| 摘要 |
PROBLEM TO BE SOLVED: To provide a ferritic heat resistant steel in which the generation of IV type damage is suppressed in the weld heat-affected zone. SOLUTION: The ferritic heat resistant steel is composed of a steel including 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, 0.002 to 0.15% N and one or more kinds selected from 0.01 to 0.20% Ti, 0.003 to 0.20% Zr, 0.01 to 0.50% Nb, 0.01 to 0.50% V and 0.01 to 0.50% Ta, in which welded heat affected zone hardenability index HD is 0.5 to 80. In the welded heat affected zone of the steel member heated to an Ac1 transformation point to an Ac<SB>1</SB>transformation point +300°C, a low temperature transformed structure where dislocation density is 1×10<SP>12</SP>pieces/m<SP>2</SP>or above (Cr: 0.4 to 3.0%) or 1×10<SP>13</SP>pieces/m<SP>2</SP>or above (Cr: >3.0 to 12.0%) is produced. COPYRIGHT: (C)2009,JPO&INPIT
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