Abstract
The main task for a ballast bed is to transmit the sleeper pressure in a form of stress cone to the subsoil, provide proper drainage and resist the sleeper displacement. Poorly maintained ballast could severely limit the maximum speed capacity and create further problems with the structural integrity, possibly leading to a complete failure of a given rail line. To prevent the unwanted corollaries, the ballast bed has to be periodically cleaned with an appropriate machinery. In this paper the authors investigated the effect of the chemical composition on the physical properties of the ballast excavating chains made of high-manganese steels. The authors focused on the wear mechanism, work hardening ability and hardness in the cross-sections areas. A microstructure analysis was performed as well, and observations revealed divergent morphology of precipitations at the grain boundaries, which influenced the size of austenite grains. The deformation twins formed as a result of operation were noticed in the samples. Research has shown that less carbon and chromium reduces the hardness of cast steel, and it specifically affects the ability to strain hardening. The authors explained the role of adjustments in chemical composition in the operational properties of high-manganese cast steels. It has been shown in the paper that different chemical compositions affect the properties of the alloys, and this causes different types of wear. The high content of chromium increases the hardness of materials before and after plastic deformation hardening, which in the conditions of selector chains results in greater dimensional stability during wear of holes in pin joints and will be more susceptible to abrasive wear in the presence of dusts from the ballast than creep.
Highlights
The general obstacle in stability of any system is the continuous necessity to put much effort in maintenance, which happens to use the resources that could be otherwise used for development [1,2,3]
The findings presented above match with some of the study results of Lindroos et al [39], despite that in their research only one type of Mangalloy was examined
Presented research utilizes an innovative approach for a quantitative estimation of the surface work-hardenability in high-manganese cast steels by consecutive application of Brinell and Rockwell hardness testers in the same spot
Summary
The general obstacle in stability of any system is the continuous necessity to put much effort in maintenance, which happens to use the resources that could be otherwise used for development [1,2,3]. In the case of railway system, the maintenance of the infrastructure is a complex subject, responsible for safety of passengers and goods, and for efficiency of the whole logistic system [6,7]. This maintenance necessity is connected with every sub-part of the rail track: rail profiles, fastenings, sleepers and the ballast bed (Figure 1)—each having its own methodology of wear evaluation [7,8]. While keeping the rail track in a good shape is obvious to any observer, he or she may omit the importance of bedding conservation
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