INVESTIGATION ON LOW CYCLE FATIGUE PROPERTIES OF Ti-2Al-2.5Zr ALLOY TUBE AND ROD

摘要

The low cycle fatigue (LCF) properties of Ti-2Al-2.5Zr alloy tube and rod specimens were determined at R.T. The stress～strain curve equation under cyclic and monotonic loading and the relation of total strain vs fatigue life of Ti-2Al-2.5Zr alloy were established. The effects of strain ratio R, strain amplitude ε_a, and specimen shape on cyclic deforming behavior and fatigue properties were analyzed. The fatigue fracture features were also discussed according as SEM observation. The results show, at R = 0.1,the cyclic stress-strain curves of Ti-2Al-2.5Zr alloy tube and rod specimens appear as cycle softening. When R is -1, its rod specimen behaves as cycle softening; at low ε_a, values; whereas it behaves as cycle hardening at high ε_a, values. The LCF properties determined with tube specimen is lower apparently than that with rod one. There are much irregular recrystalline convex in LCF fractures of Ti-2Al-2.5Zr alloy tube and rod specimens, and much secondary cracks, fatigue striations and holes also exist among them.