| 摘要 |
PROBLEM TO BE SOLVED: To provide ferritic heat resistant steel which has excellent creep characteristics even at a high temperature of >600 deg.C. SOLUTION: The steel has a composition at least containing, as constitutional elements, by weight, 1.0 to 13% chromium, 0.1 to 8.0% cobalt, 0.01 to 0.20% nitrogen, <=3.0% nickel, one or more kinds of elements selected from the group consisting of vanadium, niobium, tantalum, titanium, hafnium and zirconium as MX type precipitate forming elements, and <=0.01% carbon, and the balance substantially iron with inevitable impurities. MX type precipitates are precipitated onto the boundaries and the whole face within the grains, and the abundance ratio in the boundaries of M23 C6 type precipitates precipitated onto the boundaries is <=50%.
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