A method for forming and microstructure control of a medium thickness gh4169 / ss304 weld

Abstract

The application relates to a method for forming and regulating the structure of a medium-thickness GH4169 / SS304 weld, and belongs to the technical field of heterogeneous metal connection. The application aims to solve the problem that, in the existing laser welding of medium-thickness heterogeneous metals, the structure asymmetry caused by the material difference and non-uniform solidification cannot be inhibited while ensuring sufficient penetration and good surface forming. The method comprises the following steps: 1, assembling the heterogeneous metal components to be welded; 2, vacuumizing; and 3, swinging laser welding. The application is suitable for the forming and structure regulation of a medium-thickness GH4169 / SS304 weld.

Description

Technical Field

[0001] This invention belongs to the field of heterogeneous metal joining technology. Background Technology

[0002] Dissimilar metal welding can comprehensively utilize the advantages of different metal materials in terms of strength, corrosion resistance, heat resistance, high temperature resistance, electrical and thermal conductivity, cost, and functional compatibility, and has significant application value in high-end manufacturing fields such as aerospace, energy equipment, and nuclear power. As equipment structures develop towards lightweight, high load-bearing, high reliability, and multi-functional integration, the demand for high-quality welding of medium-thickness dissimilar metal components is becoming increasingly prominent. However, compared with homogeneous metal welding, dissimilar metal welding not only needs to solve macroscopic forming problems such as insufficient penetration, inadequate interface fusion, porosity, and spatter, but also faces more complex problems of uneven weld microstructure, especially the asymmetry of weld microstructure caused by differences in the base materials on both sides.

[0003] The asymmetry in the microstructure of dissimilar metal welds primarily stems from differences in chemical composition, melting point, boiling point, thermal conductivity, coefficient of linear expansion, liquid metal fluidity, grain size, and crystal orientation between the two base metals. Under the influence of welding thermal cycling, the melting, heat conduction, and solidification behaviors of the two base metals differ, resulting in significant asymmetry in the temperature field, flow field, composition field, and solidification front within the molten pool. During solidification, the grains at the fusion line on both sides of the weld often undergo associative crystallization based on the base metal grains. When the grain size and crystal orientation of the two base metals differ significantly, problems such as preferential growth of columnar crystals on one side, different degrees of grain orientation inheritance, inconsistent dendrite growth directions, microstructure shift in the weld center region, and mismatch in grain size and texture intensity between the two sides are likely to occur. For dissimilar metal systems containing easily segregating elements or those prone to forming low-melting-point eutectic phases or brittle intermetallic compounds, the aforementioned microstructure asymmetry can further induce compositional segregation, local enrichment of brittle phases, increased crack susceptibility, and inhomogeneous mechanical properties.

[0004] In medium-thickness dissimilar metal welds, the problem of microstructure asymmetry is more prominent. On the one hand, medium-thickness components require a large penetration capability during welding, and the welding heat source needs to form a stable, deep keyhole to ensure sufficient fusion at the weld root. On the other hand, during the welding process of forming the deep keyhole, the dynamic behavior of the keyhole and the molten pool is more intense, with significant differences in temperature gradient, flow velocity, and solidification conditions along the depth direction of the molten pool, easily leading to asynchronous microstructure evolution in the upper, middle, and root parts of the weld. Simultaneously, the different absorption, melting, and mixing capabilities of the base materials on both sides of the dissimilar metal to laser energy make it difficult to maintain a balanced distribution of heat input and elemental mixing within the weld cross-section, thus exacerbating the asymmetry of the weld microstructure in the transverse and depth directions. Therefore, the key challenge in welding medium-thickness dissimilar metals is not simply achieving sufficient penetration depth, but rather suppressing the microstructure asymmetry caused by differences in base materials and non-uniform solidification while ensuring sufficient penetration and good surface formation.

