Laser-electric arc hybrid welding process for stainless steel ferrule joint

Abstract

The invention relates to the technical field of welding, in particular to a laser-arc hybrid welding process for a stainless steel ferrule joint, which comprises the following steps: adopting a filling material containing Cr, Ni, Mo, 0.1-0.5% of rare earth Ce and the like, and utilizing a laser and pulsed arc hybrid heat source; during welding, parameters such as the laser power of 1500-3000W and the like are set, operation is performed according to the processes of joint pretreatment, material preparation, parameter setting, hybrid welding and annealing after welding, a molten pool is purified by Ce, and the welding quality and efficiency are guaranteed. According to the process, the strength, toughness and corrosion resistance of a joint are improved through rare earth purification of a molten pool and composite heat source welding, and the porosity and deformation are reduced; welding efficiency is improved, cost is reduced, sealing performance is excellent, environmental protection benefits are remarkable, and multi-scene requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of welding, in particular to a laser arc hybrid welding process for a stainless steel ferrule joint. Background Art

[0002] Stainless steel compression fittings, as key components for pipe connections, are widely used in fields such as petrochemicals, aerospace, and nuclear power. Their welding quality directly impacts system safety and reliability. Traditional welding methods (such as TIG and MIG welding) have numerous shortcomings when welding stainless steel compression fittings, making them difficult to meet the stringent requirements of high-end applications.

[0003] From a welding quality perspective, traditional arc welding requires high heat input, which can easily lead to coarse grains in the overheated zone of the joint, reducing the joint's strength and corrosion resistance. For example, when TIG welding 304 stainless steel compression fittings, the heat-affected zone can reach 2-3mm wide, reducing hardness by 15%-20%, and making intergranular corrosion more likely to occur in corrosive environments. Furthermore, when the weld pool is inadequately protected, impurities such as oxygen and nitrogen in the air can be incorporated into the weld, forming oxide and nitride inclusions, reducing weld toughness and increasing crack susceptibility. A petrochemical company once suffered a pipeline system leak due to inclusion issues in compression fitting welds, resulting in significant economic losses.

[0004] In terms of welding efficiency, traditional welding methods have limited single-pass penetration. For compression fittings with a wall thickness of 2-3mm, multiple passes are required, resulting in low production efficiency. For example, MIG welding a 10mm diameter pipe with a 2mm wall thickness takes approximately 30 seconds per weld, and completing the entire circumference requires four to five passes, totaling over two minutes. Frequent weld pass changes are also required, making the process cumbersome. This inefficient welding method is difficult to meet the needs of large-scale industrial production.

[0005] In terms of joint sealing performance, the sealing of compression fittings relies on a tight fit between the tapered surface and the pipe. Thermal deformation during traditional welding can reduce the precision of the tapered surface, affecting the sealing effect. Statistics show that the probability of seal failure for compression fittings using traditional welding processes is approximately 3%-5%, and the failure probability is even higher under high pressure, high temperature, or vibration environments. A compression fitting seal failure in an aircraft engine piping system resulted in a fuel leak, causing a serious safety incident.

[0006] While researchers have explored laser welding technology to address these issues, single-use laser welding suffers from issues like unstable melt pools and sensitivity to assembly gaps. When the assembly gap exceeds 0.1mm, laser welding is prone to incomplete fusion defects, reducing joint strength by over 30%. Furthermore, the high laser reflectivity of stainless steel (approximately 60%-70%) results in low energy efficiency, requiring high-power lasers for effective welding and prohibitively expensive equipment.

[0007] Furthermore, existing welding filler materials have a single composition design, making it difficult to simultaneously meet the requirements of high strength, high toughness, and good corrosion resistance. Joints welded with traditional 308L welding wire exhibit poor pitting corrosion resistance in chloride-containing environments, with a pitting potential approximately 100mV lower than that of the base material. This limits the application of compression fittings in harsh corrosive environments.

