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U.S. Department of Energy
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Stress corrosion cracking behavior of 3.5NiCrMoV steel in carbonated pure water

Conference ·
OSTI ID:350088
; ;  [1]
  1. Takasago Works Materials Research Lab. (Japan). Steel Casting and Forging Plant
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 HPO{sub 4}{sup 2{minus}} ion showed that HPO{sub 4}{sup 2{minus}} ion accelerates the repassivation of a fresh surface, indicating that P segregation to grain boundary might be mainly attributed to the crack-sharpening effect due to repassivation by the formation of phosphate species at the crack tip.
OSTI ID:
350088
Report Number(s):
CONF-980316--
Country of Publication:
United States
Language:
English