Investigation on the rolling contact fatigue behaviours of different laser cladding materials on the damaged rail

2021 ◽  
pp. 1-33
Author(s):  
Tianxing Xie ◽  
Liang Zhou ◽  
Haohao Ding ◽  
Yi Zhu ◽  
Wenbin Yang ◽  
...  

Abstract Surface damages on rail became severe with the increasing in the axle load and speed. Laser cladding was used to repair the local damages on rail surfaces to ensure the service performance and prolong the life of rails. In the present study, five types of cladding materials (304, 314, 2Cr13, 316L and 434L) were clad at a small part (trapezoidal shape) of the rail disc to simulate the defected rail in the field. Vickers hardness tester, Optical microscopy (OM), scanning electron microscopy (SEM) and electron-dispersive X-ray spectroscopy (EDS) were employed to investigate the service properties of the repaired rail discs. Results indicated that all these five clad rail discs had lower wear rates than the un-clad rail disc. The wear rates decreased with the increasing in the initial hardness of the cladding coatings. Cracks with large angle mainly propagated along the bonding line at the front edge; while at the rear edge, the crack morphology was closely related to the hardness of clad coatings. 434L would induce the minimum wear loss and the modest rolling contact fatigue (RCF) of the repaired rail disc, which could be the potential cladding material for repairing the damaged rail.

Author(s):  
John W. Lucek

Rolling-contact fatigue test methods were used to measure the wear performance of several silicon nitride materials. Sintered, hot pressed and hot isostatically pressed materials exhibited wear rates ranging over three orders of magnitude. Hot isostatically pressed materials had the lowest wear rates. Despite the disparity in wear performance, all materials tested had useful rolling-contact fatigue lives compared to steel. Fatigue life estimates, failure modes, and rolling wear performance for theses ceramics are compared to M-50 steel. This work highlights the rapid contact stress reductions that occur due to conformal wear in rolling-contact fatigue testing. Candidate bearing materials with unacceptably high wear rates may exhibit useful fatigue lives. Rolling contact bearing materials must possess useful wear and fatigue resistance. Proper performance screening of candidate bearing materials must describe the failure mode, wear rate, and the fatigue life. Guidelines for fatigue testing methods are proposed.


Author(s):  
Gerald E. Arnold

Ball or roller bearings have much in common with a railway wheel running on a rail. Both have high Hertzian stresses and are subject to rolling contact fatigue. Silicone Nitride (Si3N4), a Technical Ceramic, has now firmly established itself in the engineering marketplace as part of a hybrid bearing, where the rolling elements are silicone nitride and the races are steel. The paper explores the possibility of a Silicon Nitride/steel wheel/rail combination and finds that, because Silicon Nitride has a higher Modulus of Elasticity, it is not suitable as a direct replacement on existing systems, because it would produce a smaller contact patch and greater contact stress. The low toughness of Silicon Nitride in comparison to steel could be an obstacle to its general railway use, however, it could made into a composite material in the same manner as Carbon Reinforced Silicon Carbide (C/SiC) is used in brake discs. There is a possibility that, under the right conditions, Silicon Nitride could return very low wear rates, because of its extreme hardness, and because it’s excellent resistance to rolling contact fatigue (noted in hybrid bearings). This could give a wheel high mileage, without the need to remove fatigued material by controlled wear or by turning. A promising future application for the material is a cable-hauled system, where the predicted lower adhesion between Silicon Nitride and a steel rail is not a problem and the wheels are not required to be conductive.


2011 ◽  
Vol 83 ◽  
pp. 191-196
Author(s):  
Justyna Rozwadowska ◽  
Katsuyuki Kida ◽  
Edson Costa Santos ◽  
Takashi Honda ◽  
Hitonobu Koike ◽  
...  

The influence of gas nitriding of commercial pure titanium and Ti-6Al-4V (Ti64) alloy by using a Q-sw laser on the wear loss during rolling contact fatigue is investigated. Despite very good biocompatibility, high strength to weight ratio and corrosion resistance, the tribological properties of titanium alloys are inferior to those of other metal alloys, such as steel. Fretting and wear related aspects become important issues when titanium alloys are used in rolling contact applications. Titanium bearings are employed in applications requiring high strength, light weight, and minimum maintenance (for example, aerospace and defense industries). In this work, a Q-sw laser was used to coat pure commercial titanium and Ti-6Al-4V bearings with TiN in a closed chamber in nitrogen atmosphere. The samples were tested under water by using a thrust-type rolling contact fatigue machine. The microstructure, morphology and crystallographic texture of the layers were observed by laser confocal microscope, scanning electron microscope and electron backscatter diffraction (EBSD). By optimizing the laser processing parameters, such as laser scanning speed, power and beam diameter, thin TiN coats of 1 to 3 mm were produced. The wear loss of the coated samples was at least ten times lower than that of the uncoated bearings.


