Print ISSN: 1681-6900

Online ISSN: 2412-0758

Author : Ezzat, Nawal


Study of the Microstructure Semi Solid Al-Si-Mg Casting

Nawal Ezzat; Nada Taher Sultan

Engineering and Technology Journal, 2013, Volume 31, Issue 1, Pages 1-11

Semi-solid metal processing involves processing metallic alloys between the
solidity and the liquidity. The microstructure must be non-dendritic and consist of
spheroids of solid in a liquid matrix. In this work two potential routes are used:
First, The superheated Al-Si-Mg alloy was continuously cooled down to various
temperatures above its liquidity (620,630,640) o C . When the desired temperature of
the melt has been reached, then mechanical stirring with rotational speed of
(800)rpm for (30)sec. was started. The resultant slurry was bottom poured into a
stainless steel mold placed below the crucible. The solidified samples were reheated
to the semi-solid metal processing temperature, held there for (10) min, and rapidly
quenched in into water tank to retain the semi solid microstructures. In the second set
of experiments , the superheated melt was continuously cooled down to various
temperature in semi solid range (610,600,595,590,580)o C, then mechanically stirred
at rotating speed(800)rpm for (30)sec. the resultant slurry was bottom poured into a
stainless steel mold placed below the crucible. The metallic mold is then rapidly
quenched in water to room temperature. Metallographic examinations indicate that
the mixing method leads to highly globular semi-solid slurries of fine particle size.
The particle sizes of slurry quenched at various temperatures within the semi solid
metal range are much smaller when compared to the reheated structures. The particle
size gradually increases as the slurry temperature decrease.