A welding method and device for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint

Abstract

The application provides a welding method and device for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint, and belongs to the technical field of welding. The method solves the problem that the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint are difficult to be considered simultaneously. The welding method comprises the following steps: pretreating a low-nickel high-nitrogen austenitic stainless steel plate to be welded, clamping and assembling two low-nickel high-nitrogen austenitic stainless steel plates after pretreatment in a welding clamp, adjusting the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates, and preparing for welding; turning on the power supply of a welding machine, controlling the welding heat input, opening a protective gas cylinder to introduce protective gas, installing welding wire used for welding into a wire feeder, setting welding parameters and the relative position of a welding torch and a weld, setting the motion track of a welding motion mechanism, and welding until the filling of the low-nickel high-nitrogen austenitic stainless steel plate is completed. The method is mainly used for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of welding, and particularly relates to a welding method and device for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint. BACKGROUND

[0002] Low-nickel high-nitrogen austenitic stainless steel is a new type of steel developed in recent years. It uses low-cost N element to replace expensive Ni element and still maintains the excellent corrosion resistance of austenitic stainless steel, and gradually obtains engineering application. Since the N element dissolved in the steel has a high stacking fault energy, the microstructure of the material can be optimized and the comprehensive performance of the material can be greatly improved. In recent years, it has attracted widespread attention in the marine equipment and pressure vessel industries.

[0003] The specific strength and specific stiffness of low-nickel high-nitrogen austenitic stainless steel increase with the increase of N content. High specific strength and high specific stiffness can significantly reduce the overall structure weight, so the demand for low-nickel high-nitrogen austenitic stainless steel for structures with light weight and corrosion resistance is more urgent. At present, the actual engineering application of low-nickel high-nitrogen is largely dependent on its welding performance. During welding, N element is easy to gather and escape in the molten pool, resulting in a significant reduction in the N content of the welded joint. At the same time, part of N will remain in the molten pool due to the decrease of the molten pool temperature, eventually forming a porosity defect, which causes the carrying capacity of the welded structure to decrease sharply. At the same time, the loss of N will also cause corrosion to occur, thereby seriously affecting the safety and stability of the service of the welded structure. Therefore, reducing the loss of N during welding, inhibiting the porosity defect in the weld, and improving the corrosion resistance of the welded joint are the key technologies to ensure the wide application of low-nickel high-nitrogen austenitic stainless steel. A large number of studies have shown that adding an appropriate amount of N2 in the protective atmosphere and increasing its nitrogen partial pressure can achieve the effect of increasing the nitrogen content of the weld, compensating for the loss of N element, avoiding the generation of a large amount of ferrite and the precipitation of Cr-rich phase, and facilitating the solid solution of N element into the molten pool. However, excessive N2 does not have obvious effect on the increase of N content in the weld. Not only does it reduce the corrosion resistance and worsen the stability of the welding process, but also it deteriorates the mechanical properties of the welded joint. High welding heat input can increase the grain size of the low-nickel high-nitrogen stainless steel weld, increase the number of precipitates, increase the loss of N2, and reduce the strength of the joint. However, it can also reduce the content of high-temperature ferrite in the weld and improve the comprehensive mechanical properties of the welded joint. At present, the research on welding heat input process in fusion welding still stays in the stage of N element loss in the molten pool and the generation of precipitates, and the optimal temperature curve for optimizing the loss of N element and the generation of nitrides has not been determined.

