FERRITIC HEAT RESISTANT STEEL HAVING TEMPERED MARTENSITIC STRUCTURE AND ITS PRODUCTION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a ferritic heat resistant steel in which deterioration in creep strength is reduced even when used at high temperature for a long time compared with the conventional ferritic heat resistant steel, and which is suitable as a high temperature structural member for a boiler, a thermal power generation device, a nuclear power generation device, a chemical industry device or the like.;SOLUTION: A steel is subjected to quenching or normalizing at ≥1,000°C, and, within 10 hr, is cooled to ≤700°C. Further, in a cooling stage, the steel is held at a fixed temperature in the temperature range of 800 to 400°C for at least ≥10 min, and is thereafter naturally let to cool, and tempering is performed at ≥730°C.;COPYRIGHT: (C)2006,JPO&NCIPI