Patent ID: 8153056

Claim:
Steel, characterised in that the composition thereof is, in percentages by weight: —C=0.18-0.30% —Co=5-7% —Cr=2-5% —Al=1-2% —Mo+W/2=1-4% —V=trace levels−0.3% —Nb=trace levels−0.1% —B=trace levels−50 ppm —Ni=10.5-15% with Ni≧7+3.5 Al —Si=trace levels−0.4% —Mn=trace levels−0.4% —Ca=trace levels−500 ppm —Rare earth elements=trace levels−500 ppm —Ti=trace levels−500 ppm —O=trace levels−200 ppm if the steel is obtained by means of powder metallurgy, or trace levels−50 ppm if the steel is obtained by means of production in air or under vacuum from liquid metal —N=trace levels−100 ppm —S=trace levels−50 ppm —Cu=trace levels−1% —P=trace levels−200 ppm the remainder being iron and inevitable impurities resulting from the production operation, wherein Rm at ambient temperature is between 2200 and 2350 MPa.