Heat resistant steel

Abstract

A heat resistant steel which comprises, by mass %, C: 0.01-0.25%, Cr: 0.5-8%, V: 0.05-0.5%, Si: not more than 0.7%, Mn: not more than 1%, Mo: not more than 2.5%, W: not more than 5%, Nb: not more than 0.2%, N: not more than 0.1%, Ti: not more than 0.1%, Ta: not more than 0.2%, Cu: not more than 0.5%, Ni: not more than 0.5%, Co: not more than 0.5%, B: not more than 0.1%, Al: not more than 0.05%, Ca: not more than 0.01%, Mg: not more than 0.01%, Nd: not more than 0.01%, with Fe and impurities accounting for the balance, the chemical composition of which satisfies the relations C−0.06×(Mo+0.5 W)≧0.01 and Mn+0.69×log(Mo+0.5 W+0.01)≦0.60 wherein the symbols for elements represent the contents, on the % by mass basis, of the elements in the steel, and in which, among precipitates inside grains, precipitates having an average diameter of not more than 30 nm are present at a density of not less than 1/μm3.

Dependencies are inferred from the claim text.