Investigation on monotonic and cyclic stress-strain characteristics of Ti-2Al-2.5Zr alloy

The monotonic and cyclic deforming regularity of Ti-2Al-2.5Zr alloy rod, tu be and profiled tube (PT) specimen was determined at room temperature (RT). The effects of tension speed, V, cycle number, N, strain ratio, R, strain amplitude, epsilon(a) and specimen shape on tensile and cyclic deforming be havior and characteristics were analyzed. The stress-strain relation equati ons under monotonic and cyclic loading, and the fatigue life prediction equ ations of Ti-2Al-2.5Zr alloy were established. The structure and fracture w ere also observed with optical and scanning electron microscope (OM, SEM). The tensile properties of Ti-2Al-2.5Zr alloy are related with V and specime n shape. At R = 0.1, the cyclic stress-strain curves of tube and rod appear as cyclic softening. But the rod (at R = -1) and PT (at R = 0) behave as c yclic softening at low epsilon(a) value (less than or equal to 9.0%), where as they appear as cyclic hardening at high epsilon(a) value (> 2.0%). The f atigue life of Ti-2Al-2.5Zr alloy determined with tube is lower than that w ith rod. The twinning is closely related to epsilon(a), N value, etc. The t ensile fractures show typical dimple features. There are many irregular cry stalline convexes in fatigue fractures where many secondary cracks, fatigue striations and holes also exist. Published by Elsevier Science S.A.