Effect of chromium addition on the recrystallized grain size and aging characteristics in an Al-4%Cu-1.5%Mg alloy

Abstract

Recrystallized grain size, age-hardenability and quench-sensitivity have been examined for Al-4%Cu-1.5%Mg alloys containing chromium (0.10-0.49%), in comparison with the alloys containing manganese (0.30-1.28%). Coldrolled specimens were solution-treated at 500°C, and then subjected to different aging treatments. Recrystallized grain size of the alloy containing chromium (0.31-0.49%) is nearly the same as that of usual manganese contained alloy (0.64%). There is no difference in the age-hardenability at natural aging between the two sorts of alloys. However, the chromiun contained alloy is inferior in the age-hardenability at artifical aging and in the quench-sensitivity to the manganesec ontained alloy. These results are discussed in view of the differences in the density of insoluble compounds and the facility of loop formation mainly around the compounds.