Welded parts and manufacturing method thereof

Abstract

To improve fatigue strength of a welded part, in a welded component in which a member made of copper is joined by welding to a member composed of austenite stainless steel.SOLUTION: A welded component comprises a first member composed of austenite stainless steel, a second member composed of copper, a welded part joining the first member to the second member. The welded part includes a first region made mainly of elements included in the austenite stainless steel constituting the first member and a second region made mainly of copper, arranged to form an interface between the first region and the second region. A plurality of first bird-like regions made mainly of the elements included in the austenite stainless steel constituting the first member exist separately from each other in the second region. A plurality of second bird-like regions made mainly of copper exist separately from each other in the first region. The first region and the second region form metallic bond on the interface.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to welded components and methods of manufacturing welded components. [Background technology]

[0002] There is known a technique for joining a copper member and a steel member by welding. It is also known that an alloy of copper and iron can be used as a filler rod (filler metal) used in welding (see, for example, Patent Document 1 and Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-087688 A [Patent Document 2] JP 2020-076136 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, a copper member and a steel member can be joined by welding using a conventional method. However, when a copper member and an austenitic stainless steel member are joined by welding, there is a problem that the strength of the welded portion is insufficient. In particular, when the welded part is used in an environment where repeated stress acts, there is a problem that fatigue fracture occurs in the welded portion due to the insufficient fatigue strength of the welded portion.

[0005] Therefore, it is an object of the present disclosure to improve the fatigue strength of a welded portion in a welded component in which a member made of copper and a member made of austenitic stainless steel are joined by welding. [Means for solving the problem]

[0006] A welded component according to the present disclosure includes a first member made of austenitic stainless steel, a second member made of copper, and a welded portion joining the first member and the second member. The welded portion includes a first region mainly composed of an element contained in the austenitic stainless steel constituting the first member, and a second region mainly composed of copper and arranged to form an interface between the first region and the second region. In the second region, a plurality of first island regions mainly composed of an element contained in the austenitic stainless steel constituting the first member are present and separated from one another. In the first region, a plurality of second island regions mainly composed of copper are present and separated from one another. The first region and the second region form a metallic bond at the interface.

[0007] A method for manufacturing a welded component according to the present disclosure includes the steps of: preparing a first member made of austenitic stainless steel and a second member made of copper, supplying a filler metal into an arc formed between an electrode and the first and second members, and heating and melting the first and second members and the filler metal with the arc to form a molten pool, and solidifying the molten pool to form a weld that joins the first and second members. The filler metal contains 4.0% by mass or more and 4.9% by mass or less of iron, with the remainder being copper and unavoidable impurities. Effect of the Invention

[0008] According to the above-described welded part and manufacturing method for a welded part, in which a member made of copper and a member made of austenitic stainless steel are joined by welding, the fatigue strength of the welded portion can be improved. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the structure of a welded component. [Diagram 2] FIG. 2 is a schematic diagram showing the structure of the welded portion. [Diagram 3] FIG. 3 is a flow chart showing an outline of a method for manufacturing a welded component. [Figure 4]FIG. 4 is a schematic cross-sectional view for explaining the method for manufacturing the welded component. [Diagram 5] FIG. 5 is a schematic cross-sectional view for explaining a method for manufacturing a welded component. [Figure 6] FIG. 6 is a photograph showing the state of the welded parts after the tensile test. [Figure 7] FIG. 7 is a photograph showing the state of the welded component after the fatigue test carried out under Condition 1. [Figure 8] FIG. 8 is a photograph showing the state of the welded component after the fatigue test carried out under condition 2. [Figure 9] FIG. 9 is an optical microscope photograph showing the metal structure of the weld. [Figure 10] FIG. 10 is a diagram showing the analysis results of the distribution of elements in the welded portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Overview of the embodiment] The welded component of the present disclosure includes a first member made of austenitic stainless steel, a second member made of copper, and a welded portion that joins the first member and the second member. The welded portion includes a first region mainly composed of an element contained in the austenitic stainless steel that constitutes the first member, and a second region mainly composed of copper that is arranged to form an interface between the first region and the first region. In the second region, a plurality of first island regions mainly composed of an element contained in the austenitic stainless steel that constitutes the first member are present and separated from one another. In the first region, a plurality of second island regions mainly composed of copper are present and separated from one another. The first region and the second region form a metallic bond at the interface.

