Study of the effect of inter-pass temperature on weld overlap start-stop defects and mitigation by application of laser defocusing

Abstract Laser keyhole initiation and termination-related defects, such as cracking cavities due to collapse, are a well-known issue in laser welding of thick section steels. In longitudinal welding, run-on run-off plates used avoid this problem. However, an approach is not applicable circumferential where start/stop defects remain within the workpiece. These issues can hinder industry from applying for applications. paper, effect inter-pass temperature on termination at weld overlap start-stop region was investigated. This study has identified that occurring were rather than because instabilities regardless thermal cycle. The mitigated by defocusing regime reduce depth gradually control closure keyhole.