Instability deformation analysis of laser welded joint of 316L ultra-thin plate

Based on the thin plate stability theory determined by energy criterion, the finite element model of unstable deformation of ultra-thin plate laser welded joint was established. The temperature field and stress field of 316L steel foil plate surfacing welding with 0.07 mm thickness were simulated by ABAQUS, and the distribution of inherent strain was obtained. The eigenvalue buckling analysis of the post-welding instability deformation behavior in thin plate was carried out by using inherent strain obtained by integral calculation as equivalent load. Compared with the measured deformation results of laser welding, it was found that the ultra-thin metal plate presents concave-convex deformation mode after lower heat input, while convex-concave deformation occurs after higher heat input in the thin plate. The parameters of the numerical model were optimized, and the reasons for the change of the deformation mode of the thin plate were discussed. The nonlinear buckling analysis was carried out by introducing the low-order eigenvalue buckling mode as the initial deformation trend, and the unstable deformation was simulated, which is basically consistent with the actual deformation measurement results. Keeping the ratio of length to width of the thin plate at 1:1 and changing the size of the thin plate, the numerical relationship between the critical instability load and the size of the thin plate was fitted. The results show that the smaller the area of the thin plate is, the greater the critical buckling load of the thin plate is. With the increase of the thickness of the thin plate, the critical buckling load is increased significantly. © 2020, Journal of Materials Engineering. All right reserved.