[0004] The common defect in the melting welding process of low-nickel high-nitrogen austenitic stainless steel is the loss of solid solution nitrogen, and the solid solution nitrogen content in the weld can be increased by adjusting the protective atmosphere structure, designing the alloy composition system of the welding wire, and optimizing the welding process parameters, but there is always a critical solubility of nitrogen, which is determined by the system composed of the protective gas structure, the welding wire composition, the base material composition and the process parameters, and the related research is difficult to realize the plasticity and toughness of the welded joint of low-nickel high-nitrogen austenitic stainless steel. SUMMARY

[0005] Therefore, the present application aims to provide a welding method and device for optimizing the strength and toughness of the welded joint of low-nickel high-nitrogen austenitic stainless steel to solve the problem of difficult to balance the strength and toughness of the welded joint of low-nickel high-nitrogen austenitic stainless steel.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a welding method for optimizing the strength and toughness of the welded joint of low-nickel high-nitrogen austenitic stainless steel, which comprises the following processes:

[0007] The low-nickel high-nitrogen austenitic stainless steel plates to be welded are pretreated, and the two pretreated low-nickel high-nitrogen austenitic stainless steel plates are clamped and assembled in the welding fixture, the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates is adjusted, and the welding is prepared;

[0008] The power of the welding machine is turned on, the welding heat input is controlled, the protective gas cylinder is opened to introduce the protective gas, the welding wire used for welding is installed into the wire feeder, and the welding parameters and the relative position of the welding torch and the weld are set;

[0009] In the welding parameters, the welding heat input is:

[0010] Re=〔(I1+I2)·U〕÷V1

[0011] In the formula, Re is the welding heat input, KJ / cm; I1 is the base current; I2 is the peak current; U is the welding voltage; and V1 is the welding speed;

[0012] The protective gas type is a mixed gas of N2+Ar, and the N2 content in the mixed gas is:

[0013] Q=N%×100 / Re=0.9~1.1

[0014] In the formula, Q is the proportionality coefficient, cm / KJ; and N% is the N2 content in the mixed gas;

[0015] The welding wire is a Ni-Cr-Mo nickel-based solid welding wire;

[0016] The motion trajectory of the welding motion mechanism is set, and the welding is carried out until the filling of the low-nickel high-nitrogen austenitic stainless steel plate is completed.

[0017] Further, the pretreatment of the low-nickel high-nitrogen austenitic stainless steel plate to be welded is that the welding groove of the low-nickel high-nitrogen austenitic stainless steel plate to be welded is processed, and the two low-nickel high-nitrogen austenitic stainless steel plates processed are mechanically polished to remove oil stains and oxides at the processed groove.

[0018] Further, the welding groove shape is Y-shaped or U-shaped, and the groove angle is ≤ 150°.

[0019] Further, the thickness of the low-nickel high-nitrogen austenitic stainless steel plate is 4mm-6mm.

[0020] Further, the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates is 0mm-0.8mm.

[0021] Further, the welding wire diameter is 0.8mm-1.6mm.

[0022] Further, the welding parameters include welding current, welding voltage, dry elongation, wire feeding speed, welding speed, protective gas type and protective gas flow.

[0023] Further, the protective gas flow is 20L / min-25L / min.

[0024] Further, the relative position of the welding gun and the weld is that the welding gun is inclined back 0°-15° to the surface of the weld to be welded.

[0025] The application also provides a welding device for optimizing the toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint, which is used to realize the welding method described above, and comprises:

[0026] A welding clamp is used to clamp and tighten the two low-nickel high-nitrogen austenitic stainless steel plates after pretreatment, and adjust the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates.

[0027] A welding machine is connected with a welding gun, and the welding gun is used to weld the weld;

[0028] A wire feeder is used to feed a Ni-Cr-Mo nickel-based solid welding wire;

[0029] A controller is used to control the welding heat input;

[0030] A protective gas cylinder is used to introduce N2+Ar protective gas;

[0031] A welding motion mechanism is used to control the welding motion trajectory.

[0032] Compared with the prior art, the present application has the beneficial effects that: the present application makes up the loss of solid solution nitrogen in the weld by adding N2 in the welding protective gas in a reasonable proportion; the present application realizes the smooth transition of the microstructure from the weld to the base material by using the Ni-Cr-Mo nickel-based solid welding wire with a high Ni content as the filler metal; and the present application solves the technical problem that the strength and toughness of the welded joint of the low-Ni high-N austenitic stainless steel are difficult to be compatible by synchronously controlling the weld nitrogen fixation, the welding wire composition and the welding process in three aspects through the way of controlling the welding heat input.

