Recent progress on interpretation of tensile ductility loss for various austenitic stainless steels with external and internal hydrogen

Osamu Takakuwa, Junichiro Yamabe, Hisao Matsunaga, Yoshiyuki Furuya, Saburo Matsuoka

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Citations (Scopus)

Abstract

Slow-strain rate tensile (SSRT) tests on various metals having γ-Fe phase; Type 304 and 316L stainless steels, HP160 high strength stainless steel, and A286 Fe-based super alloy were conducted in external hydrogen and with internal hydrogen. The external hydrogen indicates non-charged specimens tested in high-pressure hydrogen-gas environment, whereas the internal hydrogen indicates hydrogen-charged specimens, with uniform distribution of hydrogen, tested in inert gas. The hydrogen distribution was calculated based on the measured hydrogen diffusivity and solubility. The fracture morphologies were observed by scanning electron microscopy (SEM). For Types 304, 316L, and HP160 the relative reduction in area (RRA of the steels was successfully reproduced by the nickel equivalent, Nieq, showing the higher Nieq, the lager RRA. Furthermore, at a low Nieq, the RRA of the steel with external hydrogen was nearly equal to that with internal hydrogen. In contrast, at a high Nieq, the RRA of the steel with internal hydrogen was slightly degraded by hydrogen, RRA ∼ 0.8, whereas that in external hydrogen was not degraded, RRA ∼ 1. For A286, despite a high Nieq, the RRA of the alloy with internal hydrogen was significantly degraded by hydrogen, RRA ∼ 0.5. The fracture morphologies were categorized into four types: quasi-cleavage fracture associated with hydrogen-assisted surface cracks; ordinary void formation with no hydrogen effect; small-void formation associated with void sheet enhanced by hydrogen; facet formation induced by hydrogen. These categorized morphologies could be interpreted in terms of hydrogen distribution (internal or external hydrogen), austenitic stability (a low or high Nieq), and microstructure (solution or precipitation-hardened treatment).

Original languageEnglish
Title of host publicationMaterials and Fabrication
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791858004
DOIs
Publication statusPublished - Jan 1 2017
EventASME 2017 Pressure Vessels and Piping Conference, PVP 2017 - Waikoloa, United States
Duration: Jul 16 2017Jul 20 2017

Publication series

NameAmerican Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP
Volume6B-2017
ISSN (Print)0277-027X

Other

OtherASME 2017 Pressure Vessels and Piping Conference, PVP 2017
CountryUnited States
CityWaikoloa
Period7/16/177/20/17

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering

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