[0011] The present inventors have investigated ways to improve the fatigue strength of a welded part in which a copper member and an austenitic stainless steel member are joined by welding, and have obtained the following findings.

[0012] When a member made of copper and a member made of austenitic stainless steel are welded together, it is difficult to form a welded joint in which copper and austenitic stainless steel are uniformly mixed, and a first region containing elements contained in the austenitic stainless steel as the main component and a second region containing copper as the main component are formed so as to form an interface between the first region. In this case, by making the second region contain a plurality of first island regions containing elements contained in the austenitic stainless steel as the main component and being separated from each other, and the first region contain a plurality of second island regions containing copper as the main component and being separated from each other, the first region and the second region can be made to form a metallic bond at the interface. In such a welded joint, the fatigue strength of the welded joint is improved.

[0013] In the welded component of the present disclosure, the second region includes a plurality of first island regions mainly composed of elements contained in the austenitic stainless steel constituting the first member. The first region includes a plurality of second island regions mainly composed of copper. The first region and the second region form a metallic bond at the interface. As a result, according to the welded component of the present disclosure, in a welded component in which a member made of copper and a member made of austenitic stainless steel are joined by welding, the fatigue strength of the weld can be improved.

[0014] In the welded component, the austenitic stainless steel may be JIS standard SUS 304 or JIS standard SUS 316. SUS 304 and SUS 316 are suitable as the austenitic stainless steel constituting the first member in the welded component of the present disclosure.

[0015] In the welded part, the first member and the second member may have a tubular shape. The first member and the second member may be joined to each other at longitudinal ends by the weld. In a welded part in which members having a tubular shape are joined to each other, fatigue strength at the weld may become an issue due to the influence of a fluid flowing inside, the influence of vibration, and the like. The welded part of the present disclosure, which has improved fatigue strength at the weld, is suitable for application to such parts.

[0016] The manufacturing method of the welded component of the present disclosure includes the steps of preparing a first member made of austenitic stainless steel and a second member made of copper, supplying a filler metal into an arc formed between an electrode and the first and second members, and heating and melting the first and second members and the filler metal by the arc to form a molten pool, and solidifying the molten pool to form a weld that joins the first and second members. The filler metal contains 4.0% to 4.9% by mass of iron, with the remainder being copper and unavoidable impurities.

[0017] According to the inventors' investigations, by using a filler metal containing 4.0 mass % to 4.9 mass % iron with the remainder being copper and unavoidable impurities in arc welding, it becomes easy to achieve a state in which a plurality of first island regions are present separately from one another in the second region and a plurality of second island regions are present separately from one another in the first region, and the first region and the second region form a metallic bond. Therefore, according to the manufacturing method for a welded part disclosed herein, it is possible to improve the fatigue strength of the welded part in a welded part in which a member made of copper and a member made of austenitic stainless steel are joined by welding.

[0018] [Specific Example of the Embodiment] Next, an example of a specific embodiment of the welded component of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and the description thereof will not be repeated.

[0019] Fig. 1 is a schematic cross-sectional view showing the structure of a welded component. Fig. 2 is a schematic view showing the structure of a welded portion. Referring to Fig. 1, a welded component 1 of the present embodiment includes a first member 10 made of austenitic stainless steel, a second member 20 made of copper, and a welded portion 30 that joins the first member 10 and the second member 20 together.

[0020] For example, JIS standard SUS304 or JIS standard SUS316 can be used as the austenitic stainless steel constituting the first member 10. The second member 20 is made of pure copper, that is, copper with a purity of 99.9 mass % or more.

[0021] The first member 10 includes an outer peripheral surface 10A and an inner peripheral surface 10B. The outer peripheral surface 10A has a cylindrical surface shape. The inner peripheral surface 10B has a cylindrical surface shape having a common central axis with the outer peripheral surface 10A. The first member 10 has a through hole 10H, which is a space surrounded by the inner peripheral surface 10B. The first member 10 has a tubular shape. The first member 10 is a stainless steel pipe.