[0033] The present application controls the proportion of N2 in the welding mixed protective gas, and the proportion of N2 has a strict corresponding relationship with the welding heat input. The addition of N2 makes the weld realize the nitrogen-increasing effect during the welding process, compensates for the loss of N element, avoids the generation of a large amount of ferrite and the precipitation of Cr-rich phase, and is beneficial to the solid solution of N element into the molten pool. However, a small amount of N2 gas does not have obvious effect on the improvement of the N content of the weld. Excessive N2 gas can reduce the corrosion resistance, make the welding process stability worse, and also deteriorate the mechanical properties of the welded joint. Therefore, strictly controlling the proportion of N2 in the welding mixed protective gas plays an important role in optimizing the strength and toughness of the welded joint of the low-Ni high-N austenitic stainless steel.

[0034] The present application realizes the smooth transition of the microstructure from the weld to the base material by using the Ni-Cr-Mo nickel-based solid welding wire with a high Ni content as the filler metal. The addition of Ni element increases the growth of the secondary dendrite arm of the weld metal, and realizes the smooth transition of the microstructure from the weld to the base material.

[0035] The present application controls the grain size of the weld by controlling the welding heat input. Too small welding heat input can cause the weld grain to be refined, increase the plasticity of the welded joint and reduce the strength. At the same time, due to the reduction of the welding heat input, the decomposition of N2 in the mixed protective gas is insufficient, and it is difficult to realize the nitrogen-increasing effect. Too high welding heat input can cause the weld grain to be coarsened, increase the strength of the welded joint and reduce the plasticity. Too high welding heat input can cause excessive decomposition of N2 in the mixed protective gas, reduce the corrosion resistance, and make the welding process stability worse.

[0036] The present application optimizes the strength and toughness of the welded joint of the low-Ni high-N austenitic stainless steel by the reasonable proportion of N2 in the welding protective gas, the Ni-Cr-Mo nickel-based solid welding wire as the filler metal and the way of controlling the welding heat input. The three work together to realize the technical effects of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0037] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0038] Figure 1A schematic structural diagram of a welding device for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to the present application;

[0039] Figure 2 A schematic structural diagram of an electronic universal testing machine according to the present application;

[0040] Figure 3 A schematic diagram of the size specification of a tensile specimen according to the present application;

[0041] Figure 4 A cross-sectional macroscopic morphology diagram of a welded joint obtained at different heat inputs according to the present application;

[0042] Figure 5 A microstructure morphology diagram of a welded joint when the heat input is 6.0 KJ / cm according to the present application;

[0043] Figure 6 A microstructure morphology diagram of a welded joint when the heat input is 7.5 KJ / cm according to the present application;

[0044] Figure 7 A microstructure morphology diagram of a welded joint when the heat input is 9.1 KJ / cm according to the present application;

[0045] Figure 8 A welded joint corrosion test result diagram according to the present application.

[0046] In the figure:

[0047] 1-welding machine, 2-wire feeder, 3-controller, 4-welding torch, 5-protection gas cylinder, 6-welding motion mechanism. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0049] Specific embodiment 1: see Figures 1-8 This embodiment describes a welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint, which comprises the following processes:

[0050] The low-nickel high-nitrogen austenitic stainless steel plates to be welded are pretreated, and the two pretreated low-nickel high-nitrogen austenitic stainless steel plates are clamped and assembled in a welding clamp, the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates is adjusted, and the welding is prepared;

[0051] Turning on the power of the welding machine, controlling the welding heat input, turning on the protective gas cylinder to input the protective gas, installing the welding wire used for welding into the wire feeder, setting the welding parameters and the relative position of the welding torch and the weld;

[0052] In the welding parameters, the welding heat input is:

[0053] Re=〔(I1+I2)·U〕÷V1

[0054] In the formula, Re is the welding heat input, KJ / cm; I1 is the base current; I2 is the peak current; U is the welding voltage; and V1 is the welding speed;

[0055] The protective gas type is a mixed gas of N2+Ar, and the proportion of N2 in the mixed gas is:

[0056] Q=N%×100 / Re=0.9~1.1

[0057] In the formula, Q is the proportion coefficient, cm / KJ; and N% is the proportion of N2 in the mixed gas;

[0058] The welding wire is a Ni-Cr-Mo nickel-based solid welding wire;

[0059] The motion trajectory of the welding motion mechanism is set, welding is performed, and the filling of the entire low-nickel high-nitrogen austenitic stainless steel plate is completed.

