TITLE:
Effect of Slow Cooling in Reducing Pore Size in a Sintered Powder Metallurgical 6061Aluminium Alloy
AUTHORS:
S. Solay Anand, B. Mohan, T. R. Parthasarathy
KEYWORDS:
Powder Metallurgy, Particle Size, Cooling Rate, Precipitation Hardening, Porosity
JOURNAL NAME:
Materials Sciences and Applications,
Vol.2 No.7,
July
29,
2011
ABSTRACT: The usage of powder metallurgy aluminium compacts in lieu of ferrous components in automotives helps to lower vehicle weight. The major drawback in the commercially available press sintered aluminium alloy is porosity which is mainly dependent on the powder metallurgical process parameters such as compaction pressure, sintering temperature and cooling rate after sintering. In this paper the effect of particle size and furnace controlled cooling after sintering on porosity level and micro hardness of an elemental 6061 aluminium alloy has been investigated. Aluminium particle sizes of 20 µm and 150 µm were used. The elemental 6061 aluminium alloy powders are warm compacted at 175 MPa. After sintering for about one hour at 600°C, the aluminium compacts were furnace cooled at the rate of 1°C /min to different temperatures of 500°C, 400°C, 300°C and 200?C. When the cooling temperature after sintering inside the furnace is effected at various temperatures from 600°C to 200°C, for a precipitate hardened aluminium compacts with aluminium particle size of 20 µm, the porosity level reduced by 26% and that for aluminium particle size of 150µm, the porosity level reduced by 23%. Marked improvement in micro hardness value is also observed correspondingly.