[0008] With the development of high-end equipment manufacturing, higher requirements are being placed on the welding quality, efficiency, and reliability of stainless steel compression fittings. Developing a new welding process that can ensure the overall performance of the fitting while improving welding efficiency and reducing costs has become a key issue that needs to be addressed in this field. Summary of the Invention

[0009] (1) Technical problems solved In view of the deficiencies in the prior art, the present invention provides a laser arc hybrid welding process for stainless steel ferrule joints. Technical Solution

[0010] A laser arc hybrid welding process for stainless steel ferrule joints uses a filler material containing trace amounts of rare earth elements and a laser and pulse arc composite heat source. The filler material comprises, by weight percentage, 16-18% Cr, 8-10% Ni, 2-3% Mo, 1-2% Mn, 0.1-0.5% rare earth element Ce, 0.2-0.8% Ti, and the balance Fe. During welding, Ce reacts with S and P impurities in the weld pool according to the reaction formulas: 2Ce + 3S = Ce2S3, and Ce + P = CeP. The welding process steps are as follows: S1: Joint pretreatment: mechanically grind the stainless steel ferrule joint to be welded to remove the oxide film, and then clean it with acetone to remove oil stains; S2: Filler material preparation: prepare the filler material according to the above ratio and process it into welding wire with a diameter of 1.0-1.6mm; S3: Welding parameter setting: set appropriate welding parameters according to the numerical range of laser power, pulse arc current, pulse frequency, laser and arc distance, and welding speed; S4: Hybrid welding, using a paraxial hybrid welding method with laser in front and pulse arc in the back, the laser and pulse arc act on the welding part at the same time, and the filling material is fed into the molten pool; S5: Post-weld treatment: stress relief annealing treatment is performed on the weld joint at a temperature of 550-650°C for 1-2 hours, followed by cooling with the furnace.

[0011] Preferably, the stainless steel ferrule joint is made of 304 stainless steel or 316L stainless steel, and the carbon content thereof does not exceed 0.08% and 0.03% respectively.

[0012] Preferably, in step S1, the surface roughness Ra after mechanical polishing is 0.8-1.6 μm.

[0013] Preferably, 0.05-0.2% of B element is also added to the filler material to reduce the surface tension of the welding pool.

[0014] Preferably, in step S4, the protective gas is a mixed gas of 95% Ar + 5% N2, and the gas flow rate is 15-25 L / min.

[0015] Preferably, the laser is a fiber laser with a wavelength of 1064 nm and a fundamental mode beam mode.

[0016] Preferably, after step S5, the method further includes performing ultrasonic impact treatment on the weld joint, with an ultrasonic frequency of 20-40 kHz and a treatment time of 5-15 minutes.

[0017] Preferably, when setting parameters in step S3, the ratio of laser power to welding speed is adjusted according to the joint wall thickness, and the ratio range is 1000-2000 W·min / m.

[0018] Preferably, the laser arc hybrid welding process of the stainless steel ferrule joint is used in welding stainless steel ferrule joints with a pipe diameter of 10-50 mm and a wall thickness of 1-3 mm.

[0019] Preferably, when the pipe diameter is less than 20 mm, a circumferential continuous welding method is adopted; when the pipe diameter is greater than or equal to 20 mm, a segmented symmetrical welding method is adopted.

[0020] (3) Beneficial technical effects Compared with the existing technology, the beneficial effects of the present invention are: 1. The addition of the rare earth element Ce effectively purifies the molten pool by forming high-melting-point Ce2S3 and CeP compounds, removing harmful impurities such as S and P, thereby reducing inclusion content in the weld. 304 stainless steel compression fittings welded using this process achieve a tensile strength exceeding 550 MPa, higher than conventional TIG welding; an impact toughness (AKV) exceeding 100 J; and an intergranular corrosion rate of less than 0.05 mm / year. Furthermore, the addition of element B reduces the surface tension of the molten pool, resulting in a more uniform and aesthetically pleasing weld, with an undercut depth of less than 0.05 mm and a porosity below 0.5%.

[0021] 2. The synergistic effect of laser and pulsed arc increases welding speed. For a 10mm diameter, 2mm wall-thick compression fitting, a single pass can be completed, reducing welding time to under 40 seconds and significantly improving production efficiency. Furthermore, this process offers greater tolerance for assembly gaps than laser welding alone, lowering assembly precision requirements and reducing scrap rates due to assembly errors.

[0022] 3. The combined heat source welding process reduces heat input, resulting in a heat-affected zone width of only 0.5-1.0mm, effectively reducing welding deformation. After welding, the roundness error of the ferrule fitting's tapered surface is less than 0.03mm, and the cylindricity error is less than 0.02mm, significantly improving sealing performance. During pressure testing, the joints welded using this process achieved zero leakage.

