Wheel rail wear and surface cracks

This paper aims to investigate the influence of the asmanufactured steel microstructure and hardness along with the influence of wheel rail contact conditions on the observed damage such as rolling contact fatigue rcf cracks and plastic flow on the tread of railway wheels. Damage is considered to be either already present i. Furthermore, these defects may cause the failure of heavyhaul wheel rail or potential derailment. This can be used because a competition exists between wear and surface initiated rcf. This study presents the experimental results to explore the formation and damage mechanism of rolling contact fatigue rcf surface cracks of wheel rail materials under dry condition. Grinding shaves off the top surface of the rail, removing the cracks before they have a chance to propagate down into the web and thus preventing rail breaks. The text outlines the action to be taken when defects are found. Using high hardness high cleanliness rail steels gauge face and top of the rail friction management grinding to recommended rail profiles gauge corner relief, optimized high rail, low rail, and tangent track rail profiles grinding on preventive cycle chase the magic wear rate 37. When the train passes it, the top surface of the rail will be impacted by machining effect.

This leads to a redistribution of the contact stresses. Experimental characterization of wheelrail contact patch. These are influenced by the steel composition, wheel manufacturing process, and thermal and mechanical loading during operation. The aim of this work was to use ultrasound to nondestructively quantify the stress distribution in new, worn, and damaged wheelrail contacts. This effect includes the downward crush and the vertical wear. Abrasionwear is developed on a tread when it is in contact with a rail. Evaluation of surface defects of wheel and rail for korean. Wheel and rail wear understanding the effects of water.

At a high wear rate, rcf does not have the opportunity to develop further. Cracks very close to the surface are often at angles below 30, and this amplifies the vertical wear rate to give a large reduction in crack length with each wheel passage. The force on the high rail would be backwards and towards the inside of the curve. Evaluation of rail wear characteristics on heavy haul track. The susceptibility of railway wheels to wear and rolling contact fatigue damage is influenced by the properties of the wheel material. This typically results in general damage from wear to fatigue. Rolling contact fatigue, rcf, rail gauge corner cracking, wheel tread cracking. Steel rail is the fixed road of train running, so its safety is very important for train. Grinding and milling are essential for rail quality. Effects of profile wear on wheelrail contact conditions. The inservice properties therefore vary with depth below the surface and with position across the wheel tread. Wear of wheels occurs on the wheel tread and flange. Simple search advanced search research publications advanced search student.

According to the union pacific railroad wheel fracture database, 65% of railroad wheel failures are caused by shattered rims, a. As wheel or rail wear or surface damage takes place the contact patch size and shape will change. This can be minimized by correct alignment of the wheels, flange lubrication, material of wheel and rail being similar and equipment in proper mechanical condition. Vertical wear occurs on the running surface due to the wheelrail interaction and rail grinding patterns. Evaluation of rail wear characteristics on heavy haul. Contact mechanics and wear of rail wheel systems, cm2015, august 2015 edited by stuart grassie, roger lunden, anders ekberg, sebastian stichel, mats berg volumes 366367.

The relationship between vertical wear rate and crack length reduction depends on the angle of the crack below the rail surface. Because shelling cracks are oriented at 30 to 50 deg to the tread surface they are assumed to be caused by high shear stresses developed by rolling loads. Refining approaches to corrective and preventive rail grinding. Further, rail wear occurs at the top of the rail as head top wear, or at the side as gauge face wear or can be described to occur in the form of combined. Here is a little animation of how a rail can wear in service on a curve. To delay the fatigue by surface of the rail profile is required to adequately track surface, moving the contact wheel rail side. Effects of profile wear on wheelrail contact conditions and. Rcf damage is also referred to as surface fatigue, pitting, or flaking in the. Micro cracks develop at the most stressed portion of the rail surface.

Wheelrail wear and surface cracks request pdf researchgate. Abrasion wear is developed on a tread when it is in contact with a rail. On the formation and damage mechanism of rolling contact. It is generally believed that the shear stress under the rail surface caused by the contact stress is the main reason for the rail damage caused by the vertical force. Evaluation of rail wear characteristics on heavy haul track section using measurement data ihha 2015 conference 21 24 june 2015 perth, australia thermal and oxidative wear processes 4. Steel rail wear is a common but dangerous phenomenon that impacts the train track safety. When wheelrail damage in terms of wear and rcf can be predicted, measures can be taken to decrease it. Specimens of various railway wheel steels were coupled with specimens of the same rail steel, subjected to rolling and sliding wet contact with varying slidingrolling ratio. R8t wheel steel wear rates and regimes from 18 at low t. Abstractdamage mechanisms such as surface cracks and wear on a rail can. Plastic fl ow plastic fl ow, or mechanical deformation of the rail.

