High Strength Sintered Steels Containing Chromium and Manganese

By replacing Ni and Mo as alloying elements in sintered steels with Cr and Mn it is possible to achieve high strength at a lower cost for the raw material. Powder compacts containing these elements must however be sintered at high temperatures (around 1250°C) to prevent oxidation. An even carbon content in the sintered parts is reached simply by covering the sintering box with a lid. After single pressing and single sintering at 1250°C for 30 minutes a material containing 1.5% Cr, 0.5% Cu and 0.7% C reaches a tensile strength above 700 N/mm² and a very small dimensional change (−0.07%) almost independent of the eventual scatter of the carbon content. In order to combine high strength and dimensional precision in the sintered parts the amount and type of alloying additive must be correctly chosen.