Effect of Chromium Content on Creep Rupture Properties of a High Chromium Ferritic Heat Resisting Steel

抄録

The effect of chromium content in the range of 10 to 13% on the mechanical properties has been investigated of a heat resisting steel for turbine rotors. It is revealed that increase in chromium content brings about increased amounts of dissolved chromium and the Cr₂(C, N) type carbides, both of which enhance room temperature and elevated-temperature strengths. However, excessive addition of chromium to about 13% results in the formation of delta-ferrite, which is detrimental to creep rupture strength, especially on the long-term side. Thus, the optimum chromium content is considered to be at around 11.5%.