Abstract: In order to decrease the thermal stress and suppress the generation of cracks during LMDS process, it is of great importance to understand the effects of substrate preheating on thermal stress. According to the “element birth and death” technique of finite element analysis (FEA), a three-dimensional multi-track and multi-layer numerical simulation model for LMDS is developed with APDL. Through the model, the effects of preheating on thermal stress are deeply researched by setting the temperature of substrate at room temperature or 400 ℃. The results show that preheating can remarkably decrease the thermal stress fluctuation of sample, and at the same time preheating can decrease the Von Mises thermal stress of sample by 10 percent, and decrease the x-direction thermal stress by 8.5 percent and decrease the z-directional thermal stresses by 8.1 percent. Using the same process parameters, the features of samples fabricated by self-developed LMDS system show good agreement with the simulation results.

Key words: Laser metal deposition shaping, Numerical simulation, Substrate preheating, Thermal stress