A mathematical model to predict the thermal history and microstructure developed in laser surface alloying

Laser surface alloying involves tailoring the surface microstructure and composition by rapid melting, intermixing and solidification of a pre/co-deposited surface layer with a part of the underlying substrate. It is a potential method of enhancing hardness and wear resistance of engineering components. In the present study, a one-dimensional heat transfer model based on the explicit finite difference method has been developed to predict the thermal history (i.e., temperature profile, thermal gradient, cooling rate and solid-liquid interface velocity) and hence, the microstructure of the alloyed zone developed by laser surface alloying. The incident laser power and laser-matter interaction time are chosen as the main variables to study the effect of laser parameters on thermal history, and consequently, microstructure of the alloyed zone. The numerical calculations have been carried out for the model system of AISI 304 stainless steel laser surface alloyed with pre-deposited molybdenum. The predicted results have been compared with same relevant experimental data.