| 摘要 |
PROBLEM TO BE SOLVED: To provide low Cr ferritic heat resistant steel suppressed in tempering embrittlement and creep embrittlement in the use for a long time, stably high in creep strength at the high temp. of 400 to 625 deg.C and having good toughness, weldability and corrosion resistance equal to or above those of the existent low Cr heat resistant steel. SOLUTION: This steel contains, by weight, 0.01 to 0.25% C, 0.5 to 3% Cr, 0.05 to 0.5% V, 0.05 to 2.5% Mo, <=0.01% N, 0 to 0.5% Ti, <=0.03% P and <=0.015% S, and the structure after normalizing and quenching is composed of a lower bainitic single phase structure or a mixed structure contg. a lower bainitic structure of >=20 vol.%, and the balance either or both of a martensitic structure and an upper bainitic structure.
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