Welding mode transition and process stability in high power laser welding

For high-power COlaser welding, besides two well known stable welding processes, i.e. stable deep penetration welding (DPW) and stable heat conduction welding (HCW), the authors have found the third welding process, i.e. unstable-mode welding (UMW) under the certain condition. UMW has its basic feature that the two welding modes (DPW and HCW) appear intermittently, with jumping of penetration depth and weld width between large and small levels. In this paper, effects of welding parameters (focal position, laser power and traveling speed) on laser welding mode and weld appearance have been comprehensively studied Double-U curves of laser welding mode transition have been obtained, which indicate the ranges of the three mentioned welding processes. This work affords science foundation for selecting the welding process parameters correctly and obtaining stable laser welding.