers hardness of the weld metal part 50A was H. w This was set to 300HV.

[0102] For example, in the hot-pressed product of Sample No. 1, the minimum first outer edge angle θ11 was set to 30°. The minimum first ridge angle θ21 was set to 90°. The minimum second ridge angle θ22 was set to 90°. The minimum second outer edge angle θ12 was set to 30°. The shape of the weld metal part 50A was made into a folded line shape that is symmetrical with respect to a predetermined axis parallel to the longitudinal direction X. A tensile test was performed using the hot-pressed product of sample No. 1. As a result, fracture occurred at the second member 30A, with a fracture load of 565 kN.

[0103] Similarly, tensile tests were also performed on the hot-pressed products of samples No. 2 to 6. Samples No. 1-4 and 6 are examples of hot-pressed products, while sample No. 5 is a comparative example. It was found that compared to sample No. 5, hot-pressed products No. 1-4 and 6 showed suppressed fracture at the weld metal portion 50A and a higher fracture load.

[0104] Although one embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and modifications, combinations, deletions, etc., of the configuration are also included without departing from the spirit of the present invention. For example, in the above embodiment, the first steel plate 10 in the tailored blank does not have to have the first part third piece 18 and the first part second ridge line planned portion 22.

[0105] The first steel plate 10 may be composed of four or more pieces. The second steel plate 30 does not have to have the second part third piece 38 and the second part second ridge line planned portion 42. The steel plate 30 may be composed of four or more pieces. The same applies to the first member 10A and the second member 30A in the hot-pressed product. [Explanation of Symbols]

[0106] 1, 2, 3 Tailored Blanks 1A, 2A, 3A, 4A, 5A, 6A Hot press-formed products 1B Shaft 10 First steel plate 10A First Member 16 Part 1 Part 1 17 Part 1 Part 2 18 Part 1 Part 3 21 Part 1, First Ridge (Planned Section) 21A Part 1 1st ridgeline 22 Part 1, Second Ridge (Planned Section) 22A Part 1 2nd ridgeline 30 Second steel plate 30A Second component 36 Part 2 Part 1 36d, 37d outer edge 37 Part 2 Part 2 38 Part 2 Part 3 41 Part 2, First Ridge (Planned Section) 41A Part 2 1st ridgeline 42. Part 2, Second Ridge (Planned Section) 42A Part 2 2nd ridgeline 50, 50A, 60A, 70A Weld metal part 56 Weld start 57 Weld termination Q1 1st intersection Q2 2nd intersection Q3 3rd intersection Q4 4th intersection θ11 Minimum first outer edge angle θ12 Minimum second ridge angle θ21 Minimum first ridge angle θ22 Minimum second ridge angle S10 Method for manufacturing hot-pressed products S11 Tailored Blank Manufacturing Method S12 Placement process S13 Welding Process S16 Molding process U in a predetermined direction X Longitudinal direction Y-direction (orthogonal direction) Z-axis thickness direction

Claims

1. First member and A second member is positioned such that its end abuts against the end of the first member, A welded metal portion that joins the end of the first member and the end of the second member, A hot press-formed product comprising, At least one of the first member and the second member is an aluminum plated member. The first member is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the first ridge of the first part, It has, The second member is, The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first ridge of the first part and the first ridge of the second part joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the first ridge of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, The longitudinal direction of the hot-pressed product in relation to the portion near the welded metal when the hot-pressed product is unfolded into a planar shape is defined as follows: When the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the first ridge of the second part of the first piece and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the second piece of the second part from the first ridge of the second part and the welded metal part, the angle formed by the portion of the welded metal part that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, At the third intersection, which is the intersection of the first ridge of the second part and the welded metal part, of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection, at least one of the angles formed is 80° or less. The concentration of aluminum contained in the welded metal portion is 0.3% by mass or more and 2.5% by mass or less. A hot-pressed product, in which the welded metal portion is folded in a line shape including a portion perpendicular to the longitudinal direction when the hot-pressed product is unfolded into a planar shape.

2. First member and A second member is positioned such that its end abuts against the end of the first member, A welded metal portion that joins the end of the first member and the end of the second member, A hot press-formed product comprising, At least one of the first member and the second member is an aluminum plated member. The first member is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the first ridge of the first part, It has, The second member is, The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first ridge of the first part and the first ridge of the second part joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the first ridge of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, The longitudinal direction of the hot-pressed product in relation to the portion near the welded metal when the hot-pressed product is unfolded into a planar shape is defined as follows: When the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the first ridge of the second part of the first piece and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the second piece of the second part from the first ridge of the second part and the welded metal part, the angle formed by the portion of the welded metal part that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, At the third intersection, which is the intersection of the first ridge of the second part and the welded metal part, of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection, at least one of the angles formed is 80° or less. The concentration of aluminum contained in the welded metal portion is 0.3% by mass or more and 2.5% by mass or less. When the hot-pressed product is unfolded into a planar shape, the welded metal portion has a portion connected to the first intersection and a portion connected to the second intersection that are inclined in opposite directions with respect to the longitudinal direction.

