Manufacturing method for stainless steel and high alloy parts, and stainless steel and high alloy parts

Abstract

To remarkably improve productivity and dimensional accuracy of a component parts with metal three-dimensional lamination molding by arc-welding by performing three-dimensional lamination molding by arc-welding together with cold forging and cutting of a stainless steel and a high alloy.SOLUTION: In a stainless steel / high alloy component and a method for manufacturing the same, a cold molded part 1, which is cold-molded so that a maximum thickness thereof becomes 6 mm or more by cold forging or cold pressing, is provided, and thereafter, a three-dimensional lamination molding part 2, in which three-dimensional molding is performed with a maximum thickness of 10 mm or less by arc-welding of a stainless steel / high alloy welding material onto a portion of the cold molded part 1 with a thickness of 6 mm or more, is provided. Thereafter, the three-dimensional molding part is cut or ground as necessary.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a manufacturing method for stainless steel or high alloy parts, and to stainless steel or high alloy parts that have high strength, high corrosion resistance, and excellent dimensional accuracy. [Background technology]

[0002] In recent years, metal 3D additive manufacturing (AM) technology has been expected to be an innovative production method for complex-shaped parts, and various production technologies have been proposed. Particularly for products made from stainless steel and high alloys, which require expensive raw materials, high strength, high corrosion resistance, and poor cold workability, AM is expected to be significantly more effective than conventional part molding methods that rely on cutting processes. Among these, the application of highly productive 3D AM by arc welding has the potential to achieve groundbreaking productivity. However, disadvantages of 3D AM by arc welding have been pointed out, such as the need for an appropriate base plate, which must be separated after AM, thermal distortion, and poor processing accuracy.

[0003] For this reason, for example, in 3D additive manufacturing technology using arc welding, a technology has been proposed in which different types of welding materials are used on the base plate and additive manufacturing conditions are changed between the first and second layers, making it easy to separate the additively manufactured object from the base plate after 3D additive manufacturing (Patent Document 1).

[0004] Additionally, a composite processing technology has been proposed in which high-precision parts are obtained by cutting in the same area immediately after three-dimensional additive manufacturing by welding or the like (for example, Patent Document 2). Furthermore, an efficient part forming technology has been proposed that combines cold forging, laser welding, and cutting (for example, Patent Document 3). However, there is a problem that the number of parts and welding points is large, resulting in low productivity.

[0005] As described above, techniques for improving productivity have been proposed in the past, but these methods do not ensure sufficient productivity, and are not necessarily more efficient than conventional forging or cutting processes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-144447 [Patent Document 2] Patent No. 6199511 [Patent Document 3] Japanese Patent Publication No. 2021-38439 Summary of the Invention [Problem to be solved by the invention]

[0007] The present inventors have recognized that there are problems to be solved in increasing productivity in three-dimensional additive manufacturing using arc welding to inexpensively manufacture products with high dimensional accuracy. First, in 3D additive manufacturing, a processing technique is required that does not use a base plate, which needs to be separated after 3D additive manufacturing.

[0008] Furthermore, in 3D additive manufacturing using arc welding, thermal distortion causes deformation of the product, resulting in a deterioration in dimensional accuracy, so it is necessary to reduce thermal distortion. Furthermore, it is necessary to improve the surface and dimensional accuracy of the product.

[0009] The present invention aims to provide a method for manufacturing stainless steel and high-alloy parts, and stainless steel and high-alloy parts, which can dramatically improve the productivity and dimensional accuracy of parts that involve metal 3D additive manufacturing by arc welding, by combining cold forging and cutting of stainless steel and high-alloy parts with 3D additive manufacturing by arc welding. [Means for solving the problem]