[0005] Conventional atmospheric laser welding offers advantages such as high energy density, fast welding speed, and small heat-affected zone. However, in welding medium-thickness dissimilar metals, simply increasing laser power to achieve greater penetration often enhances metal vapor plume, spatter, and keyhole fluctuations, leading to decreased welding process stability and an extremely narrow window for high-quality weld formation. Furthermore, it often requires high welding heat input, failing to meet the requirements of narrow heat-affected zones and high aspect ratios in high-end equipment manufacturing. Low-vacuum laser welding can significantly improve weld penetration and surface quality by suppressing metal vapor plume above the keyhole and its attenuation of laser energy, thereby improving laser energy coupling efficiency and reducing the material boiling point to some extent. However, the low-vacuum environment primarily improves welding energy transmission and the macroscopic forming process; it lacks the ability to actively control the mixing of components within the molten pool, grain competitive growth, and solidification orientation. Therefore, low-vacuum laser welding alone is insufficient to fully address the asymmetric microstructure of dissimilar metal welds. Summary of the Invention

[0006] This invention aims to address the problem in existing medium-thickness dissimilar metal laser welding that cannot simultaneously ensure sufficient penetration and good surface formation while suppressing microstructure asymmetry caused by differences in base materials and non-uniform solidification. It provides a method for forming and microstructure control suitable for medium-thickness GH4169 / SS304 welds.

[0007] A method for forming and microstructure control of medium-thickness GH4169 / SS304 welds, comprising the following steps:

[0008] I. Assembly of dissimilar metal components to be welded:

[0009] The GH4169 and SS304 metal base materials are assembled and fixed with a fixture to obtain the dissimilar metal components to be welded.

[0010] II. Vacuuming:

[0011] Place the dissimilar metal component to be welded in a sealed welding chamber, or cover the area to be welded with a local sealed vacuum cover, and start the vacuum system to evacuate.

[0012] III. Oscillating Laser Welding:

[0013] A method for shaping and microstructure control of dissimilar metal components to be welded is to perform oscillating laser welding and finally cool the weld. This method is applicable to medium-thickness GH4169 / SS304 welds.

[0014] The oscillation frequency of the oscillation laser welding is 50Hz~120Hz, and the oscillation amplitude is 0.5mm~1.2mm.

[0015] The beneficial effects of this invention are:

[0016] The method of this invention utilizes a low vacuum environment to enhance the penetration ability of the weld and improve the surface formation of the weld. At the same time, it uses a oscillating laser to periodically stir and reconstruct the thermal field of the molten pool, suppressing the dominant growth of unilateral syngenetic crystals and promoting the homogenization of the molten pool composition, temperature and solidification structure. Ultimately, it obtains a heterometallic weld with large penetration depth, excellent formation and uniform structure.

[0017] 1. Improve weld penetration. A low vacuum environment can weaken the shielding effect of metal vapor plume on the laser and improve keyhole stability, which is beneficial for obtaining greater penetration depth at the same or lower line energy.

[0018] 2. Improve weld surface formation and internal quality. The low vacuum environment reduces plume disturbance and keyhole collapse probability, which helps to reduce forming defects such as spatter and undercut, resulting in a smoother and cleaner weld surface.

[0019] 3. Suppressing microstructure asymmetry in dissimilar metal welds. The oscillating laser energy field periodically alters the heat input position and molten pool flow path, enabling more thorough heat and composition exchange between the base metals on both sides in the weld center region. This changes the solidification front morphology and weakens the directional growth of columnar crystals, thereby mitigating the uneven co-crystallization caused by differences in grain orientation and size between the base metals on both sides. The oscillating laser also refines the microstructure and improves weld uniformity.

[0020] 4. Achieve coordinated control of macroscopic forming and microstructure. The vacuum environment and the synchronous action of the oscillating laser can produce high-quality dissimilar metal welds with large penetration depth, narrow heat-affected zone, low defects, and uniform microstructure. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the structure of the device used for vacuum oscillating laser welding in the method of the present invention. 1 is a vacuum control unit, 2 is a vacuum pump group, 3 is a vacuum chamber, 4 is a transmission optical fiber, 5 is a laser, 6 is a fixture, 7 is a dissimilar metal component to be welded, and 8 is a laser welding head with an oscillation module.

