May 13 - 16, 2008
Gaylord Palms
Orlando, Florida USA

Billet Process and Equipment

057 BP
Thursday, May 15 - 2:15pm

Measurements and Modelling of Precipitation and Dissolution during Cooling and Preheating of Extrusion Billets

Børge Holme, Sylvain Gouttebroze, Calin Marioara -- SINTEF Materials and Chemistry, Norway
Bjørn Rune Henriksen -- Elkem Aluminium, Norway
Kristina Lewin -- Sapa Technology, Sweden

A semi-empirical mathematical model quantitatively predicts amount and sizes of Mg-Si containing phases in 6xxx alloy billets during cooling after homogenization (soaking), and during preheating prior to extrusion. Laboratory heat treatment experiments on AA6063 are reviewed, and extensively characterized using FEGSEM, TEM, and butanol dissolution, for tuning and verifying model predictions. Calculations shed light on microstructure evolution during billet cooling and preheating.