[0010] That is, the gist of the present invention is as follows. [1] A method for manufacturing stainless steel or high-alloy parts consisting of a cold-formed portion and a three-dimensional additive manufacturing portion, characterized in that the cold-formed portion having a thickness of 6 mm or more is formed by cold forging or cold pressing, and then the three-dimensional additive manufacturing portion is formed by arc welding using a stainless steel or high-alloy welding material on the 6 mm or more thick portion of the cold-formed portion to a thickness of 10 mm or less. [2] A method for manufacturing a stainless steel or high-alloy part according to [1], characterized in that the three-dimensionally additively manufactured part is finished by cutting or grinding. [3] A method for manufacturing a stainless steel or high-alloy part consisting of a cold-formed portion and a three-dimensionally additively manufactured portion, comprising: forming the cold-formed portion having a thickness of 4 mm or more by cold forging or cold pressing; then, performing three-dimensional additive manufacturing (3D manufacturing) on ​​the 4 mm or more thick portion of the cold-formed portion by arc welding using a stainless steel or high-alloy welding material to form the three-dimensionally additively manufactured portion having a thickness of 12 mm or less; pouring a water-soluble cooling medium over the three-dimensionally additively manufactured portion within 60 seconds of the start of the three-dimensional additive manufacturing to cool it; and then finishing the three-dimensionally additively manufactured portion by cutting or grinding. [4] A method for manufacturing stainless steel / high alloy parts according to any one of [1] to [3], characterized in that the welding material is a stainless steel welding material, and the C content of the welding material is 0.15 mass% or less and the Cr content is 10 to 30 mass%.

[0011] [5] A stainless steel or high-alloy part comprising a cold-formed portion and a three-dimensional additive manufacturing portion, wherein the thickness of the cold-formed portion where the three-dimensional additive manufacturing portion is located is 4 mm or more, the thickness of the three-dimensional additive manufacturing portion is 12 mm or less, the additive manufacturing interval is 2 mm or less, and part of the surface of the part is finished by cutting or grinding. [6] A stainless steel / high alloy part according to [5], characterized in that one or both of the cold-formed part and the three-dimensional additive manufacturing part are made of stainless steel and have a C content of 0.15 mass% or less and a Cr content of 10 to 30 mass%. [7] A stainless steel or high-alloy part according to [5] or [6], characterized in that the average residual stress near the interface between the three-dimensionally additively manufactured part and the cold-formed part is 500 MPa or less. [Effects of the Invention]

[0012] The stainless steel and high-alloy parts of the present invention, which consist of a cold-formed portion and a 3D additively manufactured portion, are stainless steel and high-alloy parts that involve metal 3D additive manufacturing by arc welding. By optimally allocating the manufacturing process in combination with cold forming and cutting, the parts can be made highly productive and have dimensional accuracy, and additively manufactured products can be produced at low cost. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 10 is a diagram showing a part consisting of a cold-formed portion and a three-dimensional additive manufacturing portion, and is a diagram showing an example having a disk-shaped cold-formed portion on the bottom and a cylindrical three-dimensional additive manufacturing portion on the top.

[0014] [Figure 2] 2A and 2B are diagrams showing the part shown in FIG. 1 after further cutting, where FIG. 2A shows the relationship before and after cutting, and FIG. 2B shows the shape after cutting, as well as the position and direction of residual stress measurement near the interface between the cold-formed part and the 3D additively manufactured part.

[0015] [Figure 3] This is a macro photograph of the metal structure of the 3D additive manufacturing part after etching of the cross-section embedded polished surface of the part, showing the pitch of the additive manufacturing.

[0016] [Figure 4] These are photographs showing the typical metal structure of a stainless steel / high-alloy part consisting of a cold-formed portion and a 3D additive manufacturing portion. (A) is a photograph of the metal structure of the cold-formed portion, and (B) is a photograph of the metal structure of the 3D additive manufacturing portion. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be described with reference to FIGS. The present invention relates to a stainless steel or high-alloy part consisting of a cold-formed portion 1 and a 3D additively manufactured portion 2, and a method for manufacturing the same. The part has a cold-formed portion 1 formed by cold forging or cold pressing, and a 3D additively manufactured portion 2 formed by 3D additive manufacturing using arc welding with a stainless steel or high-alloy welding material. This enables high-precision, high-strength, and highly corrosion-resistant complex-shaped parts to be manufactured inexpensively and efficiently. Here, the 3D additively manufactured portion 2 refers to the portion formed by additive manufacturing of welded material, and the additively manufactured portion constitutes a three-dimensional shape. The 3D additively manufactured portion 2 can be identified as being made by additively manufacturing welded material because its metal structure exhibits a dendritic structure.

[0018] The 3D additive manufacturing part 2 can be formed by deposition additive manufacturing using a metal 3D printer that uses metal wire as a welding material. For example, a robotic MIG arc welding machine is used to repeatedly weld stainless steel or high-alloy wire as a welding material, continuously stacking it in a spiral shape in the welding direction 11 shown in Figure 1, and then stacking it in the stacking direction 12 shown in Figure 1, thereby producing a 3D additive manufacturing part 2 consisting of a hollow cylinder as shown in Figure 1.

