Study On Dynamic Mechanical Behavior And Fracture Mechanism Of 35CrMnSi Under Strong Impact Loading

A High-Strength-Low-Alloy steel35CrMnSi is selected as the object of this study. Itsheat treatments are double quenching and low-temperature tempering. Quasi-static and SHPBmechanical experiments were carried out to obtain stress-strain curve of material at differentstrain rate. Ballistic experiments were made to study behavior and mechanism of fractured. Inaddition, numerical simulation was used to test and verify the experimental result.Fracturedmode and criterion were obtained by analytical result. It provides experimental basis andreference in theory for engineering application of35CrMnSi.Using the double quenching and low-temperature tempering can improve strength andhardness of the material, diminish the toughness. Based on the SHPB experimental data,stress-strain curve was obtained at high strain rate. which strain rate was under the range of1070~2710/s. Johnson-Cook model parameters were fitted for35CrMnSi using SHPBexperimental data.35CrMnSi fragment was launched to impacted steel plate by ballistic gun. It obtained thefailure and fracture behavior at higher strain rate. The result showed that the failure mode of35CrMnSi fragment included heading deformation,tensile/shear cracking and compositefailured. Microscopic observation shows that microcosmic fractured mechanism was cleavagesplitting,with the emerging of high-temperature product.Numerical simulation was used to test and verify experimental data by AUTODYN.Simulation result showed that the degree of failured and fractured were intensified with theincreasing of the impacting velovity and steel’s thickness. The main failured modes whichincluded heading deformation,tensile/shear cracking and fragmentation were analysed. Theresults of the analyses showed that area of failured and fractured were concentrated in plasticdeformation band with high strain rate, following with high temperature effect. These mayresulted in higher penetration resistance and trajectory deflection, and reducing penetratingability. Using the results of simulation, the failured criterion was provided for35CrMnSifragment under the strong impacting loading.