The effect of microstructure and deformation behavior on the hot ductility of Ti-6Al-2Nb-1Ta-0. 8Mo
Hot ductility of the alloy Ti-6Al-2Nb-1Ta-0.8Mo has been correlated with microstructure and fracture behavior. Low hot ductility was found to be associated with strain localization within the grain boundary alpha phase, producing void formation along the prior-beta grain boundaries and intergranular fracture. Microstructural features that appear to be critical to the strain localization process are beta grain shape and alpha phase morphology. For the case of Widmanstatten + grain boundary alpha phase morphologies, equiaxed prior-beta grains formed by annealing above the beta transus ar required to produce significant strain localization. For the beta processed structure with elongated beta grains due to working above the beta transus temperature, the orientation of the grain boundary alpha phase limits strain localization due to low resolved shear stress. The martensitic Widmanstatten alpha prime structure formed by quenching from above the beta transus temperature rapidly forms grain boundary alpha upon reheating to temperatures high in the alpha + beta phase field. This results i strain localization in the grain boundary regions in an apparently similar manner to that observed in the Widmanstatten + grain boundary alpha phase morphologies with equiaxed prior-beta grains.
- Research Organization:
- McDonnell Douglas Research Laboratory St. Louis, Mo
- OSTI ID:
- 6346963
- Journal Information:
- Metall. Trans., A; (United States), Journal Name: Metall. Trans., A; (United States) Vol. 15A:9; ISSN MTTAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360101* -- Metals & Alloys-- Preparation & Fabrication
360103 -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
CRYSTAL STRUCTURE
CRYSTAL-PHASE TRANSFORMATIONS
DEFORMATION
DUCTILITY
FABRICATION
FRACTURE PROPERTIES
GRAIN BOUNDARIES
HOT WORKING
MATERIALS WORKING
MECHANICAL PROPERTIES
MICROSTRUCTURE
MOLYBDENUM ADDITIONS
MOLYBDENUM ALLOYS
NIOBIUM ALLOYS
PHASE TRANSFORMATIONS
QUENCHING
SHEAR
STRAINS
TANTALUM ALLOYS
TEMPERATURE EFFECTS
TENSILE PROPERTIES
TITANIUM ALLOYS
TITANIUM BASE ALLOYS
VOIDS