In situ observations on effects of hydrogen on deformation and fracture of A533B pressure vessel steel

Journal Article · Wed Dec 01 04:00:00 EST 1993 · Journal of Materials Engineering and Performance; (United States)

DOI:https://doi.org/10.1007/BF02645681· OSTI ID:5362509

Haenninen, H E ^[1]; Lee, T C; Robertson, I M; Birnbaum, H K ^[2]

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1. Technical Research Centre of Finland, Espoo (Finland). Metals Lab.
2. Univ. of Illinois, Urbana, IL (United States). Materials Research Lab.

External hydrogen gas atmospheres enhanced dislocation motion, multiplication of dislocations, and dislocation source activation under applied loading during in situ high-voltage electron microscopy (HVEM) observations of A533B pressure vessel steel. However, in both vacuum and hydrogen atmospheres, fracture occurred in a ductile manner in specimen areas transparent in the 1,000-keV HVEM. The principal effect of the hydrogen atmosphere was to decrease the stress required for deformation near the crack tip and for crack propagation. Deformation at the crack tip was highly localized in both atmospheres, and a yielding strip plastic zone, analogous to the Dugdale-Barenblatt model for crack growth, formed ahead of the crack tip. The crack tip plasticity was confined to this strip. Inside the yielding strip, final cracking occurred through a sliding-off mechanism in the thin areas of the HVEM specimen. In the thicker areas of the specimen, where the yielding strip ahead of the crack was no longer transparent, crack tip blunting and void/microcrack formation ahead of the main crack tip could be observed directly. Crack tip blunting occurred by a two-corner mechanism, and further crack growth initiated by strain localization at one of the crack tip vertices. Also, void/microcrack formation ahead of the main crack tip was operative and resulted in coalescence into the main crack tip along the anticipated shear bands. Fractography of the thicker areas showed a ductile, dimpled fracture mechanism both in vacuum and hydrogen atmospheres.

• OSTI ID: 5362509
• Journal Information: Journal of Materials Engineering and Performance; (United States), Journal Name: Journal of Materials Engineering and Performance; (United States) Vol. 2:6; ISSN 1059-9495; ISSN JMEPEG
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CARBON STEELS
CONTAINERS
CRACK PROPAGATION
EMBRITTLEMENT
HYDROGEN EMBRITTLEMENT
IRON ALLOYS
IRON BASE ALLOYS
MECHANICAL PROPERTIES
PRESSURE VESSELS
STEEL-ASTM-A533-B
STEELS