[0022] The second member 20 includes an outer peripheral surface 20A and an inner peripheral surface 20B. The outer peripheral surface 20A has a cylindrical shape with the same diameter as the outer peripheral surface 10A of the first member 10 and a common central axis. The inner peripheral surface 20B has a cylindrical shape with the same diameter as the inner peripheral surface 10B of the first member 10 and a common central axis. The inner peripheral surface 20B has a common central axis with the outer peripheral surface 20A. The second member 20 has a through hole 20H, which is a space surrounded by the inner peripheral surface 20B. The second member 20 has a tubular shape. The second member 20 is a copper pipe. The through hole 10H and the through hole 20H are in communication with each other.

[0023] The first member 10 and the second member 20 are joined to each other by a welded portion 30 at their longitudinal ends. Referring to FIG. 2, the welded portion 30 includes a first region 31 and a second region 32. An interface 33 is formed between the first region 31 and the second region 32. The second region 32 is disposed so as to form the interface 33 with the first region 31. The first region 31 is a region mainly composed of elements contained in the austenitic stainless steel constituting the first member 10. The second region 32 is a region mainly composed of copper. With the interface 33 in between, the first region 31 is disposed on the first member 10 side, and the second region 32 is disposed on the second member 20 side. The interface 33 is formed in the center of the welded portion 30 in the longitudinal direction of the welded part 1.

[0024] In the second region 32, a plurality of first island regions 321, each composed mainly of an element contained in the austenitic stainless steel constituting the first member 10, are present and separated from one another. In the first region 31, a plurality of second island regions 312, each composed mainly of copper, are present and separated from one another. The first region 31 and the second region 32 form a metallic bond at the interface 33. Here, the state in which a metallic bond is formed at the interface 33 means a state in which the lattice of metal atoms constituting the first region 31 and the lattice of metal atoms constituting the second region 32 have continuity at the interface 33.

[0025] In the welded component 1 of the present embodiment, the second region 32 contains a plurality of first island regions 321 containing as a main component an element contained in the austenitic stainless steel constituting the first member 10. The first region 31 contains a plurality of second island regions 312 containing as a main component copper. The first region 31 and the second region 32 form a metallic bond at the interface 33. As a result, the welded component 1 of the present embodiment is a welded component in which the fatigue strength of the welded portion 30 is improved.

[0026] Next, an example of a method for manufacturing the welded part 1 of the present embodiment will be described. Fig. 3 is a flow chart showing an outline of the method for manufacturing the welded part. Fig. 4 and Fig. 5 are schematic cross-sectional views for explaining the method for manufacturing the welded part.

[0027] With reference to FIG. 3, in the manufacturing method of the welded component 1 of the present embodiment, a material preparation step is first performed as step S10. In this step S10, a first member 10 made of austenitic stainless steel and a second member 20 made of copper are prepared as materials. With reference to FIG. 4, the first member 10 and the second member 20 have a hollow cylindrical shape having the same inner diameter and outer diameter, for example. The first member 10 and the second member 20 are arranged such that an end face 10C of the first member 10 and an end face 20C of the second member 20 face each other with a gap (root distance W). The end faces 10C and 20C are tapered surfaces (Bell angle θ) in which the distance between them increases as they approach the outer peripheral surface 10A and the outer peripheral surface 20A. The first member 10 and the second member 20 are arranged such that their central axes coincide with each other.

[0028] Next, a molten pool forming step is performed as step S20. In step S20, referring to Fig. 5, in a state in which an arc 71 is formed between the first member 10 and the second member 20 prepared in step S10 and the electrode 52, a filler rod 61 is supplied as a filler material into the arc 71, and the first member 10, the second member 20, and the filler rod 61 (filler material) are heated and melted by the arc 71, and a molten pool 81 is formed.

[0029] The electrode 52 is made of a high melting point metal material such as tungsten (W). The outer peripheral surface of the electrode 52 is surrounded by a hollow cylindrical nozzle 51, and the tip of the electrode 52 is exposed to the outside from the nozzle 51. The nozzle 51 and the electrode 52 constitute a welding torch 50. A shielding gas is discharged along the arrow A from the annular space between the outer peripheral surface of the electrode 52 and the inner peripheral surface of the nozzle 51 toward the outer peripheral surface 10A of the first member 10 and the outer peripheral surface 20A of the second member 20. For the shielding gas, an inert gas such as argon (Ar) can be used. A mixed gas of Ar and helium (He) may be used as the shielding gas. In addition, a back shielding gas is flowed along the arrow B in the through hole 10H and the through hole 20H. As with the shielding gas, an inert gas such as Ar or a mixed gas of Ar and He can be used as the back shielding gas.

