Investigation on Residual Deformation of Nanoindentation Micro-Region During Temperature Recovery

Abstract

Observation of residual indent is widely adopted to evaluate the mechanical properties of material in temperature indentation test. However, the potential influence of the difference between the testing and observing temperatures (20°C) on the material is always neglected. In this study, crystal plasticity finite element model of copper was constructed, and the processes of high-temperature indentation test and specimen temperature reduction to the observed temperature after the test were simulated. The simulations showed that the error of test hardness calculated from the residual area at 20°C compared to that at 800°C can reach up to 4.92% as the residual indent area reduces with temperature decreasing. The stress values of the indentation influence zone were also reduced considerably, in which the maximum stress at 20°C was 59% of that at 800°C. The distribution of stresses at surface and subsurface both changed substantially, while the depth of the influence zone increased by 31% from 800°C to 20°C. Therefore, the influence of temperature variation between the testing and observing processes on residual indent should be seriously considered.

Keywords: residual indent, FEA, temperature, morphology, stress