电子束焊接熔池流场数值模拟研究

Numerical simulation of EBW pool fluid flow field

基于电子束焊接"钉型"焊缝特征,建立了高斯面和旋转高斯衰减体复合热源模型,采用ANSYS FLOTRAN CFD有限元软件,对焊接熔池流场进行了数值模拟,研究了熔池内液态金属在温度场作用下涡漩流动过程,电子束、熔池、液态金属蒸汽之间相互作用关系,电子束匙孔效应、匙孔壁能量传递方式,熔深方向液态金属流动机理等;将316L不锈钢热物性参数输入复合热源模型,通过仿真计算,得到了316L不锈钢焊接工艺规范,即加速电压为60 kV,电子束流为30 mA,焊接速度为8 mm/s,采用该规范焊接的316L不锈钢试件焊缝拉伸强度为425 MPa,满足设计要求。通过对比数值模拟与实际焊接结果表明:模拟熔池形貌与实际焊缝形貌一致,数值计算结果与焊接试验结果相吻合,从而证明复合热源模型是正确和适用的。

Gauss area and rotary Gauss decay body hybrid heat source model was established based on the seam feature of nail-shaped electron beam welding （EBW）. The weld pool fluid flow field in EBW was simulated numerically with the finite element software ANSYS FLOTRAN CFD. The vortex flow of liquid-state metal in weld pool under temperature field, interaction among electron beam, weld pool and liquid-state metal vapor, electron beam keyhole effect and energy transmission pattern of keyhole wall as well as liquid-state metal flow mechanism along welding penetration were in,Jestigated. The welding specifications （60 kV accelerating voltage, 30 mA electron beam current and 8 mm/s welding speed） of 316L stainless steel were obtained by simulation calculation and solution that inputs thermophysical properties of 316L stainless steel into hybrid heat source model. Applying the above specifications, the welded joint tensile strength of 316L stainless steel specimen reached 425 MPa, which satisfys the design requirement. The comparison result of simulated weld shape and actual weld shape indicates that numerical calculation results is in accordance with actual testing results, which proves the validity and applicability of the heat source model.