A welded joint for a steel piece, a manufacturing method and an application

Abstract

The present application belongs to the technical field of welding, and particularly relates to a welded joint of a steel piece, a manufacturing method and application. The welded joint comprises two steel plates and a weld seam, the weld seam is arranged at the butt joint part of the two steel plates, the upper and lower retardation angles of the welded joint satisfy a specific relationship, and / or the front, back and narrowest fusion widths of the welded joint satisfy a specific relationship, so that the problem of aluminum enrichment in the weld seam after laser wire filling of the aluminum-silicon hot-formed steel in the prior art can be overcome.

Description

Technical Field

[0001] This invention belongs to the field of welding technology, specifically relating to a welded joint for steel components, its manufacturing method, and its application. Background Technology

[0002] To meet increasingly stringent collision regulations and improve vehicle crash safety, the automotive industry is gradually increasing the use of hot-formed steel in car bodies. Hot-formed steel achieves high strength primarily through alloying and heat treatment to strengthen the steel's microstructure. Typically, alloying elements such as manganese and boron are added to increase its hardening tendency, resulting in high impact energy absorption and significant weight reduction potential.

[0003] In order to prevent the surface oxidation of parts from affecting subsequent use during the heat treatment process, hot-formed steel with aluminum or aluminum alloy coatings is increasingly being used. During heating, the aluminum or aluminum alloy coating forms an alloy layer with the steel substrate, ensuring that the steel sheet does not oxidize further. This avoids affecting subsequent welding and assembly, so hot-formed steel sheets with aluminum or aluminum alloy coatings are widely used in the automotive industry.

[0004] However, laser welding of this type of blank presents the following problems: During the process of welding hot-formed steel sheets with aluminum or aluminum alloy coatings onto the surface, the aluminum element in the coating will accumulate in the weld joint; during the hot stamping of the blank into components, the joint will be heated above the austenitizing temperature and held for a period of time before being rapidly cooled to undergo a martensitic transformation. As is well known, aluminum is a ferrite-forming element. The aluminum-rich areas in the weld joint will form ferrite and / or intermetallic compounds during the welding process and subsequent heat treatment. The hardness of this structure is lower than that of the surrounding martensitic structure; during load-bearing, the joint is prone to forming crack initiation points and eventually cracking, greatly reducing the load-bearing capacity of the joint and seriously affecting the use of the welded components.

[0005] To address these issues, one approach to manufacturing steel plate components with aluminum or aluminum alloy coatings is to remove the coating before laser welding. The main methods for removal include mechanical, chemical, and laser treatment. While removing the aluminum coating avoids aluminum enrichment, it requires an additional removal process with low efficiency, increasing welding costs and reducing the product's market competitiveness.

[0006] Another type involves welding directly with the coating intact, primarily by adding a certain amount of alloying elements (γ elements) to the molten pool during welding to eliminate the influence of aluminum elements in the coating on the joint welding process and post-weld hot stamping. However, the inventors discovered that simply considering γ elements (elements that expand the austenite phase region, such as C, Mn, Ni, etc.) to offset the adverse effects caused by aluminum and silicon elements in the coating entering the weld pool is insufficient to completely solve the problem. This is because the actual weld shape and welding process affect the flow of the molten pool during welding, leading to varying degrees of aluminum enrichment in the molten pool. Therefore, simply calculating the element content of the filler wire seems insufficient to solve the problem of aluminum enrichment. Consequently, joints welded using this method have a risk of weld breakage during performance testing, resulting in a significant reduction in the joint's load-bearing capacity.

[0007] To improve the performance of welded joints, researchers have begun to control the welding process or the joint cross-sectional shape to obtain joints with excellent performance under specific service conditions. Therefore, there is an urgent need to propose a method that can address aluminum enrichment in welded joints and improve weld quality and impact resistance by controlling the welding process or joint cross-sectional shape. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the difficulties such as aluminum enrichment in the weld seam after laser wire filling of aluminum-silicon hot-formed steel, which makes it impossible to guarantee the welding quality and impact performance of the welded joint, thereby providing a welded joint of steel parts and a manufacturing method thereof.

[0009] To this end, the present invention provides the following technical solution.

