The effects of partial pressure and strain rate on water vapor- and hydrogen gas-induced embrittlement of Co{sub 3}Ti alloys

Journal Article · Sat Nov 01 00:00:00 EST 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00091-8· OSTI ID:590027

Takasugi, T; Kimura, A ^[1]; Sugimoto, T; Saitoh, H; Misawa, T ^[2]

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1. Tohoku Univ. (Japan). Inst. for Materials Research
2. Muroran Inst. of Technology (Japan). Dept. of Materials Science and Engineering

The effects of partial pressure and strain rate on the embrittlement owing to water vapor and hydrogen as are observed on Co-23 mol% Ti and Co-21 mol% Ti alloys by SP and tensile tests at room temperature. The Co{sub 3}Ti alloys are very susceptible to environmental embrittlement owing to water vapor and hydrogen gas. Critical partial pressures (CPPs) below which the embrittlement does not occur are determined for both testing atmospheres, both alloy compositions and three cross-head speeds. Also, critical strain rates (CSRs) beyond which the embrittlement does not occur are determined in air for both alloy compositions. The difference in the susceptibility to the embrittlement between water vapor and hydrogen gas is attributed to the difference in the decomposition rate on the alloy surface. The compositional dependence of the susceptibility to the environmental embrittlement is considered to be due to the difference in the intrinsic grain boundary cohesion between two alloy compositions, i.e. to the difference in the critical hydrogen content causing intergranular cracking.

• OSTI ID: 590027
• Journal Information: Acta Materialia, Vol. 45, Issue 11; Other Information: PBD: Nov 1997
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COBALT BASE ALLOYS
TITANIUM ALLOYS
HYDROGEN EMBRITTLEMENT
CRACK PROPAGATION
PRESSURE DEPENDENCE