Study on Microstructure and Mechanical Properties of Laser Welded Joints of 316L Stainless Steel Sheet

The lap welding test of 316L stainless steel sheet with thickness of 0.3 mm was carried out by pulse laser welding equipment, and the influence of process parameters on the weld characteristics and mechanical properties was analyzed.The results show that through orthogonal test, under the optimal welding process parameters of laser peak power of 2.6 kW, welding speed of 8 mm/s and defocusing amount of+1.0 mm, the shear stress of the welded joints is largest, and the defocusing amount has the greatest influence on the shear stress of welded joints. There are overlapping areas of multiple solder joints in the cross section of the weld. No obvious heat affected zone is observed near the fusion line. The columnar crystals are approximately perpendicular to the fusion line and grow towards the center of the weld.The hardness of the weld zone is smaller than that of the base metal, and gradually increases from the weld center to the fusion line at both ends.In the vertical direction of the cross section, the hardness increases with the increase of the weld depth.