Microstructure And Mechanical Behavior On Lap Laser Welding Joint Of Stainless Steel Sheet For Railway Vehicle

As the progress of life rhythm, the development of railway vehicle is attachedimportance to society. With so many advantages, such as energy absorbing, lightweight,antirust and simple manufacturing process, the production of stainless steel railway vehiclehas become the development strategies of developed nations.The resistant spot welding process is the main technology of manufacturing stainlesssteel railway vehicles until laser welding technology is imported. The lap laser welding ofstainless steel is investigated in this study to replace resistant spot welding with the aim toincrease the aesthetics of the car body by eliminating visible indentation on the surface andthe flatness of the side panel reducing welding deformations.The processing parameters of lap laser welding is optimized on the basis of technologicaltest. The analyses on stress distributions and concentration factors of lap laser and resistantspot welding joints in different external loadings were made. It was emphasized that themetallographic structure, intercrystalline corrosion resistance, mechanical property andfatigue property are influenced by welding surroundings. Obtained following conclusions:1) The technological test shows that the tensile shear strength of lap laser welding joint isalways higher as laser power is higher and welding speed is lower.2) On the framework, the SCF of lap laser welding is73.4%lower than resistant spotwelding. Meanwhile on the flankwall, the SCF of lap laser welding is81.6%lower thanresistant spot welding.3) Compared with lap laser welding joint with assist gas, the tensile shear property ofjoint welded in air is in decline as the thickness largen. The phenomenon appears significantlywhen the thickness is above2.0mm be different from the steel less than2.0mm.4) The fatigue limit of lap laser welding joint welded in argon and atmosphere are4.07kN and4.12kN respectively when the fatigue life is107, nearly the same.5) The metallographic structure and intercrystalline corrosion resistance aren’t influencedby welding surroundings.