Numerical Simulation Of Temperature Field And Stress Field Of Laser Powder Deposition

Laser repair based on laser powder deposition belongs to advanced repair technology. It has extensive applicable prospect. But the stress and distortion produced in the laser repair process hampers its application, especially in the high precision repair. So it is important to research the thermal field and stress field of laser powder deposition and analyze influence of the powder materials and processing factors in order to control and decrease the stress and distortion.In this thesis the thermal field and stress field of laser powder deposition were dynamically simulated by ANSYS finite element software. In the model, the moving Guass thermal source was adopted. The influence of heat transfer, convection, radiation and phase transformation heat was considered comprehensively. The powder addition was simulated by killing and activating element. As a result, the finite element simulation of thermal field and stress field of laser powder deposition was well realized.38CrSi steel was used as substrate material. Ni-Cr-B-Si, Co-Cr-W and Fe-Mn alloy powders were deposited. Laser powder deposition process was simulated under the various laser power, scanning velocity and beam diameter. The variation of the thermal field and stress field with the powder materials and processing parameters was obtained. The mechanism of the thermal field and stress field variations was analyzed. The simulated results was proved by X diffraction experiments.With the increased laser power, increased scanning velocity and decreased beam diameter, the temperature gradient was increased and the residual stress was also increased. The beam diameter had the most intensive effect on the temperature field and stress field. The residual stress and its distribution are basically in accord with the measured practical results. So the finite element numerical simulation can well inflect the variation and distribution of laser powder deposition.