Mg-Gd-Y-Zr激光焊接工艺优化及高温力学性能

利用光纤激光焊对T6态Mg-10Gd-3Y-0.5Zr板材进行焊接. 以高温抗拉强度为评价指标，采用正交试验对工艺参数进行优化，分析了激光功率对接头高温力学性能的影响. 利用SEM，XRD及HRTEM对最优工艺参数下接头焊缝中心组织、热影响区组织、高温拉伸断口进行观察与分析. 结果表明，激光功率对焊接接头高温力学性能影响最显著. 最优工艺参数下焊接接头200 ℃平均高温抗拉强度为292.1 MPa，为母材的84.5%，断后伸长率为8.6%，达母材的71.1%. 激光功率的变化会导致焊缝中心晶粒尺寸、热影响宽度及其晶粒尺寸和相组成发生变化，从而影响接头高温力学性能. 200 ℃下焊接试件与母材断裂模式均为韧性断裂且热影响区为接头薄弱部分.

Optimization of Mg-Gd-Y-Zr laser welding process parameters and study on high temperature mechanical properties

The fiber laser welding is used to weld the T6 state Mg-10Gd-3Y-0.5Zr plate. Taking the high temperature tensile strength as the reference index. The process parameters were optimized by orthogonal test, and the influence of laser power on the high temperature mechanical properties of the joint was analyzed. The paper use SEM, XRD and HRTEM to observe and analyze the joint weld center structure, heat affected zone structure and high temperature tensile fracture. The results show that the laser power has the most significant effect on the high temperature mechanical properties of the welded joint. Under the optimal process parameters, the average high-temperature tensile strength of the welded joint is 292.1 MPa at 200 ℃, which is 84.5% of the base material. The elongation is 8.6%, which is up to 71.1% of the base material at 200 ℃. The change of laser power will affect the grain size, heat-affected width and phase composition of the weld, which will affect the high-temperature mechanical properties of the joint. The fracture modes of the welded joint and the base metal are ductile fractures at 200 ℃.The heat-affected zone is the weak part of the joint.