Flow stress of AISI H13 die steel in hard machining

In general, the flow stress models used for theoretic analysis and computer simulation in machining processes are a function of strain, strain rate and temperature during the cutting process. However, these models do not adequately describe the material behaviour in hard machining, where the workpiece material is machined in its hardened condition. This hardness modifies the strength and work hardening characteristics of the material being cut. An approach is presented to characterize the stress response of workpiece in hard machining, accounted for the effect of the initial workpiece hardness in addition to temperature, strain and strain rate on flow stress in this paper. AISI H13 die steel was chosen to verify this methodology. The proposed flow stress model demonstrates a good agreement with data collected from published experiments. Therefore, the proposed model can be used to predict the corresponding flow stress–strain response of AISI H13 die steel with variation of the initial workpiece hardness in hard machining.