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mMINING METALLURGY MATERIALS<br />
m m<br />
WWW.UNILEOBEN.AC.AT<br />
Universitätslehrerverband der<br />
<strong>Montanuniversität</strong> <strong>Leoben</strong> (<strong>ULV</strong>)<br />
Semi-solid processing of an AlSi7 alloy<br />
The effect of a cooling slope on the semi-solid processing of an unmodified non-grain<br />
refined A357 AlSi7 alloy with an aim to improve as-cast properties has been investigated.<br />
Schematic representation of experimental set-up<br />
The following conclusions have been drawn from the results:<br />
- Contact time, shear force and surface contact between cooling<br />
plate and the melt are the dominant factors in the control of the<br />
microstructure, rather than inclination angle and cooling plate<br />
length, in the cooling slope technique.<br />
- A 40° inclination angle gave a condition where all the factors<br />
were optimum and the same microstructure was obtained<br />
regardless of the initial pouring temperature for a given constant<br />
contact time.<br />
- Microstructures observed were non-dendritic but also not globular<br />
in shape, the latter being characteristic of alloys with good<br />
thixotropic properties.<br />
Muhammad Kamran<br />
Chair of Casting Research<br />
at MUL since: 2003<br />
The Author:<br />
2000: MSc (Engneering) NED UET, Pakistan<br />
2001-2003: University of the Punjab, Pakistan<br />
Since 2003: PhD student at MUL<br />
Semi-solid processing is a beneficial process due to its ability<br />
to form a near net shape and sound product with uniform and<br />
improved properties. The alloy was processed with pouring<br />
temperatures of 680, 660 and 640 °C on a graphite coated<br />
copper cooling slope, at inclination angles of 20°, 40° and 60°<br />
for different contact lengths. These channel lengths had equivalent<br />
contact times of 0.04, 0.09 and 0.13 seconds. The semisolid<br />
slurry was poured into a sand mould and the resultant<br />
microstructures compared.<br />
Research Work:<br />
- Casting behaviour of Al-alloys<br />
- Semi-solid proceesing<br />
- Anodizing of mild steel sheets<br />
- Enrichment of Iron Ores<br />
0.04 s<br />
0.09 s<br />
0.13 s<br />
Effect of contact time on microstructure