Static and cyclic creep properties of Ti-6Al-4V for several heat treatments. Technical report

Technical Report · Tue Apr 01 00:00:00 EDT 1975

OSTI ID:7330871

Gilmore, C M; Imam, M A

The room temperature static and 'cyclic' creep properties were determined for Ti-6Al-4V in three anneal conditions (alpha beta) anneal, beta anneal and recrystallized anneal). The static and 'cyclic' creep strains were inversely related to microstructure. The beta annealed alloy has the smallest static creep strain and the largest 'cyclic creep' strain; the recrystallized anneal alloy has the largest static creep and the smallest 'cyclic creep.' This behavior indicates that static creep and 'cyclic creep' are a result of different mechanisms. It is proposed that the static creep is a result of dislocation motion within the grains, and the dislocation motion is impeded by phase and grain boundaries to limit static creep strains. The 'cyclic creep' deformation appears to be localized at the grain and phase boundaires. It is proposed that in 'cyclic creep' the dislocations migrate to the strong boundaries and then move back and forth under the cyclic loading producing vacancies at jog sites during each cycle. The vacancies condense into microcracks that are observed after etching.

• Research Organization: George Washington Univ., Washington, D.C. (USA). Inst. for the Study of Fatigue Fracture and Structural Reliability
• OSTI ID: 7330871
• Report Number(s): AD-A-011842
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOY SYSTEMS
ALLOYS
ALUMINIUM ALLOYS
ANNEALING
CRACKS
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEFORMATION
DISLOCATIONS
ETCHING
GRAIN BOUNDARIES
HEAT TREATMENTS
LINE DEFECTS
MECHANICAL PROPERTIES
MEDIUM TEMPERATURE
MICROSTRUCTURE
POINT DEFECTS
RECRYSTALLIZATION
STRAINS
STRESSES
SURFACE FINISHING
TERNARY ALLOY SYSTEMS
TITANIUM ALLOYS
TITANIUM BASE ALLOYS
VACANCIES
VANADIUM ALLOYS