Overview of metastability and compositional complexity effects for hydrogen-resistant iron alloys: Inverse austenite stability effects

•Hydrogen embrittlement resistance in austenitic steels requires compositional complexity.•ε-martensite has higher resistance to hydrogen embrittlement than ά-martensite.•The low diffusivity of ε-martensite can be a reason for the superior hydrogen-resistance.•Ductility of ε-martensite is another ke...

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Bibliographic Details
Published inEngineering fracture mechanics Vol. 214; pp. 123 - 133
Main Authors Koyama, Motomichi, Tasan, Cemal Cem, Tsuzaki, Kaneaki
Format Journal Article
LanguageEnglish
Published New York Elsevier Ltd 01.06.2019
Elsevier BV
Subjects
Austenitic stainless steels
Crack propagation
Diffusivity
Ductile fracture
Environmentally assisted cracking
Fatigue crack growth
Fatigue failure
Ferrous alloys
Fracture mechanics
High entropy alloys
Hydrogen
Hydrogen embrittlement
Martensite
Martensitic stainless steels
Martensitic transformations
Metal fatigue
Plasticity
Resistance factors
Slow strain rate tests
Steels
Fatigue crack growth
Steels
Slow strain rate tests
Hydrogen embrittlement
Plasticity
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Summary:•Hydrogen embrittlement resistance in austenitic steels requires compositional complexity.•ε-martensite has higher resistance to hydrogen embrittlement than ά-martensite.•The low diffusivity of ε-martensite can be a reason for the superior hydrogen-resistance.•Ductility of ε-martensite is another key for developing ε-stability-based alloy design.•The ε-stability-based alloy design strategy is compatible to high-entropy concept. The main factors affecting resistance to hydrogen-assisted cracking are hydrogen diffusivity and local ductility. In this context, we note fcc (γ) to hcp (ε) martensitic transformation, instead of γ to bcc (ά) martensitic transformation. The γ-ε martensitic transformation decreases the local hydrogen diffusivity, which thereby can increase strength without critical deterioration of hydrogen embrittlement resistance. Furthermore, ε-martensite in a high-entropy alloy is extraordinary ductile. Consequently, the metastable high-entropy alloys showed lower fatigue crack growth rates under a hydrogen effect compared with those of conventional metastable austenitic steels such as type 304.
ISSN:0013-7944
1873-7315
DOI:10.1016/j.engfracmech.2019.03.049