Workability of a gamma titanium aluminide alloy during equal channel angular extrusion
- Wright Laboratory Materials Directorate, Wright-Patterson AFB, OH (United States)
- Texas A and M Univ., College Station, TX (United States). Mechanical Engineering Dept.
- UES, Inc., Dayton, OH (United States)
Canned performs of the titanium aluminide Ti-45.5Al-2Cr-2Nb were hot worked via equal channel angular extrusion (ECAE). The following conclusions are drawn regarding the effects of extrusion temperature and microstructural condition on workability controlled by shear localization: (1) The tendency for nonuniform deformation during ECAE increases rapidly as the preheat temperature decrease. The trend is most pronounced for material in a cast + HIP`ed condition as compared to that in a wrought condition. The nonuniform flow may develop into well defined shear bands and shear cracks in the cast + HIP`ed titanium aluminide. (2) The occurrence of shear bands and the severity of flow localization within the shear bands can be correlated at least on a first-order basis to material flow behavior as quantified by the alpha parameter, the ratio of the normalized flow softening rate to the strain rate sensitivity exponent. (3) Multi-pass ECAE sequences to breakdown and refine the structure of near-gamma titanium aluminide ingot can be designed through proper consideration of the effect of temperature and material condition on flow localization tendencies. However, can design to minimize die chilling may play an important role in industrial implementation of the ECAE process for this alloy system.
- OSTI ID:
- 103565
- Journal Information:
- Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 4 Vol. 33; ISSN 0956-716X; ISSN SCRMEX
- Country of Publication:
- United States
- Language:
- English
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