3. The hot press-formed product has the weld metal portion, at least a part of the first member connected to the weld metal portion, and at least a part of the second member connected to the weld metal portion, and includes a shaft portion extending in a predetermined direction. The hot press-formed product according to claim 1 or 2, wherein the longitudinal direction corresponds to the predetermined direction.

4. (1) A hot press-formed article according to any one of claims 1 to 3, satisfying formula (1). T ｗ H ｗ <T ２ H ２ <T １ H １ ・・(1) However, T １ : The thickness (mm) of the first member, H １ : The Vickers hardness (HV) of the first member, T ２ : The thickness (mm) of the second member, H ２ : The Vickers hardness (HV) of the second member, T ｗ : The thickness of the welded metal part (the thinner one of the thickness T １ and the thickness T ２ )(mm), H ｗ : The Vickers hardness (HV) of the welded metal part.

5. When the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction of the second member, The hot press-formed product according to any one of claims 1 to 4, wherein at the third intersection, at least one of the four angles formed between the portion of the welded metal portion connected to the third intersection and the longitudinal direction passing through the third intersection is 60° or less.

6. The hot press-formed product according to any one of claims 1 to 5, wherein the welded metal portion has a weld start end and a weld end.

7. The first member is, The first part has a third piece which is connected to the first piece of the first part via the first ridge of the first part, and the second piece of the first part has a third piece which is connected to the second ridge of the first part. The second member is, The second ridge of the first part and the second ridge of the second part joined via the welded metal portion, The second part has a third piece which is joined to the third piece which is joined to the third piece which is joined to the third piece which is joined to the third piece which is joined to the third piece which is joined to the first third piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined When the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction, At the third intersection, of the four angles formed by the portion of the welded metal portion connected to the third intersection and the longitudinal direction passing through the third intersection, at least one of the angles formed is 80° or less. The hot press-formed article according to any one of claims 1 to 6, wherein at the fourth intersection, which is the intersection of the second ridge of the second part and the welded metal part, at least one of the four angles formed between the portion of the welded metal part connected to the fourth intersection and the longitudinal direction passing through the fourth intersection is 80° or less.

8. The hot press-formed article according to claim 7, wherein, over the entire length between the first ridge of the second part and the second ridge of the second part, at least one of the four angles made between the welded metal portion and the longitudinal direction is 80° or less.

9. A hot-pressed product according to any one of claims 1 to 8, which is a part for an automobile.

10. First steel plate and, A second steel plate is positioned such that its end abuts against the end of the first steel plate, A welded metal portion that joins the end of the first steel plate and the end of the second steel plate, A tailored blank equipped with, At least one of the first steel sheet and the second steel sheet is an aluminum-plated steel sheet. The first steel plate is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the planned first ridge line of the first part, It has, The second steel plate is The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first part first ridge line planned portion and the second part first ridge line planned portion joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the planned first ridge line portion of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, When defining the longitudinal direction in the portion of the tailored blank near the weld metal, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the first piece and the welded metal portion, the angle between the portion of the welded metal portion connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the second piece of the second part from the planned first ridge line of the second part and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, At the third intersection, which is the intersection of the planned first ridge of the second part and the welded metal part, of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection, at least one of the angles formed is 80° or less. The concentration of aluminum contained in the welded metal portion is 0.3% by mass or more and 2.5% by mass or less. A tailored blank in which the welded metal portion is folded in the shape of a line, including a portion perpendicular to the longitudinal direction.

11. First steel plate and, A second steel plate is positioned such that its end abuts against the end of the first steel plate, A welded metal portion that joins the end of the first steel plate and the end of the second steel plate, A tailored blank equipped with, At least one of the first steel sheet and the second steel sheet is an aluminum-plated steel sheet. The first steel plate is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the planned first ridge line of the first part, It has, The second steel plate is The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first part first ridge line planned portion and the second part first ridge line planned portion joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the planned first ridge line portion of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, When defining the longitudinal direction in the portion of the tailored blank near the weld metal, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the first piece and the welded metal portion, the angle between the portion of the welded metal portion connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the second piece of the second part from the planned first ridge line of the second part and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, At the third intersection, which is the intersection of the planned first ridge of the second part and the welded metal part, of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection, at least one of the angles formed is 80° or less. The concentration of aluminum contained in the welded metal portion is 0.3% by mass or more and 2.5% by mass or less. The welded metal portion is a tailored blank in which the portion connected to the first intersection and the portion connected to the second intersection are inclined in opposite directions with respect to the longitudinal direction.

