• Jure Bernetič PROTAC d.o.o., c. F. Prešerna 61, 4270 Jesenice, Slovenia
  • Borut Kosec University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, Ljubljana, Slovenia
  • Gorazd Kosec ACRONI d.o.o., c. B. Kidriča 44, Jesenice, Slovenia
  • Mirko Gojić University of Zagreb, Faculty of Metallurgy, Aleja narodnih heroja 3, Sisak, Croatia
  • Zijah Burzić Military Institute VTI, R. Resanovića 2, 10000 Belgrade, Serbia
  • Aleš Nagode University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, Ljubljana, Slovenia
  • Mirko Soković University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva 6, Ljubljana, Slovenia
  • Milan Bizjak University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, Ljubljana, Slovenia




The engineers of PROTAC d.o.o. and the biggest Slovenian steelwork ACRONI d.o.o., in cooperation with domestic and foreign institutions of science, have been designed and developed a new generation of armored steel PROTAC 500. Steel PROTAC 500 belongs to the group of high strength low alloy (HSLA) steels. It is made in steelwork ACRONI d.o.o. by the standard industrial procedures. The relevant mechanical properties of that steel are achieved by corresponding heat treatment procedure: quenching and tempering.

Preliminary tests of the mechanical properties of the steel have indicated the possibility of using steel PROTAC 500 for light armored vehicles. The presented work studied the response of new generation armored steel plates PROTAC 500 to the ballistic testing with armored piercing bullets with a core of tungsten carbide, charge 7.62 mm. However, the interactions between the piercing bullets and the armored steel plate were also investigated. The most obvious and significant phenomena in penetrating of the piercing bullets Nammo AP8 in steel target PROTAC 500 are strain hardening of steels, the appearance of cracks and local failure, adiabatic shear bands (ASB) with related phase transformations, and melting as well as alloying at the interface between bullet and steel plate


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