Developing Complete Prediction Capability for Thermal Damages in Finish Machining of a Hardened Steel

Abstract

The material thermal damages in hard turning can be classified as re-tempering and re-quenching, and the capability of predicting both damages is critical to obtaining optimal machining parameters for best part service performance. In this study, thermal damages were represented by material hardness change, and models for re-quenching and re-tempering were constructed through heat treatment experiments. The model for re-tempering describes hardness change based on material thermal history, while the re-quenching model defines material hardness as a function of material quenching temperature. In the meantime, a valid finite element (FE) model was adopted to calculate the material temperature histories in 3D hard turning. The obtained thermal histories were fed into the damage models, and thus the distributions of thermal damages beneath machined surfaces could be predicted.