[0010] The first aspect of the present invention provides a welded joint for a steel component, the welded joint comprising two steel plates and a weld, the weld being disposed at the butt joint of the two steel plates; the welded joint satisfies at least one of (1)-(2):

[0011] (1) The maximum angle formed by the fusion line on the upper side of the welded joint cross-section and the thickness direction of the steel plate is the upper hindrance angle θ1; the maximum angle formed by the fusion line on the lower part of the welded joint cross-section and the thickness direction of the steel plate is the lower hindrance angle θ2; the upper hindrance angle θ1 and the lower hindrance angle θ2 satisfy relation 1:

[0012] Relationship 1: θ1+θ2≤45°

[0013] Wherein, θ1 ≤ 30°;

[0014] θ2≤30°;

[0015] (2) The welded joint includes the front weld width, the back weld width, and the narrowest weld width; the front weld width x, the back weld width y, and the narrowest weld width z satisfy the relationship 2-3:

[0016]

[0017] Where x is in mm;

[0018] The unit for y is mm;

[0019] The unit for z is mm.

[0020] The relationship z: 0.7mm≤z≤1.5mm is given by equation 4.

[0021] The weld includes a first protrusion and a second protrusion that exceed the thickness of the steel plate. The height of the first protrusion is the weld reinforcement height h1 on the front side, and the height of the second protrusion is the weld reinforcement height h2 on the back side. The minimum thickness h of the steel plate, the front reinforcement height, and the back reinforcement height satisfy relationship 5:

[0022]

[0023] The unit of h is mm, and the minimum thickness of the steel plate refers to the thickness of the thinner steel plate among the two steel plates.

[0024] The unit of h1 is mm;

[0025] The unit of h2 is mm.

[0026] The minimum thickness h of the steel plate, the front excess height h1, and the back excess height h2 satisfy the relationship 6-7:

[0027]

[0028] The minimum thickness h of the steel plate is: 0.5mm ≤ h ≤ 5mm.

[0029] Two steel plates are welded together using laser welding to form the welded joint; the laser power P, the set welding speed V1, and the minimum thickness h of the steel plates in the laser welding method satisfy the relationship 8:

[0030]

[0031] Wherein, the unit of P is W;

[0032] The unit of V1 is m / s;

[0033] The unit of h is mm, and the minimum thickness of the steel plate refers to the thickness of the thinner steel plate among the two steel plates.

[0034] The welding speed V1 is: 0.02m / s ≤ V1 ≤ 0.1m / s;

[0035] Preferably, the laser power P is 1000W ≤ P ≤ 10000W.

[0036] The steel plate includes a substrate and a coating, wherein the coating is an aluminum coating or an aluminum alloy coating.

[0037] Preferably, the coating comprises 5-11 wt% Si, 0-4 wt% Fe, with the balance being Al and unavoidable impurities;

[0038] Preferably, the matrix comprises the following components by weight percentage: 0.05% ≤ C ≤ 0.5%, 0.1% ≤ Mn ≤ 5%, 0.01% ≤ Si ≤ 2%, 0.01% ≤ Cr ≤ 3%, Ti ≤ 0.2%, Nb ≤ 0.3%, V ≤ 0.3%, Al ≤ 0.5%, Mo ≤ 0.5%, Ni ≤ 0.5%, S ≤ 0.05%, P ≤ 0.015%, B ≤ 0.01%, with the balance being Fe and / or unavoidable impurities in the manufacturing process.

[0039] A second aspect of the present invention provides a method for manufacturing a welded joint of a steel component, comprising: welding two steel plates using a laser welding method to form the welded joint.

[0040] A third aspect of the present invention provides a welded component including the aforementioned welded joint.

