电子束定点焊接304不锈钢熔池流动行为数值模拟

Numerical simulation of molten pool flow behavior in stationary electron beam welding of 304 stainless steel

关键词:  电子束焊接  304不锈钢  金属蒸汽反作用力  表面张力  熔池流场

Key words:  electron beam welding  304 stainless steel  reaction force of metal vapor  surface tension  fluid flow of molten pool

摘要:

基于电子束焊接过程的传热与受力物理过程分析,建立相应模型,对电子束定点焊接304不锈钢的温度场与流场进行数值模拟,研究电子束焊接熔池流动行为及焊缝成形规律.结果表明,电子束加热阶段,熔池上表面温度梯度达到10⁶ K/m,熔池表面峰值温度高,在沸点温度附近波动,强烈的金属蒸汽反作用力成为熔池流动的主要作用力,促使熔池中心下凹并不断波动,熔池冷却凝固阶段,金属蒸汽反作用力下降,熔池金属表面张力梯度引起的Marangoni对流成为熔池金属流动主要驱动力,促使焊缝表面熔宽增大,熔池凝固后焊缝上表面宽度为1.9 mm,中心处宽度为1.6 mm,下表面宽度为1.8 mm.

Abstract:

The physical model of electron beam welding was established in consideration of all the thermal process and forces during electron beam welding. The molten pool behavior and weld shape of 304 stainless steel heated by stationary electron beam were studied by numerical simulation of the temperature field and fluid flow field. The results shown that the temperature gradient of top surface was higher than 10⁶ K/m and the peak temperature of the molten pool fluctuated at boiling point of 304 stainless steel. The reaction force of metal vapor was the main driven force during heating stage. The top surface was depressed due to the impact of metal vapor and shacked with time. The Marangoni convection caused by surface tension gradient became the main driven force during cooling stage due to the reduction of metal vapor reaction force in the cooling stage. The weld width at the top and bottom surface was large than the center of thickness direction. The weld width at the top surface, bottom surface and the center were 1.9 mm, 1.8 mm and 1.6 mm respectively.