PRODUCTION OF OXIDE DISPERSION STRENGTHENED TYPE STEEL

摘要

PROBLEM TO BE SOLVED: To improve the high temp. strength, ductility and toughness of the steel by heating previously prepd. steel having a structure in which oxide grains are dispersed into a martensitic phase to a specified temp., after that, gradually cooling it at a specified cooling rate and executing cooling to a room temp. SOLUTION: Oxide grain dispersion strengthened steel having a martensitic structure is heated at 900 to 1,300 deg.C and is thereafter cooled to a room temp. at a slow cooling rate of =200 deg.C, preferably =150 deg.C per hr. The heating at 900 to 1,300 deg.C is made for obtaining an austenitic phase, and the heating holding time is suitably controlled to 0.5 to 2 hr. Then, the reduction of the cooling rate is made for obtaining a ferritic single phase structure, and, in the case the cooling rate is made too high, by rapid cooling, a martensitic phase is caused. Since the steel obtd. by such heat treatment is low in hardness and excellent in ductility, it is suitable for working requiring high dimensional precision.