Optimization of homogenization for a low alloyed AlMgSi alloy

The homogenization practice for EN AW 6060 was investigated. It takes an 8-hour soak at 580 °C to level out the Mg and Si distribution in the matrix and to transform the monoclinic β-Al5FeSi plates into relatively small α-AlFeSi particles. The solute Si and Mg are largely retained in solution during subsequent cooling at > 500 °C h− 1. Mg2Si precipitation is considerable, however, during cooling at < 250 °C h− 1, producing a hardness decrease from 39.5 ± 1.4 HV to 34.4 ± 0.2 HV, by 15%, over the range investigated. The solvus temperatures of the homogenized samples are below 500 °C regardless of the cooling rate, ensuring full solutionizing of the Mg2Si precipitates below the typical industrial press exit temperatures. An 8 hour soak at 580 °C followed by cooling at 250 °C h− 1 is identified to be the optimum homogenization treatment as it gives a homogeneous structure with predominantly round αc-Al12(Fe,Mn)3Si particles and sufficiently low hardness for improved extrudability and a solvus temperature below 500 °C to ensure adequate age hardening capacity.