[0060] In the embodiment, the pretreatment of the low-nickel high-nitrogen austenitic stainless steel plate to be welded is: machining the welding groove of the low-nickel high-nitrogen austenitic stainless steel plate to be welded, and mechanically polishing the two low-nickel high-nitrogen austenitic stainless steel plates machined to remove oil stains and oxides at the machined groove.

[0061] In the embodiment, the welding groove shape is Y-shaped or U-shaped, and the groove angle is ≤150°.

[0062] In the embodiment, the thickness of the low-nickel high-nitrogen austenitic stainless steel plate is 4mm~6mm.

[0063] In the embodiment, the gap between the two low-nickel high-nitrogen austenitic stainless steel plates ranges from 0mm to 0.8mm.

[0064] In the embodiment, the diameter of the welding wire is 0.8mm~1.6mm.

[0065] In the embodiment, the welding parameters include welding current, welding voltage, dry elongation, wire feeding speed, welding speed, protective gas type, and protective gas flow.

[0066] In the embodiment, the protective gas flow is 20L / min~25L / min.

[0067] In the embodiment, the relative position of the welding torch and the weld is that the welding torch is inclined backward 0°-15° to the surface of the weld to be welded.

[0068] The embodiment is a welding device for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint, which is used to realize the welding method described above, and comprises:

[0069] A welding fixture is used to clamp and assemble the two pretreated low-nickel high-nitrogen austenitic stainless steel plates, and adjust the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates.

[0070] The welding machine 1 is connected with the welding torch 4, and the welding torch 4 is used to weld the weld;

[0071] The wire feeder 2 is used to feed the Ni-Cr-Mo nickel-based solid welding wire;

[0072] The controller 3 is used to control the welding heat input;

[0073] The protective gas cylinder 5 is used to introduce N2+Ar protective gas;

[0074] The welding motion mechanism 6 is used to control the welding motion trajectory.

[0075] Specific implementation 2: see Figures 1-8 In this embodiment, the low-nickel high-nitrogen austenitic stainless steel plate is welded in the form of a test plate and related verification tests are performed, and the welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint is performed according to the following steps:

[0076] An 08Cr19Mn6Ni3Cu2N low-nickel high-nitrogen austenitic stainless steel plate with a size of 300 mm×200 mm×5.5 mm is selected as the base material, and the test plate to be welded is processed into a Y-shaped groove, the groove root face thickness is 1 mm, the single-sided groove angle is 60°, the filler metal is a Ni-Cr-Mo nickel-based solid welding wire with a diameter of 1.2 mm, and the chemical composition of the base material and the welding wire is shown in Table 1.

[0077] Table 1 Chemical composition of base material and welding wire (mass fraction, %)

[0078]

[0079] The two finished test plates are mechanically polished to remove oil and oxides at the processing groove. The pretreated test plates are placed in the welding fixture for assembly and preparation for welding. The polished test plates are placed on the sample platform for clamping and assembly. The joint gap is 0 mm. The welding device uses Cloos StarT 502 Premium welding machine 1. The welding power supply, protective gas cylinder 5, and other welding devices are turned on. The Ni-Cr-Mo nickel-based solid welding wire used for welding is installed in the wire feeder 2 to ensure stable wire feeding during welding. The welding device structure is shown in Figure 1 .

