Fatigue and corrosion-fatigue strength of hot rolled Ti35Nb2.5Sn alloy

• The Ti35Nb2.5Sn alloy was obtained by vacuum arc melting.
• The alloy was heat treated and hot rolled with 40% reduction and quenched in water.
• Fatigue tests were done in air and in environment containing 0.9% NaCl.
• The fatigue limit is regarded to the formation of the martensitic α″ phase.
• The corrosion effect is higher in low cycle fatigue in corrosive environments.

The Ti35Nb2.5Sn alloy was obtained by vacuum arc melting. The alloy was homogenized and solubilized. It was then hot rolled with 40% reduction and quenched in water. Samples were also solubilized and quenched in water after hot rolling to check the procedure's effect on the formation of metastable phases. The microstructures were analyzed by microscopy and X-ray diffraction. Tensile tests were performed. Fatigue tests were also done to obtain the S–N curves in air and in environment containing 0.9% NaCl dissolved in water. The fracture micromechanics were analyzed in scanning electron microscope. The results were compared with published data from other beta titanium alloys. The fatigue limit is associated with critical stress by dislocations. The fatigue limit is higher than the stress required to drive the formation of the martensitic α″ phase. The study showed that the corrosion effect is higher in low cycle fatigue.

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