Method of manufacturing high strength and high toughness stainless steel

Abstract

A high strength, high toughness stainless steel consisting, by weight, of C more than 0.16% but less than 0.25%, Si not more than 2.0%, Mn not more than 1.0%, Ni not more than 2.0%, Cr from 11 to 15%, Mo not less than 0.5% but less than 3.0%, Co from 12 to 21%, at least one kind selected from the group consisting of V from 0.1 to 0.5% and Nb less than 0.1% which at least one kind is added as occasion demands, and the balance Fe and incidental impurities. This steel is produced by a method comprising the steps of: preparing a stainless steel having the composition of any one of the claims 1 to 4; subjecting the stainless steel to a solution heat treatment at a temperature of 950.degree. to 1150.degree. C.; quenching the steel; subjecting the steel to a sub zero treatment at a temperature of -50 to -100.degree. C.; and subjecting the steel to a tempering at a temperature of 120.degree. to 450.degree. C.

Dependencies are inferred from the claim text.