Low-cycle fatigue behavior of Ti-6Mo-5V-3Al-2Fe alloy with various types of secondary α phase

Abstract

Low-cycle fatigue (LCF) behavior of a novel near β titanium alloy Ti-6Mo-5V-3Al-2Fe (wt%) with various types of secondary α phase was investigated. Results indicate that No.1 microstructure containing crossed and fine intragranular α, as well as discontinuous GB α, is obtained through low temperature (480 °C) aging treatment. No.2 microstructure containing parallel and coarse intragranular α, as well as parallel WGB α, forms after high temperature (600 °C) aging treatment. Under all strain amplitudes, stress amplitudes and LCF life of the samples with No.1 microstructure are higher than those of the samples with No.2 microstructure. For the samples with No.1 microstructure, more and deeper secondary cracks and dimples form in fatigue crack propagation and fast fracture regions, respectively. Such fatigue fracture behavior reflects a longer LCF life.