| 摘要 |
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 x (Mo + 0.5 W) ~ 0.01 and Mn + 0.69 x 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/.mu.m3.
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