Warm compaction is an advanced manufacturing technique which consists of two consecutive steps, i.e. powder compaction at above ambient temperature and sintering in a controlled environment. Due to the relative movement between the powder mass and die wall as well as sliding among powder particles, frictional force is generated during the compaction stage. Admixed lubricant is used during the compaction step in order to minimize friction and hence improve the uniformity of the density of distribution inside the component. However, during the sintering process, trapped lubricant is often found to be burnt out hence leaving pores or voids which result in the lower strength of the final products. Warm compaction was initiated in the nineties, however not much information has been published about the effects of lubrication on the quality of the components produced through this route. Therefore, this paper presents the outcome of an experimental investigation about the effects of lubrication on manufacturing near-net shape components through the warm compaction route. Iron powder ASC 100.29 was mixed mechanically with zinc stearate to prepare the feedstock. Mixing time, weight percentage of lubricant content and compaction temperature were varied during green compact generation while sintering temperature, heating rate and holding time were manipulated during sintering. The relative densities and strengths of the final products were investigated at every compaction as well as sintering parameter. The results revealed that lubrication could provide significant effects at the compaction temperature of 180ºC while no significant effect of lubrication was observed during sintering. The suitable lubricant content was found to be 0.4 wt% and mixing time was around 30 min and the sintering temperature was around 990ºC.
This paper presents an experimental investigation on the effects of sintering temperature to the mechanical properties and microstructures of FeCrAl powder compacts formed through warm powder compaction route. Elemental iron powder ASC 100.29, copper and aluminum powder were blended mechanically in a low speed mixer. The blended powder mass was compacted at a temperature of 200°C and was later sintered in an argon gas fired furnace by varying the sintering temperature, i.e., 600°C, 750°C and 900°C for 90 minutes. The sintered products were then subjected to density measurement, flexure strength measurement as well as microstructure analysis through scanning electron microscopy. The results revealed that the suitable sintering temperature is 600°C which generated light weight products with higher bending strength, lower volumetric expansion, and better microstructure.