Patent ID: 7540711

Claim:
A heat resisting steel made of a Cr—Mo—V low-alloy steel containing 0.15-0.40% by weight of C, not more than 0.5% of Si, 0.05-0.50% of Mn, 0.5-1.5% of Ni, 0.8-1.5% of Cr, 0.8-1.8% of Mo and 0.05-0.35% of V, and having a (Ni/Mn) ratio of 3.0-10.0; and wherein the Cr—Mo—V low-alloy steel has a ratio of (rupture time of a notched sample/rupture time of a smooth gauge sample) being not less than 2 in a creep test at the same temperature and under the same stress.