Abstract:

Due to surface undercut in the process of welding of SUS 304 stainless steel plate with 12mm thickness using high power fiber laser, the flow of molten pool was captured by a highspeed camera based on “sandwich” method. The influences of the welding orientations, welding speed and the root hump on the surface undercut were discussed, and the formation causes of the surface undercut were investigated. The results show that the average depth decreases gradually with varying the welding orientations from horizontal orientation welding to the vertical orientation welding. Moreover, as the welding speed becoming smaller, the size of the “shelf” on the keyhole front wall increases and the undercut becomes deeper. With generation of the root hump, the top molten pool lacks the liquid metal resulting in surface undercut.

Key words: laser technique, laser welding, surface undercut, thick plate, welding orientation, high speed photography

摘要：

针对12mm厚的SUS 304不锈钢板的大功率光纤激光焊接过程中,焊缝表面容易出现塌陷的问题,利用高速相机及“三明治”焊接方法拍摄了熔池的流动状况。讨论了焊接位置和焊接速度以及底部驼峰的形成对表面塌陷的影响,研究了塌陷产生的原因。结果表明:从水平焊接位置到竖直焊接位置的过程中,表面塌陷平均深度逐步减小。焊接速度越小,小孔前沿孔壁上“凸台”越大，表面塌陷越严重。底部驼峰的形成，导致熔池熔融金属不足，形成表面塌陷。

关键词: 激光技术, 激光焊接, 表面塌陷, 厚板, 焊接方位, 高速摄像