CN-122007628-A - Laser filler wire welding method for ultra-high strength stainless steel, filler wire and ultra-high strength stainless steel welding part

Abstract

The invention discloses a laser filler wire welding method, welding flux and a welding part for ultra-high strength stainless steel, which are used for providing two stainless steel blank workpiece component assemblies, and using filler wires to enable the blank component assemblies and the welding flux to be melted under the action of a laser heat source to form a welding joint, wherein the filler wires are provided with elements such as C, mn, si and the like, the components in the welding wires are 0.01% -0.45%, 0.5% -3.0%, 0.1% -2.0%, cr is 25%, ni is 15% -5%, mo is the balance Fe and unavoidable impurities, and the components in the filler wires and the specific proportion added into a welding pool are such that the austenite content in the welding joint is not lower than 70%, and the average microhardness of a welding joint melting zone is not more than 350HV. The welded joint has ultrahigh strength, can reach over 90 percent of the strength of a base metal in a typical low-temperature (-196 DEG) environment, and can meet the application of environments with different assembly clearances.

Inventors

• WANG YANJUN
• Yang Shanglu
• ZHANG JIAZHI
• QI MINGGANG
• YANG QINGYUN
• ZHANG JINGJIE
• ZHANG FENG

Assignees

• 中国科学院上海光学精密机械研究所
• 浙江蓝箭航天空间科技有限公司

Dates

Publication Date

20260512

Application Date

20260209

Claims (10)

1. 1. The laser filler wire welding method for the ultra-high strength stainless steel is characterized by comprising the following steps of: Providing an ultra-high strength stainless steel base material to be welded, wherein the base material is austenitic stainless steel strengthened by cold rolling plastic deformation; Assembling the base material to form an assembly with an assembly clearance not greater than 0.5 mm; Welding the joint part of the assembly by adopting a laser filler wire welding process to form a welding joint, wherein in the welding process, filler wires with specific components are used, and the part formed by melting the filler wires in a molten pool accounts for 30-100% of the total volume of the molten pool by controlling welding heat input and wire feeding speed so as to regulate and control dilution of a base material, thereby ensuring that the fusion area of the finally formed welding joint meets the conditions that the average volume content of austenite is not less than 70% and the average microhardness is not more than 350 HV; Wherein the chemical components of the filler wire are, by weight, 0.01% or more of C or less than 0.45%,0.5% or less of Mn or less than 3.0%,0.1% or less of Si or less than 2.0%, 25% or less of Cr, 15% or less of Ni, 5% or less of Mo, and the balance of Fe and unavoidable impurities.
2. 2. The laser filler wire welding method for ultra-high strength stainless steel of claim 1, wherein the portion of the molten pool formed by melting the filler wire is 50% to 80% of the total volume of the molten pool.
3. 3. The method for laser filler wire welding of ultra-high strength stainless steel according to claim 1, wherein the filler wire has chemical composition of 0.01% or less of C or less of 0.2%,10% or less of Cr or less of 20%,2% or less of Ni or less of 10%, mo or less of 3%, and the balance of Fe and unavoidable impurities in weight percent.
4. 4. The laser filler wire welding method for ultra-high strength stainless steel of claim 1, wherein the chemical composition of the weld joint fusion zone satisfies the relationship in weight percent: 0≤500-400×C-30×Mn-18×Cr-12×Ni-7.5×Mo≤100 Wherein C, mn, cr, ni, mo is the weight percentage value of each element.
5. 5. The laser filler wire welding method for ultra-high strength stainless steel according to claim 1, wherein the austenite volume content in the mixed structure of the melting region in the welded joint is not less than 80%, and the average hardness HV of the melting region is not more than 320HV.
6. 6. The laser filler wire welding method for ultra-high strength stainless steel of claim 1, wherein the chemical composition of the base material comprises, in weight percent: c is more than or equal to 0.05% and less than or equal to 0.3%, mn is more than or equal to 0.5% and less than or equal to 3.0%, si is more than or equal to 0.1% and less than or equal to 2.0%, cr is more than or equal to 12% and less than or equal to 25%, ni is more than or equal to 3% and less than or equal to 12%, N is less than or equal to 0.6%, and the balance is iron and unavoidable impurities.
7. 7. A filler wire for carrying out the method as claimed in any one of claims 1 to 6, characterized in that it comprises, in weight%, 0.01% C≤0.45%, 0.5% Mn≤3.0%, 0.1% Si≤2.0%, cr≤25%, ni≤15%, mo≤5%, the balance Fe and unavoidable impurities, and is suitable for laser filler wire welding, by regulating the proportion of which in the molten pool, the resulting weld joint fusion zone is made to satisfy an austenite content of not less than 70% and a hardness of not more than 350 HV.
8. 8. The filler wire of claim 7, wherein the composition comprises, by weight, 0.01% C0.45%, 0.5% Mn 3.0%,0.1% Si 2.0%, cr 25%, ni 15%, mo 5%, and Fe and unavoidable impurities as the balance.
9. 9. An ultra-high strength stainless steel welded component, characterized in that the welded component is welded by the laser filler wire welding method of any one of claims 1-6, and the tensile strength of a welded joint of the welded component at-196 ℃ is not lower than 90% of the tensile strength of a parent material of the welded joint.
10. 10. The ultra-high strength stainless steel welded component according to claim 9, wherein the weld joint has a fusion zone austenite average volume content of not less than 70% and an average microhardness of not more than 350 HV.