[0023] 3. This process can use medium-power lasers, reducing equipment investment compared to high-power single-laser welding. Furthermore, the amount of rare earth elements added to the filler material is only 0.1%-0.5%. While this slightly increases costs, overall welding efficiency is improved, scrap rates are reduced, and total costs are reduced.

[0024] 4. Hybrid welding produces less spatter and produces less smoke and dust than traditional arc welding, improving the working environment. Furthermore, the improved joint quality extends the service life of compression fittings, reducing production losses caused by fitting replacement in fields such as petrochemicals, resulting in significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a process flow chart of laser arc hybrid welding of a stainless steel ferrule joint proposed by the present invention; Figure 2 is a line comparison chart of the tensile strength and yield strength of the embodiment and the comparative example; Figure 3 is a bar chart comparing the elongation, hardness and fatigue strength of the embodiment and the comparative example; Figure 4 is a comparison chart of the intergranular corrosion rate and the maximum pitting depth of the embodiment and the comparative example; Figure 5 It is a radar comparison chart produced after unifying the dimensions of the performance indicators of the embodiment and the comparative example. DETAILED DESCRIPTION

[0026] according to Figures 2 to 5 , the specific implementation methods of the present invention are as follows: Example

[0027] Material preparation and pretreatment Compression fitting: 304 stainless steel seamless pipe (GB / T 14976-2012) is selected. The chemical composition (wt%) is as follows: C≤0.08, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Cr 18.0-20.0, Ni 8.0-11.0. It is machined into a compression fitting with an outer diameter of 25mm and a wall thickness of 2mm. The taper surface accuracy is IT6 level and the surface roughness is Ra 0.8μm.

[0028] Filler Material: Alloy powder (purity ≥ 99.9%) is prepared by weight and processed through vacuum induction melting (1600°C, Ar shielding), atomization pulverization (particle size ≤ 150μm), cold isostatic pressing (200MPa), and sintering (1200°C, H2 atmosphere) to produce a φ1.2mm welding wire. Specific composition: Cr 17.5%, Ni 9.2%, Mo 2.8%, Mn 1.5%, Ce 0.35%, Ti 0.6%, B 0.12%, balance Fe.

[0029] Surface treatment: The area to be welded was mechanically polished with 800-grit sandpaper, then chemically polished with 10% oxalic acid solution (50°C) for 3 minutes, rinsed with deionized water, and then immersed in acetone ultrasonic cleaning (frequency 40kHz, power 300W) for 15 minutes, and finally baked in a vacuum drying oven at 120°C for 2 hours.

[0030] Welding equipment and parameter settings Laser system: IPG YLS-2000 fiber laser, wavelength 1064nm, beam quality M²=1.1, output mode TEM 00 , using 600μm core diameter optical fiber transmission, focusing lens focal length 200mm, spot diameter 0.6mm.

[0031] Arc system: Fronius TPS 500i pulsed MIG welder with a water-cooled welding gun, a wire feed mechanism with an accuracy of ±0.1 mm / s, and DCEN polarity (DC reverse polarity).

[0032] Composite device (parallel composite welding gun): self-designed parallel composite welding gun, the distance between laser and arc is adjustable (2mm), angle α=15° (laser in front, arc in the back), the inner diameter of the protective gas hood is 16mm and the length is 40mm.

[0033] Process parameters: laser power 2000W, pulse arc average current 120A (base current 60A, peak current 180A), pulse frequency 30Hz, duty cycle 50%, welding speed 1m / min, wire feeding speed 5m / min, shielding gas 95%Ar+5%N2 (purity ≥99.999%), flow rate 20L / min, back shielding gas flow rate 10L / min.

[0034] Welding operation process Assembly positioning: Assemble the two pairs of connectors coaxially, leaving a gap of 0.1mm, and use three-spot positioning welding (laser power 800W, pulse width 5ms, frequency 10Hz), with a welding point diameter of 1.5mm and a spacing of 120°.

[0035] Base welding: Start the laser and arc, preheat at a speed of 0.5m / min for 3 seconds, then switch to the set parameters for circular welding. The welding gun swing amplitude is ±1mm, the swing frequency is 2Hz, and the interlayer temperature is controlled at 80-100℃.