Materials ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 4678
Author(s):  
Jiapeng Liu ◽  
Yingqi Li ◽  
Yinhua Zhang ◽  
Yue Hu ◽  
Lubing Shi ◽  
...  

This study aims to deeply understand the effect of contact stress and slip ratio on wear performances of bainitic rail steels. The results showed that the wear loss increased as the contact stress and slip ratio increased. Based on the surface damage morphology and microstructural analyses, it revealed that the rolling contact fatigue wear mechanism played a significant role under the low slip ratio, but the dominant wear mechanism transferred to the abrasive wear at the high slip ratio. Meanwhile, the bainitic steel specifically presented worse wear resistance under the abrasive wear mode. Compared with the influence of a slip ratio, the increase in contact stress led to severer plastic flows and contributed to the propagation of cracks. In addition, the contact stress and slip ratio had the opposite effect on the friction coefficient, that is, the friction coefficient of bainitic steels behaved the inverse proportion with the contact stress, but positive proportion with the slip ratio. At last, the increase in slip ratio had more significant effect on the reduction of retained austenite (RA) than the enlargement of contact stress due to the fact that the RA would probably be removed before the martensitic transformation occurred under the abrasive wear mechanism.


Author(s):  
T. Tajiri ◽  
N. Sakoda ◽  
S. Yamamoto ◽  
S. Watanabe

Abstract Two types of WC-12wt%Co powders, each manufactured by a different process, were thermally sprayed on a medium carbon steel by HVOF, and repeated load tests (rolling contact fatigue test and high cycles fatigue test) were carried out. The surface damages for the two types of coatings were investigated. It has been clear that the coating damages depend on the types of powders. It has been found that in rolling contact fatigue, there are the coatings, in which damage is characterized by delamination, and by a mixture of delamination and cracks. And it has also been found that in high cycles fatigue, there are the coatings, in which damage is characterized by net-like fatigue cracks, and by linear fatigue cracks.


2012 ◽  
Vol 457-458 ◽  
pp. 557-562 ◽  
Author(s):  
Koshiro Mizobe ◽  
Edson Costa Santos ◽  
Takashi Honda ◽  
Hitonobu Koike ◽  
Katsuyuki Kida ◽  
...  

In order to establish an optimal combination of materials used for polymer thrust bearings, two types of components (polyetheretherketone (PEEK) races - polytetrafluoroethylene (PTFE) retainer and PEEK races – PEEK retainer) were tested by rolling contact fatigue. Their wear properties were investigated and it was concluded that using a PTFE retainer, the wear loss was improved due to PTFE wear debris attaching to the wear track and acting as a lubricant.


2013 ◽  
Vol 418 ◽  
pp. 205-208 ◽  
Author(s):  
Xiao Chen Shi ◽  
Koshiro Mizobe ◽  
Yuji Kashima ◽  
Katsuyuki Kida

In the previous study on PPS race-PTFE retainer Hybrid polymer bearings, the relationship between thrust load, rotation speeds and wear loss under dry condition was investigated. It was found that the wear loss obviously changed under the thrust load ranging from 400N to 500N at the rotation speeds of 450rpm and 600rpm. The object of this study is to observe the friction coefficient at the rotation speeds ranging from 450rpm and 600N under thrust load of 400N. Rolling contact fatigue tests were performed and it was concluded that friction coefficient decreases with the rotation speeds.


2014 ◽  
Vol 563 ◽  
pp. 270-274 ◽  
Author(s):  
Xiao Chen Shi ◽  
Yuji Kashima ◽  
Katsuyuki Kida

There were two procedure about surface failure in rolling contact fatigue (RCF), wear and crack propagation. In our previous study, it was concluded that the main reason for PPS bearings failure in water was flaking due to surface crack propagation. The relationship between wear loss, rotation speed and thrust load of PPS bearings under RCF in water was investigated. In this study, the detailed surface profiles under heavy load were studied by using both LCM and two-dimensional measurement sensor to study the process of flaking failure.


2013 ◽  
Vol 683 ◽  
pp. 77-81 ◽  
Author(s):  
Shintaro Hazeyama ◽  
Shunsuke Oyama ◽  
Katsuyuki Kida ◽  
Takashi Honda ◽  
Koshiro Mizobe ◽  
...  

The polymer bearings have been widely used in recent years. In this study, ultra-high-molecular-weight-polyethylene (UHMWPE) is investigated. In order to investigate the relation between the lives, loads and rotation speeds, rolling contact fatigue tests were conducted. It was found that rotation speed related to the bearing life and wear loss.


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