Description: The article presents the results of research on the behavior and nature of the fracture of welded joints of HB 500Mod steel under explosion loading. Based on the physical and mechanical characteristics of steel НВ 500Mod, according to quality certificates, the mechanical properties of the weld metal and zones of thermal impact have been calculated. These data have been obtained using thermodynamic calculation of the chemical composition in using JMatPro software. Using the finite element method, a study of the behavior of welded joints of type U6 ( GOST 14771) have been carried out. During simulation, the explosive charge was placed at different points relative to the dummy of the welded joint. The resistance of the welded joint has been estimated by the values of the plate deflection and the presence of the fracture of the weld. In addition, an estimation of the mechanism of formation and kinetics of crack formations in a welded joint has been made. The value of deflections has been compared with the calculated values of the deflections of the conditionally monolithic connection of the two plates. According to the results of the conducted researches, the kinetics of crack formation in a welded joint under explosion loading has been established. It was discovered that the site of destruction of the metal of welded joints was the fusion area - the transition zone from the weld metal to the least plastic part of the zone of thermal influence - the site of overheating. In this case, the origin of the crack is expected to occur on the concentrator of stresses - in the place of transition from the weld metal to the main, both from the front side of the seam, and from the side of the root. It was found that the difference between the deflections at the control points is slightly different depending on the type of welded joint, which allows us to conclude that it is advisable to choose the type of welded joints to increase its resistance under explosion loading. The results of the research can be used in the development of methods for assessing the resistance of samples of armored vehicles and the test of directions to increase the resistance of welded joints to explosive loading.
Keywords: armored vehicles, mine resistance, explosive loading, welded joints