On the low-cycle fatigue behavior of aluminum alloys under influence of tensile pre-strain histories and strain ratio

The present study attends to the effect of tensile pre-strain histories and strain ratio on cyclic deformation behavior of 6061 aluminum alloy and 2024 aluminum alloy. Low-cycle fatigue tests performed in this study covered two areas; Under fully reversed conditions, with 8% tensile pre-strain, 4% tensile pre-strain, and 0% tensile pre-strain, at strain amplitudes varying in the range 0.6–1.75%; Under strain-controlled circumstances at three different strain ratios [−1, 0, and 0.5] with strain amplitudes varying in the range 0.60–1.75%. The outcomes indicate that the material demonstrates a cyclic strain-softening behavior whose degree rises with rising values of strain ratio and reducing values of strain amplitude. The material demonstrates a non-Masing behavior for higher strain amplitudes amid the interval [1.00%−1.75%]. The material demonstrates a nearly-Masing behavior for lower strain amplitudes amid the interval [0.6%−0.85%]. Under non-zero mean strain, a total relaxation of mean stress is observed at higher strain amplitudes, whereas at lower strain amplitudes, no such behavior is observed.