Deformation behavior of a newly-developed T4-treated Al–Si die cast alloy

Abstract

The aim of this study was to identify the monotonic and cyclic deformation behavior of a high-pressure die cast Silafont®-36 alloy in a naturally-aged T4 state. The T4 heat treatment led to a significant microstructural change from the as-cast coralloid-like eutectic Si particles to spheroidal Si particles embedded in the Al matrix, while the prior Fe-, Mn-rich inclusions remained. Although the strength became lower, the ductility of the T4 alloy was higher. Low cycle fatigue life was observed to be longer than its as-cast state at lower strain amplitudes. The T4 alloy exhibited strong cyclic hardening, where the degree of cyclic hardening was found to increase linearly with increasing strain amplitude along with the absence of Masing behavior, due to the strong particle-dislocation interactions during deformation. Strain energy density-based model by incorporating the microstructural aspects in the form of intrinsic fatigue toughness can be used to predict the fatigue life of the T4 alloy.