Modeling of Phase Transformation in Induction Hardening

Mechanical properties of machined components are controlled by inducing phase transformations in the outer layer of the materials. Induction hardening is one such manufacturing process where the surface hardness is enhanced while the core is retained with the original structure and characteristics. In this study, a mathematical model had been developed to predict the hardness and the volume fraction of martensite present in the hardened surface. Experiments applying induction hardening were conducted on the following specimen materials AISI 1040, AISI 4140, AISI 4340, AISI 1055, AISI 6150 and AISI 9255. The microstructures obtained from the experiment showed a moderate phase transformation of austenite to martensite. The hardness and the volume fraction of martensite estimated from the experiments were found to match the results of mathematical modeling as well as the theoretical model using regression analysis.