Effect of Slow Cooling in Reducing Pore Size in a Sintered Powder Metallurgical 6061Aluminium Alloy

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

An ANN Approach in Prediction of Microhardness in a Furnace Cooled Sintered P/M 6061 Aluminium Compacts

“…The variations in experimental microhardness value of the furnace controlled aluminium compacts have been well explained in earlier works by Solay Anand et. al., (2011) [9]. These values are used as training set for the ANN algorithm.…”

“…Although responses move in a forward direction, weights are calculated by moving backward, hence the name back propagation. The results obtained from the earlier work by the authors [9] for microhardness, by controlled cooling temperature after sintering, trained data set has been prepared for artificial neural network algorithm and microhardness value has been obtained by artificial neural network technique and compared with experimental values.…”

“…In the earlier works by Solay Anand et. al., 2011 [9], the effect of slow cooling in reducing the volume of porosity level and enhanced hardness value has been discussed. The output properties of powder metallurgical products vary non-linearly with varying input parameters.…”

Extended CT Void Analysis in FDM Additive Manufacturing Components

“…Furthermore, high void content results in a decrease in delamination of the composites [ 59 ]. Studies of void size, measured in 1, 2, and 3 dimensions, have shown that components with large voids have a decrease in their strength [ 52 , 60 , 61 , 62 ], while other results do not show an impact of void sizes with respect to fatigue test results [ 57 ]. The shape of voids measured by different descriptors, like sphericity and compactness, also express a variation of the Young’s modulus; spherical voids show less impact than those with elongated shape [ 52 , 55 , 60 , 63 ].…”