The Influence of the Microstructure of an HHA Steel on the Formation of Adiabatic Shear Bands, after High Deformation Rates

Abstract

High hardness armor (HHA) steels, when subjected to high deformation rates, are prone to adiabatic shear bands formation. These heterogeneities, formed in a narrow zone, are the result of an intense plastic deformation in which the rate of heat dissipation is low. The generated shear bands can lead to a decrease in ballistic performance and impose to an armor a catastrophic failures. The appearance of these bands may be related to the microstructure or the deformation rate to which the material is subjected. Therefore, this work aims to analyze the influence of the microstructure of an HHA steel, tempered at 310, 425 and 610° C for 2 h, after high deformation rates, in the appearance of adiabatic shear bands. Specimens were dynamic tested in a split Hopkinson pressure bar. It was shown that tempering temperature at 310 ° C for 2h, which produced bainite and martensite with high hardness, was the most susceptible to the adiabatic shear bands appearance.