Correcting the stress-strain curve in hot compression process to high strain level

Abstract

This article provides a model that regards the evolution behavior of the friction coefficient in the cylindrical compression test as a function of true strain on the basis of experimental results, allowing the effect of friction on the deformation curve at extremely high strain level to be evaluated and corrected for the first time. The compressive tests were carried out at a stroke rate of 1.2 mm/s on IHS38MSV hypoeutectoid steel with various lubricants at temperatures ranging from 800 °C to 1200 °C. The results showed that the friction coefficient for the compressive process was not constant and the variation could be approximated by an exponential equation along with the true strain. Microstructure observation showed that the stress increase in the later stages of process should be closely related to the large increase in the friction coefficient. The corrected curves were found to correlate well with the microstructure observation. © 2009 The Minerals, Metals & Materials Society and ASM International.