Overview of fatigue performance of Cu processed by severe plastic deformation

This study investigates discrepancies regarding cyclic softening of Cu processed by severe plastic deformation (SPD). All samples softened if the microhardnesses before and after fatiguing are compared. However, the effect decreases if the strain amplitude is small, Delta epsilon(p) <1 x 10(-3). Samples with equiaxed subgrains were more resistant to softening and thermal recovery. All samples had "persistent" shear bands except those tested at the highest amplitudes, Delta epsilon(p) >1 x 10(-2). Cu processed by SPD exhibits an enhanced fatigue life at low amplitudes. However, low thermal stability, potential for softening, and poor low-cycle properties discredit this advantage.