The Preheating Temperature Effects on the Residual Stresses of the Welded Rails Sections
Aluminothermy welding is one of the most common processes in the railway industry. Nevertheless, this process leaves, locally, significant residual stresses that may, eventually, be responsible of the potential damaging process. These residual stresses de
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Abstract Aluminothermy welding is one of the most common processes in the railway industry. Nevertheless, this process leaves, locally, significant residual stresses that may, eventually, be responsible of the potential damaging process. These residual stresses depend highly of the preheating temperature. Failure of an efficient application of this preheating temperature is often pinpointed with the occurrence of significant internal defects and sometimes exposed cracks. In this study, we intend to highlight the correlation that bound the preheating temperature and the residual stress, and discuss the potential damaging risks. Keywords Simulation stresses
Aluminothermy Temperature Preheating Residual
1 Introduction As known, rail junctions are connected by through thermite welding. Both rail ends are joined by a metal casting [1, 2]. This procedure is the main practice of the rail system in Morocco. The quality of this joining depends on the conditions of the realization generally not observed [3, 4]. However, this process generates significant residual stresses as seen on every permanent joining process [5, 6]. Adding these constraints to the cyclic external stresses, affecting the rails behavior [7–9]. Depending on their levels, these constraints may decrease the resistance of rail [10, 11]. Consequently, it is important to identify the origin of these constraints and the involved parameters. Most studies of the rail termite welds stress the analysis of fatigue cracks spread. However, the welding process parameters are generally overlooked, although it O. Bouazaoui A. Chouaf (&) Laboratory of Control and Mechanical Characterization of Materials and of Structures, National School of Electrical and Mechanical, Hassan II University, El Jadida Road, Oasis Casablanca, Morocco e-mail: [email protected] © Springer International Publishing Switzerland 2017 T. Boukharouba et al. (eds.), Applied Mechanics, Behavior of Materials, and Engineering Systems, Lecture Notes in Mechanical Engineering, DOI 10.1007/978-3-319-41468-3_13
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raises significant issues being addressed, for example by Skattebol [6, 11]. That acts on the rail behavior and reduce its resistance to cyclic external loading. At the end, therefore ensuring the safety of railway traffic, it seems necessary to determine these constraints and to highlight the effect of preheating temperature on their severity and take the necessary precautions. So in order to ensure the safety of railway traffic, it seems necessary to highlight these constraints and to stress out the effect of preheating temperature on their seriousness, and take the necessary precautions.
2 Modelling We have conducted a numerical simulation of the finite element method using the calculation code (ABAQUS) to describe the thermo-mechanical stresses evolution on the rails welded area. For this, we have considered a thermal loading. In this loading, we have given the temperature difference between the final state (Tf ¼ 20 C), the molten zone TMZ ¼ 600
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