Grinding–hardening using dry air and liquid nitrogen: Prediction and verification of temperature fields and hardened layer thickness

This paper investigates the grinding–hardening both theoretically and experimentally with a plunge surface-grinding process. Theoretically, the paper presents a temperature-dependent finite element heat transfer model, incorporating a triangular moving heat source and various cooling conditions, to investigate the phase transformation kinetics, thus to predict the thickness of a layer hardened. The temperature variation and thickness of the hardened layer were also investigated experimentally on quenchable steel 1045 using dry air and liquid nitrogen as the cooling media. The predictions were in good agreement with the experimental results. It was found that the phase transformation follows the martensitic kinetics. The application of liquid nitrogen enhances the transformation of retained austenite to martensite and results in a refinement of the martensitic structure.