Intrinsic high cycle fatigue behavior of ultrafine grained pure Cu with stable structure

Abstract

Ultrafine grained (UFG) materials have attracted considerable attention owing to their unique microstructure and mechanical properties. However, the easy formation of large-scale shear bands and severe grain coarsening during cyclic deformation gives rise to enormous difficulties when investigating the intrinsic fatigue behavior of UFG materials. Herein, we discuss the fabrication of an ideal model material, based on pure Cu, by friction stir processing (FSP), which exhibits equiaxed ultrafine grains, low dislocation density, and a high ratio of high-angle grain boundaries. This model material was used to investigate the intrinsic high cycle fatigue behavior of UFG material. It was found that an enhanced fatigue limit and fatigue ratio can be achieved by FSP Cu due to its uniform and stable UFG structure. Instead of traditional large-scale shear bands, protrusion was found to be the main surface damage morphology for FSP Cu during high cycle fatigue deformation, and no obvious grain coarsening was observed. Dislocation related activity also dominated, but was limited to the ultrafine grains without the formation of regular dislocation structures.

Mechanical and Damping Behavior of Age-Hardened and Non-age-hardened Al Alloys After Friction Stir Processing

“…1b). The heat input during FSP increased with increasing the rotation rate [18,[22][23][24]. Thus, increasing the tool rotation rate enhanced the temperature, thereby dissolving some of Al 3 Mg 2 phase due to the high solubility of Mg atoms in the Al lattice.…”

Achieving equal fatigue strength to base material in a friction stir welded 5083-H19 aluminium alloy joint

“…Usually, the is nearly equal to the true tensile strength after modification with necking and b represents the degree of the fatigue damage, which is associated with the initial microstructure characteristics [26, 27]. Compare with the BM, the of the A-200 sample decreased clearly but the similar b value was obtained, so the fatigue limit was reduced to 180 MPa.…”

The processing route towards outstanding performance of the severely deformed Al–Mg–Mn-Sc-Zr alloy

“…The increase of the Basqiun exponent after deformation processing, including SPD, has been frequently reported in the literature, e.g. [58][59][60], and this is associated with the strengthening effect, which tends to increase the susceptibility of the material to the internal imperfections inherited from SPD as well as to cyclically induced damage. Thus, compared to the as-cast state, the deformation processing increases the fatigue strength coefficient A in parallel with the microstructure refinement and the increasing monotonic strength.…”