Ti6321钛合金在Taylor杆冲击下的动态断裂微观组织观测

The duplex and lamellar structures were obtained by heat treatment of near α-Ti6321 alloy. The influences of different microstructures on the dynamic damage and fracture behavior of material are investigated under Taylor bar impact test. The Taylor bar is used to test the cylindrical samples under dynamic compression loading, with impact velocity ranging from 146 m/s to 228 m/s. The microstructure evolution is observed and analyzed by using optical microscope, scanning electronic microscopy and quantitative metallography. The experimental results show that Ti6321 alloy with duplex structure exhibits better impact resistance property. All samples deform significantly after dynamic compression loading. With increase in impact velocity, the primary α grain size of the duplex structure decreases from 25.3 μm to 16.7 μm, and the secondary α phase and β phase are deformed and crushed under dynamic loading. The secondary α phase of lamellar structure samples is significantly elongated along the direction of the loading. The smooth melting areas and dimple areas can be observed from the impact fracture morphologies, and the boundary between two areas is not obvious. The failure mode of titanium alloy with both the structures is adiabatic shear banding. Compared to lamellar structure samples, Ti6321 alloy with duplex structure exhibits a better capability to resist an adiabatic shear damage.