[0080] The welding parameters are set as shown in Table 2. The relative position of the welding torch 4 to the weld is 10° backward to the surface of the weld. According to the welding heat input of 7.5 KJ / cm, the allowable range of N2 content is calculated to be 6.75%~8.25% according to the N2 content formula. In this test, the N2 content is selected as 8%. The test uses 8% N2+92% Ar mixed shielding gas with a protective gas flow of 20 L / min.

[0081] Table 2 Verification test welding parameter table

[0082]

[0083] This test sets up two groups of comparison tests. The comparison test parameters are shown in Table 3. The relative position of the welding torch 4 to the weld is 10° backward to the surface of the weld. The test uses 8% N2+92% Ar mixed shielding gas with a protective gas flow of 20 L / min.

[0084] Table 3 Comparison test welding parameter table

[0085]

[0086] The FANUC robot is used as the welding motion mechanism 6 to control the welding trajectory and perform welding until the entire test plate is filled. After welding, the verification test and comparison test use OLYMPUS GX71 optical microscope (OM), FEI Quanta-200 scanning electron microscope, electron backscatter diffraction (EBSD), and D / MAX-rB X-ray diffractometer to observe the microstructure and phase of the weld. Hardness testing: HVS-1000Z microhardness tester is used for hardness testing. Tensile property testing: DIC testing is performed on the INSTRON 5569 electronic universal testing machine at room temperature, as shown in Figure 2 and Figure 3 .

[0087] Figure 4The cross-section macro-morphology of the welded joints obtained for 3 groups of different heat inputs was observed, and no welding defects such as pores, cracks and incomplete fusion were found. When the heat input is 6.0 KJ / cm, the penetration is 5328 μm, the width is 8103 μm, and the reinforcement is 1110 μm. When the heat input increases to 7.5 KJ / cm and 9.1 KJ / cm, the weld penetration reaches 5550 μm and 5555 μm respectively, the weld width increases to 10878 μm and 12765 μm respectively, and the reinforcement increases to 1399 μm and 2997 μm respectively. With the increase of welding heat input, the weld width and reinforcement show an increasing trend.

[0088] Figures 5-7 The microstructure of the welded joints obtained for 3 groups of different welding heat inputs was observed, and it was found that with the increase of heat input, the width of the heat affected zone (HAZ) increased from 95 μm to 140 μm and 156 μm, showing a gradually increasing trend; the weld region was mainly composed of yellow area (γ phase), gray area (segregation band) and black precipitated phase, among which the black precipitated phase was mainly Laves phase, Laves / γ eutectic structure and a small amount of carbide. Under the condition of larger heat input, there are more columnar crystal structures in the weld; the solidification rate of the weld liquid pool metal obtained under lower heat input is slower, resulting in more equiaxed crystals in the weld. With the increase of heat input, the secondary dendrite arm spacing in the weld is about 2.52 μm, 5.55 μm and 6.11 μm respectively, indicating that the larger the heat input, the more developed the dendrite, and the more concentrated and larger the size of the interdendritic region.

[0089] In summary, only when the welding heat input is strictly controlled to be 7.5 KJ / cm, and the N2 gas ratio is within the allowed range of 6.75% to 8.25%, can the weld nitrogen enrichment effect be achieved during welding, the addition of Ni element can increase the growth of the secondary dendrite wall of the weld metal, and the microstructure can be smoothly transitioned from the weld to the base material, and the most appropriate grain size can be obtained.

[0090] Table 4 is the test results of the room temperature tensile properties of the welded joints obtained for 3 groups of different heat inputs. When the welding heat input is 6.0 kJ / cm, the average tensile strength of the welded joint is 680 MPa, the average elongation is 45%, and the fracture position is in the weld region; when the welding heat input is 7.5 kJ / cm, the average tensile strength of the welded joint is 740 MPa, and the average elongation is 52%; when the welding heat input is 9.1 kJ / cm, the average tensile strength of the welded joint is 785 MPa, and the average elongation is 42%. In summary, only when the welding heat input is strictly controlled to be 7.5 KJ / cm, can the high strength and toughness of the welded joint be achieved.

