Analytical and experimental investigation of subsurface characteristics and their depth-dependent modifications in grinding of case-hardened steel

This study investigates the influence of depth-dependent microstructural differences in case-hardened workpieces on process loads and subsurface characteristics. Specimen preparation using EDM and polishing enables analysis of hardness depth profiles and microstructural modifications after single-stage grinding for different depths within the case-hardened layer. Results show reduced modification depths for deeper levels. To understand underlying mechanisms, phase fractions (martensite, retained austenite, cementite) and hardness depth profiles were calculated analytically. Carbon-dependent softening of martensite is the main factor influencing hardness modification depths. In two-stage grinding, measurements and simulations reveal depth-dependent increased modification depths due to roughing and reduced loads in finishing.