High temperature fatigue behavior in tensile hold LCF of near-alpha Ti-1100 with lamellar structure

Abstract

The effect of various tensile hold times on high temperature LCF behavior of Ti-1100 with a lamellar structure was investigated at 600 degrees C. It was found that fatigue lives for 10 and 30 min hold times were lower than those in continuous cycle fatigue due to additional creep resulting from stress relaxation during the tensile hold, Creep deformation during hold time resulted in a change of dislocation structure from a planar form to an homogeneous distribution within the alpha lamellae. An apparent activation energy for creep deformation of about 520 kJ/mol was obtained from the stress relaxation curve and was consistent with results of other near-alpha titanium alloys. In all cases failures were fatigue-dominated, although creep cavity formation was observed in hold time spcimens. (C) 1999 Kluwer Academic Publishers.