Light AlloysNo Access

STUDIES ON AGE HARDENING FOR IMPROVEMENT OF 6261 AND 6060 EXTRUDED ALUMINIUM ALLOYS

KA KI (KATIE) AU

Chemical and Materials Engineering, University of Auckland, Auckland 1142, New Zealand

Search for more papers by this author

MICHAEL HODGSON

Chemical and Materials Engineering, University of Auckland, Auckland 1142, New Zealand

Search for more papers by this author

TIMOTIUS PASANG

Mechanical and Manufacturing Engineering, AUT University, Auckland 1142, New Zealand

Search for more papers by this author

, and

YU LUNG CHIU

Department of Metallurgy and Materials, University of Birmingham, UK

Search for more papers by this author

https://doi.org/10.1142/S0217979210064757Cited by:0 (Source: Crossref)

Abstract

The magnesium silicide precipitates in the 6XXX series alloy are the main components contributing to the heat treatable properties and T6 strength of the alloy, which is influenced by the size, morphology and distribution of this phase. During the extrusion process, the strength contributing phase, magnesium silicide is supposed to dissolve and form again in a controlled state during age hardening. Whereas the intermetallic AlFeSi phase has little if any influence on the strength, the β phase of this intermetallic is known to cause brittle fracture of this alloy, as opposed to the less detrimental, more equiaxed α phase formed during homogenisation.

This study investigates the as-extruded 6060 and the more heavily alloyed 6261 aluminium alloys, as well as the subsequent heat treated forms to investigate the ageing conditions to optimise hardening and shorten age hardening times for higher cost effectiveness. The microstructure, texture and precipitate size and distributions were studied using optical microscopy, SEM, EBSD and DSC. SEM and EDAX results have indicated signs of evenly distributed α AlFeSi and β Magnesium Silicide precipitates. The phase responsible for hardening is believed to be the much smaller scaled β" magnesium silicide, requiring much higher resolution studies.

Keywords:

You currently do not have access to the full text article.
Recommend the journal to your library today!

References

T. Pasang, TIF Proposal (Auckland University of Technology, Auckland, 2007) p. 2. Google Scholar
W. Z. Misiolek , ASM Handbook ( ASM International , 2005 ) . Google Scholar
A. K. Gupta, D. J. Lloyd and S. A. Court, Materials Science and Engineering A 301, 6 (2001), DOI: 10.1016/S0921-5093(00)01814-1. Google Scholar
N. C. W. Kuijpers , Intermetallic Phase Transformations During Homogenisation of 6XXX Al Alloys ( Netherlands Institute for Metals Research , Delft , 2000 ) . Google Scholar
N. C. W. Kuijpers , Materials Science and Engineering , Kinetics of the b-AlFeSi to a-Al(FeMn)Si Transformation in Al-Mg-Si alloys ( Delft University of Technology , Delft , 2004 ) . Google Scholar
K. B. S. Coutoet al., Materials Science and Techonology 21, 6 (2005). Google Scholar
T. Sheppard , Extrusion of Aluminium Alloys ( Kluwer Academic Publishers , Dordrecht , 1999 ) . Crossref, Google Scholar
W. H. V. Geertruyden, Materials Science in Engineering (Lehigh University, Pennsylvania, 2004) p. 173. Google Scholar
Semiatin , ASM Handbook ( ASM International , 2005 ) . Google Scholar
Bjerkaas, H., et al., Texture and Microstructural Gradients in an Extruded Aluminium Profile. A Collection of OIM Applications. 2005 . Google Scholar
H. Inagaki and A. Umezawa, Materials Science Forum 495-497, 5 (2005), DOI: 10.4028/www.scientific.net/MSF.495-497.1273. Google Scholar
V. Randle and O. Engler, Introduction to Texture Analysis (Overseas Publishers Association, Amsterdam, 2000) p. 388. Crossref, Google Scholar
D. P. Field, ASM Handbook (ASM International, 2004) pp. 215–226. Google Scholar
M. Takedaet al., Materials Science Forum 217-222, 5 (1996), DOI: 10.4028/www.scientific.net/MSF.217-222.815. Google Scholar
M. Takedaet al., Journal of Materials Science 33, 6 (1998), DOI: 10.1023/A:1004355824857. Web of Science, Google Scholar
R. Visserset al., Acta Materialia 55(11), 9 (2007), DOI: 10.1016/j.actamat.2007.02.032. Google Scholar