[0030] The arc 71 is isolated from the outside air by the shielding gas being discharged along the arrow A. The filler rod 61 melts as it is heated by the arc 71, and reaches the molten pool 81 as a molten droplet 62. The molten pool 81 is composed of the molten first member 10, the molten second member 20, and the molten filler rod 61. The filler rod 61 contains 4.0 mass % or more and 4.9 mass % or less of iron, with the remainder being copper and unavoidable impurities.

[0031] Next, a solidification step is performed as step S30. In this step S30, the molten pool 81 formed in step S20 is solidified to form the welded portion 30 that joins the first member 10 and the second member 20. Specifically, the first member 10 and the second member 20 in which the molten pool 81 is formed in step S20 are rotated in the circumferential direction by a predetermined angle, for example, about 5 to 10 degrees. As a result, the arc 71 forms a new molten pool 81 in an area adjacent to the previously formed molten pool 81, and the previously formed molten pool 81 solidifies to become the welded portion 30 (bead) (see FIG. 1). This procedure is repeated to form the welded portion 30 over the entire circumference of the first member 10 and the second member 20, thereby completing the manufacturing method of the welded component 1 of this embodiment and obtaining the welded component 1 of this embodiment.

[0032] In step S20 of the manufacturing method of the welded component 1 of the present embodiment, a filler rod 61 (filler metal) containing 4.0 mass% or more and 4.9 mass% or less of iron, with the balance being copper and unavoidable impurities, is used. This makes it easy to achieve a state in which a plurality of first island regions 321 exist in the second region 32 and a plurality of second island regions 312 exist in the first region 31, and the first region 31 and the second region 32 form a metallic bond. As a result, the manufacturing method of the welded component 1 of the present embodiment can improve the fatigue strength of the welded portion 30. The filler rod 61 preferably contains 4.0 mass% or more and 4.8 mass% or less of iron, with the balance being copper and unavoidable impurities. Since the melting point of iron is higher than that of copper, in a temperature range exceeding the melting point of copper and below the melting point of iron, solid phase iron and liquid phase copper coexist. By reducing the iron content to 4.8 mass % or less, iron segregation is suppressed, which contributes to improving the strength of the welded portion 30. EXAMPLES

[0033] Welded components according to the present disclosure were fabricated, and experiments were conducted to confirm the effects of the welded components according to the present disclosure and to confirm the metal structure of the welded portion. The procedure of the experiments was as follows.

[0034] A welded part was produced by joining a straight stainless steel pipe and a straight copper pipe by the manufacturing method for the welded part described in the above embodiment. JIS standard SUS304 was used as the austenitic stainless steel constituting the first member 10. Ar gas was used as the shielding gas and back shielding gas. The diameter of the electrode 52 was 2.4 mm, and the inner diameter of the nozzle 51 was 6 mm. Tungsten (W) with 2 mass % of cerium (Ce) added was used as the material constituting the electrode 52.

[0035] The composition of the filler rod 61 was set to a composition containing 4.5 mass% iron and 95.5 mass% copper (containing 4.5 mass% iron, with the remainder being copper and unavoidable impurities) (hereinafter, may be indicated as "Cu-4.5%Fe"). For comparison, welding was also performed in the same manner to produce welded parts for the cases where the composition of the filler rod 61 was pure copper (hereinafter, may be indicated as "Cu"), a composition containing 3 mass% silicon (Si) and 97 mass% copper (containing 3.0 mass% silicon, with the remainder being copper and unavoidable impurities) (hereinafter, may be indicated as "Cu-3%Si"), and a composition containing 5 mass% tin and 95 mass% copper (containing 5.0 mass% tin, with the remainder being copper and unavoidable impurities) (hereinafter, may be indicated as "Cu-5%Sn") were used. The obtained welded parts were subjected to (1) confirmation of workability, (2) tensile tests, (3) low-temperature tensile tests, (4) corrosion tests, and (5) fatigue tests, as described below.

