Creep Strength Property of Precipitation Strengthened 15Cr Ferritic Creep Resistant Steel

摘要

Creep strength property of the full annealed 15Cr ferritic steel whose chemical composition is Fe-0.1C-15Cr-1Mo-3W-0.2V-0.05Nb-0.07N-0.003B and the effects of alloying elements such as vanadium, niobium, tungsten and cobalt on it have been investigated. Increase in V and Nb contents does not improve creep strength. On the other hand, increases in creep strength with increase in W and addition of Co have been obviously observed. About 10 times and 30 times longer time to rupture than that of the base steel have been observed at 923K-100MPa by increase in W content from 3 to 6mass% and addition of 3mass% of Co, respectively. Moreover, significant improvement in creep strength that is about two orders of magnitudes in time to rupture, has been obtained by the combination of increase in W content and addition of Co. Creep rupture strength of that is almost the same as that of ASME T92. Higher Cr content of the full annealed 15Cr steel than those of the conventional ferritic creep resistant steels is desirable for good oxidation resistance. It has been concluded that full annealed 15Cr ferritic creep resistant steel should be one of the candidate materials for new Ultra Supercritical (USC) power plant in the 21st century.