Fatigue Failure Stages of VT1-0 Titanium in Different Structural States. Study by Acoustic Emission Method.

The paper studies the kinetics of fatigue damage accumulation in VT1-0 titanium by the acoustic emission (AE) method. Technical grade titanium VT1-0 in various structural states was tested under cyclic bending. Submicrocrystalline Ti-specimens (SMC, with subgrain size of 200-300 nm) were fabricated by equal channel angular pressing (ECAP) from polycrystalline titanium. Ingots with ultrafine grain structure (UFG, with structure element size of 1-2 µm) and coarse grain structure (CG, with structure element size of 20-30 µm) were prepared by annealing at different temperatures. Fatigue stages were identified by analyzing the AE signal parameters with their classification by the source type (dislocations, micro- and macrocracks). It was revealed that the specimens with a smaller grain size are of higher fatigue durability, while AE signals at the stages of yielding and microcracking are detected later because of their low energy. [ABSTRACT FROM AUTHOR]