Theoretical analysis of the effects of grain size and orientation on rail damage

• Published in: Engineering fracture mechanics 2022-01, Vol.259, p.108148, Article 108148
• Main Authors: Ma, Wentao, Li, Xiaotao, Wang, Qiangsheng, Jiang, Xiaoyu
• Format: Article
• Language: English
• Subjects: Crack initiation; Damage; Dislocation pileup; Finite element method; Grain boundaries; Grain orientation; Grain refinement; Grain size; Microcrack nucleation; Microcracks; Rail damage; Slip; Slippage; Stress concentration
• ISSN: 0013-7944; 1873-7315
• DOI: 10.1016/j.engfracmech.2021.108148

•A theoretical model for the grain effect on the damage of rail was established.•The grain orientation most likely to cause micro-cracks is about 30°.•The larger the grain size is, the easier it is to produce corrosion. The rail damage has been studied by many scholars based on the finite element method and experiments. However, the theoretical analysis of the microscopic mechanism of rail damage is studied hardly. In this work, the effects of grain size and grain orientation on the slip surface slippage under Hertz pressure are analyzed. The theoretical solution is given based on the distributed dislocation technique. The slip amount of the slip surface of the grains on the rail surface and the stress concentration at the grain boundary due to the dislocation pileup product are obtained. The results show that the amount of slip and stress concentration intensity become larger with grain size increasing. The amount of slip and stress concentration intensity increases first and then decreases as the grain orientation increases, reaching a maximum between 20° and 30°. The grain refinement and grain orientation control can reduce the corrosion of the rail surface and suppress the initiation of micro-cracks. This is helpful for the design of the rail materials.