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°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.;COPYRIGHT: (C)2001,JPO
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