Research on warm laser shock sheet micro-forging

Abstract

This paper introduces warm laser shock sheet micro-forging, which combines the advantages of sheet bulk metal net forming, laser shock dynamic micro forming and warm forming. The influence of AZ31B magnesium alloy on laser energy and forming temperature was investigated by experiment and simulation. The mechanism that warm temperature has better properties than room temperature has been revealed from the aspects of microstructure, stress wave transmission and material flow. The results show that the forming depth of workpiece increases with the increase of laser energy. Forming depth increases with increasing temperature at the same laser energy, but serious ablation occurs on the surface of workpiece at 250 °C, which affects the forming quality of workpiece. EBSD results show that with the increase of forming temperature, the number of twins decreases, the dislocation density decreases and the forming depth increases. The grain refinement after laser shock forming is obvious, and the increase of grain dislocation density promotes the improvement of microhardness, which indicates that laser shock can improve the mechanical properties of materials. The numerical simulation results show that the elastic wave propagates faster than the plastic wave. The stress on the workpiece at 150 °C is less than that at room temperature, but the equivalent plastic strain is higher than that at room temperature. After plastic deformation, the material in the workpiece gradually flows to the cavity. At 150 °C, the material flow inside the workpiece is faster, the filling effect is better and the forming uniformity is better.