| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a high-Cr heat-resistant ferritic steel material superior in creep strength in an environment of high temperature in a long period of time. Ž<P>SOLUTION: The steel material has a composition including, by mass%, 0.05 to 0.12% C, 0.2 to 0.5% Si, 0.3 to 0.6% Mn, 0.02% or less P, 0.005% or less S, 8.0 or more but less than 12% Cr, 0.15 to 0.25% V, 0.03 to 0.08% Nb, 0.005 to 0.07% N, 0.015% or less sol. Al, 0.5% or less Ni, further one or two elements of 0.1 to 1.1% Mo and 1.5 to 3.5% W, and the balance Fe with impurities. The steel material may further include one or more elements among 0.015% or less B, 1.5% or less Cu, 5% or less Co, 0.05% or less Ti, 0.05% or less Ta, 0.05% or less Nd and 0.01% or less Ca. The method for manufacturing the high-Cr heat-resistant ferritic steel material includes working and heat-treating the steel material through the following steps (1) to (5) of: (1) hot-working the steel so as to finish final working at 1,000°C or lower; (2) softening the hot-worked material for 20 min to 2 hr in a range of 750 to 820°C; (3) cold-working the material with a reduction rate of 15% or more in a cross-sectional area; (4) softening the cold-worked material for 20 min to 2 hr in a range of 750 to 820°C; and (5) normalizing and tempering the material. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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