12. A positioning step in which the end of the first steel plate and the end of the second steel plate are positioned to abut against each other, A welding process to manufacture a tailored blank by joining the end of the first steel plate and the end of the second steel plate by welding to form a weld metal portion, A forming step comprising: hot press forming the tailored blank to form a first ridge line of the first part on the first member obtained from the first steel plate, and forming a second ridge line of the second part on the second member obtained from the second steel plate; A method for manufacturing hot press-formed products, which involves performing the following steps to produce a hot press-formed product: At least one of the first member and the second member is an aluminum plated member. The first member is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the first ridge of the first part, It has, The second member is, The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first ridge of the first part and the first ridge of the second part joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the first ridge of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, When the hot-pressed product is unfolded into a planar shape, and the longitudinal direction of the hot-pressed product in the vicinity of the welded metal portion is defined, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the first ridge of the second part of the first piece and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the second piece of the second part from the first ridge of the second part and the welded metal part, the angle formed by the portion of the welded metal part that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, The hot press-formed product is manufactured such that, at the third intersection, which is the intersection of the first ridge of the second part and the welded metal part, at least one of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less when the hot press-formed product is unfolded into a planar shape and viewed in the thickness direction of the second member, and the concentration of aluminum contained in the welded metal part after hot press forming is 0.3% by mass or more and 2.5% by mass or less. A method for manufacturing a hot-press-formed product, wherein, when the hot-press-formed product is unfolded into a planar shape, the welded metal portion is in the shape of a folded line including a portion perpendicular to the longitudinal direction.

13. A positioning step in which the end of the first steel plate and the end of the second steel plate are positioned to abut against each other, A welding process to manufacture a tailored blank by joining the end of the first steel plate and the end of the second steel plate by welding to form a weld metal portion, A forming step comprising: hot press forming the tailored blank to form a first ridge line of the first part on the first member obtained from the first steel plate, and forming a second ridge line of the second part on the second member obtained from the second steel plate; A method for manufacturing hot press-formed products, which involves performing the following steps to produce a hot press-formed product: At least one of the first member and the second member is an aluminum plated member. The first member is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the first ridge of the first part, It has, The second member is, The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first ridge of the first part and the first ridge of the second part joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the first ridge of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, When the hot-pressed product is unfolded into a planar shape, and the longitudinal direction of the hot-pressed product in the vicinity of the welded metal portion is defined, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the first ridge of the second part of the first piece and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the hot-pressed product on the opposite side of the second piece of the second part from the first ridge of the second part and the welded metal part, the angle formed by the portion of the welded metal part that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, The hot press-formed product is manufactured such that, at the third intersection, which is the intersection of the first ridge of the second part and the welded metal part, at least one of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less when the hot press-formed product is unfolded into a planar shape and viewed in the thickness direction of the second member, and the concentration of aluminum contained in the welded metal part after hot press forming is 0.3% by mass or more and 2.5% by mass or less. A method for manufacturing a hot-press-formed product, wherein when the hot-press-formed product is unfolded into a planar shape, the welded metal portion has a portion connected to the first intersection and a portion connected to the second intersection that are inclined in opposite directions with respect to the longitudinal direction.

14. The hot press-formed product has the weld metal portion, at least a part of the first member connected to the weld metal portion, and at least a part of the second member connected to the weld metal portion, and includes a shaft portion extending in a predetermined direction. The method for manufacturing a hot press-formed article according to claim 12 or 13, wherein the longitudinal direction corresponds to the predetermined direction.

15. (2) A method for manufacturing a hot press-formed article according to any one of claims 12 to 14, satisfying formula (2). T ｗ H ｗ <T ２ H ２ <T １ H １ ・・(2) However, T １ : Thickness of the first member (mm), H １ : Vickers hardness (HV), T of the first member of the hot press-formed product ２ : Thickness of the second member (mm), H ２ : Vickers hardness (HV), T of the second member of the hot press-formed product ｗ : The thickness of the welded metal portion (the thickness T) １ and the thickness T ２ (Of which, the thinner thickness) (mm), H ｗ : This is the Vickers hardness (HV) of the weld metal portion of the hot-pressed product.

16. A method for manufacturing a hot press-formed product according to any one of claims 12 to 15, wherein at the third intersection, the hot press-formed product is manufactured such that, when the hot press-formed product is unfolded into a planar shape and viewed in the thickness direction of the second member, at least one of the four angles formed between the portion of the welded metal portion connected to the third intersection and the longitudinal direction passing through the third intersection is 60° or less.

