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Ausformed specimens of the chromium-molybdenum steel JIS-SCM440 were subjected to fatigue tests in both air and 90 MPa hydrogen gas. The results were compared with those of non-ausformed specimens of the same material with similar tensile strengths (≈ 950 MPa and ≈ 1050 MPa). The ausformed materials demonstrated excellent resistance to hydrogen-induced acceleration of fatigue crack-growth (FCG), effectively reducing the crack propagation rate under cyclic loading in hydrogen environments compared to their non-ausformed counterparts. They maintained an acceleration ratio (i.e., relative FCG rate in hydrogen with respect to that in air) within 10 to 40 times, an order of magnitude lower than that of the non-ausformed counterparts. Despite their high strength levels (i.e., tensile strengths greater than 900 MPa), the FCG rate in the ausformed materials was almost independent of loading frequency at a stress intensity factor range of 20 and 30 MPa·m1/2. Fractographic observations revealed that no intergranular fracture occurred in the ausformed materials, unlike in the non-ausformed ones. These findings suggest that two factors possibly caused the mitigation of FCG rate in hydrogen: (i) modification of the microstructure morphology, i.e., refinement and elongation, and (ii) an increase in the cohesive strength of interfaces under the influence of hydrogen.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: Hydrogen embrittlement, Martensitic steel, Fatigue crack growth, Thermo-mechanical treatment

刊行年月日: 2025-01-11

出版者: Elsevier BV

掲載誌:

• International Journal of Fatigue (ISSN: 01421123) vol. 193 108814

研究助成金:

• Government of Japan Ministry of Education Culture Sports Science and Technology

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1016/j.ijfatigue.2025.108814

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更新時刻: 2025-01-20 16:30:27 +0900

MDRでの公開時刻: 2025-01-20 16:30:27 +0900