Residual stress analysis of laser spot welding of steel sheets

Experimental and numerical studies were conducted to characterize laser and resistance spot welds to gain an understanding of load carrying capacity, temperature distributions and residual stress states of different joint geometries used in the automotive industry. Different laser spot weld path geometries are compared with conventional resistance spot welds to find the residual stress distributions in each. It was found out that the weld region in laser spot welding is surrounded by a compressive region which has higher compressive stress values and larger size than that of resistance spot welds. Simulations showed good agreement with experimental temperature distributions, and were able to qualitatively predict the residual stress distributions in each of the weld geometries. The thermal history at known failure locations within the welds and the influence of the weld geometries on cooling rate are also discussed.