Plastic Flow and Fatigue Behavior of Alpha-Beta Titanium Alloys.
Annual rept. no. 1, 1 Apr 75-31 Mar 76,
POLYTECHNIC INST OF NEW YORK BROOKLYN
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Void formation, void growth and tensile fracture was studied in ELI Ti-6Al-4V heat treated to strengths of 110 ksi 758 MNsq m to 140 ksi 965 MNsq m for both equiaxed and Widmanstatten plus grain boundary alpha structures. Void formation occurred at alpha-matrix interface, at alpha-alpha boundaries and at twin-untwin interfaces within alpha particles. Void growth was found to be a function of microstructure, being more rapid at grain boundary alpha-matrix locations than in equiaxed alpha structures. A plot of corrected fracture stress, shows separate curves with about the same slope, for equiaxed and grain boundary alpha structures, with the equiaxed alpha structures showing the higher fracture stresses. The dependency of void growth at grain boundaries on grain size and strain hardening rate is discussed. Initial work on low cycle fatigue behavior at constant strain of the Ti-6Al-2Sn-4Zr-6Mo alloy is outlined, and plans for the study of factors controlling the yield strength of alpha-beta Ti alloys are presented.
- Metallurgy and Metallography