Growth mechanism of a small surface crack of ultrafine-grained copper in a high-cycle fatigue regime

• Published in: Scripta materialia Vol. 60; no. 8; pp. 729 - 732
• Main Authors: Goto, M., Han, S.Z., Kim, S.S., Ando, Y., Kawagoishi, N.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-04-2009
• Subjects: Copper; Equal channel angular pressing; Fatigue test; Reversible plastic zone; Small crack; Reversible plastic zone; Fatigue test; Equal channel angular pressing; Copper; Small crack
• ISSN: 1359-6462; 1872-8456
• DOI: 10.1016/j.scriptamat.2009.01.003

High-cycle fatigue tests were carried out on specimens of ultrafine-grained copper produced by equal channel angular pressing. The growth behavior of a small surface crack was monitored. A major crack, which led to the final fracture of the specimen, initiated from shear bands. After initiation, the crack grew linearly in the shear direction of the final pressing. A decrease in growth rate with a change in growth path morphology occurred when the crack length reached
l
∼
0.1
mm. This decrease occurred because of a change in the crack growth mechanism and is explained by considering the interrelation between grain size and the reversible plastic zone size at the crack tip.