Mechanical Behavior Of Near Beta-Type Tlm Titanium Alloy Tube With Small Diameter And Thin Wall

Near beta-type TLM titanium alloy tubes with small diameter and thin wall were fabricated by a combination of cold rolling and intermediate annealing. The mechanical behaviors related to the phases and microstructures were studied using optical metallography (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and tensile tests. The results show that the cold-rolled microstructure composed of beta phase and stress induced martensite (SIM alpha") exhibits obvious non-linear elastic deformation behavior, while the annealed single beta phase displays the "double-yielding" associated with stress-induced martensitic phase transformation. Present authors consider that the non-linear elasticity has certain dependence on both of SIM alpha" and complicated sub-structures induced by the cold deformation, but both of then make an inconspicuous contribution to the plasticity. Although the elongation decreases after the cold rolling, the cold rolled microstructure still shows the ductile fracture mode similar to that of annealed specimens, which indicates that wider plasticity range of the present TLM alloy supplies a tremendous potential in its deep cold deformation.