Yield Point Elongation in Al-Mg Alloys

Abstract

To investigate the nature of the pinning point inducing yield point elongation in Al-Mg alloys, AA5052 and AA5182 alloys were quenched from 723 K and subjected to quench ageing experiments. In AA5052 alloy, yield point elongation was not developed at all ageing temperatures. In AA5182 alloys, yield point elongation was observed after ageing at temperatures between 348 and 673 K. Since pinning of dislocations thus occurred even at 673 K, it was strongly suggested that pinning points formed during such ageing process were quite stable. Tensile tests made at various temperatures on these alloys by varying strain rate revealed that pinning points formed in AA5182 alloy are much more unstable than those formed in AA5052 alloy.