以钛合金Ti6Al4V与纯金属铅Pb为研究对象, 对激光熔钎焊接的焊缝界面裂纹与应力状态进行了实验观察和数值仿真, 探讨了异种金属激光焊接熔池中形成界面的现象, 以及界面上微观裂纹形成原因。计算结果显示, 界面两侧材料具有明显的力学性能差异, 由此导致焊缝界面上存在应力不连续, 最大等效应力出现在焊缝界面端部, 裂纹可能由此萌生并扩展至整个界面。

Laser welding-brazing is a kind of techniques for joining dissimilar materials, and is suitable for joining dissimilar metals with different thermophysical properties. Couple of Ti6Al4V/Pb were used for investigating the interface characteristics of Laser welding-brazing, especially the microstructure and stress state of the welds interface. Interface formation in molten pool during laser welding Ti6Al4V and Pb was found. Mixed fusion zone and region of Pb had significant difference in microhardness, that might affect the mechanical properties of the joint. Two-dimensional (2D) finite element model of quasi-steady state laser welding process was established to determine the temperature field and stress field under plane strain condition. The calculated results show that the stress on the interface of fixed fusion zone and Pb was not continuous. The maximum equivalent stress in the weld region was at the interface edge, the crack may initiate at this position and extended to the entire interface.