THE IMPACT OF STEEL QUALITY ON THE FATIGUE STRENGTH OF WROUGHT WHEELS

The goal of the study is to consider the impact of the structure and nonmetallic inclusions on the initiation and development of corrosion damage, as well as to analyze the mechanical properties of wheel steel in various environmental conditions to develop the effective methods providing increase in the corrosion resistance and protection of railway wheels against corrosion damage. Ensuring of the high quality of the railway wheels, their reliability and durability requires a comprehensive analysis of the mechanisms of the structure formation and changes in properties of wheel materials, not only at the stage of their manufacturing, but also during their storage, transportation and operation under various conditions. This requires a systematic approach to the study of the properties of wheel steel along with a complex of environmental parameters. The solid-rolled railway wheel has a complex design and the microstructure of the steel differs for various elements, in addition to the microstructural changes attributed to in-service wear of the rolling surface, stresses in different elements, and environmental impact. The composition and structure of wheel steel are one of the important factors determining the corrosion processes occurring in the surface layers of railway wheels. To describe those processes we carried out metallographic study of the material of solid-rolled wheels and tests for corrosion cracking and low cycle fatigue. Analysis of the mechanisms of formation and changes in the structure and properties of the material of solid-rolled wheels during their storage, transportation and operation under different conditions is carried out for the first time. New aspects of the impact of nonmetallic inclusions on the formation of corrosion damage are considered. The coefficients of environmental impact which present the degree of influence of nonmetallic inclusions on the low-cycle durability of steel are determined for the first time. Test for the susceptibility of wheel steel to stress-corrosion cracking were carried out.

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