[0022] Figure 2 This is a schematic diagram of the welding joint form of the GH4169 metal base material and SS304 metal base material assembled in step one of the present invention. 9 and 11 are GH4169 metal base materials in two types of lock-bottom butt joints, 10 and 12 are SS304 metal base materials in two types of lock-bottom butt joints, 13 is GH4169 metal base material in type I bevel butt joint, and 14 is SS304 metal base material in type I bevel butt joint.

[0023] Figure 3 This is a schematic diagram of the swing pattern in step three of embodiments one to three. 15 is linear swing, 16 is circular swing, 17 is infinite swing, and 18 is swing amplitude.

[0024] Figure 4 The images show the weld surfaces and cross-sections of GH4169 / SS304 welded parts prepared in Examples 1 to 3 and Comparative Experiments 1 to 2. 19 shows the Comparative Experiment 2 at normal pressure without oscillation, 20 shows the Comparative Experiment 1 in vacuum without oscillation, 21 shows the Vacuum Linear Pendulum in Example 1, 22 shows the Vacuum Circular Pendulum in Example 3, and 23 shows the Vacuum ∞ Pendulum in Example 2.

[0025] Figure 5 24 shows the EBSD microstructure of the weld seam of the GH4169 / SS304 welded parts prepared in Examples 1 to 3 and Comparative Experiment 1; 25 shows the vacuum non-oscillating structure in Comparative Experiment 1; 26 shows the vacuum linear oscillating structure in Example 1; 27 shows the vacuum ∞ oscillating structure in Example 2; and 28 shows the vacuum circular oscillating structure in Example 3.

[0026] Figure 6 This is a schematic diagram of the bottom locking connection in step one of the embodiments. 28 is the bottom locking depth, 29 is the bottom locking width, and 30 is the thickness of the base material. Detailed Implementation

[0027] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0028] Specific implementation method one, combined with Figure 1 Detailed explanation: This embodiment describes a method for forming and controlling the microstructure of medium-thickness GH4169 / SS304 welds, which is carried out according to the following steps:

[0029] I. Assembly of dissimilar metal components to be welded:

[0030] The GH4169 and SS304 metal base materials are assembled and fixed with a fixture to obtain the dissimilar metal components to be welded.

[0031] II. Vacuuming:

[0032] Place the dissimilar metal component to be welded in a sealed welding chamber, or cover the area to be welded with a local sealed vacuum cover, and start the vacuum system to evacuate.

[0033] III. Oscillating Laser Welding:

[0034] A method for shaping and microstructure control of dissimilar metal components to be welded is to perform oscillating laser welding and finally cool the weld. This method is applicable to medium-thickness GH4169 / SS304 welds.

[0035] The oscillation frequency of the oscillation laser welding is 50Hz~120Hz, and the oscillation amplitude is 0.5mm~1.2mm.

[0036] This embodiment, after setting conventional laser welding parameters to ensure the required weld penetration, sets oscillating laser parameters to cause the laser focus to oscillate periodically relative to the welding centerline along a predetermined trajectory. The laser oscillation mode is the movement trajectory of the laser focus during welding, which can be circular, linear, transverse reciprocating, figure-eight, or infinity-shaped. The principle for setting the oscillation parameters is: the oscillation amplitude should cover the weld centerline; the oscillation frequency should create a continuous thermal zone between adjacent oscillation trajectories; and the oscillation mode should preferably be one that can reciprocate and stir the molten material at both ends of the weld pool. Furthermore, the oscillation parameters significantly affect the symmetry of the microstructure, eliminating asymmetry. Without causing severe surface spatter, a larger oscillation amplitude and frequency yield better results.

[0037] In this embodiment, a continuous laser output and a oscillating scanning module are simultaneously activated in a low-vacuum environment. This allows the vacuum environment to regulate plume, keyhole, and penetration capability, while the oscillating laser regulates the temperature and flow fields of the molten pool. During welding, the vacuum environment reduces the shielding of laser energy by plume and improves keyhole stability; the oscillating laser periodically changes the local heat input position and molten pool flow direction, promoting the mixing of the base metal melts on both sides, suppressing elemental segregation, and weakening the inheritance of unilateral grain orientation and the directional growth of columnar crystals through molten pool stirring.

