Bilyy O. Assessment of cracks nucleation at stress concentrators under cyclic loading of steels in corrosive environments

The fracture processes of the specimens with structural steels that contain the stress concentrators of different types and subjected joint action of cyclic loading and corrosive environments. To assess the nucleation and propagation of the crack-like defects at stress concentrators of different types (semicircular notch, welded joint, corrosion pit) on the base of developed model schemes, which take into account the specific of local action of deformed metal and corrosive environment. The methods of fracture mechanics of structural metals and alloys under presence of corrosive environments. The model scheme of interaction of environment with deformed metal at semicircular stress concentrator has been proposed and criterion of corrosion fatigue macrocrack nucleation is developed. The corrosion fatigue peculiarities of the tee joints with asymmetric weld as specific type of technological stress concentrators were determined under conditions of electrochemical corrosion. The basic diagrams of corrosion fatigue crack growth resistance of the joint “anticorrosive fusing - hull steel” were constructed. The method for assessment of safe exploitation period has been proposed for damaged tubular elements of superheaters of heat power plant units. Field of application – serviceability and durability of industrial structures, in particular heat power-engineering equipment.