Publication: Plastic deformation and ageing characteristics of cast Al-Mg-Si alloy
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Date
2012-06-01
Authors
Soon, Vern Yee
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Abstract
This study was aimed to investigate the effect of severe plastic deformation (SPD) on mechanical properties of cast Al-Mg-Si alloy and including ageing. Aluminium 6061 T6 alloy was melted and casted into a rod of 13mm diameter and 60mm length. The rod samples were then subjected to equal channel angular pressing (ECAP) for SPD, up to 3 passes, through BC route. The changes in the microstructure and mechanical properties of Al-alloy rods deformed by various numbers of ECAP passes were investigated. Cast samples and ECAP-ed samples were solution heat treated at 530℃, quenched in water and held at 180 °C at various aging period to determine the effect of artificial aging. The ECAP-ed and casted alloy were evaluated for microstructure, hardness and X-ray Diffraction (XRD) pattern. Cast alloy consisted of α phase grains that were surrounded by Mg2Si particles which located at the grain boundaries. The crystallite size was decreasing with increasing number of ECAP passes with smallest value of 2.9 nm. The hardness increased with accumulative applied strain by ECAP with the highest value was 107 Hv. Longitudinal planes showed higher aspect ratio of grain than transverse plane but the hardness trend for both planes was same. For heat treated samples, peak hardness was achieved after 5 hour ageing. However, ECAP-ed samples achieved peak hardness sooner than the cast samples and has good thermal stability.