SEDL / STP / STP642-EB / STP28722S

Corrosion-Fatigue Properties of Recrystallization Annealed Ti-6A1-4V

Ryder, JT
Research scientist, group engineer, and research scientist, Lockheed-California Company, Rye Canyon Research Laboratory, Burbank, Calif

Krupp, WE
Research scientist, group engineer, and research scientist, Lockheed-California Company, Rye Canyon Research Laboratory, Burbank, Calif

Pettit, DE
Research scientist, group engineer, and research scientist, Lockheed-California Company, Rye Canyon Research Laboratory, Burbank, Calif

Hoeppner, DW
Professor of engineering, University of Missouri, Columbia, Mo

Pages: 21    Published: Jan 1978

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Abstract

The corrosion-fatigue crack growth properties of recrystallization annealed (RA) Ti-6A1-4V were studied in room-temperature laboratory air, dry air, high-humidity air, sump-tank water, and 3.5 percent sodium chloride (NaCl) solution environments. The alloy was characterized by chemical, microstructural, and tensile properties. Corrosion fatigue tests were conducted using wedge-opening-load (WOL), center-cracked-through (CCT) and part-through-cracked (PTC) specimens. Frequency and environmental interactions were studied as well as the effects of orientation and stress ratio. The effect of frequency was to increase the fatigue crack growth rate as the frequency was decreased. A severe effect of frequency was noted in sump-tank water and saltwater where at low frequencies, crack growth rates increased to such a high level that failure occurred at K^max levels significantly below those expected. Fractographic studies showed no apparent cause of this phenomenon.