[0036] Filling welding: The first layer is filled in a spiral trajectory with a pitch of 1.2mm. The subsequent layers are filled in a lateral swing manner with a swing speed of 50mm / s. The thickness of each layer is 0.8mm, and a total of 2 layers are filled.

[0037] Cover welding: reduce the welding speed to 0.8m / min, increase the shielding gas flow to 25L / min, ensure that the weld surface is well-formed, with a residual height of 0.5-1.0mm.

[0038] Post-weld treatment Stress relief annealing: Place the weldment in a box-type resistance furnace, heat it to 600℃ at 150℃ / h, keep it at that temperature for 1.5 hours, cool it to 150℃ with the furnace, and then take it out of the furnace and air cool it.

[0039] Surface treatment: Polish the weld surface with a 120-mesh sandpaper belt, then passivate with a mixture of 20% nitric acid and 5% hydrofluoric acid (room temperature) for 10 minutes, and finally rinse with deionized water and dry. Example

[0040] Material preparation and pretreatment Ferrule fitting: 316L stainless steel (ASTM A312), chemical composition (wt%): C≤0.03, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Cr 16.0-18.0, Ni 10.0-14.0, Mo 2.0-3.0, outer diameter 40 mm, wall thickness 3 mm, cone surface plated with 0.02 mm thick nickel-phosphorus alloy (P content 10-12 wt%).

[0041] Filler material: Cr 18%, Ni 10%, Mo 3%, Mn 2%, Ce 0.5%, Ti 0.8%, B 0.2%, balance Fe, made into φ1.6mm welding wire.

[0042] Surface treatment: mechanical polishing to Ra 0.4μm, acetone degreasing and baking at 150℃ for 1 hour, and coating with 0.01mm thick borax coating (50% borax + 50% alcohol solution).

[0043] Welding equipment and parameter settings Laser system: Trumpf TruDisk 3000 laser, power 2500W, spot diameter 0.8mm.

[0044] Arc system: Lincoln Power Wave R450 pulsed MIG welder, current 150A (base value 80A, peak value 220A), frequency 40Hz.

[0045] Composite parameters: filament spacing 3mm, angle α=20°, welding speed 0.8m / min, wire feeding speed 6m / min, shielding gas 95%Ar+5%N2 (flow rate 25L / min).

[0046] Welding operation process Segment welding: Divide the circumference into 6 segments (60° each), use symmetrical jump welding method, the welding interval between adjacent segments is ≥2 minutes, and the interlayer temperature is ≤100℃.

[0047] Back side forming control: Use copper liner (slot width 4mm, depth 2mm) and introduce Ar gas protection to ensure good back side weld forming.

[0048] Post-weld treatment Post-weld treatment: Keep at 550℃ for 2 hours, cool to 100℃ and take out of the furnace.

[0049] Ultrasonic impact: Use HC-UIII ultrasonic impact equipment with a frequency of 30kHz, an amplitude of 10μm, a pressure of 0.4MPa, and impact a 10mm wide area on both sides of the weld at a processing speed of 50mm / min. Example

[0050] Material preparation and pretreatment Compression fitting: Thin-walled 304 stainless steel (outer diameter 10 mm, wall thickness 1 mm), bright annealed (1050°C, N2 protection), surface roughness Ra 0.2 μm.

[0051] Filler material: Cr 16%, Ni 8%, Mo 2%, Mn 1%, Ce 0.1%, Ti 0.2%, B 0.05%, balance Fe, made into φ1.0mm welding wire.

[0052] Surface treatment: chemical degreasing (NaOH 10g / L+Na2CO320g / L, 60℃, 5 minutes), rinsing with deionized water and drying.

[0053] Welding equipment and parameter settings Laser system: IPG YLR-1500-SM ​​single-mode laser, power 1500W, spot diameter 0.4mm.

[0054] Arc system: Panasonic YD-350GL5 pulse MIG welder, current 80A (base value 40A, peak value 120A), frequency 20Hz.

[0055] Composite parameters: filament spacing 1mm, angle α=10°, welding speed 1.5m / min, wire feeding speed 4m / min, shielding gas 95%Ar+5%N2 (flow rate 15L / min).

[0056] Welding operation process Micro-plasma arc assistance: 10A micro-plasma arc (Ar flow rate 3L / min) is used to preheat the area to be welded, with a distance of 2mm from the laser.