[0019] Here, we define the "layering direction 12" in additive manufacturing. In a coordinate system fixed to the molded product, the movement direction of the welding machine is the welding direction 11, and the welded material 13 is arranged linearly in the welding direction 11 to form a layer 16. Further welding is repeated on the linear layer 16 (welded material 13) that has already been welded. In the case shown in Figure 1, a new welded material 13 is formed on top of the previously welded welded material 13. By sequentially repeating this process, a layered structure in which layers 16 (welded material 13) are stacked is formed. The interface between layers 16 is called the layering interface 15. Here, the direction in which the layers 16 (welded material 13) are sequentially stacked is called the "layering direction 12." The 3D additive manufacturing unit 2 is usually formed in a "plane" shape, and this surface is called the "layering surface 14" here. In the example shown in Figure 1, the layering surface 14 forms a cylindrical surface. Both the welding direction 11 and the stacking direction 12 are parallel to the stacking surface 14 , and the stacking direction 12 is perpendicular to the welding direction 11 .

[0020] The three-dimensional additive manufacturing portion 2 of the stainless steel / high alloy part manufactured in this manner is also characterized by being finished by cutting or grinding.

[0021] In order for the present invention to be economically viable compared to conventional machined products, the material itself must have cold formability and weldability from the viewpoint of material yield. This led to the idea that it would be preferable to use high-alloy materials, such as stainless steel or expensive high-alloy materials containing mainly Fe, Ni, and Cr, to produce high-alloy products.

[0022] Furthermore, by replacing the conventional base plate with a cold-formed part 1 that forms part of the part using a cold-formed product such as cold forging of the material, it was found that the work of separating it from the base plate can be omitted, making it possible to improve the efficiency of part molding.Furthermore, it was found that by specifying the size of the cold-formed part 1 and the size of the 3D additive manufacturing part 2 formed on top of the cold-formed part 1, thermal distortion can be suppressed, and when combined with cutting processing, it becomes possible to manufacture complex parts with high precision. This will be explained in detail below.

[0023] The reason for limiting the material is that stainless steel and high alloys containing a large amount of alloying elements are preferred from the viewpoint of material yield, and stainless steel and high alloys are particularly preferred from the viewpoint of high hardness, corrosion resistance, and cold forming, and are the target materials of the present invention. Here, high alloys mean alloys containing expensive elements such as Cr, Ni, and Mo as main elements.

[0024] In the present invention, a cold-formed portion 1 is first formed by cold forming, such as cold forging or cold pressing, and the cold-formed portion 1 is used as part of a component product, serving as a substrate for forming a 3D additively manufactured portion 2 on top of it by arc welding. If the thickness of the portion of the cold-formed portion 1 where the 3D additively manufactured portion 2 is to be formed is less than 6 mm, thermal distortion will occur during the next 3D additive manufacturing process by arc welding, leading to deformation of the component. For this reason, the thickness of this portion of the cold-formed portion 1 to be initially manufactured is limited to components having a thickness of 6 mm or more (preferably 8 mm or more).

[0025] Next, additive manufacturing by arc welding is performed on the portion of the cold-formed portion 1 described above that is 6 mm or thicker. If the thickness of the 3D additive manufacturing portion 2 is greater than 10 mm, a large amount of heat is transferred from the 3D additive manufacturing portion 2 to the cold-formed portion 1, resulting in significant thermal distortion of the cold-formed portion 1 and significant deformation of the part. For this reason, the thickness of the 3D additive manufacturing portion 2 is limited to 10 mm or less (preferably 8 mm or less). Note that the compositions of the cold-formed portion 1 and the 3D additive manufacturing portion 2 do not necessarily need to be the same; the effects of the present invention will be achieved as long as they are made of stainless steel or high-alloy materials.

