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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/4393

Title: Semi-solid rheocasting of grain refined aluminum alloy 7075
Authors: Curle, UA
Govender, G
Keywords: High pressure die casting
F condition
T6 condition
Incipient melting
Grain refined aluminum alloy
Nonferrous metals
Issue Date: Sep-2010
Publisher: Editorial office of Transactions of Nonferrous Metals Society of China
Citation: Curle, UA and Govender, G. 2010. Semi-solid rheocasting of grain refined aluminum alloy 7075. Transactions of Nonferrous Metals Society of China, Vol. 20(3), pp 832-836
Abstract: Near-net shape rheocasting with the Council for Scientific and Industrial Research Rheo casting system(CSIR–RCS) and a high pressure die casting machine was successfully performed on Al–5Ti–1B grain refined aluminum alloy 7075. Grain refinement levels used were 0.03% Ti, 0.13% Ti and 0.29% Ti (mass fraction). Tensile tests reveal that the ultimate tensile strengths, at all levels of grain refinement, are at least 97% of the specified minimum. Elongation at fracture increases with the increase of level of grain refinement although a maximum elongation is only 76% of the required minimum elongation in the case of 0.29% Ti. Incipient melting, during solution treatment, of the low melting point multinary eutectic causes porosity in the material and accounts for poor elongation results. 0.03% Ti has a coarse eutectic structure forming larger pores while 0.29% Ti has a fine structure forming fine pores in the multinary eutectic. The 0.2% offset yield strengths of all the grain refinement levels are at least equal to or above the specified minimum and a decrease is observed with the increase of grain refinement level. There is a clear reduction in grain size from 0.03% Ti to 0.29% Ti in the as-cast condition. An underlying grain structure develops in the T6 condition material which has an inverse size to the as-cast structure; coarse grained as-cast material results in fine grained T6 condition material after solution heat treatment. The decrease in the offset yield strength as grain refinement increases correlates very strongly with the T6 grain sizes according to a Hall–Petch type relationship.
Description: Copyright: 1997-2008 Editorial office of Transactions of Nonferrous Metals Society of China
URI: http://hdl.handle.net/10204/4393
ISSN: 1003-6326
Appears in Collections:Metal and metal processes
Manufacturing science and technology
General science, engineering & technology

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