[0041] The technical solution of this invention has the following advantages:

[0042] 1. The welded joint of the steel component provided by this invention comprises two steel plates and a weld. The weld is located at the joint of the two steel plates. The upper and lower retardation angles of the welded joint satisfy a specific relationship, and / or the front weld width, back weld width, and narrowest weld width of the welded joint satisfy a specific relationship. This can overcome the defects such as aluminum enrichment in the weld after laser wire filling of aluminum-silicon hot-formed steel in the prior art. Specifically, satisfying the specific relationship between the upper and lower retardation angles of the welded joint allows the cross-section of the welded joint to have a specific shape, resulting in more sufficient aluminum flow during welding and reducing the degree of aluminum enrichment. The specific relationship between the front weld width, back weld width, and narrowest weld width of the welded joint controls the melting area, resulting in a larger melting area of ​​the weld cross-section under the condition of melting the same amount of aluminum in the coating, thus reducing the average aluminum content entering the molten pool. It also makes the weld cross-section resemble a cross-section with a large radius of curvature, avoiding a severely necked-out section at the waist, thus preventing the problem of aluminum enrichment caused by the severe necking affecting aluminum flow.

[0043] 2. The welded joint of the steel part provided by the present invention further adjusts the front and back reinforcement parameters of the weld, which can make the weld have a full cross-sectional shape, ensure that the weld has good load-bearing capacity, and not affect the subsequent hot stamping process of the steel part in the mold.

[0044] 3. The welded joint of the steel parts provided by the present invention controls the laser power, welding speed and steel plate thickness during the welding process, which can ensure that the welded edges of the aluminum-silicon coated steel parts can be effectively melted through. At the same time, it controls the shape of the molten pool during the welding process, so that the cross-section or longitudinal section does not have an excessive bulging effect, and thus the molten pool does not have problems such as layered flow and poor fluidity. The weld obtained by this manufacturing method has no aluminum element enrichment.

[0045] When the welded joint of the steel component provided by this invention is applied to welded parts, after hot stamping, the tensile test specimen of the welded joint fractures at the base material, and does not fracture at the weld seam. In the V-notch Charpy impact test at -40℃, the impact absorption energy of the welded joint is not less than 80% of the impact absorption energy of the base material, and the impact absorption energy is not less than 40 J / cm. 2 The tensile strength is 450MPa-2100MPa. Attached Figure Description

[0046] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0047] Figure 1 This is an illustration of the welding process during the preparation of steel parts according to the present invention;

[0048] Figure 2 This is a cross-sectional morphology diagram of the weld seam of the present invention;

[0049] Figure 3 This is a schematic diagram of the sampling area when testing steel parts according to the present invention. Detailed Implementation

[0050] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0051] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0052] Existing technologies for steel products, due to the presence of aluminum-silicon coatings, are prone to aluminum enrichment at the joints during welding, leading to a significant reduction in the joint's load-bearing capacity and severely impacting the usability of the welded components. On one hand, existing technologies remove the coating during welding, but this method complicates the process, increases costs, and reduces product competitiveness. On the other hand, existing technologies involve direct welding without any coating treatment. Even adding welding wire containing elements that expand the austenite phase region to the molten pool to eliminate the adverse effects of aluminum entering the weld from the coating still results in varying degrees of aluminum enrichment in the molten pool.

[0053] To address the aforementioned problems in the existing technology, this invention provides a welded joint for steel components, a manufacturing method, and an application. When welding steel plates using a laser beam as a heat source, the cross-sectional shape of the molten joint and the enrichment degree of aluminum in the molten pool are observed. When the weld meets specific requirements, the aforementioned problems in the existing technology can be solved.

[0054] In a first aspect, the present invention provides a welded joint for a steel component, the welded joint comprising two steel plates and a weld, the weld being disposed at the butt joint of the two steel plates; the welded joint satisfies at least one of (1)-(2):

[0055] (1) The maximum angle formed by the fusion line on the upper side of the welded joint cross-section and the thickness direction of the steel plate is the upper hindrance angle θ1; the maximum angle formed by the fusion line on the lower part of the welded joint cross-section and the thickness direction of the steel plate is the lower hindrance angle θ2; the upper hindrance angle θ1 and the lower hindrance angle θ2 satisfy relation 1:

[0056] Relationship 1: θ1+θ2≤45°

[0057] Wherein, θ1 ≤ 30°;

[0058] θ2≤30°;

[0059] (2) The welded joint includes the front weld width, the back weld width, and the narrowest weld width; the front weld width x, the back weld width y, and the narrowest weld width z satisfy the relationship 2-3:

[0060]

[0061]

[0062] Where x is in mm;

[0063] The unit for y is mm;

[0064] The unit for z is mm.

