Warm compaction of ferrous powders in the 400°C to 520°C range—Part 1: Tool concept and compacting studies

Density is the single most important property of sintered steels; it controls virtually all other properties. In the present feasibility study, warm compaction in the temperature range of 400 °C to 520 °C was investigated. A special warm compacting tool was designed, which enabled powder preheating and compacting under a protective atmosphere. It showed that density levels of up to >7.6 g cm −3 can be attained with plain iron base powder. Since standard organic lubrication is not possible, graphite was used as a pressing lubricant. It was found that a mix of moderately fine artificial graphite and ultrafine natural graphite resulted in an acceptable combination of lubrication and alloying at least on a laboratory scale, while the higher density of graphite compared to organic lubricants increased the theoretical—and thus also the practically attainable—density.