[0091] Table 4 Tensile properties of welded joints

[0092]

[0093] Figure 8 The electrochemical corrosion test results of the weld joint of the three groups in 3.5% NaCl solution are as follows: when the heat input is 6.0 kJ / cm, the self-corrosion potential is-157.03 mV; when the heat input is 7.5 kJ / cm, the self-corrosion potential is-148.44 mV; and when the heat input is 9.1 kJ / cm, the self-corrosion potential is-181.57 mV. In the same corrosion environment, the corrosion tendency of the welded joint is smaller when the welding heat input is 7.5 kJ / cm.

[0094] The above disclosed embodiments of the present application are only used to help explain the present application. The embodiments do not describe all the details of the present application, and the present application is not limited to the described embodiments. According to the content of the present application, many modifications and changes can be made. The present application selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application.

Claims

1. A welding method for optimizing the strength and toughness of a welded joint of a low-nickel high-nitrogen austenitic stainless steel, characterized by: It comprises the following processes: The low-nickel high-nitrogen austenitic stainless steel plates to be welded are pretreated, the two low-nickel high-nitrogen austenitic stainless steel plates after pretreatment are clamped in a welding fixture, the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates is adjusted, and the welding is prepared; The power of the welding machine is turned on, the welding heat input is controlled, the protection gas cylinder is opened to introduce the protection gas, the welding wire used for welding is installed into the wire feeder, and the welding parameters and the relative position of the welding torch and the weld are set; In the welding parameters, the welding heat input is: Re=〔(I1+I2)·U〕÷V1 In the formula, Re is the welding heat input, KJ / cm; I1 is the base current; I2 is the peak current; U is the welding voltage; and V1 is the welding speed; The mixed gas of N2+Ar is used as the protection gas, and the proportion of N2 in the mixed gas is: Q=N%×100 / Re=0.9~1.1 In the formula, Q is the proportion coefficient, cm / KJ; and N% is the proportion of N2 in the mixed gas; The welding wire is a Ni-Cr-Mo nickel-based solid welding wire; The motion trajectory of the welding motion mechanism is set, and the welding is performed until the filling of the low-nickel high-nitrogen austenitic stainless steel plate is completed.

2. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The pretreatment of the low-nickel high-nitrogen austenitic stainless steel plate to be welded is that the welding groove of the low-nickel high-nitrogen austenitic stainless steel plate to be welded is processed, and the two low-nickel high-nitrogen austenitic stainless steel plates after processing are mechanically polished to remove oil stains and oxides at the processing groove.

3. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 2, characterized in that: The welding groove shape is Y-shaped or U-shaped, and the groove angle is ≤150°.

4. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The thickness of the low-nickel high-nitrogen austenitic stainless steel plate is 4mm-6mm.

5. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The gap range of the two low-nickel high-nitrogen austenitic stainless steel plates is 0mm-0.8mm.

6. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The diameter of the welding wire is 0.8mm-1.6mm.

7. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The welding parameters include the welding current, the welding voltage, the dry elongation, the wire feeding speed, the welding speed, the protection gas type, and the protection gas flow.

8. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The protection gas flow is 20L / min-25L / min.

9. The welding method for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint according to claim 1, characterized in that: The relative position of the welding torch and the weld is that the welding torch is inclined backward 0°-15° from the surface of the weld to be welded.

10. A welding device for optimizing the strength and toughness of a low-nickel high-nitrogen austenitic stainless steel welded joint, characterized by, The welding method of claim 1 is implemented, comprising: A welding fixture is used to clamp the two low-nickel high-nitrogen austenitic stainless steel plates after pretreatment and adjust the gap range of the two low-nickel high-nitrogen austenitic stainless steel plates; A welding machine (1) is connected with a welding torch (4), and the welding torch (4) is used to weld the weld; A wire feeder (2) is used to feed the Ni-Cr-Mo nickel-based solid welding wire; A controller (3) is used to control the welding heat input; A protection gas cylinder (5) is used to introduce the protection gas of type N2+Ar; A welding motion mechanism (6) is used to control the welding motion trajectory.

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