[0065] The upper and lower retardation angles of the welded joint in this invention satisfy Equation 1, and the fusion line and the thickness direction of the steel plate form a specific angle, giving the welded joint a specific shape. This allows for more complete flow of aluminum elements during welding, reducing aluminum enrichment. The front weld width, back weld width, and narrowest weld width of the welded joint in this invention satisfy Equations 2-3. Under the condition of incorporating the same amount of aluminum elements in the coating, this results in a larger molten area in the weld cross-section, a lower average aluminum content entering the molten pool, and a weld cross-section with a larger radius of curvature. This invention avoids the problem of a severely necked, narrow-waisted cross-section, preventing aluminum enrichment caused by the reduced flow of aluminum elements due to severe necking. This invention, by giving the welded joint a specific shape, overcomes the defects of existing technologies where aluminum enrichment occurs in the weld after laser wire filling of aluminum-silicon hot-formed steel, resulting in compromised weld quality and impact resistance.

[0066] In one alternative implementation, the relationship z: 0.7mm≤z≤1.5mm is given by equation 4.

[0067] In one optional embodiment, the weld includes a first protrusion and a second protrusion exceeding the thickness of the steel plate, the height of the first protrusion being the weld front reinforcement height h1, and the height of the second protrusion being the weld back reinforcement height h2; the minimum thickness h of the steel plate, the front reinforcement height, and the back reinforcement height satisfy relationship 5:

[0068]

[0069] The unit of h is mm, and the minimum thickness of the steel plate refers to the thickness of the thinner steel plate among the two steel plates.

[0070] The unit of h1 is mm;

[0071] The unit of h2 is mm.

[0072] The minimum thickness h of the steel plate, the front excess height h1, and the back excess height h2 satisfy the relationship 6-7:

[0073]

[0074] This invention controls the weld reinforcement, giving the weld joint a fuller shape, ensuring good load-bearing capacity of the weld, and not affecting the subsequent hot stamping process of the steel part in the mold. At the same time, it avoids problems such as depressions and reduced load-bearing capacity of the weld joint.

[0075] In one alternative embodiment, the minimum thickness h of the steel plate is: 0.5mm ≤ h ≤ 5mm.

[0076] In one optional embodiment, two steel plates are welded together using a laser welding method to form the welded joint; the laser power P, the set welding speed V1, and the minimum thickness h of the steel plates in the laser welding method satisfy relationship 8:

[0077]

[0078] Wherein, the unit of P is W;

[0079] The unit of V1 is m / s;

[0080] The unit of h is mm, and the minimum thickness of the steel plate refers to the thickness of the thinner steel plate among the two steel plates.

[0081] This invention controls the laser power, welding speed, and steel plate thickness during the welding process, which can ensure that the welded edges of aluminum-silicon coated steel parts can be effectively melted through. At the same time, it controls the shape of the molten pool during the welding process, so that the cross-section or longitudinal section does not have an excessive bulging effect, and thus the molten pool does not have problems such as layering and poor fluidity.

[0082] In one optional embodiment, the welding speed V1 is: 0.02m / s ≤ V1 ≤ 0.1m / s;

[0083] Preferably, the laser power P is 1000W ≤ P ≤ 10000W.

[0084] In one alternative embodiment, the steel plate includes a substrate and a coating, wherein the coating is an aluminum-coated coating or an aluminum alloy coating.

[0085] Preferably, the coating comprises 5-11 wt% Si, 0-4 wt% Fe, with the balance being Al and unavoidable impurities.

[0086] Preferably, the matrix comprises the following components by weight percentage: 0.05% ≤ C ≤ 0.5%, 0.1% ≤ Mn ≤ 5%, 0.01% ≤ Si ≤ 2%, 0.01% ≤ Cr ≤ 3%, Ti ≤ 0.2%, Nb ≤ 0.3%, V ≤ 0.3%, Al ≤ 0.5%, Mo ≤ 0.5%, Ni ≤ 0.5%, S ≤ 0.05%, P ≤ 0.015%, B ≤ 0.01%, with the balance being Fe and / or unavoidable impurities in the manufacturing process.

