环形构件激光束钎焊过程的有限元模拟

Finite element simulation of a ring structurieon laser brazing

对铍环激光束钎焊过程的温度场和应力场进行了有限元模拟。分析采用轴对称模型和热力耦合的有限元方法 ,并假定沉积到钎缝表面的激光束能量满足Gauss分布。结果表明 ,焊接温度场分析得到的熔池大小与金相分析得到的焊缝几何尺寸比较一致 ;在离钎缝 2 .5mm以内的区域 ,焊接残余应力非常大 ,材料发生塑性屈服 ,环向应力大于轴向应力 ,从而使得铍环容易发生轴向开裂 ;远离钎缝区域 ,铍环内外表面同时发生向内的径向收缩 ,离钎缝 1mm范围内 ,铍环外表面向外膨胀 ,内表面继续向内收缩 ;焊接残余应力主要分布在离钎缝 15mm以内的区域。

The temperature and stress fields of a ring structure laser welding are simulated by finite element method (FEM).A axial symmetry model and a thermal-mechanical coupled FEM are adopted,and it is assumed that the energy distribution of the laser beam is Gaussian distribution on the weld pool surface.The results show that the fusion zone (FZ ) profile by FEM is much similar as that by metallurgic analysis.The brazing residual stresses are rather large within 2.5 mm from the brazing seam,which results in plastic deformation.The circumferentia1 stress is larger than the axial stress,thus the axial cracking is easily occurred in beryllium ring.Radial shrinkage in beryllium ring is the same far from the brazing seam,but within 1 mm from the brazing seam,outer surface is outward expand and inner surface is inward shrinkage.The welding residual stresses exist mainly within 15 mm from the brazing seam.