SCC susceptibility of 3.5NiCrMoV steel in a carbonated pure water at 157°C decreased with the decrease of P content in steel. SCC susceptibility also decreased by the addition of Nb. It was also confirmed that the SCC cracks were primarily intergranular. An Auger electron spectroscopy (AES) analysis revealed that P segregation to grain boundary might play an essential role in accelerating SCC susceptibility, and Nb could suppress the P segregation to grain boundary. The role of Nb in raising resistance to SCC is thought to be attributed to the decreasing P segregation to grain boundary, resulting from increasing segregation interface due to fine NbC formation in steel. The
measurement of anodic current decay in a carbonated solution with and without...
Keywords: stress corrosion cracking, intergranular cracking, 3.5NiCrMoV steel, LP turbine rotor forgmgs, segregation, impurity, phosphorus, grain boundary