Heat matters when matter heats – The effect of temperature-dependent material properties on metal cutting simulations

The goal of metal cutting research is to predict process conditions accurately with a model or a simulation, in order to optimize and develop the processes. Development of such a model requires understanding of multiple branches of physics and engineering such as continuum mechanics, thermodynamics, tribology and materials science. For an accurate model, each aspect of the process must be modelled properly, or at least the effects of a certain phenomenon must be shown to be negligible. This paper investigates the effect of the temperature dependence of material properties on metal cutting simulations for three different engineering materials: AISI 1045 steel, AISI 7075 aluminium and AISI 304 stainless steel. It is generally accepted that the flow stress of metals is dependent on the temperature, but modulus of elasticity, thermal expansion, heat capacity and thermal conductivity are often considered constants and their effect is considered negligible. In this study, orthogonal turning of the materials is simulated with constant material properties and material properties that are functions of temperature. Each material property combination is simulated to test their effect on the results to investigate the individual and interdependent effects. Based on the results, a general guideline can be formed regarding the importance of heat capacity, thermal conductivity, modulus of elasticity and heat transfer.