Rolling contact fatigue (RCF) can damage and reduce the life of the wheel and rail materials due to the degradation of surfaces in contact. The complex combination of RCF with corrosion can also ...contribute to the rapid surface degradation of wheel and rails materials. It is a serious problem when a railway system's environmental conditions can lead to severe corrosion.Even in some cases, severe corrosion caused by rainwater was observed in some open warehouse facilities. This work aims to investigate the influence that corrosion by artificial rainwater has on the generation and propagation of cracks caused by RCF. Twin disk tests were conducted on disk specimens manufactured from wheel and rail sections with corrosion and without corrosion zones on their contact surfaces. Corrosion on the wheel and rail disk specimens was accelerated by the potentiodynamic anodic polarization (PAP) process. The results show that PAP tests can promote pits and micro-cracks formation with different morphologies and sizes in both materials. These surface defects in rail material can grow and accelerate the cracks from the surface and down deep into the subsurface. Finally, pitting and corrosion were removed by the wear action in the wheel material. However, longer and deeper cracks were observed. Results showed that corrosion significantly influences RCF development on rail material.
•Evaluation of corrosion by artificial rainwater on wheel and rail materials.•Corrosion influences on the generation of cracks in rail material by RCF.•Development of a novel method to produce corrosion on twin disk samples.
Rail grinding as a maintenance strategy plays an important role in controlling rail defects due to rolling contact fatigue, noise reduction, and train stability by reshaping the rail. However, the ...effect of roughness topography of the rail surface after a grinding process has not been extensively studied in terms of friction coefficient and running-in behaviour.
In this work, rail disks specimens with different textures were characterized by different roughness parameters: Ra, Rq, Rt, Rp, Rv, Rz, Ssk, and Sku. All the textures were achieved by varying the amount of material removed and the work speed by using some emery stones with similar properties in rail grinders. The tests were performed by using a pin-on-disk tribometer in dry and grease-lubricated conditions. Pin specimens were manufactured from a wheel section with standard roughness.
The results showed that in dry conditions, rail disk specimens with rougher surface patterns yield a higher friction coefficient and higher wear rate. On the other hand, under lubricated conditions, a rough surface does not give a low static friction coefficient in some cases. Additionally, microstructural analyses were carried out on the cross-section of rail specimens and some images were taken from the existing wear scars identifying the wear mechanisms and finding in some textures the presence of a white etching layer (WEL) and a brown etching layer (BEL).
•A pin-on-disk rig was used to evaluate the running-in in different rail textures.•Rougher surfaces produced high traction coefficient.•A lubricated contact and rough surface does not guarantee a low friction coefficient.•White etching layer and in some cases a brown etching layer were revealed.
•Rail and wheel materials from different standards were tested.•Wear maps of different standards were displayed.•In this study, the sliding speed is the most influencing parameter.
Wheel and rail ...materials are exposed to a large number of factors that affect their wear-resistant performance such as, large contact pressures, sliding speeds, high temperatures, material degradation by natural and artificial contaminants, etc. This directly affects the maintenance operations, so, an accurate wear prediction is required. Wear maps are an important tool to predict and identify wear regimes that impact maintenance schedules and consequently cost reduction.
This work aimed to develop wear maps for a 115RE rail material and an ER8 wheel material, which are materials used in railways systems in Mexico, as well as identify the wear regimes and wear mechanisms replicating the wheel-rail interface conditions.
Metallographic analysis and hardness tests were carried out for both materials. Wear tests were carried out by using a pin-on-disk tribometer. The resulting wear maps showed that a catastrophic wear regime occurs at medium sliding speed and low contact pressure values for the wheel. On the other hand, for rail, catastrophic wear regime occurs at high sliding speed and low contact pressure values.
