The effects of hydrogen on the deformation and fracture behavior of the metastable beta-titanium alloy, TIMETAL(RTM) 21S

The metastable β-titanium alloy, TIMETAL$\sp\circler$ 21S, exhibits a sharp ductile-to-brittle transition when the hydrogen concentration is increased slightly above H/M $=$ 0.22. To understand this sharp transition, a series of experiments was devised to test for the possible hydrogen embrittlement mechanisms. In situ straining experiments in an environmental cell TEM showed that hydrogen enhances the mobility of dislocations. However, this mechanism cannot account for the abrupt transition that is observed. No evidence for the formation of hydrides on fracture surfaces or in the stress fields of active cracks was found suggesting that the stress-induced hydride mechanism is not responsible for the observed transition. Therefore, the most viable mechanism is hydrogen-induced decohesion. Bulk testing showed that internal hydrogen reduces the yield strength of ductile specimens and decreases the fracture stress of the brittle specimens. All of the observed phenomena are consistent with a decohesion mechanism.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Engineering, Metallurgy

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Teter, David F.

Contributors dc:contributor

• Robertson, Ian M.

• Engineering, Metallurgy
• Engineering, Materials Science

Statement dc:rights

• Copyright 1996 Teter, David F.

Language dc:language

eng

Identifier

9780591199390
AAI9712457
(UMI)AAI9712457

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/22426