The Response of the Heat Affected Zone to Natural Aging in Friction Welded Al-Mg-Si-T6 Alloy

In this work, it is aimed to study the effect of welding parameters on the response of the fully reverted zone of the heat affected zone in Al-Mg-Si-T6 alloy to natural aging. The study takes in consideration the effect of welding time which usually receives less attention than other parameters. Rods of 25 mm diameter were friction welded at varying welding times and forge pressures. The highest hardness recovery in the fully reverted zone was obtained by a combination of a high heat input with a short welding time. These welding conditions produced a thermal welding cycle with higher cooling rate with a relatively longer time at the peak temperature. The high cooling rate is important to avoid the formation of the non-hardening $Mg_2Si$ precipitates which do not contribute to the hardness. The longer hold time at peak temperature permits more precipitate dissolution to increase the solute concentration in the solution before the rapid cooling.