激光深熔焊接下临界功率的确定

在准稳态传热控制模型的基础上，推导了激光焊接热传导问题的有限差分方程。改变热物性参数(比热)替代相变潜热确定了热传导焊接的临界温度值，利用自编的MATLAB程序对有限差分方程进行求解，数值模拟了焊件的温度场。当材料表面刚好出现汽化时，激光焊接处于热传导焊与深熔焊之间的临界状态。在此临界状态下材料处于固相，可以避开材料的相变而简化模型。在此基础上，数值模拟了激光焊接时工件的热传导温度场，得到激光深熔焊接下临界功率的变化规律，即激光焊接的下临界功率随焊接速度的增加成一定比例地增加，为激光精密焊接中工艺参数的确定提供理论指导。

Definition of Lower Critical Power in Laser Deep Penetration Welding

Based on quasi-stable state heat-transfer control mode, finite difference equation of thermal conductivity in laser welding is deduced. Physical parameter (specific heat) substitutes for phase-changing latent heat, then critical temperature of thermal conductivity welding is determined, so finite difference equation can be solved by MATLAB software. Temperature field distribution is simulated to weldment. When vapourization of surface appears, laser welding is on critical condition between thermal conductivity and deep penetration welding, the material is solid phase, so the model is simple. under this condition thermal conductivity Temperature field of laser welding is simulated, The result indicates that Lower Critical Power in Laser Deep Penetration Welding is increased with welding speed, it can supply guidance for definition of processing parameter in laser deep fine welding.