On Mechanical Properties of New Railway Wheel Steels for Desert Environments and Sand Caused Wheel Damage Mechanisms
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JMEPEG (2019) 28:2946–2953 https://doi.org/10.1007/s11665-019-04049-4
On Mechanical Properties of New Railway Wheel Steels for Desert Environments and Sand Caused Wheel Damage Mechanisms Michela Faccoli, Candida Petrogalli, and Andrea Ghidini (Submitted April 17, 2018; in revised form November 29, 2018; published online April 22, 2019) Worn railway wheels after service in the desert were investigated by means of failure analysis, hardness measurements, tensile tests, fracture toughness tests and low-cycle fatigue (LCF) tests. The results complete both previous small-scale laboratory experiments and FEM simulations performed by the authors on widely used steels and new steel grades allowing to better understand the main damage mechanisms due to the sand. These new steel grades were developed for forged-rolled solid wheels in alternative to AAR Class B/C/D steel grades and were designed to ensure high resistance to wear and rolling contact fatigue in the presence of sand, debris or gravel on the rails. This paper covers the in-depth mechanical characterization of wheels made of the new steels. Hardness measurements, tensile tests, fracture toughness tests and LCF tests were carried out. The results are compared with AAR Class B/C/D steels showing an excellent combination of fracture toughness, cyclic yield strength and ductility. Keywords
cyclic yield strength, micro-alloyed steel grades, railway wheel steels, sand, wear
1. Introduction Historically, most of the transport demands have been developed in railway-friendly environments, according to the human logic of minimizing the efforts, largely avoiding sandy environments. However, recently, the need to extent the railway networks in desert environments emerged, mainly motivated by the following: •
an increased interest in connecting more people more rapidly in specific countries requires passing through some of the most inhospitable territory on the planet in terms of the combination of heat, cold, sand, sometimes snow, ice, etc.; • minerals, oil, fuel and the main raw materials are increasingly extracted in extreme environments; in these cases, the railway becomes an essential infrastructure for the very existence of such industries. Sand and extreme temperatures are the main stressing factors that the engineers have to deal with and form the basis of new topics for the research and development of rolling stock components and materials. From the point of view of the wheel, in addition to optimized profile design and maintenance procedures, there are two main reasons for the need to design a new class of materials: Michela Faccoli and Candida Petrogalli, Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123 Brescia, Italy; and Andrea Ghidini, Lucchini RS, Via G. Paglia 45, 24065 Lovere, BG, Italy. Contact e-mail: [email protected].
2946—Volume 28(5) May 2019
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to mitigate the very severe abrasive wear and ratcheting caused by sand entering the wheel–rail contact interface; • to couple the newly introduced high-
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