[0036] (1) Checking workability Welding was performed according to the procedure described in the above embodiment, and it was confirmed whether or not a good weld was achieved. If a weld was visually good, it was judged as "passed," and if a weld was not visually good, for example because a large number of voids were generated, it was judged as "failed."

[0037] (2) Tensile test A tensile test was conducted in which the welded part 1 was pulled in the longitudinal direction and broken. The test was conducted when the welded part 1 was at room temperature. If the welded part 1 broke at a place other than the welded part 30, it was judged as "passed", and if the welded part 30 broke, it was judged as "failed".

[0038] (3) Low-temperature tensile test A tensile test was conducted in which the welded part 1 was pulled in the longitudinal direction and broken. The test was conducted in a state in which the welded part 1 was cooled to -40°C. If the break occurred at a place other than the welded part 30, it was judged as "passed", and if the break occurred at the welded part 30, it was judged as "failed".

[0039] (4) Corrosion test Electrolytic etching was performed on the welded portion 30 using a 5% oxalic acid aqueous solution to check whether corrosion occurred. The electrolytic etching was performed under conditions of applying a voltage of 5 V and holding the voltage for 60 seconds. If no corrosion was observed in the welded portion 30, it was judged as "passed", and if corrosion was observed in the welded portion 30, it was judged as "failed".

[0040] (5) Fatigue test A fatigue test was conducted in which a cyclically repeated tensile stress was applied to the welded part 1 in the longitudinal direction. The cyclically repeated tensile stress was applied to the welded part 1 under two conditions: a maximum tensile stress of 126 MPa and a minimum tensile stress of 13 MPa (condition 1), and a maximum tensile stress of 137 MPa and a minimum tensile stress of 14 MPa (condition 2). The stress repetition period was 15 Hz under both conditions. The fatigue test was continued until the welded part 1 broke due to fatigue. If the break was due to a crack only in a part other than the welded part 30, it was judged as "passed", and if the break included a crack in the welded part 30, it was judged as "failed".

[0041] Next, the results of the above experiments (1) to (5) will be explained. Table 1 shows the results of the above experiments.

[0042] [Table 1]

[0043] With reference to Table 1, when a Cu-5%Sn filler rod 61 was used, many voids occurred in the welded portion 30, and so the workability was judged to be unacceptable. The welded parts 1 produced using a Cu-5%Sn filler rod 61 were excluded from the other experiments because it was clear that they would also fail a tensile test or the like. The welded parts 1 produced using a filler rod 61 other than Cu-5%Sn were judged to pass the workability as well as the tensile test and low-temperature tensile test.

[0044] Fig. 6 is a photograph showing the state after a tensile test of the welded component 1 produced using a Cu-4.5% Fe filler rod 61. As is clear from Fig. 6, the welded component 1 is fractured in an area other than the welded portion 30, specifically, in the second member 20.

[0045] Regarding the corrosion test, corrosion was confirmed in the welded part 1 produced using the Cu filler rod 61, and therefore it was determined to have failed. Specifically, obvious corrosion was confirmed in the area of ​​the welded part 30 in contact with the first member 10. Regarding the welded part 1 produced using the Cu-4.5%Fe filler rod 61 and the welded part 1 produced using the Cu-3%Si filler rod 61, no corrosion was confirmed and therefore they were determined to have passed. Regarding the welded part 1 produced using the Cu filler rod 61, since it failed the corrosion test, it was excluded from the fatigue test.

[0046] Referring to Table 1, in the fatigue test, the welded component 1 produced using the Cu-4.5%Fe filler rod 61 was judged to have passed, while the welded component 1 produced using the Cu-3%Si filler rod 61 was judged to have failed.

[0047] FIG. 7 is a photograph showing the state of the welded component 1 after the fatigue test carried out under condition 1. FIG. 8 is a photograph showing the state of the welded component 1 after the fatigue test carried out under condition 2. In FIG. 7 and FIG. 8, one each of sample 91 of the embodiment which is the welded component 1 produced using a Cu-4.5%Fe filler rod 61 and sample 92 of the comparative example which is the welded component 1 produced using a Cu-3%Si filler rod 61 is shown. In both FIG. 7 and FIG. 8, sample 91 of the embodiment is fractured due to a crack in an area other than the welded portion 30, specifically, only in the second member 20. On the other hand, sample 92 of the comparative example is fractured in a state including a crack in the welded portion 30.

