Suppression of deformation and enhancement of weld properties in thin stainless steel using synchronous heat sink plus ultrasonic hybrid laser welding

Laser welding deformation poses a significant challenge in thin stainless steel applications. While numerous methods have been proposed to mitigate this issue, the potential impact of these methods on the mechanical properties of welds has often been overlooked in the context of deformation suppression. A new method of Synchronous heat sink + ultrasonic hybrid laser welding (SHS+UHLW) is proposed in this paper, which not only greatly suppresses the deformation, but also improves the mechanical properties of the weld. This method can achieve collaborative control of welding deformation and weld properties. The simulation models of Synchro-nous heat sink assisted laser welding (SHSLW), ultrasonic assisted laser welding (UALW), SHS+UHLW were established to study the distribution of stress and deformation in different welding processes. The results show that compared with conventional laser welding (LW), the residual stress and post weld deformation of the weld seam are reduced by SHSLW, UALW and SHS+UHLW. Among them, the SHS+UHLW is more significant, and the stress and deformation are reduced by 8% and 40% respectively. In the process of SHS+UHLW, the constitutional supercooling (CS) is increased through ultrasonic cavitation effect and cooling, and the weld grain is refined to the maximum extent, thus improving the mechanical properties of the weld. Compared with LW, the hardness and tensile mechanical properties of SHS+UHLW joint increased by 11.8% and 13.62% respectively. Finally, it was confirmed that SHS+UHLW is the most effective for welding deformation in the subway roof thin plate.