LOW-CYCLE FATIGUE BEHAVIORS OF COMMERCIAL-PURITY TITANIUM

Low-cycle fatigue behaviors of commercial-purity titanium (TA2) were i nvestigated under constant total strain amplitude control at room temp erature in air. It was found that commercial-purity titanium exhibited a complex cyclic hardening behavior over the strain range 0.5-2.4%. B y optical microscope (OM) and Image Scan Analyzer, the cyclic deformat ion twins were observed and the quantitative relations of twin fractio n F-T versus strain amplitudes and cyclic numbers were proposed. Meanw hile, the dislocation structures in cyclically deformed commercial-pur ity 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 e xperimental results: the effect of microstructures (including deformat ion twins and dislocation patterns) on the cyclic stress-strain respon se was discussed. (C) 1998 Elsevier Science S.A. All rights reserved.