Laser Engineered Net Shaping Process for 316L/15% Nickel Coated Titanium Carbide Metal Matrix Composite

This paper presents the investigation of the macrostructure, microstructure, and solidification structure of a 316L/15% nickel coated TiC metal matrix composite produced by the laser engineered net shaping (LENS TM) process. The focus of this work was to (1) identify the solidification structure and to estimate growth/cooling rates at the solid/liquid interface, (2) identify and quantify discontinuities in the build structure, and (3) examine the effect of solidification and thermal history on the sample microstructure to further the understanding of the LENS process. A Numerical method was also developed to examine the influence of material type and LENS TM process parameters on the forming of the specific microstructures from thermodynamics and fluid dynamics point of view. Samples of 316L stainless steel were examined, microstructures of samples were used to estimate the corresponding cooling rate, and the cooling rate was compared with the results of numerical modeling. The computational results show reasonable agreement with experimentally determined cooling rate.