Low-cycle fatigue behaviors of commercial-purity titanium

Low-cycle fatigue behaviors of commercial-purity titanium (TA2) were investigated under constant total strain amplitude control at room temperature in air. It was found that commercial-purity titanium exhibited a complex cyclic hardening behavior over the strain range 0.5-2.4%. By optical microscope (OM) and Image Scan Analyzer, the cyclic deformation twins were observed and the quantitative relations of twin fraction F-T versus strain amplitudes and cyclic numbers were proposed. Meanwhile, the dislocation structures in cyclically deformed commercial-purity titanium were observed by transmission electron microscopy (TEM). In combining the observations of dislocation patterns and deformation twins, a microstructure evolution map was given. On the basis of the experimental results: the effect of microstructures (including deformation twins and dislocation patterns) on the cyclic stress-strain response was discussed. (C) 1998 Elsevier Science S.A. All rights reserved.