Constitutive equation for AISI4140 steel applicable to a wide range of strain rates at elevated temperatures

Abstract

This paper presents a method to determine a constitutive equation of AISI4140 steel when it deforms at a wide range of strain rates (0.05-1900 s(-1)) under high temperatures. The fundamental idea considered here is that the dependency of flow stress upon strain rate and temperature is described by the power law model of the Arrhenius equation. Strengthening coefficient and work hardening exponent are introduced to take a simplified treatment to the flow stress behaviour characteristics without losing accuracy of the model. The validity of the proposed constitutive equation has been examined using results obtained from the hot compression test (GLEEBLE (R) 3500C) and Split Hopkinson-Pressure Bar test at high temperature. Results revealed the proposed constitutive equation could predict flow stress-strain curve of the steel with an acceptable amount of error at the ranges of strain rates.