The tensile deformation, cyclic fatigue and final fracture behavior of dispersion strengthened copper

Abstract

The tensile deformation, cyclic stress response characteristics, cyclic stress–strain response, cyclic strain resistance and fatigue properties of an oxide dispersion strengthened copper alloy were studied over a range of cyclic plastic strain–amplitudes. The specimens were cycled using tension-compression loading under total strain–amplitude control. In the as-drawn condition, the dispersion strengthened copper alloy displayed continuous softening to failure at all cyclic plastic strain amplitudes. The rolled plus heat-treated microstructure displayed initial hardening followed by rapid softening to failure. The strain–fatigue life relationship is predicted using the parameters obtained from the fatigue test. Potential mechanisms controlling the stress response and concomitant cyclic strain resistance and cyclic fatigue life are also evaluated, and rationale for observed behavior is discussed in light of concurrent and interactive influences of initial state of the matrix dislocation arrangement, magnitude of cyclic strain amplitude, response stress and intrinsic microstructural effects.