Mechanism and experiment of surface modification by means of laser cladding combined with laser shot peening

Abstract

The defects and residual tensile stress in laser cladding layer may cause crack propagation, and will decrease the fatigue resistance of components by laser cladding. Based on analyzing the forming mechanism of the crack and residual tensile stress during the process of laser cladding, a novel surface treatment technique which combines laser cladding with laser shot peening (LSP) was presented, the mathematical model of thermal stress induced by laser cladding was established, the mechanisms of improving the quality of cladding coating by LSP were studied. The results indicate that under the combination effects of high density dislocation microstructure and residual compressive stress, the defects of the cladding coating in the laser peened area were overcome effectively, and the rate of crack growth was delayed. Finally, the feasibility of the novel technique was validated by experiments, and the hardness and residual stress distribution in the peened and unpeened coating of laser cladding were compared.