Thermal Simulation on 316L + 20% vol WC composite sample produced by laser cladding additive process

Abstract

In this study, a 2D thermal model of the manufacturing of a bulk sample by laser cladding process with a mixture of 316L stainless steel enriched with 20% vol of WC carbides is developed. The simulations consider the middle track of each layer of the clad. The substrate consists in pure 316L produced by conventional turning. The most important results carried out by thermal simulations are the peak temperature achieved at each layer as well as the apparent substrate temperature and the melt pool depth. Correlations between these computed features and the sample microstructure are performed for a better understanding of the genesis of the microstructure morphology, the cell and grain size, dissolution of partially melted carbides and heat accumulation that occur during the real deposition process. The numerical temperature field and its evolution along time simulation are computed by Finite Element software LAGAMINE, developed at ULiege. The bi-dimensional Finite Element model is validated considering the thermal history of the substrate recorded by a thermocouple and the experimental melt pool depth measured at each layer by an optic microscope. A sensitivity analysis is performed analyzing the effect of input laser power, the uncertainty of thermo-physical properties (thermal conductivity and specific heat capacity) and the radiation heat versus convection one. The lack of fluid mechanic within the melt pool does not prevent the model to provide good results about the prediction of the heat accumulation. The manuscript ends with a discussion about some possible numerical model developments to improve the quality of the temperature predictions and the microstructure correlations.