AbstractThe ‘KHA process’ for producing PM high-speed steels using gas-atomizing equipment and the hot isostatic press has been developed by Kobe Steel Ltd. Measurement of the secondary dendrite arm spacing of gas-atomized powders indicated that the relation between the dendrite arm spacing S II (μm) and the powder particle diameter d (m) was described by S II= K□d where K is a constant. To establish suitable hot isostatic pressing (HIP) conditions with high productivity, density and bending strength were studied in relation to various HIP conditions. It was found that, for example, the combination of 1373K, 40MPa, 30 min was sufficient to obtain full density, but that 1473K, 40MPa, 30min was required to obtain the maximum bending strength. By studying various properties of KHA high-speed steels, it was found that they were superior to the conventional steels for toughness, grindability, and hot workability. Tools such as drills, end mills, hobs, etc. produced from KHA materials exhibited better cutting p...