[0038] The beneficial effects of this embodiment are:

[0039] This method utilizes a low-vacuum environment to enhance weld penetration and improve weld surface formation. Simultaneously, it employs a oscillating laser to periodically stir and reconstruct the thermal field of the molten pool, suppressing the dominant growth of unilateral associative crystals and promoting the homogenization of molten pool composition, temperature, and solidification structure. Ultimately, it yields a heterometallic weld with deep penetration, excellent formation, and uniform microstructure.

[0040] 1. Improve weld penetration. A low vacuum environment can weaken the shielding effect of metal vapor plume on the laser and improve keyhole stability, which is beneficial for obtaining greater penetration depth at the same or lower line energy.

[0041] 2. Improve weld surface formation and internal quality. The low vacuum environment reduces plume disturbance and keyhole collapse probability, which helps to reduce forming defects such as spatter and undercut, resulting in a smoother and cleaner weld surface.

[0042] 3. Suppressing microstructure asymmetry in dissimilar metal welds. The oscillating laser energy field periodically alters the heat input position and molten pool flow path, enabling more thorough heat and composition exchange between the base metals on both sides in the weld center region. This changes the solidification front morphology and weakens the directional growth of columnar crystals, thereby mitigating the uneven co-crystallization caused by differences in grain orientation and size between the base metals on both sides. The oscillating laser also refines the microstructure and improves weld uniformity.

[0043] 4. Achieve coordinated control of macroscopic forming and microstructure. The vacuum environment and the synchronous action of the oscillating laser can produce high-quality dissimilar metal welds with large penetration depth, narrow heat-affected zone, low defects, and uniform microstructure.

[0044] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the GH4169 and SS304 metal base materials mentioned in step one are obtained after mechanical grinding and cleaning. Everything else is the same as in Specific Implementation Method One.

[0045] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the thickness of the GH4169 metal base material and SS304 metal base material mentioned in step one is 4.5mm~20mm. Everything else is the same as in Specific Implementation Method One or Two.

[0046] Specific implementation method four, combined with Figure 2 Specific explanation: This embodiment differs from one of the specific embodiments one to three in that: in step one, the GH4169 metal base material and the SS304 metal base material are assembled using an I-bevel joint or a lock-bottom joint. Everything else is the same as in specific embodiments one to three.

[0047] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the weld gap of the dissimilar metal components to be welded in step one is 0mm to 0.2mm. Everything else is the same as in Specific Implementation Methods One to Four.

[0048] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step two, the vacuum system is activated, and the vacuum is evacuated until the ambient pressure in the welding area is ≤1 kPa. Everything else is the same as in Specific Implementation Methods One to Five.

[0049] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that, in step three, the laser beam is aligned with the center of the weld interface of the dissimilar metal components to be welded. Everything else is the same as in Specific Implementation Methods One to Six.

[0050] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that, in step three, under the conditions of a laser power of 3kW~4.5kW, a welding speed of 0.4m / min~1.2m / min, and a defocusing amount of -2mm~-6mm, oscillating laser welding is performed on the dissimilar metal components to be welded. Everything else is the same as in Specific Implementation Methods One to Seven.

[0051] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the oscillation mode of the oscillating laser welding described in step three is circular, linear, figure-eight, or infinity-shaped. Everything else is the same as in Specific Implementation Methods One to Eight.

[0052] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the cooling described in step three specifically involves cooling the workpiece within the cavity to between room temperature and 60°C before removing it. Everything else is the same as in Specific Implementation Methods One to Nine.

[0053] The beneficial effects of the present invention are verified using the following embodiments:

[0054] Example 1, combined with Figure 3 and 6 Detailed explanation:

[0055] A method for forming and microstructure control of medium-thickness GH4169 / SS304 welds, comprising the following steps:

[0056] I. Assembly of dissimilar metal components to be welded:

[0057] The GH4169 metal base material and the SS304 metal base material are assembled in a lock-bottom butt joint manner and fixed by a fixture to obtain the dissimilar metal component to be welded.

