保护气流量对不锈钢激光-MAG复合焊接头组织和性能的影响

对8 mm厚SUS301L-MT不锈钢进行激光-MAG复合焊接,研究不同保护气流量对焊缝成形、显微组织和力学性能的影响。试验结果表明:当其他焊接参数一定时,在该试验条件下保护气流量对焊缝成形影响较小,焊缝区域组织相似,主要为柱状奥氏体树枝晶+少量的δ铁素体。接头显微硬度和冲击韧性随保护气流量的变化不明显。接头的抗拉强度随保护气流量的增加而提高,当保护气流量为40 L/min时,接头抗拉强度最高为765 MPa,达到母材抗拉强度的86.5%。分析拉伸断口发现,不同保护气流量断口微观形貌相似,断口中分布着大量韧窝,表现为韧性断裂。

Effects of flowrate of shielding gas flow on microstructure and properties of laser-MAG welding-welded joints of stainless steel

The laser-MAG hybrid welding was applied to weld the stainless steel with 8 mm thickness.The influence of shielding gas flow (SGF) on weld formation,microstructure and mechanical properties.The results showed that SGF under the test conditions had less effect on the bead shape,the weld microstructure were similar,mainly for branches of columnar austenite grain and small amount of δ-ferrite when other parameters were unaltered.The micro-hardness and impact toughness of joint didn't change obviously with the change of SGF.The tensile strength of the weld would increased with the increase of SGF,and the tensile strength of the welding joint would reach its maximum 765 MPa when the SGF rate was 40 L/min,reaching 86.5％ of the base material.It was found by analyzing tensile fracture of weld,the fracture morphology was similar with the different SGF,fracture morphology of the joint was a dimple pattern with feature of ductile fracture.