Dynamic deformation and fracture surface investigation of rolled homogenous armor steel through Charpy impact testing

Abstract

The amount of energy that can be absorbed by armor steel during dynamic loadings, such as a crash, impact, or blast, is crucial. To characterize the behaviour of material deformation under such loading, rigorous testing and a suitable material model are needed. Within the scope of this research, relevant tensile tests in the dynamic range are carried out to obtain the parameters necessary for three different material models, namely, the Johnson-Cook (J-C), Rusinek and Klepaczko (R-K), and a newly proposed modified Johnson-Cook (MJ-C) model. Tensile tests are simulated using these three material models, and the results are compared with the experimental results. The Charpy impact test at five different striking velocities, viz. 3, 4, 5, 6, and 8 ms−1 are numerically simulated using these material models. Upon comparing the obtained results with the experimental data, it becomes evident that the J-C model with modification (MJ-C) exhibits the best fit in prediction with regard to the specimen energy absorption and force versus displacement. A fractography investigation is also carried out to estimate the number of voids and void size with striking velocities. It shows that at higher strain rates, the number of voids increases. Additionally, the plastic deformation is restricted at high strain rates, leading to higher stress and reduced ductility.