| About this Abstract |
| Meeting |
2025 TMS Annual Meeting & Exhibition
|
| Symposium
|
Steels in Extreme Environments
|
| Presentation Title |
Understanding the critical role of microstructure in enhanced resistance to H-assisted fatigue crack growth in ausformed and tempered martensitic steels |
| Author(s) |
Rama Srinivas Varanasi, Motomichi Koyama, Timothee Redarce, Kosei Kobayashi , Hiroshi Kakinuma, Akinobu Shibata, Hisao Matsunaga, Eiji Akiyama |
| On-Site Speaker (Planned) |
Rama Srinivas Varanasi |
| Abstract Scope |
When the H-assisted fatigue crack growth (HAFCG) is time-dependent, the fatigue life is unpredictable. Previous empirical evidence suggested that while martensitic steels with tensile strength (TS)< 900 MPa showed cycle-dependent HAFCG, those with TS> 900 MPa exhibited time-dependent HAFCG. Recently, Matsunaga et al. demonstrated that ausformed and tempered (AFT) martensitic steel with a TS of 1050 MPa exhibits cycle-dependent HAFCG. To clarify the microstructural origins of enhanced resistance to HAFCG in AFT steel, we study:
(i) Hydrogen trapping and diffusion
We performed thermal desorption spectroscopy (TDS) and hydrogen permeation experiments.
(ii) Crack propagation pathways
We determined the HAFCG paths via electron backscatter diffraction (EBSD) analysis. Transmission Kikuchi diffraction and transmission electron microscopy studies were conducted on focused ion beam lift-out consisting of a fatigue crack. We characterized the prior austenite grain boundary morphology using 3-D EBSD. We investigate the morphology and distribution of carbides and report their effect on HAFCG. |
| Proceedings Inclusion? |
Planned: |
| Keywords |
Iron and Steel, Sustainability, Characterization |