Description

Laser filler wire welding method for ultra-high strength stainless steel, filler wire and ultra-high strength stainless steel welding part Technical Field The invention relates to the technical field of metal material welding, in particular to a laser filler wire welding method for ultra-high strength stainless steel, a filler wire and an ultra-high strength stainless steel welding part. Background Stainless steel materials are widely applied to the key fields of energy, chemical industry, medical treatment, aerospace and the like by virtue of excellent corrosion resistance and comprehensive mechanical properties. Particularly in a low-temperature environment, the austenitic stainless steel has excellent toughness and low-temperature brittleness resistance due to a stable face-centered cubic structure, and becomes a first-choice material for storing and transporting low-temperature media such as liquid oxygen, liquid nitrogen and the like. However, conventional austenitic stainless steels have low strength and often require mechanical properties to be improved by cold deformation work hardening, e.g., cold rolling processes can significantly improve the yield strength and tensile strength of the material. In the aerospace field, the rocket tank is used as a key component for propellant storage, the requirement on the comprehensive performance of materials is extremely high, and cold rolled austenitic stainless steel is gradually replacing the traditional materials due to the high strength and the good low-temperature toughness, so that the rocket tank is used for a new generation of lightweight and high-reliability tank structure. However, cold rolled stainless steel gives a new challenge in terms of weld softening while achieving high strength. Due to the high dislocation density and lattice distortion introduced by cold work hardening, dynamic recovery, recrystallization and grain growth occur under the high temperature heat cycle effect of the laser welding process, resulting in significant reduction of the strength and hardness of the heat affected zone and the weld zone. This softening effect makes the welded joint a weak link in the structure, particularly in parts subjected to complex loads and extreme temperature conditions, such as rocket tanks, which are more particularly affected. The rocket tank is subjected to ultralow-temperature (-196 ℃) service temperature in the service process, and the mechanical property, fatigue resistance and low-temperature toughness of the welded joint directly determine the structural integrity and service safety of the tank, and particularly the welded joint structure needs to have higher yield strength and tensile strength. Moreover, in the actual manufacturing link, the workpiece is difficult to ensure gapless assembly during assembly, and high-quality welding of the ultra-high strength stainless steel under the condition of large assembly gap is needed. The invention patent of application number 201410806107.5 discloses a method for improving the mechanical property and corrosion resistance of a welding seam area by using ultrasonic and electric pulse coupling, pulse current is led to the welding seam surface of a metal piece and the welding heat affected zone surface to carry out electro-plastic treatment, and simultaneously ultrasonic impact equipment sequentially carries out ultrasonic impact treatment on the surface of the working area through a high-hardness impact pressure head of the ultrasonic impact equipment. The method requires very complex equipment and processing procedures, and has high cost and low efficiency. CN117548807B discloses an ultrasonic impact device with welding, which strengthens the welded joint by performing immediate ultrasonic impact after welding, and the ultrasonic device used in the method is complex, low in efficiency and high in cost. CN 102658416A discloses a mixed gas shielded welding process of precipitation strengthening high-strength steel. And the mixed gas shielded welding, single-double welding double-sided forming and other technologies are adopted to weld the precipitation-strengthening high-strength steel with the tensile strength of 600MPa, so that the softening width of a welding heat affected zone is effectively reduced. The welding process parameters are optimized, 80 percent Ar+20 percent CO 2 mixed gas is adopted, the welding current is 90-140A, the line energy is 7-12kJ/cm, precipitation strengthening and fine crystal strengthening are generated through Ti (C, N), and the tensile strength of the welded joint reaches 710MPa through testing. The method mainly reduces the width of the heat affected zone through optimization of various protective gases and technological parameters, but is only aimed at 600 Mpa-level high-strength steel, and has the advantages of smaller application range and complex technological control process. CN116529407B discloses a welded joint with excellent properties under low temperature