Accessible Requires Authentication Published by De Gruyter January 11, 2014

Homogenization of direct chill cast AlSi1MgMn billets

Yucel Birol

Abstract

The homogenization practice for direct chill cast AlSi1MgMn billets was investigated. It takes 8 h at 570 °C and at least 4 h at 580 °C to even out the Mg and Si distribution in the aluminium matrix and to obtain relatively small discrete αc-Al12(Fe, Mn)3Si particles with a “necklace” configuration. Once Mg and Si are solutionized, the equilibrium β-Mg2Si phase precipitates during post-soaking cooling at ≥ 500 K h–1. β′-Mg2Si precipitates are also identified in samples cooled at ≤ 250 K h−1. Hardness produced in this cooling rate range is relatively lower suggesting improved extrudability. These billet samples are fully solutionized at 500 °C during billet pre-heating. Typical press exit temperatures may suffice for adequate age hardening in billet samples soaked at 580 °C for 8 h and subsequently cooled at 250 K h−1. This is a very attractive feature as it implies a full age hardening capacity even without the need for a separate solution heat treatment.


* Correspondence address, Dr. Yucel Birol, Materials Institute, Marmara Research Centre, TUBITAK, Gebze, Kocaeli, Turkey, Tel.: +90 262 677 3084, Fax: +90 262 641 2309, E-mail:

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Received: 2013-04-24
Accepted: 2013-07-10
Published Online: 2014-01-11
Published in Print: 2014-01-09

© 2014, Carl Hanser Verlag, München