Research on dynamic mechanical properties and plastic constitutive relation of Ti3Al intermetallic compounds under mechanical-thermal coupling

Abstract

Ti3Al intermetallic compounds is a lightweight, high-temperature resistant rare aerospace materials, whose dynamic mechanical properties concern the accuracy of simulation analysis and further development in material manufacturing. To obtain the plastic constitutive relation of Ti3Al under the action of mechanical-thermal coupling, material rheological behavior was investigated by using the separation Hopkinson pressure bar (SHPB) system with a high-temperature synchronous assembly. Meanwhile, the Johnson-Cook plastic constitutive model was calculated and modified by introducing strain compensation and adiabatic temperature rise at the range of strain rate of 0.001–6500 s−1 and deformation temperature of 293–1173 K. Furthermore, the microstructure evolution of Ti3Al fracture surface morphology was discussed. Experimental results showed that the flow stress had a weak positive strain rate enhancement effect, significant negative temperature thermal softening effect and strain rate plasticizing effect. Adiabatic temperature rise was accompanied by the high strain rate, and its value increased exponentially with the strain rate. The adiabatic deformed shear band (ADSB) appeared at an edge of 45° along the loading direction at the strain rate 4500 s−1 and the deformation temperature 273 K, respectively. ADSB tended to expand internally along with the strain rate and evolved into an adiabatic transformed shear band (ATSB) when the temperature rose to 973 K. The maximum relative errors in the modified J-C model at the high strain rate and the room temperature, the high strain rate and the high temperature were 3.11% and 14.91%, respectively. Consequently, the modified J-C model described in dynamic mechanical properties of Ti3Al was more accurate than the conventional J-C model.