The effect of frequency and microstructure on corrosion fatigue crack propagation in high strength aluminium alloys

Journal Article · Mon Sep 01 04:00:00 EDT 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00033-5· OSTI ID:540962

Gingell, A D.B.; King, J E ^[1]

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1. Univ. of Cambridge (United Kingdom). Dept. of Materials Science and Metallurgy

Fatigue crack growth in high strength aluminium alloy 7150 commercial plate material has been studied in both laboratory air and acidified aqueous salt solution. The aggressive aqueous environment enhanced fatigue crack growth rates by up to an order in magnitude compared to laboratory air. The enhancement in fatigue crack growth rate was accompanied by evidence of embrittlement in the crack path, involving both brittle intergranular and transgranular failure mode. Both the enhancement of fatigue crack growth rates and the extent of intergranular growth modes are dependent on cyclic frequency which, along with the absence of a similar frequency effect in a spray-formed version of the material with a significantly different grain structure, supports a mechanism of grain boundary hydrogen diffusion for intergranular corrosion fatigue crack growth. The convergence of corrosion fatigue crack growth rates at high {Delta}K in both spray-formed and conventional plate materials coincides with the operation of identical transgranular corrosion fatigue modes dependent on strain-controlled hydrogen diffusion ahead of the crack up.

• OSTI ID: 540962
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 9 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
AIR
ALUMINIUM BASE ALLOYS
COPPER ALLOYS
CORROSION FATIGUE
CRACK PROPAGATION
FREQUENCY DEPENDENCE
GRAIN BOUNDARIES
HYDROGEN EMBRITTLEMENT
MAGNESIUM ALLOYS
MICROSTRUCTURE
SODIUM CHLORIDES
ZINC ALLOYS