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Journal of Metallurgy
Volume 2012 (2012), Article ID 921235, 7 pages
http://dx.doi.org/10.1155/2012/921235
Research Article

Mechanical Response of Al-1.09Mg2Si Alloy under Varying Mould and Thermal Ageing Conditions

Department of Metallurgical and Materials Engineering, Faculty of Engineering, University of Lagos, Lagos 101017, Nigeria

Received 23 August 2012; Revised 12 November 2012; Accepted 16 November 2012

Academic Editor: Gerhard Sauthoff

Copyright © 2012 O. I. Sekunowo et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Samples of the 6063 (Al-1.09Mg2Si) alloy ingot were melted in a crucible furnace and cast in metal and sand moulds, respectively. Standard tensile, hardness, and microstructural test specimens were prepared from cast samples, solution treated at 520C, soaked for 6 hrs, and immediately quenched at ambient temperature in a trough containing water to assume a supersaturated structure. The quenched specimens were then thermally aged at 175C for 3–7 hrs. Results show that at different ageing time, varied fractions of precipitates and intermetallics evolved in the specimens’ matrices which affect the resulting mechanical properties. The metal mould specimens aged for four hours (MTA-4) exhibited superior ultimate tensile strength of 247.8 MPa; microhardness, 68.5 HV; elongation, 28.2% . It is concluded that the extent of improvement in mechanical properties depends on the fractions, coherence, and distribution of precipitates along with the type of intermetallics developed in the alloy during ageing process.