THE RELATIONSHIP BETWEEN PLASTIC DEFORMATION AND FRACTURE IN ALPHA TITANIUM.
Summary rept. Jun 65-Jun 66,
TRW EQUIPMENT GROUP CLEVELAND OH MATERIALS RESEARCH AND DEVELOPMENT DEPT
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Crack initiation and propagation behavior was studied in unalloyed titanium containing between 0.25 and 0.6 oxygen and in Ti-5Al-2.5Sn alloy containing between 0.07 and 0.37 oxygen. Large-grained tensile specimens were tested at -320 F and metallographically examined to identify the mechanism of microcrack formation. Precracked single edge notched specimens were tested at -320 F in order to relate crack propagation events to fracture energy and grain orientation. Second order twin induced microcracking, which is responsible for brittle behavior in unalloyed titanium at 0.25 oxygen, becomes restricted at 0.5 and 0.6 oxygen. In Ti-5Al-2.5Sn alloy containing 0.3 oxygen, slip induced microcracks form in addition to twin induced microcracks. A general correlation was found between fracture energy, grain orientation and crack propagation events in unalloyed titanium containing 0.25 to 0.6 oxygen. Author
- Metallurgy and Metallography