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Optimal Parameters in Precipitation Hardening of 6061 Aluminium Alloy Using Box-Behnken Design

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Somsak Kaewploy

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Precipitation hardening process is important to increase the hardness of 6061 aluminium

alloy. In order to achieve the desired hardness, this process has several controlled parameters

including solution soaking temperature, solution soaking time, aging temperature and

aging time. The identification of each appropriate parameter is important in the precipitation

hardening process of aluminium alloy. Because there has been no method or exact pattern,

therefore this research work applies the response surface methodology with Box-Behnken

design to determine these appropriate parameters. The experimental result is found that

there are three factors significantly affecting on the hardness obtained from the precipitation

hardening process. The experimental data is well fit a quadratic model due to high coefficient

of determination (R2=0.92). When this regression model is taken to construct the threedimensional

surface response plot and the contour plot, it is found that the optimum

condition is the solution treatment time of 5 hours and 18 minutes, aging temperature of

181°C and the aging time of 10 hours which yield the maximum predicted Vicker hardness

of 132.5 HV.

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6061 aluminium alloy; Box-Behnken design; precipitation hardening