The Effect of Chemical Composition and Microstructure on the Flow Stress during Hot Deformation of Aluminium Alloys

Abstract

The effect of magnesium and silicon in solid solution on the flow stress during hot deformation is determined by means of torsion and uniaxial compression. The flow stress increases both with magnesium and silicon in solid solution, but the effect of magnesium is much stronger than the effect of silicon. Homogenising AA6082 at 480°C resulted in the formation of smaller dispersoids than homogenising the same alloy at 600°C. The material with the smallest dispersoids exhibited the highest flow stress. Manganese additions to AA6005 facilitated the transformation of the elongated β-AlFeSi to the more rounded α-AlFeSi, especially at high homogenisation temperatures. The flow stress was lower for the manganese-containing alloy homogenised at 580°C compared with the alloy homogenised at 550°C. For the AA6005 alloys without the manganese addition the flow stress increased with increasing homogenisation temperature.