Hydrogen-assisted failure of Alloys X-750 and 625 under low strain-rate conditions

R. S. Daum, A. T. Motta, D. A. Koss, D. D. Macdonald

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

1 Scopus citations

Abstract

Slow strain-rate tensile testing of Ni-based Alloys X-750 and 625 was performed in high-purity, deaerated water in order to determine whether hydrogen embrittlement occurs in these alloys at room temperature and 288°C. These tests were conducted at an initial strain-rate of 4.6×10-7/sec under both 30 psig nitrogen (0 cc H2/kg H2O STP) and 40 psig hydrogen (60 cc H2/kg H2O STP), on Alloy X-750 in two heat-treatment conditions and on Alloy 625 in a solution annealed and aged condition. At room temperature in the hydrogenated environment, both alloys showed a pronounced susceptibility to hydrogen embrittlement. The presence of hydrogen reduced both the elongation to failure and the reduction in area at fracture by about 50%. Fractography indicated a transition from ductile, transgranular failure in the nitrogen environment to predominantly intergranular fracture under hydrogenated conditions. Fractography of the specimens tested at room temperature showed a transition in crack growth behavior from mixed mode slip band decohesion in nitrogen environments to Mode I intergranular fracture path in hydrogenated environments. In contrast, hydrogen had no discernible effect on the measured properties at 288°C under the slow strain-rate conditions imposed.

Original languageEnglish (US)
Title of host publicationProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors -
EditorsS. Bruemmer, P. Ford, G. Was, S. Breummer, P. Ford, G. Was
Pages179-187
Number of pages9
StatePublished - Dec 1 1999
EventProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors - - New Portbeach, CA, United States
Duration: Aug 1 1999Aug 5 1999

Publication series

NameProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors -

Other

OtherProceedings of the Ninth International Symposium on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors -
CountryUnited States
CityNew Portbeach, CA
Period8/1/998/5/99

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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