Nanostructural evolution of hard turning layers in response to insert geometry, cutting parameters and material microstructure

Nanostructural characterization of hard turned surface layers of carburized steels was done to study the effect of tool design, tool wear and turning parameters on the near surface material transformations. To quantify subsurface evolution, numerical predictions were correlated with the measured structural and hardness parameters. Results show that the process design space can be partitioned into three regions based on thermal phase transformations, plastic grain refinement, and where both mechanisms are active. These relationships between the processing conditions and structural parameters are further explored through process maps based on Zener-Holloman parameter and the Hall-Petch relationship.