Influence of Microstructures on High Cycle Fatigue Properties of TB17 Titanium Alloy
The effects of three typical microstructures(bi-modal microstructure,basketweave microstructure and lamellar microstructure)on the high cycle fatigue properties of TB17 titanium alloy were studied,and the high cycle fatigue fracture morphology was analyzed.The results show that the TB17 titanium alloy with bimodal microstructure has the highest matching level of strength and plasticity,but its fatigue life has a bilinear relationship with stress,and its fatigue performance is not stable.The strength and plasticity of the TB17 alloy with basketweave structure are slightly worse,but it has the highest fatigue strength and fatigue ratio.The fatigue strength of the TB17 alloy with lamellar structure is slightly lower than that of the alloy with basketweave structure,but its fatigue ratio and tensile plasticity are the worst.When the high-cycle fatigue loading stress is in a low stress state,fatigue crack is prone to initiate inside the specimen and from a single source;however,when it is in a high stress state,the fatigue crack tends to initiate on the surface of the sample and from multi-source.In the basketweave microstructure,more secondary cracks appear,the fatigue bands are clearer and denser,the crack propagation path is more tortuous,and more energy is consumed during propagation than the cases in the other microstructures.
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