SUPERSOLIDUS SINTERING AND MECHANICAL-PROPERTIES OF WATER ATOMIZED -10-CENTER-DOT-5CO-6-CENTER-DOT-5V-6-CENTER-DOT-5W HIGH-SPEED STEEL

ASP60 high speed steel is produced from gas atomised powder, subsequen tly encapsulated and hot isostatically pressed below the solidus tempe rature, the billets being further rolled as bars or rods. The microstr uctures of this material show a very fine carbide distribution which r esults in high values of fracture strength and wear resistance. This p aper presents results of a study of the processing of steel of the sam e composition by an alternative PM route, using water atomised powder, die compacted and vacuum sintered, in order to obtain near net shapes . The density achieved by supersolidus liquid phase sintering at simil ar to 1240 degrees C was similar to 99.9% of the theoretical, but the carbides were coarser, similar to 20 mu m, compared with < 4 mu m for ASP60. After heat treatment, the steel produced by this more economica l route has a fracture strength of similar to 2000 MN m(-2), near the optimum for vacuum sintered high speed steels, compared with 3000-4000 MN m(-2) for ASP60 as currently produced. Hardness values were simila r: similar to 960 compared with similar to 1030 HV30 of the hipped all oy.