Microscopic Simulation Of Failure Behavior Of Ti-6Al-4V Alloy

  Ti-6Al-4V alloy has excellent mechanical properties, corrosion resistance and biocompatibility, and can be used in many fields. This alloy is a typical two-phase titanium alloy, and its phase size, volume fraction and distribution will affect its failure behavior. S. Katani et al. used the finite element method to simulate the microstructure morphology of the Ti-6Al-4V alloy ( Contains 55% α phase and 45% β phase) mechanical properties and failure mechanism.
In the experiment, an annealed Ti-6Al-4V alloy rolled plate with a thickness of 0.7 mm was used. Its chemical composition (mass fraction) was 0.016 C, 0.01 N, 0.18 Fe, 6.13 Al, 3.80 V, 0.16 O, 0.003 H, The balance Ti. After cutting, polishing, and ultrasonic cleaning of the Ti-6Al-4V alloy plate used in the experiment, it was etched with a mixed solution of 10 mL hydrofluoric acid + 5 mL nitric acid + 85 mL distilled water to obtain a sample for scanning electron microscope observation. The room temperature tensile test specimens were prepared according to the ASTM E8/8M-11 standard with a tensile strain rate of 1 mm/min. The finite element method was used to simulate the stress size and distribution of α-phase and β-phase during the deformation process, and combined with the microstructure and mechanical property data, the aging mechanism of Ti-6Al-4V alloy was analyzed. The study found that the reason for the ductile fracture of the Ti-6Al-4V alloy sheet is that the micro-cavity formed on the side of the α/β two-phase interface close to the α-phase before fracture caused shear fracture. From the finite element simulation and test results, the fracture failure mechanism of this α/β two-phase alloy is similar to that of typical ductile fracture. The results of GTN model characterizing the α matrix show that the stress-strain curves obtained by simulation and experiment fit well. The experiment also found that the relative deformation of β grains will cause a large local deformation of the α matrix, which will play a leading role in the final stage of the fracture process of the material. The simulation method proposed in this study can also be applied to study the effect of heterogeneous nucleation morphology on the ductile fracture properties of the alloy.