Abstract
Welded joints have traditionally been a weak point in a design of continuous welded rail (CWR) tracks. Grinding can be used as a resource-saving technology. The purpose of this paper is to study the grinding technology for welded rail joints at different temperatures. The temperature in the weld grinding zone varied from 560 to 850 °С. Using methods of microstructural analysis and hardness measurement, it has been established that different temperature conditions for weld grinding lead to the creation of non-identical mechanical properties of metal and a surface structure of the rail head in the weld zone. As a result of the research, an optimum temperature range, 600 ... 560 °C, was determined. This range is recommended for grinding aluminothermic welded joints.
Highlights
At present, contact or aluminothermic welding methods are used to weld rails throughout the railway network [1, 2]
The strength of aluminothermic rail welds is lower than that of joints welded by contact welding [3]
One of ways to increase the strength of welded rail joints proposed in [4, 5] is to modify a thermite powder by titanium or zirconium
Summary
Contact or aluminothermic welding methods are used to weld rails throughout the railway network [1, 2]. Scientists of the Japanese Railway Technical Research Institute have proven that defects in welds and strength reduction are caused by incorrect installation of casting molds on rails prior to aluminothermic welding. They studied effects of the geometry of casting mold installation on filling a welding mold with liquid metal [6]. This paper proposes a method for hardening welded rail joints by hot grinding. The regulatory documents that describe the welding process by aluminothermic method [10] do not specify the temperatures at which hot grinding should be carried out. In the context of the current trend towards increasing the length of continuous welded rail tracks all over the world, this study, aimed at improving the operational stability of welded joints, is relevant
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