Effect of creep and cyclic loading on pulsating fatigue behavior for various ti alloys under stress ratio R = 0

It is well known that creep at room temperature remarkably occurs in alpha-Ti alloys. Cyclic creep also appears. Moreover, Ti alloys have different crystal structures and various mechanical properties. Although the cyclic creep behavior and the cyclic softening behavior have been studied, integrated effect of them on fatigue life has not been clarified yet. In this study, fatigue behavior under stress ratio R=0, on Ti alloys of three crystal structures, is investigated. Influence of the cyclic creep and fatigue damage, and influence of the crystal structure to fatigue life are examined. As the results, it is found that as to the alpha-Ti, creep is the dominant damage factor. On the other hand, as to the beta-Ti alloy, fatigue is the dominant damage factor. As to the alpha + beta-Ti alloy, both creep and fatigue are the dominant damage factors (intermediate type). Furthermore, it is found that the area ratio and grain diameter of alpha phase, the spacing between different phases, should influence on cyclic creep strain rate.