Homogenization of Al-Mg-Si Alloy Billets – Myths and Facts
Jostein Røyset, Øystein Bauger, Jan Anders Sæter1, Ulf Tundal, and Oddvin Reiso,
Hydro Aluminium Research and Technology Development, Sunndalsøra, Norway
Track: BILLET PROCESS & EQUIPMENT - Homogenization
ABSTRACT—During homogenization of Al-Mg-Si extrusion ingots, significant changes in the
microstructure take place. In the present work, results related to the changes in type, size, and
shape of the AlFeSi particles are presented and discussed. Shape- and size-evolution of AlFeSi
particles during and after the β-AlFeSi to α-AlFeSi transformation indicates that a significant part
of the spheroidization that takes place is not directly related to the β-AlFeSi to α-AlFeSi
transformation reaction. The effect of manganese (Mn) on the β-AlFeSi to α-AlFeSi
transformation rate and on AlFeSi sphericity is measured, and surprisingly it is found that
increasing the Mn content appears to give less spheroidized AlFeSi particles after
homogenization. A positive effect of Mn addition on extrudability is demonstrated, and this effect
appears to be related to a refinement of the Mg2Si particle distribution in the alloys, rather than to
the effect on β-AlFeSi to α-AlFeSi transformation degree, or to the AlFeSi particle shape.
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