Analyzing The Influence of Material property of Railway Wheel Steel under High Temperature on AALRT

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Date

2017-06

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Publisher

Addis Ababa University

Abstract

During the train emergency brake phenomenon, wheel locking takes place due to a high braking force applied on the wheel that exceeds the traction force between the wheel and rail. A wheel locking is a phenomenon in which the wheel stops rolling over the rail and exhibits skidding of a wheel on rail. This skidding motion of the wheel induces a rise in temperature on the wheel and rail surface. In some cases, this rise in temperature tends to change the microstructure of the wheel surface leading to the reduction of wheel strength and plastic deformation. Addis Ababa Light Rail Transit (AALRT) maintenance workshop executes the re-profile of the wheel when defects like plastic deformation, spall, and wear are encountered. In the meantime, continues re-profiling of rail wheels shortens the wheel life resulting in an increase in the maintenance cost of the company. This paper presents the mechanical property comparison of two railway wheel plates of steel with different chemical compositions. This study is carried out on UIC passenger train wheels. UIC puts a standard of wheel grade with different alloying percentages for different train applications. For this specific research two passenger wheel classes such as R6T and R8T are selected for comparison. By varying the alloying percentage of wheel steel, the variation in the mechanical and thermal property of the wheel is studied for the train emergency brake phenomenon which exhibits skidding for most of the cases. FEA software is used as a method of research to analyze the phenomenon. By increasing the alloying percentage of Silicon and Manganese the Thermal and Mechanical property of the wheel is maintained in large. Manganese increases hardness and wears resistance by increasing toughness and work hardening while Silicon plays the primary role in improving thermal stability and hightemperature strength and Chromium increases corrosion resistance. The study result complies that the specific elements alloying percentage can enhance the mechanical and thermal property by improving Solid-solution strengthening of the wheel and can reduce the plastic deformation that could be induced during emergency braking and wheel skidding phenomenon. The research outcome can help the company, AALRT to employ the proper wheel material in operation and reducing the maintenance and operational cost that could be incurred due to wheel re-profile.

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Keywords

Temperature Rise, Solid-solution strengthening, Silicon, Skidding, Re-profile

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