[0026] Because the 3D additively manufactured part 2 manufactured by arc welding has poor dimensional accuracy, it is preferable to perform finishing by cutting or grinding as necessary to achieve dimensional accuracy of ±0.5 mm. Figure 2(A) shows the relationship before and after cutting, with the 3D additively manufactured part 2 before cutting indicated by a two-dot chain line and the surface-machined part 3 of the 3D additively manufactured part indicated by a solid line. Figure 2(B) shows the shape after cutting. For areas requiring dimensional accuracy, a cutting or grinding allowance of 1.5 mm or less is sufficient. Therefore, if a part has been cut or ground, the thickness of that part plus 3 mm can be estimated as the thickness of the 3D additively manufactured part 2 manufactured by arc welding.

[0027] When 3D additive manufacturing begins, heat from the additive manufacturing object is transferred to the cold-formed portion 1, causing thermal distortion and potentially resulting in part deformation. To prevent heat transfer, it is preferable to rapidly cool the object after additive manufacturing by applying a water-soluble cooling medium (preferably within 60 seconds after the start of additive manufacturing). In this case, since thermal distortion is less likely to occur, the thickness of the cold-formed portion 1 where the 3D additive manufacturing portion 2 is located can be increased in the direction of thickness reduction to 4 mm or more (preferably 6 mm or more), and the thickness of the 3D additive manufacturing portion 2 can be increased to 12 mm or less (preferably 10 mm or less). The water-soluble cooling medium can be water, a water-soluble lubricant, a water-based lubricant, or the like.

[0028] When the stainless steel or high-alloy part of the present invention is made of stainless steel, stainless steel containing 10% or more by mass of Cr and 0.15% or less by mass of C is preferred from the viewpoints of high hardness, corrosion resistance, and cold formability. On the other hand, stainless steel or high-alloy parts containing more than 35% by mass of Cr or more than 0.15% by mass of C have poor cold formability, making it difficult to manufacture a substrate for 3D additive manufacturing using near-net forging according to the present invention, or suffer from significant thermal distortion. To achieve the effects of the present invention with parts that are high in hardness and corrosion resistance, stainless steel or high-alloy parts containing 10% or more by mass and 35% or less by mass of Cr and 0.15% or less by mass (preferably 0.12% or less by mass) of C are preferred. When the stainless steel / high alloy part of the present invention is made of a high alloy, it is preferable that the high alloy mainly contains expensive elements such as 15 to 35 mass% (preferably 20 to 30 mass%) of Cr, 5 to 80 mass% or less (preferably 8 to 50 mass%) of Ni, and 10 mass% or less (preferably 7 mass% or less) of Mo, and also contains 0.15 mass% or less of C, 0.4 mass% or less of N, 50 mass% or less of Fe, and 3.0 mass% or less of other elements such as Si, Mn, Cu, W, Co, Nb, V, Al, Ti, B, N, and REM.

[0029] For the above reasons, parts manufactured using the present invention's integrated manufacturing method of cold forming, 3D additive manufacturing, rapid cooling after lamination, and cutting and grinding possess high hardness, high corrosion resistance, and excellent dimensional accuracy. Specifically, the wall thickness of the cold-formed portion of the part where the 3D additive manufacturing portion 2 is located is 4 mm or more, and the wall thickness of the 3D additive manufacturing portion 2 is 12 mm or less. In this case, to limit the amount of heat input, the additive manufacturing interval (the interval between the lamination interfaces 5 in the lamination direction 12) is preferably 2 mm or less (1.5 mm or less is even more preferable). Furthermore, finishing the 3D additive manufacturing portion 2 by cutting or grinding improves the dimensional accuracy of the part (±0.5 mm). Regarding the cold-formed portion 1 and the 3D additive manufacturing portion 2 or the additive manufacturing interval, mirror polishing and etching the cross section allows identification of the cold-formed portion 1 with cold-worked metal flow and the 3D additive manufacturing portion 2 with a solidification structure at each additive manufacturing interval. The cut or ground areas can be confirmed by observing the machined lines on the surface of the part using a surface magnifying glass or SEM. The complex-shaped parts of the present invention that meet the above requirements are characterized by high hardness, high corrosion resistance, and high dimensional accuracy at low manufacturing costs.

