The control of texture to improve high-cyclic fatigue performance in copper after equal channel angular pressing

High-cyclic fatigue life in ultra-fine grained materials fabricated by equal channel angular pressing (ECAP) suffers from a specific shear texture induced during the fabrication as has been demonstrated in the present study on the example of pure copper. This texture promotes orientation of the easy glide crystallographic planes to be aligned parallel to the shear plane in ECAP. If specimens for the following fatigue tests are cut parallel to the pressing direction, the alignment of the easy glide crystallographic planes deteriorates the fatigue performance. It is demonstrated that the deteriorative effect can be alleviated through the controlled degradation of the texture. This goal can be achieved through (i) a consecutive ECAP processing up to equivalent strains of more than ɛ ≥ 8 requiring eight and more passes, or (ii) a pure-shear based post-ECAP processing to the equivalent strains as low as ɛ = 0.22. The second route is thought to be most effective in practical applications where improved fatigue performance is of concern.

► Fatigue properties depend on the easy glide crystallographic planes promoted by ECAP.
► HCF life can be substantially enhanced by the controlled degradation of the ECAP-induced texture.
► A pure-shear post-ECAP deformation to e = 0.22 is sufficient for remarkable improvement of HCF.