A Study of Effect of Micro-alloying of Tin on Ageing Behaviour of 6xxx Series Aluminium Alloys

Abstract

Tin (Sn) acts as an important role in the ageing behaviour of Al–Mg–Si alloy (6xxx series). In the present work the effect of micro-alloying of (0.04 wt% Sn) on the natural age hardening behaviour of Al–Mg–Si alloy is studied. Two alloy compositions of Al–1.2Mg–0.69Si and Al–1.2Mg–0.69Si–0.04Sn were prepared by casting process. Solution heat treatment of the two as-cast alloys was carried out at two different temperatures of 530 and 570 °C for 75 min followed by quenching in cold water at room temperature. The variation in the hardness with time for the alloys heat treated at different temperatures was recorded after post solutionising. Addition of 0.04 wt% Sn causes retardation in attaining peak hardness as compared to base alloy. Micro-alloying of Sn by 0.04 wt% in Al–Mg–Si alloy delayed in attaining the peak hardness value from 24 h (1 day) to 192 h (8 days).