[0030] In order to prevent deformation of the part due to thermal strain, and particularly to improve the durability of the part (preventing fatigue, delayed fracture, etc.), it is necessary to reduce the residual stress near the bonding interface between the cold-formed part 1 and the 3D additive manufacturing part 2. If the maximum residual stress exceeds 500 MPa, it will lead to deterioration in durability, such as fatigue and delayed fracture at the interface. Therefore, it is limited to 500 MPa or less, and preferably 300 MPa or less. Manufacturing using the method of the present invention makes it possible to reduce this residual stress. [Example]

[0031] Metals containing the main alloying elements such as Ni and Cr shown in Table 1 were melted in a 45 kg vacuum melting furnace and hot forged into φ60 mm steel bars, some of which were annealed and machined to produce test pieces of φ48 mm x 5-17 mm for cold pressing. The remainder of the φ60 mm steel bars was hot extruded into wire rod with a diameter of 11 mm, which was then repeatedly drawn and annealed to produce metal wire with a diameter of φ1.2 mm, which was used as a welding material for MIG arc welding.

[0032] [Table 1]

[0033] [Table 2]

[0034] The test pieces for cold pressing were first cold-compressed into a disk shape with a thickness of 3 to 10 mm using a 1000t flat press, and the end faces were machined to create a disk-shaped cold-formed part 1 with a diameter of 60 mm and a height of 3 to 10 mm.A substrate was then fabricated on top of this for forming the 3D additive manufacturing part 2.

[0035] Next, using a robotic CMT arc welder, various prototype metal wires were used as the welding material, repeatedly stacking them in a spiral pattern in the welding direction 11 shown in Figure 1 onto the previously formed cold part 1 (diameter φ60 mm, thickness 3 to 10 mm), as shown in Figure 1. By additive manufacturing in the direction perpendicular to the cold part 1 (layering direction 12), a cylindrical shape (average diameter 30 mm) with a height of 10 to 30 mm was 3D-formed, forming a composite workpiece of the cold part 1 and the 3D additive manufacturing part 2. The head movement speed and wire feed rate of the arc welder were changed to change the thickness of the 3D additive manufacturing part 2 and the additive manufacturing interval. In addition, some parts were quenched within 60 seconds of the start of additive manufacturing by spraying water as a water-soluble coolant.

[0036] The arc welding conditions were as follows: shielding gas of Ar+3% oxygen, welding current 200A, arc voltage 20V, arc welding head movement speed 10-30mm / s, and welding material supply speed 2-8kg / h.

[0037] After cooling to room temperature, the outer periphery of the 3D additive manufacturing part 2 was finished by wet machining under the conditions of a cutting depth of 1 mm, a feed rate of 0.1 mm / rev., and a cutting speed of 100 m / min, to produce a virtual part as shown in Figure 2(B). The dimensional accuracy of the machined part was well within 0.5 mm.

[0038] For the molded parts, the thickness of the 3D additively molded part 2 was measured, and the thermal distortion, the presence or absence of cracks near the interface between the cold-formed part 1 and the 3D additively molded part 2, residual stress, metal structure, and additively molded spacing were evaluated.

[0039] Thermal distortion was measured by placing the base (cold-formed part 1) of the molded part (φ60-3~10mm) on a flat floor and measuring the maximum length of the gap between the periphery of the base and the floor. In other words, if the thermal distortion is large, the base will deform and the gap will become larger, resulting in poor dimensional accuracy of the molded part. Gap values ​​of more than 1mm were evaluated as ×, values ​​of 1mm or less but more than 0.5mm as 〇, and values ​​of 0.5mm or less as ◎.

[0040] The presence or absence of cracks near the interface between the 3D additive manufacturing part 2 and the cold formed part 1 was confirmed by observation with a magnifying glass, and the case where cracks were observed was evaluated as ×, and the case where no cracks were observed was evaluated as ◯.

[0041] Residual stress near the interface between the 3D additive manufacturing part 2 and the cold-formed part 1 was measured in a direction perpendicular to the circumferential direction of the disk surface layer using X-ray stress measurement with X-rays focused to a diameter of 1 mm at a position on the surface of the cold-formed part 1 5 mm away from the interface, as shown in Figure 2(B) as "X-ray residual stress measurement location and residual stress measurement direction 4." Tensile residual stress exceeding 500 MPa was rated as × residual stress, below 500 MPa but above 300 MPa was rated as 〇 residual stress, and below 300 MPa was rated as ◎ residual stress. Note that because the surface of the machined part is affected by the affected layer, residual stress in the surface layer of the finished cold-formed part, 5 mm away from the interface, was measured.

