Stress corrosion cracking and blue brittleness of rotor steels in high temperature aqueous solutions

The tensile behaviors of two bolt steels 20Cr12NiMoWV and 25Cr2MoV, and rot or steel 30Cr2Ni4MoV used in a nuclear power plant were studied at differen t temperatures up to 280 degreesC in air and aqueous solution. The results showed that blue brittleness occurred near 230 degreesC and 180 degreesC fo r steels 30Cr2Ni4MoV and 25Cr2MoV, respectively. No blue brittleness was fo und for the steel containing higher Cr content. Susceptibility to stress co rrosion cracking.(SCC) for the steels in aqueous solution at the test tempe ratures was very low except at the blue brittleness temperature. At the blu e brittleness temperatures, however, the susceptibility to SCC was very hig h.