不锈钢激光点焊接头组织和力学性能研究

目的 改善SUS301L–HT不锈钢激光点焊焊接性能。方法 以2 mm SUS301L–HT不锈钢为母材进行激光点焊试验，并分析焊接接头的金相组织、硬度、拉伸性能以及断口形貌等。结果 焊点表面无损坏、压痕均匀、无较大焊接变形，表面无飞溅、母材颜色无明显变化。焊核区的微观组织主要是柱状晶，柱状晶依附于未熔化母材晶粒向焊核中心生长。母材硬度最高，约为309HV;焊核中心附近区域硬度适中，约为255HV，热影响区硬度最小，不到220HV。点焊接头断裂形式多为纽扣式断裂且发生在热影响区。结论 不锈钢激光点焊整体质量较好，可用于轨道列车车体加工。

Microstructure and Mechanical Properties of Stainless Steel Laser Spot Welding Joints

To improve the welding performance of SUS301L-HT stainless steel laser spot welding, the laser spot welding test was carried out with 2 mm SUS301L-HT stainless steel as the base material, and the microstructure, hardness, tensile properties and fracture morphology of the welded joints were analyzed. The test results show that there is no damage, uniform indentation, no large welding deformation, no splash on the surface and no obvious change in the color of the base material. The microstructure of welded core is mainly columnar crystals which grow towards the center of welded core attached to the unmelted base metal grains. The hardness of base material is the highest, about 309HV. The hardness of the region near the core center is moderate, about 255HV, and the hardness of the heat-affected zone is the least, less than 220HV. The fracture form of spot welded joints is button fracture and occurs in the heat affected zone. Laser spot welding of stainless steel has good overall quality and can be used for rail train body processing.