Constitutive behavior of as-cast A356

TL;DR

This study characterizes the constitutive behavior of as-cast A356 aluminum alloy across various temperatures and strain rates, comparing multiple models to identify the most accurate for different deformation conditions.

Contribution

It provides a comprehensive analysis of flow stress models for A356, extending existing models and evaluating their applicability across different strain regimes and temperatures.

Findings

Extended Ludwik-Hollomon best for small strain hardening

Kocks-Mecking model suited for large strain behavior

Zener-Hollomon model predicts flow stress accurately at high temperatures

Abstract

The constitutive behavior of aluminum alloy A356 in the as-cast condition has been characterized using compression tests performed over a wide range of deformation temperatures (30-500{\deg}C) and strain rates (\approx0.1-10 /s). This work is intended to support the development of process models for a wide range of conditions including those relevant to casting, forging and machining. The flow stress behavior as a function of temperature and strain rate has been fit to a modified Johnson-Cook and extended Ludwik-Hollomon expression. The data has also been assessed with both the strain-independent Kocks-Mecking and Zener-Hollomon frameworks. The predicted plastic flow stress for each expression are compared. The results indicate that the extended Ludwik-Hollomon is best suited to describe small strain conditions (stage III hardening), while the Kocks-Mecking is best employed for large strain (stage IV). At elevated temperatures, it was found that the Zener-Hollomon model provides the best prediction of flow stress.