304不锈钢激光深熔焊元素蒸发及焊缝合金含量变化

Vaporization and composition change of 304 stainless steel during keyhole mode laser welding

通过模拟和试验的方法对激光深熔焊304不锈钢焊缝合金成分变化进行了研究.利用电子探针X射线显微分析对母材及焊缝中的Fe,Cr,Mn,Ni元素含量进行分析.基于对焊接熔池温度场和流场的计算,建立了深熔激光焊元素蒸发和焊缝合金含量变化的模型.结果表明,深熔激光焊元素蒸发主要发生在小孔及熔池表面,其中小孔内金属蒸发强烈,而小孔外的熔池表面蒸发量较小.与母材相比,焊缝中Mn,Cr元素含量减少,而Ni,Fe元素含量增加.焊缝合金含量变化随焊接功率增大而减小,但对于焊接速度的改变不敏感.计算结果与试验检测结果吻合良好.

Composition change during Nd:YAG laser deep penetration welding of 304 stainless steel was examined by experiment and theory.Concentrations of iron,chromium,nickel and manganese in the weld metal were determined by electron probe micro-analyzer(EPMA).Based on the computation of temperature field and weld pool geometry,a comprehensive model for weld composition change was developed.The results showed that the vaporization is most pronounced in the keyhole region.The vapor flux from the weld pool surface outside the keyhole is much lower than that from the keyhole.The concentrations of manganese and chromium decreases,while the concentrations of iron and nickel slightly increase in the weld metal,compared with those in the base metal.The composition change of alloying elements decreases as the laser power increases.However,the welding speed has insignificant effect on the composition change.The calculated composition changes agree well with the corresponding experimental results under different welding conditions.