Abstract: White layer produced during hard machining process has great influence on the usability and working life of parts, thus the accurate and quantitative prediction for white layer thickness has important theoretical significance and application value. Based on the basic theory of material chemical thermodynamics, the theoretical derivation of austenitic phase transformation temperature influenced by coupling factors including alloying elements, stress, strain is carried out, on the basis of the calculated phase transformation temperature and the finite element simulation results, the prediction model of white layer thickness on the basis of phase transformation mechanism is established. The contrastive analysis of the experimental and prediction results for GCr15 hardened steel shows that this model is suitable for the cutting process dominated by thermal-mechanical coupling and can predict the thickness of phase transformation white layer in dry and hard machining more accurately considering the thermal-mechanical coupling factors.

Key words: dry and hard machining, finite element simulation, hardened steel, phase transformation temperature, white layer