Effect of heat treatment and SiC front layer on the ballistic behaviour of 34CrNiMo6 steel

In this study, the ballistic behaviour of a high strength-low alloy steel (34CrNiMo6) with various heat treatment conditions was examined in both monolithic and composite containing the SiC ceramic front layer. Three different heat treatments were applied to the 34CrNiMo6 steel in a controlled atmosphere. One of them was normalizing treatment and the others were the tempering treatments at 200 °C and 400 °C after the austenization at 860 °C followed by quenching in an oil bath. The hardness and dimensions of the silicon carbide tile were measured to be ~ 2483 HV and 50x50x8.5 mm respectively. Experimental studies were performed with the 7.62 mm armor piercing (AP) projectiles at an average speed of 778.5 m/s. After the heat treatments, the mechanical properties and microstructure of the samples were investigated. After the ballistic impact testing, the microstructural changes in the steel samples were detected using an optical microscope. According to the experimental results, the best ballistic performance was obtained for the steel sample tempered at 200 °C for the areal densities ≥ 70.6 kg/m2. On the other hand, the highest ballistic resistance was found at the composite sample, consisting of the backing steel plate tempered at 200 °C, for the areal densities ≥ 54.6 kg/m2.