Effect of homogenization heat treatment on the mechanical properties of AlMgSi alloys with different Cr content

AlMgSi alloys with two Cr compositions (0.17 wt% and 0.08 wt%) were subjected to different homogenization heat treatment soak conditions at: 560 °C, 580 °C, 600 °C with soak time duration of 6 h, 8 h, and 10 h; subsequently, alloys were cooled by air. Metallographic examination methods were used to determine microstructure after homogenization heat treatment. Hardness measurements were used to assess the mechanical properties. The results indicated that high Cr concentration in Al alloy contributed entirely transformation of β-AlFeSi into cubic α-AlFeSi phase with 580 °C–600 °C soak temperature condition. At the same time, high levels of Cr addition led to the formation of higher volume fractions in the alloy. The Mg2Si particles entirely dissolved in the Al matrix and homogeneously dispersed under this annealing condition. The specimens reached maximum hardness after homogenization heat treatment at 580 °C for 8 h. The hardness values of the sample with 0.17 wt% Cr are higher than the sample with 0.08 wt% Cr for relatively long-term soak time at 8 h–10 h and high soak temperature at 580 °C–600 °C.