FATIGUE-CRACK PROPAGATION IN BETA-TI-15MO-5ZR-3AL ALLOY

This paper describes the fatigue crack propagation (FCP) for five mate rials having different microstructures of beta Ti-15Mo-5Zr-3Al alloy. With one exception, the microstructure was found to have very little o r no influence on FCP behavior. The one exception was the material hav ing the largest beta grain size, which showed higher FCP resistance th an all other materials due to higher crack closure levels. The effects of stress ratio on the FCP behavior could not be realized solely in t erms of the crack closure mechanisms, because static fracture mechanis ms operated during FCP depending on the magnitude of the maximum stres s intensity factor, K-max. Furthermore, it was found that the FCP resi stance of all the materials was considerably lower than that of alpha/ beta Ti-6Al-4V alloy, which was primarily attributed to lower crack cl osure levels of the beta alloy. (C) 1998 Elsevier Science S.A. All rig hts reserved.