Influence of alloy composition, solidification rate and artificial aging on plastic deformation behaviour of Al–Si–Cu–Mg casting alloys

Abstract

The plastic deformation behaviour of three Al–Si casting alloys was investigated using the Kocks–Mecking strain hardening theory. Three coarsenesses of the microstructure, two aging temperatures and a number of aging times were used. For Al–Si–Mg and Al–Si–Cu–Mg alloys, the dislocation storage rate decreases while the dislocation recovery rate increases with aging time during underaging, whereas the concentration of alloying elements in solid solution decreases. The storage rate reaches a minimum at the peak aged condition and increases at overaging. The storage and recovery rates of the Al–Si–Cu alloy increase with aging time in the underaged condition and start to decrease during overaging, which indicates that a mixture of shearable and non-shearable precipitates are present during underaging, whereas all precipitates become non-shearable on overaging.