| 摘要 |
PROBLEM TO BE SOLVED: To provide a ferritic heat resistant steel material capable of suppressing the occurrence of a type IV type damage in a weld heat affected zone. SOLUTION: The ferritic heat resistant steel material having the excellent creep characteristic of the weld heat affected zone contains, by mass%, 0.01 to 0.20% C, 0.02 to 0.50% Si, 0.05 to 1.0% Mn,≤0.02% P,≤0.01% S, 0.4 to 12.0% Cr, 0.001 to 0.05% Al, 0.001 to 0.07% N, is limited to≤0.01% O, consists of the balance Fe and inevitable impurities, and is 0.5 to 80 in a weld heat-affected zone hardenability index HDL defined by formula. The low temperature transformation texture of 1×10<SP>12</SP>pieces/m<SP>2</SP>or more (in the case of 0.4 to 3.0% Cr) or 1×10<SP>13</SP>pieces/m<SP>2</SP>or more (in the case of 3.0 to 12.0% Cr) in dislocation density or 1×10<SP>12</SP>pieces/m<SP>2</SP>(in the case of 3.0 or over to 12.0% Cr) in dislocation density is created in the weld heat affected zone of the steel material heated to an AC<SB>1</SB>transformation point to the AC<SB>1</SB>transformation point +300°C. COPYRIGHT: (C)2009,JPO&INPIT
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