[0042] The additive manufacturing interval was determined by embedding the 3D additive manufacturing part 2 parallel to the lamination direction, mirror-polishing it, and then etching it using oxalic acid electrolytic etching to reveal the lamination interface 5 using the etching macropattern as shown in Figure 3, and measuring the interval between the lamination interfaces 5. The 3D additive manufacturing part exhibits a dendritic structure as shown in Figure 4(B), and the cold-formed part exhibits a cold-worked structure with metal flow as shown in Figure 4(A). The additive manufacturing interval of the present invention was 2 mm or less.

[0043] In Table 2, Examples No. 1 to 15 of the present invention have thicknesses of the cold-formed portion 1 and the three-dimensional additively formed portion 2 within the range of the present invention, whether the material is water-cooled or not after additive manufacturing. As a result of applying the manufacturing method of the present invention, it was confirmed that there was little thermal distortion, no cracking, low residual stress, and excellent dimensional accuracy.

[0044] In addition, invention examples Nos. 1 and 13 had a small thickness of the cold-formed portion 1, invention examples Nos. 3 and 15 had a large thickness of the 3D additively manufactured portion 2, and invention examples Nos. 5 and 7 had a high carbon content in the material, so they tended to have large thermal distortions and residual stresses.

[0045] In Comparative Examples 1 to 13 in Table 2, the thicknesses of the cold-formed portion 1 and the 3D additively manufactured portion 2 are outside the ranges of the present invention, resulting in large thermal distortion, high residual stress, and poor dimensional accuracy. This tendency is more pronounced in Comparative Examples 6 to 9, which have a high carbon content, and Comparative Examples 6 and 8 also exhibited cracks near the interface. [Explanation of symbols]

[0046] 1 Cold-formed section 2. 3D Additive Manufacturing Department 3. Surface cutting section of 3D additive manufacturing 4. X-ray residual stress measurement location and direction 5 Lamination interface 11 Welding direction 12 Lamination direction 13 Welding material 14 Laminated surface 16 layers

Claims

1. A method for manufacturing a stainless steel or high-alloy part consisting of a cold-formed portion and a three-dimensional additively manufactured portion, characterized in that the cold-formed portion having a portion with a thickness of 6 mm or more is formed by cold forging or cold pressing, and then the portion with a thickness of 6 mm or more of the cold-formed portion is subjected to three-dimensional additive manufacturing by arc welding using a stainless steel or high-alloy welding material to form the three-dimensional additively manufactured portion with a thickness of 10 mm or less.

2. The method for manufacturing a stainless steel or high alloy part according to claim 1, characterized in that the three-dimensional additively manufactured part is finished by cutting or grinding.

3. A method for manufacturing a stainless steel or high-alloy part comprising a cold-formed portion and a three-dimensionally additively manufactured portion, comprising: forming the cold-formed portion having a portion with a thickness of 4 mm or more by cold forging or cold pressing; then, performing three-dimensional additive manufacturing on the 4 mm or more thick portion of the cold-formed portion by arc welding using a stainless steel or high-alloy welding material to form the three-dimensionally additively manufactured portion with a thickness of 12 mm or less; pouring a water-soluble cooling medium over the three-dimensionally manufactured portion within 60 seconds from the start of the three-dimensional additive manufacturing to cool it; and then finishing the three-dimensionally additively manufactured portion by cutting or grinding.

4. The method for manufacturing a stainless steel or high alloy part according to any one of claims 1 to 3, characterized in that the weld material is a stainless steel weld material, and the C content of the weld material is 0.15 mass% or less and the Cr content is 10 to 30 mass%.

5. A stainless steel or high-alloy part comprising a cold-formed portion and a three-dimensional additive manufacturing portion, wherein the thickness of the portion of the cold-formed portion where the three-dimensional additive manufacturing portion is located is 4 mm or more, the thickness of the three-dimensional additive manufacturing portion is 12 mm or less, the additive manufacturing interval is 1 mm or more and 2 mm or less, and a portion of the surface of the part is finished by cutting or grinding.

6. The stainless steel / high alloy part according to claim 5, characterized in that one or both of the cold-formed portion and the three-dimensional additive manufacturing portion are made of stainless steel and have a C content of 0.15 mass% or less and a Cr content of 10 to 30 mass%.

7. 7. The stainless steel / high alloy part according to claim 5, wherein the average residual stress near the interface between the three-dimensionally additively manufactured part and the cold-formed part is 500 MPa or less.

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