Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds

B. P. Somerday, D. K. Balch, P. Novak, Petros Sofronis

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

Abstract

The objective of this study was to quantify the hydrogen-assisted fracture susceptibility of gas-tungsten arc (GTA) welds in the nitrogen-strengthened, austenitic stainless steels 21Cr-6Ni-9Mn (21-6-9) and 22Cr-13Ni-5Mn (22-13-5). In addition, mechanisms of hydrogen-assisted fracture in the welds were identified using electron microscopy and finite-element modeling. Elastic-plastic fracture mechanics experiments were conducted on hydrogen-charged GTA welds at 25°C. Results showed that hydrogen dramatically lowered the fracture toughness from 412 kJ/m2 to 57 kJ/m2 in 21-6-9 welds and from 91 kJ/m2 to 26 kJ/m 2 in 22-13-5 welds. Microscopy results suggested that hydrogen served two roles in the fracture of welds: it promoted the nucleation of microcracks along the dendritic structure and accelerated the link-up of microcracks by facilitating localized deformation. A continuum finite-element model was formulated to test the notion that hydrogen could facilitate localized deformation in the ligament between microcracks. On the assumption that hydrogen decreased local flow stress in accordance with the hydrogen-enhanced dislocation mobility argument, the finite-element results showed that deformation was localized in a narrow band between two parallel, overlapping microcracks. In contrast, in the absence of hydrogen, the finite-element results showed that deformation between microcracks was more uniformly distributed.

Original languageEnglish (US)
Title of host publication11th International Conference on Fracture 2005, ICF11
Pages3406-3411
Number of pages6
Volume5
StatePublished - 2005
Event11th International Conference on Fracture 2005, ICF11 - Turin, Italy
Duration: Mar 20 2005Mar 25 2005

Other

Other11th International Conference on Fracture 2005, ICF11
CountryItaly
CityTurin
Period3/20/053/25/05

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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    Somerday, B. P., Balch, D. K., Novak, P., & Sofronis, P. (2005). Mechanisms of hydrogen-assisted fracture in austenitic stainless steel welds. In 11th International Conference on Fracture 2005, ICF11 (Vol. 5, pp. 3406-3411)