Research shows structural and chemical heterogeneity affects fracture toughness in railway wheels, suggesting material optimization may enhance performance.
The effect of structural and chemical heterogeneity of steel on the fracture toughness of a railway wheel was studied. It is shown that the formation of a heterogeneous microstructure is associated with the presence of dendritic liquation of elements in the metal structure. The metal of the samples, which is characterized by a lower value of fracture toughness, in addition to sorbitol-like pearlite with excess ferrite on the boundaries of the “former” austenite grains, has acicular morphology (bainite structures) of the structure. They are concentrated, mainly, in microvolumes enriched with manganese. In the samples with high values of fracture toughness the acicular structure was not observed. The chemical composition of the structural component samples was studied. It was found that areas with an acicular structure had an increased content of manganese compared to pearlite and ferrite located nearby. It is proved that liquation phenomena in the metal of the railway wheel rim, characterized by an increased content of alloying elements (carbon, silicon and manganese), are the cause of the formation of a heterogeneous microstructure of the metal after thermal hardening of the products, and the presence of areas with bainite structures negatively affects the fracture toughness of the metal of the railway wheel rim.
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Babachenko et al. (2024) studied this question.
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