TY - JOUR
T1 - The role of intergranular fracture on hydrogen-assisted fatigue crack propagation in pure iron at a low stress intensity range
AU - Ogawa, Yuhei
AU - Birenis, Domas
AU - Matsunaga, Hisao
AU - Takakuwa, Osamu
AU - Yamabe, Junichiro
AU - Prytz, Øystein
AU - Thøgersen, Annett
N1 - Funding Information:
This work was supported by JSPS KAKENHI (Grant Nos. JP16H04238 and JP16J02960 ). The Research Council of Norway is acknowledged for its support through the Norwegian Center for Transmission Electron Microscopy, NORTEM (Grant No. 197405/F50 ). This study also forms part of the “HIPP” project from the PETROMAKS2 program, funded by the Research Council of Norway (Grant No. 102006899 ), and partly supported by Advanced Characterization Platform of the Nanotechnology Platform Japan sponsored by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2018/8/22
Y1 - 2018/8/22
N2 - Hydrogen-assisted fatigue crack growth (HAFCG) in pure iron at a relatively low stress intensity range exhibits brittle-like intergranular (IG) fracture, while the macroscopic crack acceleration is not significant. The present study focuses on the mechanism of IG fracture in terms of the microscopic deformation structures near the crack propagation paths. We found that the IG fracture is attributed to hydrogen-enhanced dislocation structure evolution and subsequent microvoid formation along the grain boundaries. The impact of such IG cracking on the macroscopic fatigue crack growth (FCG) acceleration is evaluated according to the dependency of IG fracture tendency on the hydrogen gas pressure during testing. It is demonstrated for the first time that increased hydrogen pressure results in a larger fraction of IG fracture and correspondingly faster FCG. On the other hand, the gaseous hydrogen environment also has a positive role in decelerating the FCG rate relative to air due to the absence of oxygen and water vapor. The macroscopic crack propagation rate in hydrogen gas is eventually determined by the competition between the said positive and negative influences.
AB - Hydrogen-assisted fatigue crack growth (HAFCG) in pure iron at a relatively low stress intensity range exhibits brittle-like intergranular (IG) fracture, while the macroscopic crack acceleration is not significant. The present study focuses on the mechanism of IG fracture in terms of the microscopic deformation structures near the crack propagation paths. We found that the IG fracture is attributed to hydrogen-enhanced dislocation structure evolution and subsequent microvoid formation along the grain boundaries. The impact of such IG cracking on the macroscopic fatigue crack growth (FCG) acceleration is evaluated according to the dependency of IG fracture tendency on the hydrogen gas pressure during testing. It is demonstrated for the first time that increased hydrogen pressure results in a larger fraction of IG fracture and correspondingly faster FCG. On the other hand, the gaseous hydrogen environment also has a positive role in decelerating the FCG rate relative to air due to the absence of oxygen and water vapor. The macroscopic crack propagation rate in hydrogen gas is eventually determined by the competition between the said positive and negative influences.
UR - http://www.scopus.com/inward/record.url?scp=85050276809&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85050276809&partnerID=8YFLogxK
U2 - 10.1016/j.msea.2018.07.014
DO - 10.1016/j.msea.2018.07.014
M3 - Article
AN - SCOPUS:85050276809
SN - 0921-5093
VL - 733
SP - 316
EP - 328
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
ER -