[0058] The thickness of both the GH4169 metal base material and the SS304 metal base material is 10mm;

[0059] The lock bottom depth of the lock bottom is 6mm, and the lock bottom width is 4mm;

[0060] The weld gap of the dissimilar metal components to be welded is 0 mm, and the misalignment is 0 mm.

[0061] II. Vacuuming:

[0062] Place the dissimilar metal components to be welded in a sealed vacuum chamber, start the vacuum system, and evacuate until the ambient pressure in the welding area is 1 kPa.

[0063] III. Oscillating Laser Welding:

[0064] The laser beam is aligned with the center of the weld interface of the dissimilar metal components to be welded. Under the conditions of laser power of 3.5kW, welding speed of 0.6m / min and defocusing amount of -6mm, the dissimilar metal components to be welded are subjected to oscillating laser welding. Finally, after cooling to room temperature in the cavity, the welded parts are removed to obtain GH4169 / SS304 welded parts.

[0065] The oscillation frequency of the oscillation laser welding is 100Hz, and the oscillation amplitude is 1mm.

[0066] The GH4169 and SS304 metal base materials mentioned in step one are obtained by mechanical grinding and cleaning with anhydrous ethanol to remove oxide film, oil and water stains from the upper surface and mating surface.

[0067] The oscillation mode of the oscillating laser welding described in step three is linear oscillation.

[0068] Example 2: This example differs from Example 1 in that the oscillation mode of the oscillating laser welding described in step 3 is an ∞-shaped oscillation. Everything else is the same as in Example 1.

[0069] Example 3: This example differs from Example 1 in that the oscillation mode of the oscillating laser welding described in step 3 is circular oscillation. Everything else is the same as in Example 1.

[0070] Comparative Experiment 1: This comparative experiment differs from Example 1 in that the laser welding oscillation is eliminated in step three. Everything else is the same as in Example 1.

[0071] Comparative Experiment 2: This comparative experiment differs from Example 1 in that: in step 2, the vacuuming was cancelled, and the environmental pressure was set to atmospheric pressure (101 kPa); in step 3, the oscillation was cancelled. Everything else is the same as in Example 1.

[0072] Figure 4The figures show the weld surfaces and cross-sections of GH4169 / SS304 welded parts prepared in Examples 1 to 3 and Comparative Experiments 1 to 2. Figure 19 shows Comparative Experiment 2 with no oscillation under normal pressure; Figure 20 shows Comparative Experiment 1 with no oscillation under vacuum; Figure 21 shows Comparative Experiment 1 with a vacuum linear pendulum; Figure 22 shows Comparative Experiment 3 with a vacuum circular pendulum; and Figure 23 shows Comparative Experiment 2 with a vacuum ∞ pendulum. As shown in the figures, the weld width in Comparative Experiment 2 is 3.42 mm and the weld depth is 4.33 mm; the weld width in Comparative Experiment 1 is 1.62 mm and the weld depth is 10 mm; and the weld width in Comparative Experiment 1 is 3.70 mm and the weld depth is 9.52 mm. Example 3: weld width: 2.92 mm, weld depth: 8.64 mm; Example 2: weld width: 2.66 mm, weld depth: 9.15 mm; Comparison of Experiment 2 and Experiment 1 shows that a vacuum environment can significantly improve both the surface forming quality and penetration ability of the joint. Comparison of Experiment 1 and Examples 1 to 3 shows that oscillating laser welding in a vacuum environment can significantly increase the weld width. Oscillating laser welding in a vacuum will slightly increase the tendency of spatter on the weld surface. Under the same parameters, the circular oscillating surface forming quality is the best, with almost no spatter.

