Effects of stress concentrations on the fatigue life of a gamma based titanium aluminide

Book · Sat Dec 30 23:00:00 EST 1995

OSTI ID:225162

Trail, S J; Bowen, P ^[1]

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1. Univ. of Birmingham (United Kingdom)

S-N curves for a gamma based titanium aluminide alloy of composition Ti-47.2Al-2.1Mn-1.9Nb(at.%)+2TiB{sub 2}(wt.%) have been used to define fatigue life. Effects of residual stress, stressed volume, loading ratio, loading mode, elevated temperature and surface roughness have been considered. Residual tensile stresses and micro-cracking are introduced by Electro Discharge Machining and the fatigue life is reduced slightly compared with polished samples. Notched fatigue tests show a significant notch strengthening effect which increases with increasing stress concentration factor. The fracture surfaces of specimens tested at room temperature reveal fully brittle failure mechanisms and no evidence of stable crack growth is observed. The fatigue life appears, therefore, to be determined predominantly by the number of cycles to crack initiation. At the elevated temperature of 830 C, evidence for some stable fatigue crack growth has been found. Probable sites for crack initiation are addressed.

• OSTI ID: 225162
• Report Number(s): CONF-950201--; ISBN 0-87339-304-X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
BORON ALLOYS
BRITTLENESS
CASTING
CRACKS
EXPERIMENTAL DATA
FATIGUE
FRACTURES
HOT PRESSING
INTERMETALLIC COMPOUNDS
MANGANESE ALLOYS
NIOBIUM ALLOYS
NOTCHES
OPTICAL MICROSCOPY
PREDICTION EQUATIONS
RESIDUAL STRESSES
ROUGHNESS
S-N DIAGRAM
SCANNING ELECTRON MICROSCOPY
TEMPERATURE DEPENDENCE
TITANIUM ALLOYS