Constitutive Behavior of a Homogenized AT61 Magnesium Alloy under Different Strain Rates and Temperatures: An Experimental and Numerical Investigation

Abstract

The performance of a structure is primarily determined by its material characteristics under different loading conditions, strain rates, and temperatures. In the present work, the plastic flow response of a homogenized AT61 magnesium alloy was constitutively analyzed under a wide variety of quasi-static and dynamic strain rates. The quasi-compression test was conducted at 25°C–250°C with strain rates from 10−4 to 10−1 s−1. The dynamic loading of AT61 alloy was performed on a split Hopkinson pressure bar (SHPB) apparatus under a strain rate of 1,000–4,000 s−1. The material shows hardening behavior throughout the strain rate regime, whereas the plastic flow stress significantly reduces with an increase in deformation temperature. At a very high strain rate, the accumulated energy around the cracks is attributed to the dynamic recrystallisation with the onset of adiabatic temperature rises in the materials. A phenomenological Johnson-Cook (JC) model was also calibrated and used for numerical simulation in ABAQUS/Explicit to predict the material flow response. It was observed that a strong correlation exists between experimental and numerical results.