Corrosion fatigue crack propagation in aluminum alloys

Book · Wed Dec 31 04:00:00 EST 1997

OSTI ID:293070

Zheng, X; Wang, R ^[1]

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1. Northwestern Polytechnical Univ., Xi`an (China)

Fatigue tests were carried out to measure the corrosion of fatigue crack propagation (cfcp) rates of aluminum alloys in 3.5% NaCl environment. The cfcp test data of aluminum alloys can be well fitted by following formula: (da/dN){sub cf} = B{sub cf}({Delta}K {minus} {Delta}K{sub thcf}){sup 2}. Test results and analysis show that 3.5% NaCl solution decreases the cfcp threshold {Delta}K{sub thcf} of aluminum alloys. However, the effects of 3.5% NaCl solution on the cfcp coefficient B{sub cf} depend on the composition and heat treatment of the alloy tested; 3.5% NaCl solution has no appreciable effect on cfcp coefficient of LY12CZ alloy while greatly increases that of LS4CS alloy. Test results and analysis also show that the cfcp coefficient is independent of stress ratio and the cfcp threshold decreases with increasing stress ratio. The correlation between cfcp threshold and stress ratio are also given. Consequently, general expressions of cfcp rates can be obtained for aluminum alloys tested, which reveals the correlation between the cfcp rate, {Delta}K, R, B{sub cf} and {Delta}K{sub thcf}. Loading frequency effect on cfcp rate may depend on the interaction between material and environment. In this study, loading frequency within the range of 1--15 Hz has no appreciable effect on cfcp rate of LY12CZ alloy in 3.5% NaCl solution. The increase of cfcp coefficient of LC4CS alloy can be attributed to the change of crack propagation mechanism in intermediate region in 3.5% NaCl solution. The effect mechanism of 3.5% NaCl solution on cfcp threshold of aluminum alloys needs to be further investigated.

• OSTI ID: 293070
• Report Number(s): CONF-970980--; ISBN 0-87339-382-1
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
CORROSION FATIGUE
CORROSIVE EFFECTS
CRACK PROPAGATION
EXPERIMENTAL DATA
FRACTURE MECHANICS
SODIUM CHLORIDES
STRESS INTENSITY FACTORS