Research into the relationship between the structure and coercive force of spring steels for the development of a method for non-destructive testing of elastic suspension elements in electric locomotives
DOI:
https://doi.org/10.33216/1998-7927-2025-296-10-29-32Keywords:
springs, residual deformation, coercive force, hardness, troostiteAbstract
The research is devoted to studying the relationship between the following characteristics of structural steels used to manufacture suspension springs for freight electric locomotives: hardness, residual deformation and coercive force. The results of testing the elastic elements of electric locomotive suspension for residual deformation under static load have shown that their optimal structure is troostite, which is formed during medium tempering. It is the troostite structure formed during medium tempering of pre-hardened steel that allows obtaining the optimal ratio of elastic characteristics of electric locomotive suspension elastic elements during their operation under alternating loads. The results of experimental studies prove that standard methods of measuring coercive force can be used to control and evaluate the final structure and mechanical properties of the elastic elements of electric locomotive suspension. Given that the quality control of springs for hardness and residual deformation is almost 100%, this allows for a significant reduction in the time spent on control operations. The coercive force of spring steels depends solely on their structural state. If there is a decarburised layer on the surface of the springs, it has practically no effect on the coercive force if the thickness of this layer does not exceed the values established by the applicable regulatory and technical documents. Thus, a slight deviation of the coercive force of the elastic elements of electric locomotive suspension from the optimal values of coercive force established in this study may indicate an excessive thickness of the decarburised layer. The presence of surface cracks on the elastic elements of electric locomotive suspension has no effect on the coercive force. In this context, the nature and mechanisms of crack formation are also irrelevant. The results of the study show that the optimal coercive force of the elastic elements of electric locomotive suspension, which corresponds to their optimal hardness, can only be determined on the basis of preliminary tests of the elastic elements of electric locomotive suspension for residual deformation. The latter parameter is the main operational characteristic of springs, which can be used to determine their suitability for use as elastic elements in electric locomotive suspension systems. The results of the research established a relationship between the structure and residual deformation under static load of elastic elements in electric locomotive suspension systems.
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