[0048] In this manner, it has been confirmed that the manufacturing method of the welded component according to the present disclosure using the Cu-4.5% Fe filler rod 61 provides good results in workability, tensile tests, low-temperature tensile tests, and corrosion tests, and improves the fatigue strength of the welded portion.

[0049] Next, the state of the metal structure of the welded portion 30 was confirmed for the welded component 1 produced using a Cu-4.5%Fe filler rod 61. FIG. 9 is an optical microscope photograph showing the metal structure of the welded portion 30. FIG. 10 is a diagram showing the results of analyzing the distribution of elements in the welded portion 30 using EDS (Energy Dispersive X-ray Spectroscopy). With reference to FIGS. 9 and 10, the welded portion 30 includes a first region 31 mainly composed of elements (Fe, Cr, Ni, and Mn) contained in SUS304 constituting the first member 10, and a second region 32 mainly composed of Cu, which is disposed to form an interface 33 between the first region 31 and the second region 32. In the second region 32, a plurality of first island regions 321 mainly composed of elements contained in SUS304 are present, and in the first region 31, a plurality of second island regions 312 mainly composed of copper are present. Furthermore, since no cracks were generated in the welded portion 30 in the fatigue test, it can be determined that the first region 31 and the second region 32 form a metallic bond at the interface 33. In other words, it was confirmed that the fatigue strength of the welded portion is improved in the example sample 91 that satisfies the requirements for the welded component of the present disclosure.

[0050] The above experimental results confirm that, according to the welded part and the manufacturing method for the welded part disclosed herein, the fatigue strength of the welded part in which a copper member and austenitic stainless steel member are joined by welding is improved.

[0051] It should be understood that the embodiments and examples disclosed herein are illustrative in all respects and are not limiting in any respect. The scope of the present invention is defined by the scope of the claims, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims. [Explanation of symbols]

[0052] 1 welded part, 10 first member, 10A outer peripheral surface, 10B inner peripheral surface, 10C end face, 10H through hole, 20 second member, 20A outer peripheral surface, 20B inner peripheral surface, 20C end face, 20H through hole, 30 welded portion, 31 first region, 32 second region, 33 interface, 50 welding torch, 51 nozzle, 52 electrode, 61 filler rod, 62 molten droplet, 71 arc, 81 molten pool, 91, 92 sample, 312 second island region, 321 first island region, W root spacing, θ Berl angle.

Claims

1. A first member made of austenitic stainless steel; A second member made of copper; a weld portion that joins the first member and the second member, The welded portion is A first region mainly composed of elements contained in the austenitic stainless steel constituting the first member; a second region that is disposed to form an interface with the first region and is mainly composed of copper; a plurality of first island regions, each of which is separated from the other and mainly contains an element contained in the austenitic stainless steel constituting the first member, are present in the second region; a plurality of second island regions each mainly composed of copper are present and separated from one another within the first region; The first region and the second region form a metallurgical bond at the interface.

2. 2. The welded component according to claim 1, wherein the austenitic stainless steel is JIS SUS304 or JIS SUS316.

3. the first member and the second member have a tubular shape; The welded component according to claim 1 or 2, wherein the first member and the second member are joined to each other at longitudinal ends by the welded portion.

4. Providing a first member made of austenitic stainless steel and a second member made of copper; supplying a filler metal into an arc while forming an arc between the first member and the second member and an electrode, and heating and melting the first member, the second member, and the filler metal by the arc to form a molten pool; and solidifying the molten pool to form a weld that joins the first member and the second member. The filler metal contains 4.0% by mass or more and 4.9% by mass or less of iron, with the remainder being copper and unavoidable impurities; The welded portion formed in the step of forming the welded portion is A first region mainly composed of elements contained in the austenitic stainless steel constituting the first member; a second region that is disposed so as to form an interface between the first region and the second region and that is mainly composed of copper; Including, a plurality of first island regions, each of which is separated from the other and mainly contains an element contained in the austenitic stainless steel constituting the first member, are present in the second region; a plurality of second island regions each mainly composed of copper are present and separated from one another within the first region; The first region and the second region form a metallic bond at the interface. Manufacturing method for welded parts.

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