激光焊接与重熔自由表面温度分布及熔池形状的数值分析

以固液相变的统一模型方程为基础,计算了激光焊接与表面重熔不同加热模型条件下,液态熔池的形成过程,以及温度场和流场.主要考察了激光诱导的合金元素汽化和表面张力驱动流对自由表面温度分布及熔池形状的影响.结果发现,熔池自由表面温度和溶池形状主要受表面张力驱动的流体流动的影响,它在限制自由表面最高温度方面起着主要作用,合金元素汽化热损失的影响是第二位的.熔池的形状主要受液态金属涡旋方向的影响,在负的表面张力温度系数条件下,熔池浅而宽;在正的表面张力温度系数下,熔池深而窄.

NUMERICAL SYUDY ON FREE SURFACE TEMPERATURE AND MELTED POOL SHAPE IN LASER WELDINGOR REMELTING

Transient temperature and velocity fields in laser melted pool are simulated undr different heating models through numerical solution of the one-phase continuum equations. Special attention is given to the influence of laser induced vaporization from free surface and the thermocapillary flow on peak temperature and temperature distribution at the pool surface. It has been found that the thermocapillary flow plays a major role,and the vaporization heat losses play a second role in determining the free surface temperature distribution of the molten pool. The predicted results show that the transient behavior of the pool is strongly affected by the nature of surface tension temperature coefficient.