Abstract
Following the 18th. report (Tetsu-to-Hagane, Vol. 44, 1958, No. 11, p. 36), the rapid softening method by stepped annealing of high speed steels (SKH8 & SKH6) was studied by micrography and hardness test. The results obtained were summarized as follows:
The hardness of the quenched high speed steel that had been annealed from 880°C→800°C in air, oil-or water-cooling (the so called "stepped annealing method") was nearly equal to the hardness obtained by a full annealing furnace.
