Abstract
The paper considers negative changes of mechanical properties and cyclic fracture toughness of 20L class steel that is used for cast solebars and bolsters of bogies for freight cars and also for petrochemical equipment for 25–41 years of operation. The main reason of embrittlement of steel is a high content of manganese and silicon as a result of long-term cyclic operating time. The paper presents an experimental kinetic curve of change of cyclic fracture toughness depending on life of a bogie bolster of a freight car. The paper also shows model curves of degradation of an elasticity coefficient and fracture deformation depending on relative operating time in cycles. On the basis of established effects the author has formulated an integrated theory on degradation of mechanical properties of 20L cast steel after the cyclic operating time for two chapters of mechanics — mechanics for rigid body and fracture mechanics. The reliability of the theory is confirmed by experimental tests.
Published Version
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