[0087] Secondly, the present invention provides a method for manufacturing a welded joint of a steel component, comprising the following steps:

[0088] (1) Pre-welding preparation: Use a flat steel plate as the steel plate to be welded; at least one surface of the steel plate to be welded should contain aluminum strips or aluminum coatings. Figure 1The aforementioned includes a steel plate 1 to be welded and a steel plate 2 to be welded. Both surfaces of the steel plates to be welded are provided with a coating. The steel plate 1 to be welded includes a substrate 1-1 and a coating 1-2; the steel plate 2 to be welded includes a substrate 2-1 and a coating 2-2.

[0089] (2) Loading: The prepared steel plates to be welded are placed directly on the welding fixture by manual or mechanical loading. The welding edges of the steel plates to be welded are aligned and spliced ​​together. During this process, the gap is controlled to be 0 to 0.5 mm.

[0090] (3) Welding: Combination Figure 1 As shown, when laser filler wire welding is used to weld the welded edges of steel plates 1 and 2, the laser beam 3 and the welding torch 4 move together along the welding direction WD at a welding speed V1 (m / s). During welding, the welding torch 4 feeds out the welding wire 5 and coaxially delivers multi-component shielding gas. Under the action of the laser beam 3, the welding wire 5 and the welded edges of the two steel plates melt together to form a weld pool 6.

[0091] Thirdly, the present invention provides a welded component including the aforementioned welded joint.

[0092] The composition of the steel plate substrate used in the following embodiments is shown in Table 1:

[0093] Table 1. Composition and weight percentage of the steel plate substrate to be welded

[0094]

[0095] Note: In Table 1, "-" means that the corresponding element was not detected in the matrix or its weight percentage is less than 0.001%; ​​the matrix also includes: the remainder is iron and unavoidable impurities.

[0096] Examples 1-15

[0097] Examples 1-15 provide a welded joint for a steel component and its manufacturing method, with welding schematic diagrams shown below. Figure 1 As shown, it includes:

[0098] (1) Pre-welding preparation: A flat steel plate is used as the steel plate to be welded; both surfaces of the steel plate to be welded contain an aluminum coating. Figure 1 As shown, the assembly includes steel plate 1 and steel plate 2 to be welded. Steel plate 1 includes a substrate 1-1 and a plating layer 1-2 disposed on two surfaces of the substrate; steel plate 2 includes a substrate 2-1 and a plating layer 2-2 disposed on two surfaces of the substrate. The plating layer composition is the same in all embodiments and comparative examples, comprising 2.5 wt% Fe, 10 wt% Si, with the remainder being Al and unavoidable impurities. The surfaces of the steel plates to be welded are not treated in any way, and the plating layer is not removed; the welding edges of the steel plates are sheared to be flush.

[0099] (2) Loading: The prepared steel plates to be welded are placed directly on the welding fixture by mechanical equipment. The welding edges of the steel plates to be welded are aligned and spliced ​​together. During this process, the welding gap is controlled to not exceed 0.5mm, and then the welding edges are fixed.

[0100] (3) Welding: When welding the welded edges of steel plates 1 and 2 to be welded using laser filler wire welding, the laser beam 3 and the welding torch 4 move together along the welding direction WD at a speed of V1 (m / s). During welding, the welding torch 4 feeds out the welding wire 5 and coaxially feeds out multi-component shielding gas. Under the action of the laser beam 3, the welding wire 5 and the welded edges of the two steel plates to be welded melt together to form a weld pool 6.

[0101] The differences between Examples 1-15 lie in the different base plate numbers, the different thicknesses of the steel plates to be welded, the different welding speeds, the different laser powers, and the different wire feed speeds. The base plate numbers, thicknesses, welding speeds, laser powers, and wire feed speeds for Examples 1-15 are shown in Table 2.

[0102] Comparative Examples 1-3

[0103] Comparative Examples 1-3 provide a welded joint for a steel component and its manufacturing method, the differences being the different base material number, the different thickness of the steel plate to be welded, the different welding speed, the different laser power, and the different wire feeding speed.

[0104] Table 2 shows the substrate number, thickness, welding speed, laser power, and wire feed speed of the steel plates to be welded in Comparative Examples 1-3.

