アルミニウム合金のモードII負荷における疲労き裂発生と進展挙動に及ぼす3.5%食塩水環境の影響(<特集>疲労特集)

概要

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The characteristics of fatigue crack initiation and growth of two high strength aluminum alloys (2017-T3, T4 and 7075-T6) under mode II loading have been investigated in 3.5% saltwater by the four-point-shear test method. The mode I fatigue crack growth tests have also been carried out for the same alloys in 3.5% saltwater and in air. 2017-T3, T4 and 7075-T6 aluminum alloys showed mode II growth in 3.5% saltwater as in air under the conditions of higher ΔK_<II> than a certain critical ΔK_<II> and of shaper notch than a certain critical sharpness. The minimum value of ΔK_<II> for mode Ii growth (ΔK_<II>-threshold for mode II growth) increased in 3.5% saltwater compared with that in air. An appreciable effect of environment was observed not only on the da/dN-ΔK_I relation but also on the fractograph of mode I fatigue crack growth in 7075-T6. In both alloys, little effect of environment was found on the minimum value of ΔK_<II> for mode I crack growth, on the da/dN-ΔK_<II> relation or on the fractogr fatigue crack growth.
社団法人日本材料学会の論文
1987-10-15