17. The method for manufacturing a hot press-formed product according to any one of claims 12 to 16, wherein the welded metal portion has a weld start end and a weld end.

18. The first member of the hot press-formed product is The first part has a third piece which is connected to the first piece of the first part via the first ridge of the first part, and the second piece of the first part has a third piece which is connected to the second ridge of the first part. The second member of the hot press-formed product is The second ridge of the first part and the second ridge of the second part joined via the welded metal portion, The second part has a third piece which is joined to the third piece which is joined to the third piece which is joined to the third piece which is joined to the third piece which is joined to the third piece which is joined to the first third piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the second piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined to the first piece which is joined When the hot-pressed product is unfolded into a planar shape and viewed in the thickness direction, A method for manufacturing a hot press-formed article according to any one of claims 12 to 17, wherein at the third intersection, the angle of at least one of the four angles formed between the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less, and at the fourth intersection, which is the intersection of the second ridge of the second part and the welded metal part, the angle of at least one of the four angles formed between the portion of the welded metal part connected to the fourth intersection and the longitudinal direction passing through the fourth intersection is 80° or less.

19. A method for manufacturing a hot press-formed article according to claim 18, wherein the hot press-formed article is manufactured such that, over the entire length between the first ridge of the second part and the second ridge of the second part, at least one of the four angles made between the welded metal portion and the longitudinal direction is 80° or less.

20. The method for manufacturing a hot press-formed product according to any one of claims 12 to 19, wherein the hot press-formed product is a part for an automobile.

21. A positioning step in which the end of the first steel plate and the end of the second steel plate are positioned to abut against each other, A welding step of joining the end of the first steel plate and the end of the second steel plate by welding to form a weld metal portion, A method for manufacturing tailored blanks, which involves performing the following to produce tailored blanks: At least one of the first steel sheet and the second steel sheet is an aluminum-plated steel sheet. The first steel plate is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the planned first ridge line of the first part, It has, The second steel plate is The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first part first ridge line planned portion and the second part first ridge line planned portion joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the planned first ridge line portion of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, When defining the longitudinal direction in the portion of the tailored blank near the weld metal, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the first piece and the welded metal portion, the angle between the portion of the welded metal portion connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the second piece of the second part from the planned first ridge line of the second part and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, The tailored blank is manufactured such that, at the third intersection, which is the intersection of the planned first ridge of the second part and the welded metal part, at least one of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less, and the concentration of aluminum contained in the welded metal part after hot press forming is 0.3% by mass or more and 2.5% by mass or less. A method for manufacturing a tailored blank, wherein the welded metal portion is in the shape of a folded line including a portion perpendicular to the longitudinal direction.

22. A positioning step in which the end of the first steel plate and the end of the second steel plate are positioned to abut against each other, A welding step of joining the end of the first steel plate and the end of the second steel plate by welding to form a weld metal portion, A method for manufacturing tailored blanks, which involves performing the following to produce tailored blanks: At least one of the first steel sheet and the second steel sheet is an aluminum-plated steel sheet. The first steel plate is, Part 1, Piece 1, The first piece of the first part and the second piece of the first part connected via the planned first ridge line of the first part, It has, The second steel plate is The first piece of the first part and the first piece of the second part joined via the welded metal portion, The first part first ridge line planned portion and the second part first ridge line planned portion joined via the welded metal portion, The second piece of the second part is connected to the first piece of the second part via the planned first ridge line portion of the second part, and the second piece of the second part is joined to the second piece of the first part via the welded metal portion, It has, When defining the longitudinal direction in the portion of the tailored blank near the weld metal, With the first piece of the second part as the reference, at the first intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the first ridge line of the second part of the first piece and the welded metal portion, the angle between the portion of the welded metal portion connected to the first intersection point and the longitudinal direction passing through the first intersection point, With the second piece of the second part as the reference, at the second intersection point which is the intersection point between the outer edge of the tailored blank on the opposite side of the second piece of the second part from the planned first ridge line of the second part and the welded metal portion, the angle formed by the portion of the welded metal portion that is connected to the second intersection point and the longitudinal direction passing through the second intersection point, The tailored blank is manufactured such that, at the third intersection, which is the intersection of the planned first ridge of the second part and the welded metal part, at least one of the eight angles formed by the portion of the welded metal part connected to the third intersection and the longitudinal direction passing through the third intersection is 80° or less, and the concentration of aluminum contained in the welded metal part after hot press forming is 0.3% by mass or more and 2.5% by mass or less. A method for manufacturing a tailored blank, wherein the welded metal portion has a portion connected to the first intersection and a portion connected to the second intersection that are inclined in opposite directions with respect to the longitudinal direction.

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