Numerical and experimental investigation on laser metal deposition as repair technology for 316L stainless steel

摘要

316L stainless steel plate with a trapezoidal groove was repaired by laser metal deposition (LMD) with 316L stainless steel powder. Finite element method (FEM) is adopted to predict the thermal behavior in the molten pool during the LMD. There is an overlapping between the adjacent tracks and adjacent layers during the LMD, forming a three dimensional structure. The influence of the second track in the first layer and the first track in the second layer on the first track in the first layer was investigated by the simulation process and experimental method. The numerical results indicated that the maximum temperature and the dimensions of the molten pool at the second track in the first layer and the first track in the second layer are larger than those at the first track in the first layer. The temperature of the first track in the first layer increases after the deposition of the second track in the first layer and the first track in the second layer. The microstructure evolution of the first track in the first layer was examined by the optical microscope (OM) and scanning electron microscope (SEM). The experimental results show that the thermal cycle caused by adjacent tracks brings about a significant effect on the microstructure and micro-hardness of the first track in the first layer.