Patent ID: 7686898

Claim:
A maraging heat-treatment steel, consisting of: 8.5 to 9.5% by weight of Cr; 0.15 to 0.25% by weight of Mn; 2 to 2.7% by weight of Ni; 0.5 to 2.5% by weight of Mo; 0.4 to 0.8% by weight of V; 0.001 to 0.15% by weight of Si; 0.06 to 0.1% by weight of C; 0.11 to 0.15% by weight of N; 0.02 to 0.04% by weight of Nb; maximum 0.007% by weight of P; maximum 0.005% by weight of S; maximum 0.01% by weight of Al; and remainder iron and standard impurities, wherein a weight ratio of vanadium to nitrogen V/N is in a range between 4.3 and 5.5.