Low Cycle Fatigue Behaviors of TI-6AL-4V Alloy Controlled by Strain and Stress

Abstract

The low cycle fatigue behaviors of TI-6AL-4V alloy controlled by strain were investigated by experiment. The fatigue tests were performed at room temperature, and cyclic strain and stress ratio are 0.1 with triangle load wave. The results show that TI-6AL-4V alloy is soften rapidly under the cyclic tensile stresses and it is harden rapidly under the cyclic compressive stresses during the initial-stage of strain controlled fatigue, and the rates of cyclic soften and cyclic harden are decreased with the fatigue progress. The soften rate is related to the cyclic strain but little to the cyclic stress during the overall fatigue progress. The change of cyclic stress is related to the macro friction stresses. The results of experiment show that obvious cyclic creep occurs under the stress controlled low cycle fatigue conditions, and the magnitude of cyclic creep strain is related to the maximum cyclic stress. The softening of tensile friction stresses is the main factor of cyclic creep.

Fatigue behavior of Ti6Al4V alloy components manufactured by selective laser melting subjected to hot isostatic pressing and residual stress relief

“…Wang et al 14 and Carrion et al 15 studied the fatigue behavior of the Ti6Al4V alloy produced by conventional processes, by carrying out strain controlled fatigue tests. They obtained a cyclical softening when this alloy is subjected to strain amplitudes with a nonzero plastic component.…”