Fatigue failure analysis of V-4Ti-4Cr alloy

In the present work, the fatigue fracture and failure behavior of a V-4Ti-4 Cr has been studied. Static tears were conducted to study the overloading b ehavior and to select the magnitude of the stress level for the fatigue stu dies. Fatigue tests were performed using single edge notched (SEN) specimen s under tension-tension load control conditions. Fatigue crack propagation (FCP) data such as the crack length, number of cycles, and hysteresis loops were recorded to calculate the crack speed, the energy release rate, and t he change in work expended on damage formation and dissipative processes wi thin the material. Parameters characterizing the fatigue fracture resistanc e of V-4Ti-4Cr alloy, namely the specific energy of damage (gamma'), and th e dissipative coefficient (beta'), were determined from the fatigue data us ing the modified crack layer (MCL) theory. Fracture surface examination usi ng scanning electron microscopy (SEM) revealed ductile failure mechanisms u nder tensile overloading conditions. The fatigue fracture surface of the V- 4Ti-4Cr consists of three distinct regions, corresponding to the threshold, stable and unstable crack propagation stages. (C) 1999 Elsevier Science B. V. All rights reserved.