Patent ID: 9045806
Filing Date: 2015-06-02
Classification: C21D,C22C

Abstract:
1. Method for producing a component from steel, wherein the steel comprises the following steps prior to the finishing of the component which confers the definitive shape thereon: the preparation of a steel having a composition, in percentages by weight: C=0.20 to 0.30% Co=trace levels to 1% Cr=2 to 5% Al=1 to 2% Mo+W/2=1 to 4% V=trace levels to 0.3% Nb=trace levels to 0.1% B=trace levels to 30 ppm Ni=11 to 16% Si=trace levels to 1.0% Mn=trace levels to 2.0% Ca=trace levels to 20 ppm rare earths=trace levels to 100 ppm, if N≦10 ppm, Ti+Zr/2=trace levels to 100 ppm with Ti+Zr/2≦10×N if 10 ppm<N≦20 ppm, Ti+Zr/2=trace levels to 150 ppm O=trace levels to 50 ppm N=trace levels to 20 ppm S=trace levels to 20 ppm Cu=trace levels to 1% P=trace levels to 200 ppm, the remainder being iron and inevitable impurities resulting from the production operation, and wherein the composition of the steel simultaneously satisfies the relationship Ni≧7+(3.5×Al); at least one operation for shaping this steel; a softening tempering operation at 600-675° C. for from 4 to 20 hours followed by cooling in air; a solution heat treatment at 900-1000° C. for at least 1 hour, followed by cooling in oil or air which is sufficiently rapid to prevent the precipitation of intergranular carbides in the austenite matrix; a hardening ageing operation at 475-600° C. for from 5-20 hours.