Evaluation of dynamic fracture toughness parameters of locomotive axle steel by instrumented Charpy impact test

• Published in: Fatigue & fracture of engineering materials & structures Vol. 40; no. 4; pp. 512 - 522
• Main Authors: Sorochak, A. P., Maruschak, P. O., Yasniy, O. P., Vuherer, T., Panin, S. V.
• Format: Journal Article
• Language: English
• Published: Oxford Wiley Subscription Services, Inc 01.04.2017
• Subjects: Axles; Brittle fracture; Defects; fracture; Fracture mechanics; Fracture toughness; impact loading; Impact tests; locomotive axle; Parameters; Plasticity; shear lips; stages; Steel; Stiffness; stress concentrator; Structural steels
• ISSN: 8756-758X; 1460-2695
• DOI: 10.1111/ffe.12510

The analysis of the energy of fracture of specimens from steel OSL, which is widely used for the manufacture of railway axles under shock loading, is performed. The nature and quantitative parameters of the typical stages of the processes of plastic and brittle fracture, depending on the test temperature and stiffness of the stress state at the tip of the crack‐like defect, are established. It is shown that impact loading at 20 °C leads to the formation of the local zone of plasticity and ductile–brittle fracture of the material. An increased stiffness of the stress state at the tip of the defect at −40 °C causes brittle fracture. An approach is developed, which is based on using the size of shear lips as a quantitative parameter of fracture under normal and low temperatures, similar in its physical essence to deformation approaches of nonlinear fracture mechanics. Based on this approach and the quantitative analysis of specimen fracture zones, the physical and mechanical scheme of specimen fracture is proposed in the presence of localized plasticity and in its absence near the tip of the concentrator.