Corrosion fatigue-cracking response of beta-annealed Ti-6Al-4V alloy in 3. 5% NaCl solution. Volume 5. Final report, September 1982-June 1984
A systematic investigation was conducted to examine the effect of frequency on fatigue-crack growth in a beta-annealed Ti-6Al-4V alloy in 3.5% NaCl solution at room temperature. Fractographic and metallographic examinations were also made to help identify the probable mechanism for crack growth enhancement (or embrittlement) and to evaluate the frequency effect. Fatigue crack growth tests covered a range of frequencies from 0.03 to 15 Hz and a range of K/sub max/ levels from about 16 to 61 MPA-m1/2. The results show that fatigue-crack growth rates increased with decreasing frequency, and then decreased with further decreases in frequency. The frequency at which the crack growth rates reached a maximum depended on the K level, and is inversely proportional to ..delta..K. The fracture surface morphology also depended strongly on frequency and K level, and suggested that the enhancement of crack growth resulted from the formation and rupture of a hydride phase. Based on the experimental observations, crack growth response is interpreted in terms of control by hydrogen diffusion and of a critical strain rate required for hydride formation in the crack tip region.
- Research Organization:
- Lehigh Univ., Bethlehem, PA (USA); General Dynamics Corp., Fort Worth, TX (USA). Fort Worth Div.
- OSTI ID:
- 6212121
- Report Number(s):
- AD-A-160180/6/XAB
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360103 -- Metals & Alloys-- Mechanical Properties
360105* -- Metals & Alloys-- Corrosion & Erosion
ALKALI METAL COMPOUNDS
ALLOYS
ALUMINIUM ALLOYS
CHLORIDES
CHLORINE COMPOUNDS
CORROSION FATIGUE
CORROSIVE EFFECTS
CRACK PROPAGATION
CRACKS
DIFFUSION
ELEMENTS
EMBRITTLEMENT
FATIGUE
FRACTOGRAPHY
HALIDES
HALOGEN COMPOUNDS
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
MECHANICAL PROPERTIES
METALLOGRAPHY
MORPHOLOGY
NONMETALS
OPTIMIZATION
SODIUM CHLORIDES
SODIUM COMPOUNDS
SURFACE PROPERTIES
TITANIUM ALLOYS
VANADIUM ALLOYS