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

摘要

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.