摘要
In this paper,the high speed tension experiments have been performed on ultra high strength bulletproof steel.The specimen were cut from B-grade bulletproof steel sheet after hard-module quenching with thickness of 2.3 mm.The mechanical properties at strain rates of 0.001 s-1,0.01 s-1,0.1 s-1and 1 s-1were carried out on MTS810,while those at higher strain rates of 200 s-1,500 s-1and 1 000 s-1were tested on HTM5020 high speed tension tester and Hopkinson bar.The data from the high speed tension experiments were fitted via Johnson-Cook constitutive equation,and the fracture surface of each specimen was analyzed by scanning electron microscope(SEM).The results indicate that,the shoot resistance capability of bulletproof steel is closely related to its strength,thickness and flow behaviors under high strain rate.The shoot resistance will be improved in the case of higher strength and better matching between strength and elongation.The Johnson-Cook constitutive equation fitted via experimental data provides fundament to numerical simulation.With the increase of strain rate,the size and depth of dimple trend to decrease and the depth of dimple changes less in steel with lower strength and higher elongation.The SEM analysis of fracture aspect is of benefit for further understanding of deformation and fracture mode under high strain rate.
In this paper, the high speed tension experiments have been performed on ultra high strength bulletproof steel. The specimen were cut from B-grade bulletproof steel sheet after hard-module quenching with thickness of 2.3 mm. The mechanical properties at strain rates of 0.001 s^-1, 0.01 s^-1, 0.1 s^-1 and 1 s^-1 were carried out on MTSS10, while those at higher strain rates of 200 s^-1, 500 s^-1 and i 000 s^-1 were tested on HTM5020 high speed tension tester and Hopkinson bar. The data from the high speed tension experiments were fitted via Johnson-Cook constitutive equation, and the fracture surface of each specimen was analyzed by scanning electron microscope （SEM）. The results indicate that, the shoot resistance capability of bulletproof steel is closely related to its strength, thickness and flow behaviors under high strain rate. The shoot resistance will be improved in the case of higher strength and better matching between strength and elongation. The Johnson-Cook constitutive equation fitted via experimental data provides fundament to numerical simulation. With the increase of strain rate, the size and depth of dimple trend to decrease and the depth of dimple changes less in steel with lower strength and higher elongation. The SEM analysis of fracture aspect is of benefit for further understanding of deformation and fracture mode under high strain rate.
