Article Sidebar
Published:
Jun 30, 2006Keywords:
Article Details
Tanzania Journal of Engineering and Technology (Tanz. J. Engrg. Technol.) publications are written as a basis for academic discussions. Whereas effort is made by the Editorial Board to screen out inaccurate or misleading statements, data or opinions, Tanz. J. Engrg. Technol. wishes to make it clear that the contents of the articles are the sole responsibility of the authors. Accordingly, the Editorial Board and editors, publisher, College of Engineering and Technology and the University of Dar es Salaam accept no responsibility or liability whatsoever for the opinions, inaccurate or misleading data or statement and views expressed by the authors.
However, the College of Engineering and Technology, the publisher of the Journal, reserve all rights of the articles published in the Journal. Whereas the contents of the articles are available electronically without cost, no part of the publication may be transmitted in any form or reproduced electronically or mechanically, except for short extract in critical scholarly review, research or discourse with an acknowledgement.
Main Article Content
Effectiveness of Hot Isostatic Pressing on Healing Oxide Film Defects in Cast Aluminium Alloys
Abstract
Hot isostatic pressing (hipping) of cast aluminium alloys is recognized as a means of providing improved internal soundness and mechanical properties of the castings. However, little is known about the limitations and potential benefit of the hipping process to produce reliable aluminium alloy castings containing oxide film defects due to turbulently filling of moulds. In this study, oxide film defects and fatigue lives of turbule''Zt filled unfiltered AI-7Si-Mg alloy castings have been characterised in as-cast and hipped. conditions to quantify the effectiveness of hot isostatic pressing on healing oxide film defects in the castings. The average fatigue life and fatigue life at 0.1 percent failure rate of AI-7Si-Mg alloy castings improve substantially following hipping treatment that also reduces significantly the scatter of the fatigue life data of the castings. This indicates that solid state hipping is a robust process to de-activate oxide film defects in AI-7Si-Mg alloy castings in which transformation of oxide film structure does promote the diffusion bonding across oxide film interfaces. This, however, contrasts with the behaviour of oxide inclusions in Al-lOMg alloy castings in which magnesium oxide film, whose structure is stable and does not transform during hipping, is possibly resistant to form effective bonding across the oxide film interfaces.
