钛合金激光焊接大梯度残余应力特征分析

选用可精确描述小孔和熔池形貌的旋转高斯曲面体热源,建立了一个局部细化的钛合金激光深熔焊有限元数值计算模型,研究了激光能量密度与热输入对焊缝、小孔形貌以及焊缝及近缝区大梯度残余应力的分布特征.结果表明,钛合金激光焊接高残余应力位于小孔区域,而焊缝其余区域形成了大梯度残余应力状态;残余应力梯度在能量密度过高或过低,以及热输入过小时均较大;为避免大梯度残余应力的产生,应使焊接时激光能量密度处于中低状态.

High gradient residual stresses during laser deep penetration welding of titanium alloy

A numerical calculation model with local refined mesh for laser deep penetration welding of titanium alloy is presented. A Rotatry-Gauss body heat source model was established to accurately describe the shape of keyhole and molten pool of the laser welded joint. The profile of keyhole and molten pool as well as the distribution of high gradient residual stresse are obtained. It is showed that the region of high stress locates in the keyhole region, and high gradient residual stress distributes in the other region of welded seam. The stresse gradient increases in the state of excessively high and low level of energy density as well as the state of lower linear energy. It is supposed that keeping the laser energy density in state of low and medium level or keeping the linear energy in state of low level could avoid the high gradient stresses.