[0105] Table 2. Parameters of the steel plates to be welded and the manufacturing methods in the examples and comparative examples.

[0106]

[0107]

[0108] (I) Testing the cross-sectional morphology of the weld

[0109] Observe the cross-sectional morphology AA of the weld seams of the steel components in each embodiment and comparative example, including the front weld width x, back weld width y, narrowest weld width z, upper retardation angle θ1, lower retardation angle θ2, front reinforcement height h1, and back reinforcement height h2. The sampled cross-sectional morphology of Example 1 is as follows: Figure 2 As shown. Samples were taken perpendicular to section AA to test the weld performance. The steel parts obtained in Examples 1-15 and Comparative Examples 1-3 were tested according to... Figure 3 As shown, region 7 was selected as the sample to be tested. The sample to be tested is 10mm×15mm in size. The sample to be tested was prepared by mounting, grinding and polishing according to the general metallographic sample preparation method. The sample was etched using a 4% nitric acid alcohol mixed solution. Then the cross-sectional morphology and size of the weld were observed and measured under a metallographic microscope. The results are summarized in Table 3.

[0110] Table 3. Test results of weld cross-sectional morphology

[0111]

[0112] Note: When testing the cross-sectional morphology and dimensions of welds, the same personnel and standardized measurements should be used to minimize measurement errors. " / " in the table indicates joints that could not be tested or were incomplete.

[0113] Calculate whether each embodiment and comparative example satisfies relation 1-8, and the statistical results are shown in Table 4-5.

[0114] Table 4

[0115]

[0116] Table 5

[0117]

[0118]

[0119] (II) Testing the tensile properties of welded joints

[0120] The steel parts obtained in each embodiment and comparative example were placed in a heating furnace for austenitization. The heating temperature and time are shown in Table 6. They were then rapidly transferred (within 15 seconds) to a water-cooled mold and held under pressure of 200 tons for 12 seconds. During the pressure holding period, the cooling rate of the weld blank was ensured to be greater than the critical cooling rate for martensitic transformation of the base material. After the above hot stamping treatment, the welded parts were first fully austenitized; during the pressure holding period in the mold, the welded parts underwent microstructural transformation, and then each weld joint was tested. Figure 3 As shown, region 8 was selected as sample 2 to be tested. The width of the parallel section of sample 2 was 12.5 mm, and the gauge length was 50 mm. Welded specimens were used as standard tensile specimens to test the tensile strength and elongation of the welded joints of steel components in each embodiment and comparative example. The average value of three parallel samples was taken. The test method followed GB / T228.1-2021 Metallic materials, tensile testing—Part 1: Test methods at room temperature. The test results are shown in Table 7.

[0121] Table 6 Heating Temperature and Time

[0122]

[0123]

[0124] Table 7 Tensile property test results

[0125]

[0126] The results above show that the welded joint satisfying the present invention has good tensile properties, and the fracture location is in the base material during tensile testing. The welded joint not satisfying the present invention has poor tensile properties, and the fracture location is in the weld seam during tensile testing. It should be noted that the steel part obtained in Comparative Example 2 did not form an effective weld seam, and its tensile properties could not be tested.

[0127] (III) Testing the impact toughness of welded joints

[0128] according to Figure 3 As shown, according to Example 1 and Comparative Example 3, the joint impact test specimen position (9) after welding is adjacent to the position (8) where the tensile test specimen was taken, and is denoted as the joint impact test specimen; the base material impact test specimen (10) is located 5 mm below the joint impact test specimen, as detailed in the following figure. Figure 3 The position shown in the figure is denoted as the base material impact specimen. For the impact specimen, a long strip specimen of 10×55mm is taken (for the joint specimen, the weld is centered). Three impact specimens of the same group are stacked to form a 4.5×10×55 specimen. Then, a 2mm V-shaped notch for Charpy impact testing is milled at the weld to form the impact specimen. The impact performance of the base material and the joint of the welded part is tested. The results are shown in Table 8.

[0129] Table 8 Impact performance results of Example 1

[0130]

[0131] As shown in Table 8, the steel components with welded joints of the present invention exhibit good impact resistance. In the V-notch Charpy impact test at -40℃, the impact absorption energy of the welded joint is not less than 80% of the impact absorption energy of the base material, and the impact absorption energy is not less than 40 J / cm. 2 .