[0057] Precision wire feeding: The wire feeding mechanism is driven by a stepper motor, with a wire feeding accuracy of ±0.05mm / s and a wire extension length of 8mm.

[0058] Post-weld treatment Post-weld treatment: 650℃ for 1 hour, air cooling.

[0059] Passivation: Soak in 30% nitric acid solution (40°C) for 15 minutes, rinse with deionized water and dry.

[0060] Comparative Example Material preparation and pretreatment Compression fitting: same as 304 stainless steel in Example 1.

[0061] Filler material: ER308L welding wire (AWS A5.9), diameter 1.2mm.

[0062] Surface treatment: sandpaper polishing and then wipe with alcohol.

[0063] Welding equipment and parameter settings Welding method: TIG welding, WSME-400 inverter welding machine, DC positive connection.

[0064] Parameters: current 100A, voltage 12V, welding speed 0.3m / min, pure Ar protection (flow rate 15L / min).

[0065] Welding operation process Base welding: Use broken arc method, each weld length is 5mm, and burn back for 1 second when closing the arc.

[0066] Filling cover: Weld in 3 layers, clean with a wire brush after each layer.

[0067] Post-weld treatment Natural cooling without annealing.

[0068] Performance test results comparison In various performance tests, the examples and the comparative examples showed significant differences. In terms of tensile strength, Examples 1, 2, and 3 achieved 585 MPa, 630 MPa, and 540 MPa, respectively, all exceeding the comparative example's 445 MPa. In terms of yield strength, Examples 1, 2, and 3 achieved 420 MPa, 460 MPa, and 390 MPa, respectively, compared to the comparative example's 320 MPa. The examples also outperformed the comparative example.

[0069] In terms of elongation, Example 1 was 45%, Example 2 was 42%, and Example 3 was 48%, while the comparative example was 35%, showing that the examples had a higher elongation. In the hardness test, Example 1 had a hardness of 205 HV, Example 2 had a hardness of 215 HV, and Example 3 had a hardness of 190 HV, while the comparative example had a hardness of 170 HV.

[0070] In terms of intergranular corrosion rate, Example 1 is 0.028 mm / year, Example 2 is 0.015 mm / year, and Example 3 is 0.035 mm / year, while the comparative example reaches 0.16 mm / year, indicating a lower corrosion rate. In terms of fatigue strength, Example 1 is 185 MPa, Example 2 is 210 MPa, Example 3 is 160 MPa, and the comparative example is 115 MPa, indicating greater fatigue strength.

[0071] In terms of welding deformation, Example 1 is 0.05 mm, Example 2 is 0.08 mm, and Example 3 is 0.03 mm, while the comparative example is 0.25 mm. The examples have smaller welding deformation. In terms of porosity, Example 1 is 0.2%, Example 2 is 0.1%, and Example 3 is 0.3%, while the comparative example is 1.8%, showing even lower porosity. In terms of welding efficiency, Example 1 is 4.2 cm² / min, Example 2 is 3.5 cm² / min, and Example 3 is 5.0 cm² / min, while the comparative example is 1.2 cm² / min. The examples have higher welding efficiency.

[0072] After immersion in a 3.5 wt % NaCl solution for 720 hours, the pitting potential of Example 1 was +280 mV (SCE), and the maximum pitting depth was 5 μm; the pitting potential of Example 2 was +320 mV, and no pitting occurred. In Example 3, the pitting potential was +250 mV, and the maximum pitting depth was 8 μm. In the comparative example, the pitting potential was +120 mV, and the maximum pitting depth was 50 μm, with local intergranular corrosion.

[0073] The performance test results of the embodiment and the comparative example are compared in the following table: Table 1 Test items Example 1 Example 2 Example 3 Comparative Example Tensile strength (MPa) 585 630 540 445 Yield strength (MPa) 420 460 390 320 Elongation (%) 45 42 48 35 Hardness (HV) 205 215 190 170 Fatigue strength (MPa) 185 210 160 115 Welding deformation (mm) 0.05 0.08 0.03 0.25 Porosity (%) 0.2 0.1 0.3 1.8 Welding efficiency (cm² / min) 4.2 3.5 5.0 1.2 Conclusion: The performance of all three examples significantly outperformed the comparative examples. Example 2 achieved the highest tensile strength and yield strength, reaching 630 MPa and 460 MPa, respectively; Example 1 achieved the best hardness, 205 HV; and Example 3 achieved the best elongation, 48%. The comparative examples, due to their lack of rare earth elements and the composite welding process, exhibited significantly lower strength, ductility, and hardness.

