光束倾角对激光深熔焊304不锈钢焊缝力学性能及熔池流动的影响

Effect of beam incident angle on weld mechanical properties and melt pool flow behavior in laser deep penetration welding of 304 stainless steel

在激光深熔焊接中光束倾角会直接影响匙孔形态,光束倾角对熔池流动也具有一定的影响.采用激光深熔焊接白板试验结合“半三明治”熔池流动直接观测试验,以激光倾角作为变量,研究其对304不锈钢激光深熔焊接焊缝力学性能及熔池流动的影响.结果表明,在焊缝的力学性能上,不同激光倾角对焊缝上、中部的影响差异性较小,对下部的影响较大,焊缝底部拉伸件出现较多气孔缺陷,正激光入射角下的焊缝抗拉强度和断后伸长率小于负激光入射角.正激光入射角下“上小下大”的匙孔形貌使其底部易产生涡流,不利于气泡的排出,且匙孔坍塌频率较负激光入射角大,导致熔池稳定性较差,焊缝气孔缺陷的形成概率呈现为正激光入射角高于负激光入射角态势.

In laser deep penetration welding,the laser incident angle directly affects the shape of the keyhole,and also has a certain impact on the flow behavior of the molten pool.In this work,bead-on-plate penetration welding experiment combined with"half sandwich"experiment were conducted to study the effect of laser incident angles on weld mechanical properties and melt pool flow.The results show that in terms of the mechanical properties of the weld,the laser incident angle has less impact on the upper and middle parts of the weld,but has a greater impact on the bottom part.There are more pore defects in the tensile samples from the bottom of the weld.Moreover,compared with negative laser incident angle,the tensile strength and elongation of the weld are lower for positive laser incident angle.For positive laser incident angle,the keyhole morphology is of small top and big bottom,makes it easy to generate eddy currents at the bottom and form bubbles.In addition,the keyhole collapse frequency is greater than that at the negative laser incident angle,resulting in poor stability of the molten pool which leads to more pore defects.