| 摘要 |
PROBLEM TO BE SOLVED: To produce ferritic heat resistant steel having excellent high temp. strength and usable as a pressure resistant member under high temp.-high pressure in the temp. range of 200 to 500 deg.C without damaging the toughness, workability and weldability of the conventional Mo steel series ferritic heat resistant steel by adding a adequate amt. of W instead of Mo. SOLUTION: This steel contains, by weight, 0.03 to 0.25% C, 0.10 to 1.0% Si, 0.10 to 2.0% Mn, <=0.50% Cr, 0.4 to 4.0% W, 0.01 to 0.3% Mo, 0.01 to 0.4% V, 0.01 to 0.1% Nb, <=0.0060% B, <=0.0060% N, and the balance iron with inevitable impurities. Moreover, the heat resistant steel is subjected to normalizing or quenching at 900 to 1025 deg.C and is thereafter subjected to tempering treatment at 600 to 700 deg.C.
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