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The purpose of the present study was to establish general regularities of theinfluence of local stress condition on the micromechanism of crack propagation and theplastic zone formation at the crack tip in materials with BCC-and FCC lattice structuresunder single loading (static, impact, high-speed impulse) conditions. As materials withBCC lattice we used carbon steels and also alloy steel; as materials with FCC lattice werealuminium deformed alloy and austenitic steels. Mechanical tests of samples were tested inthe temperature interval ranging from -196 to +150 0С. Fracture surfaces wereinvestigated by macro and micro fractographic methods. Quantity and also depth of plasticzones under a fracture surfaces were determined by X-ray method. As a criterion fordefinition of a local stress state at the crack tip the ratio of the maximum plastic zone depthunder the fracture surface to the sample thickness hmax/t was used. Schemes of plasticzones formation under plane deformation, plane stress, and in transient region from planedeformation to plane stress are proposed. It was shown the micro mechanism of the crackpropagation, and also the quantity and the size of plastic zones formed at the crack tip areindependent of the type of a crystalline lattice of the material and the kind of single loadingconditions, and are dictated by only the local stress state of a material at the crack tip.