[0074] The functional indicators of the embodiment and the comparative example are compared in the following table: Table 2 sample Example 1 Example 2 Example 3 Comparative Example Intergranular corrosion rate (mm / year) 0.028 0.015 0.035 0.16 Pitting potential (mV, SCE) +280 +320 +250 +120 Maximum pitting depth (μm) 5 0 8 50 Conclusion: The corrosion resistance of the examples is much stronger than that of the comparative examples. The intergranular corrosion rate of Example 2 is as low as 0.015 mm / year, and no pitting occurs. The pitting potentials of Examples 1 and 3 are +280 mV and +250 mV, respectively, and the maximum pitting depths are relatively small. The comparative example has an intergranular corrosion rate as high as 0.16 mm / year, a low pitting potential, and a maximum pitting depth of 50 μm, indicating poor corrosion resistance.

[0075] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A laser arc hybrid welding process for stainless steel ferrule joints, characterized in that: A filler material containing trace amounts of rare earth elements is used, and a laser and pulse arc composite heat source is employed; the filler material comprises, by weight percentage, 16-18% Cr, 8-10% Ni, 2-3% Mo, 1-2% Mn, 0.1-0.5% rare earth element Ce, 0.2-0.8% Ti, and the balance Fe; during welding, Ce reacts with S and P impurities in the weld pool, and the reaction formulas are: 2Ce + 3S = Ce2S3, and Ce + P = CeP; The welding process steps are as follows: S1: Joint pretreatment: mechanically grind the stainless steel ferrule joint to be welded to remove the oxide film, and then clean it with acetone to remove oil stains; S2: Filler material preparation: prepare the filler material according to the above ratio and process it into welding wire with a diameter of 1.0-1.6mm; S3: Welding parameter setting: set appropriate welding parameters according to the numerical range of laser power, pulse arc current, pulse frequency, laser and arc distance, and welding speed; S4: Hybrid welding, using a paraxial hybrid welding method with laser in front and pulse arc in the back, the laser and pulse arc act on the welding part at the same time, and the filling material is fed into the molten pool; S5: Post-weld treatment: stress relief annealing treatment is performed on the weld joint at a temperature of 550-650°C for 1-2 hours, followed by cooling with the furnace.

2. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 1, characterized in that: The stainless steel ferrule joint is made of 304 stainless steel or 316L stainless steel, and the carbon content of 304 stainless steel does not exceed 0.08%, and the carbon content of 316L stainless steel does not exceed 0.03%.

3. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 2, characterized in that: In step S1, the surface roughness Ra after mechanical polishing is 0.8-1.6 μm.

4. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 3, characterized in that: 0.05-0.2% of B element is also added to the filler material to reduce the surface tension of the welding pool.

5. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 4, characterized in that: In step S4, the protective gas is a mixed gas of 95% Ar + 5% N2, and the gas flow rate is 15-25 L / min.

6. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 5, characterized in that: The laser is a fiber laser with a wavelength of 1064 nm and a beam mode of a fundamental mode.

7. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 6, characterized in that: After step S5, the method further includes performing ultrasonic impact treatment on the weld joint, with an ultrasonic frequency of 20-40 kHz and a treatment time of 5-15 minutes.

8. The laser arc hybrid welding process for stainless steel ferrule joints according to claim 7, characterized in that: When setting parameters in step S3, the ratio of laser power to welding speed is adjusted according to the joint wall thickness, and the ratio range is 1000-2000W·min / m.

9. Application of the laser arc hybrid welding process for stainless steel ferrule joints according to claim 8 in welding stainless steel ferrule joints with a pipe diameter of 10-50 mm and a wall thickness of 1-3 mm.

10. Application of the laser arc hybrid welding process for stainless steel ferrule joints according to claim 9, characterized in that: When the pipe diameter is less than 20mm, the circumferential continuous welding method is adopted; when the pipe diameter is greater than or equal to 20mm, the segmented symmetrical welding method is adopted.

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