TY - JOUR
T1 - A comparison of stress corrosion cracking susceptibility of steam turbine blade materials for geothermal plants
AU - Wu, Lianlian
AU - Takeda, Yoichi
AU - Morita, Hiroki
AU - Shoji, Tetsuo
N1 - Publisher Copyright:
© 2017, NACE International
PY - 2017/2
Y1 - 2017/2
N2 - In order to evaluate the environmentally assisted cracking (EAC) susceptibility of three possible alloys, 16Cr-4Ni, 12Cr, and 13Cr, to be used as turbine blade materials for a geothermal power plants, corrosion fatigue tests were performed in simulated condensed geothermal environment without H2S. EAC includes an environmental fatigue crack growth under a cyclic stress and stress corrosion cracking (SCC) under a constant load, where a unique time domain analysis (TDA) can plot all of the data on a single figure. Based upon the analysis by TDA, it was found that 16Cr-4Ni had the highest SCC resistance, as well as best performance in environmental fatigue, but no conclusive difference in EAC susceptibility between 12Cr and 13Cr was observed. Intergranular cracking was observed in 13Cr at the testing condition of high frequency and high stress intensity range. The lower EAC resistance of 12Cr than 16Cr-4Ni might be attributable to its lower pitting resistance, and the local environment built up inside of the pits as well as its surrounding can be more aggressive with lower pH and higher Cl− concentration, which could accelerate the EAC growth.
AB - In order to evaluate the environmentally assisted cracking (EAC) susceptibility of three possible alloys, 16Cr-4Ni, 12Cr, and 13Cr, to be used as turbine blade materials for a geothermal power plants, corrosion fatigue tests were performed in simulated condensed geothermal environment without H2S. EAC includes an environmental fatigue crack growth under a cyclic stress and stress corrosion cracking (SCC) under a constant load, where a unique time domain analysis (TDA) can plot all of the data on a single figure. Based upon the analysis by TDA, it was found that 16Cr-4Ni had the highest SCC resistance, as well as best performance in environmental fatigue, but no conclusive difference in EAC susceptibility between 12Cr and 13Cr was observed. Intergranular cracking was observed in 13Cr at the testing condition of high frequency and high stress intensity range. The lower EAC resistance of 12Cr than 16Cr-4Ni might be attributable to its lower pitting resistance, and the local environment built up inside of the pits as well as its surrounding can be more aggressive with lower pH and higher Cl− concentration, which could accelerate the EAC growth.
KW - Condensed geothermal steam environment
KW - Corrosion fatigue
KW - Environmentally assisted cracking
KW - Geothermal turbine blade materials
KW - Pitting susceptibility
KW - Stress corrosion cracking susceptibility
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U2 - 10.5006/2058
DO - 10.5006/2058
M3 - Article
AN - SCOPUS:85070746903
SN - 0010-9312
VL - 73
SP - 125
EP - 137
JO - Corrosion
JF - Corrosion
IS - 2
ER -