[0073] Figure 5 Figure 1 shows the EBSD microstructure of the weld seam of the GH4169 / SS304 welded parts prepared in Examples 1 to 3 and Comparative Experiment 1. Figure 24 shows the vacuum non-oscillating microstructure of Comparative Experiment 1, Figure 25 shows the vacuum linear oscillating microstructure of Example 1, Figure 26 shows the vacuum infinite oscillating microstructure of Example 2, and Figure 27 shows the vacuum circular oscillating microstructure of Example 3. As shown in the figures, the linear oscillating mode used in Example 1 can weaken the uneven co-growth caused by the difference in grain orientation and grain size between the two base materials. At this time, the grain size of the weld seam is 56.7 μm, of which the grain size on the left side (SS304 side) is 53.4 μm and the grain size on the right side (GH4169 side) is 60.2 μm. Example 2 can weaken the uneven co-growth caused by the difference in grain orientation and grain size between the two base materials and refine the grains. At this time, the grain size of the weld seam is 47.1 μm, of which the grain size on the left side (SS304 side) is 43.2 μm and the grain size on the right side (GH4169 side) is 51.0 μm. Example 3 effectively mitigates the uneven co-crystallization caused by differences in grain orientation and size between the two base metals, and refines the grains. In this case, the weld grain size is 45.2 μm, with the left side (SS304 side) having a grain size of 44.8 μm and the right side (GH4169 side) having a grain size of 46.4 μm. In contrast, Experiment 1 showed significant asymmetry in the dissimilar metal weld, with the left side (SS304 side) having a grain size of 50.5 μm and the right side (GH4169 side) having a grain size of 80.5 μm.

[0074] Three sets of room temperature tensile tests were conducted on the GH4169 / SS304 welded parts prepared in Examples 1 to 3 and Comparative Experiment 1 using an Instron electronic universal testing machine (model Instron 5980). The results are shown in Table 1 below.

[0075] Table 1

[0076]

[0077] Among them, the mechanical property test is based on AWS B4.0M:2000 (R2010), and the elongation after fracture is the percentage of the length of the gauge length of the specimen to the original gauge length when the specimen is tensilely fractured.

[0078] As shown in Table 1, the welded joints of GH4169 / SS304 obtained in Examples 1 to 3 exhibit excellent strength properties, with a room temperature tensile strength > 713 MPa and an elongation after fracture > 23.8%, reaching more than 87% of the strength of the GH4169 base material (818.4 MPa). Compared with the mechanical properties improved significantly by the non-oscillating process parameters in Experiment 1, the improvement is more pronounced.

Claims

1. A method for forming and microstructure control of medium-thickness GH4169 / SS304 welds, characterized in that... It is done in the following steps: I. Assembly of dissimilar metal components to be welded: The GH4169 and SS304 metal base materials are assembled and fixed with a fixture to obtain the dissimilar metal components to be welded. II. Vacuuming: Place the dissimilar metal component to be welded in a sealed welding chamber, or cover the area to be welded with a local sealed vacuum cover, and start the vacuum system to evacuate. III. Oscillating Laser Welding: A method for shaping and microstructure control of dissimilar metal components to be welded is to perform oscillating laser welding and finally cool the weld. This method is applicable to medium-thickness GH4169 / SS304 welds. The oscillation frequency of the oscillation laser welding is 50Hz~120Hz, and the oscillation amplitude is 0.5mm~1.2mm.

2. The method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... The GH4169 and SS304 metal base materials mentioned in step one are obtained after mechanical grinding and cleaning.

3. The method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... The thickness of both the GH4169 and SS304 metal base materials mentioned in step one is 4.5mm to 20mm.

4. The method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... In step one, the GH4169 metal base material and the SS304 metal base material are assembled in the form of I-bevel butt joint or lock bottom butt joint.

5. The method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... The weld gap of the dissimilar metal components to be welded in step one is 0mm~0.2mm.

6. The method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... In step two, start the vacuum system and evacuate until the ambient pressure in the welding area is ≤1kPa.

7. The method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... In step three, the laser beam is aligned with the center of the weld interface of the dissimilar metal component to be welded.

8. A method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... In step three, under the conditions of laser power of 3kW~4.5kW, welding speed of 0.4m / min~1.2m / min and defocusing amount of -2mm~-6mm, the dissimilar metal components to be welded are subjected to oscillating laser welding.

9. A method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... The oscillation mode of the oscillating laser welding described in step three is circular, linear, figure-eight, or infinity.

10. A method for forming and microstructure control of medium-thickness GH4169 / SS304 welds according to claim 1, characterized in that... The cooling process described in step three specifically involves cooling the weldment within the cavity to between room temperature and 60°C before removing it.

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