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采用高密度Nd:YAG固态连续激光器对N6纯镍和304奥氏体不锈钢进行了焊接工艺实验,探究了激光功率和离焦量对焊缝成形的影响。对接头进行了拉伸强度和硬度的测试,并结合光学显微镜(OM)、扫描电镜(SEM)、能谱分析仪(EDS)等手段分析了接头的微观组织。结果表明:N6纯镍一侧热影响区晶粒长大明显,焊缝区靠近两侧熔合线附近为向焊缝中心区域生长的柱状晶,焊缝中心区域存在细小的胞晶区域;N6热影响区的显微硬度最低,焊缝的显微硬度介于N6镍母材和304不锈钢母材之间;接头拉伸断裂位置在焊缝区,抗拉强度达到N6纯镍母材的90%以上,可以满足实际情况下的使用要求。拉伸断口表现为准解理断裂。
High density Nd: YAG solid state continuous lasers were used to test the welding process of N6 pure nickel and 304 austenitic stainless steel, and the influence of laser power and defocusing amount on weld formation was investigated. Tensile strength and hardness of the joint were tested. Microstructure of the joint was analyzed by means of optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The results show that the grain growth in the heat-affected zone on the N6 pure nickel side is obvious. The weld zone near the fusion line near the weld line is a columnar grain growing to the center of the weld zone. The microhardness of the affected zone is the lowest, the microhardness of the weld is between N6 nickel base metal and 304 stainless steel base metal; the tensile fracture position of the joint is in the weld zone, and the tensile strength reaches 90% of the N6 pure nickel base metal, Above, can meet the actual situation of the use requirements. Tensile fracture showed quasi-cleavage fracture.