Abstract
Particle size distributions, microstructures and residual gas contents of high speed steel powders, ato-mized by spraying water or argon gas have been investigated. The particle size distributions and the micro-structures of the water-atomized powders are finer than those of the argon-atomized powders. Oxygen contents of the water-atomized powders are higher, but can be easily reduced by sintering in a vacuum furnace. In the argon-atomized powders, argon included in the powders are observed.
Sintered and hot-forged high speed steels of low oxygen contents have high transverse rupture strength and notch-toughness, because of their uniformly fine microstructures. Retained austenite is decreased and grinding is also relatively easy in the sintered and hot-forged high speed steels of fine microstructures.
