分别采用脉冲激光焊和氩弧焊对0.7 mm厚1Cr18Ni9Ti不锈钢薄板实施焊接, 并针对两种方法获得的焊接接头的表观质量、显微组织和力学性能进行了对比研究。结果表明, 激光焊接试样的热影响区宽约60 μm, 焊缝组织为垂直于熔合线外延生长的柱状晶; 氩弧焊焊接试样的热影响区宽约1.3 mm, 热影响区内形成孪晶组织, 焊缝内靠近熔合线附近为外延生长的柱状枝晶, 到焊缝中心区域转化为等轴枝晶。基于多元合金凝固柱状晶/等轴晶转变模型揭示了两种焊接方法下焊缝区凝固组织的形成机理。显微硬度及室温拉伸性能测试结果表明, 两种焊接方法获得的焊缝区的硬度均略低于母材, 氩弧焊焊接接头的硬度分布曲线呈马鞍形, 热影响区的硬度最低。激光焊接薄板试样的抗拉强度显著高于氩弧焊。

The 1Cr18Ni9Ti stainless steel sheet samples with the thickness of 0.7 mm were welded by laser welding and TIG welding, respectively, and the microstructure and mechanical properties of the weld joints were investigated. It was found that the width of the heat affected zone of laser welding sample was approximately 60 μm, and the microstructure in the weld was dominated by the columnar grains growing epitaxially to the weld bond. The width of the heat affected zone of TIG welding sample was about 1.3mm, and the twin was formed in the heat affected zone. The microstructure in the TIG weld was composed by the epitaxial columnar dendritic grains near the weld bond and the equiaxed dendritic grains in the middle of the weld. The formation mechanism of the microstructure in the laser weld and TIG weld was disclosed based on the columnar to equiaxed transition (CET) model. The microhardness and room temperature tensile testing indicated that the weld hardness obtained by laser welding and TIG welding were all lower than that of the base metal. The hardness distribution curve of the TIG welding sample was like a saddle with the hardness of the heat affected zone lowest. The strength of the laser welding sample is much higher than that of TIG welding sample.