[0132] Table 9 Impact performance results of Comparative Example 3

[0133]

[0134] As can be seen from Table 9, the impact resistance of the welded joint in Comparative Example 3 needs to be improved. In the V-notch Charpy impact test at -40℃, the impact absorption energy of the welded joint is less than 80% of that of the base metal, and the impact absorption energy is less than 40 J / cm². 2 .

[0135] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A welded joint for a steel component, characterized in that, The welded joint comprises two steel plates and a weld, wherein the weld is disposed at the butt joint of the two steel plates; the welded joint satisfies at least one of (1)-(2): (1) The maximum angle formed by the fusion line on the upper side of the welded joint cross-section and the thickness direction of the steel plate is the upper hindrance angle θ1; the maximum angle formed by the fusion line on the lower part of the welded joint cross-section and the thickness direction of the steel plate is the lower hindrance angle θ2; the upper hindrance angle θ1 and the lower hindrance angle θ2 satisfy relation 1: Relationship 1: θ1+θ2≤45° Wherein, θ1 ≤ 30°; θ2≤30°; (2) The welded joint includes the front weld width, the back weld width, and the narrowest weld width; the front weld width x, the back weld width y, and the narrowest weld width z satisfy the relationship 2-3: Where x is in mm; The unit for y is mm; The unit for z is mm.

2. The welded joint according to claim 1, characterized in that, The relationship z: 0.7mm≤z≤1.5mm is given by equation 4.

3. The welded joint according to claim 2, characterized in that, The weld includes a first protrusion and a second protrusion that exceed the thickness of the steel plate. The height of the first protrusion is the weld reinforcement height h1 on the front side, and the height of the second protrusion is the weld reinforcement height h2 on the back side. The minimum thickness h of the steel plate, the front reinforcement height, and the back reinforcement height satisfy relationship 5: The unit of h is mm, and the minimum thickness of the steel plate refers to the thickness of the thinner steel plate among the two steel plates. The unit of h1 is mm; The unit of h2 is mm.

4. The welded joint according to claim 3, characterized in that, The minimum thickness h of the steel plate, the front excess height h1, and the back excess height h2 satisfy the relationship 6-7:

5. The welded joint according to claim 3 or 4, characterized in that, The minimum thickness h of the steel plate is: 0.5mm ≤ h ≤ 5mm.

6. The welded joint according to claim 1, 3 or 4, characterized in that, Two steel plates are welded together using laser welding to form the welded joint; the laser power P, the set welding speed V1, and the minimum thickness h of the steel plates in the laser welding method satisfy the relationship 8: Wherein, the unit of P is W; The unit of V1 is m / s; The unit of h is mm, and the minimum thickness of the steel plate refers to the thickness of the thinner steel plate among the two steel plates.

7. The welded joint according to claim 6, characterized in that, The welding speed V1 is: 0.02m / s ≤ V1 ≤ 0.1m / s; Preferably, the laser power P is 1000W ≤ P ≤ 10000W.

8. The welded joint according to any one of claims 1-7, characterized in that, The steel plate includes a substrate and a coating, wherein the coating is an aluminum coating or an aluminum alloy coating. Preferably, the coating comprises 5-11 wt% Si and 0-4 wt% Fe; Preferably, the matrix comprises the following components by weight percentage: 0.05% ≤ C ≤ 0.5%, 0.1% ≤ Mn ≤ 5%, 0.01% ≤ Si ≤ 2%, 0.01% ≤ Cr ≤ 3%, Ti ≤ 0.2%, Nb ≤ 0.3%, V ≤ 0.3%, Al ≤ 0.5%, Mo ≤ 0.5%, Ni ≤ 0.5%, S ≤ 0.05%, P ≤ 0.015%, B ≤ 0.01%, with the balance being Fe and / or unavoidable impurities in the manufacturing process.

9. A method for manufacturing a welded joint of a steel component, characterized in that, include: Two steel plates are welded together using laser welding to form the welded joint.

10. A welded component, characterized in that, Includes the welded joint as described in any one of claims 1-8.

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