Analyses of Constitutive Behavior of As-Cast Aluminum Alloys AA3104, AA5182, and AA6111 During Direct Chill Casting Using Physically Based Models

Abstract

To understand the formation of direct chill (DC)-casting defects, e.g., butt curl and crack formation, it is essential to take into account the effect of temperature variation, strain rate, and their role in the constitutive behavior of the DC-cast alloys. For the correct prediction of defects due to thermal stresses during DC casting, one needs to rely on the fundamentals of mechanisms that may be relevant to the temperatures at below solidus temperatures. This research work aims to find a suitable physically based model for the as-cast aluminum alloys, namely AA3104, AA5182, and AA6111, which can describe the constitutive behavior at below solidus temperatures during complex loading conditions of temperatures and strain rates. In the present work, an earlier measured and modeled (Alankar and Wells, 2010, “Constitutive Behavior of As-Cast Aluminum Alloys AA3104, AA5182 and AA6111 at Below Solidus Temperatures,” Mater. Sci. Eng. A, 527, pp. 7812–7820) stress–strain data are analyzed using the Voce equation and Kocks–Mecking (KM) model. KM model is capable of predicting the hardening and recovery behavior during complex conditions of strain, strain rate, and temperatures during DC casting. Recovery is dependent on temperature and strain rate, and thus, relevant parameters are determined based on the temperature-sensitive annihilation rate of dislocations. For the KM model, we have estimated k1 parameter as a function of temperature, and k2 has been further modeled based on the temperature and strain rate. KM model is able to fit the constant temperature uniaxial tests within 1.5% of the regenerated data.