Draisine wpg d340 provides manual inspection of rail condition and can accurately measure the depth of surface flaws such as gage corner cracking or rolling contact fatigue. Wheelrail wear and surface damage caused by adhesion sanding. The influence of wheelrail contact conditions on the. The wheel disc showed evidence of surface cracking and material spallation caused by a fracture process. Effective predictions require computational tools and mathematical models that can accurately simulate actual material behavior and structural interactions like the contact between railway wheels and rails that. Effect of vanadium addition on the surface roughness and.

Closer examination of the wear surface of the wheel. With no sand in the contact, plastic deformation again. Wheel reprofiling owing to surface cracks andor unacceptable geometry, wheels are reprofiled. A thin streaks of martensite on the rail surface because of high creep rates from. Grinding wheel wear is an important measured factor of grinding in the manufacturing process of engineered parts and tools. Persson, subsurface crack networks and rcf surface cracks in pearlitic railway wheels, in proceedings of the 9th international conference on contact mechanics and wear of railwheel systems cm 12, chengdu, china, august 2012. A variety of damages happen on wheel rail system, which is mainly result from rail side wear fig. Wear contact mechanics and wear of rail wheel systems. Typically there are many closelyspaced cracks, only a few millimetres apart along the rail as shown below.

The wheelrail rollingsliding contact experiments were completed by using. Utrgv optimizing performance of railroad rail through. Figure 1 5 shows the cycle of crack growth into the rail surface. The issue of the rail and wheel contact is one of the most fundamental aspects in the railway system since inappropriate interactions create problems such as wear and a negative effect in the dynamic functioning of the train. The result of fatigue wear is severe plastic deformation. Cracks start at the rail surface and develop into the rail at an angle of about 20 to the running surface. These cracks are called rolling contact fatigue cracks rcf the growth rate of rail surface and subsurface fatigue cracks as shown in figures 1 and 2 is influenced by the level of contact stress between the wheel and the rail refer to section 6.

As is known, friction plays a vital role in wheel and rail wear 2,3,9,10 and investigations and applications have indicated that lubrication of the wheel rail contact is an effective method for. Effects of wheel materials on wear and fatigue damage. Simulation and measurement of wheel on rail fatigue and wear diva. Unlike the slow process of wear, fatigue causes cracks on contact areas of wheels, along with loss of material. Calculation of minimum crack size for growth under rcf between wheel and rail h. Grinding involves the removal process of material and modifying the surface of a workpiece to some desired finish which might. The surface crack of wheel rail is a significant problem affecting the safety and maintenance of railway. Figure 1 shows the cycle of crack growth into the rail surface. Nov 14, 2017 an ideal sample design for the rail and wheel profiles is demonstrated in fig. The growth rate of rail surface and subsurface fatigue cracks as shown in figures 1 and 2 is influenced by the level of contact stress between the wheel and the rail refer to section 6. Effect of wear on surface crack propagation in railwheel. For rcf damage, as the hardness of wheel steels and h w h r increased, both the wheel and rail surface damage alleviated, the fatigue cracks on wheel rollers decreased, and work hardening on rail. Wheel reprofiling and rail grinding strategies on wiener.

Wheelrail contact behaviors in the switch have been studied with a number of laboratory experiments and numerical procedures. This specification details the allowable limits for the inspection of all rail vehicle wheels for various tread and flange defects. This paper aims to investigate the influence of the asmanufactured steel microstructure and hardness along with the influence of wheelrail contact conditions on the observed damage such as rolling contact fatigue rcf cracks and plastic flow on the tread of railway wheels. The purpose of this investigation was to study the development of these two damage mechanisms on new and 3yearold rails in a commuter railway track over a period of 2 years. The transverse profile is not very indicative of ride stability and wear behavior. Some tests with a dry rollingsliding contact phase preceding wet contact were. When wheel rail damage in terms of wear and rcf can be predicted, measures can be taken to decrease it. Request pdf on mar 3, 2003, rickard nilsson and others published wheelrail wear and surface cracks find, read and cite all the research you need on. By now the focus of rail inspection was moved to surface defects induced by material fatigue. Fatigue of rails and wheels center for railway research. Effect of vanadium addition on the surface roughness and fatigue crack propagation in a railroad wheel using twin disc wear test p. For example, the combination of wheel and rail profiles, or the combination of vehicle and track, can be optimised to.

A study by the european commission suggests that rcf management is a costly exercise, with a figure of 300 million mentioned for managing the problem each year on the european railway. According to the union pacific railroad wheel fracture database, 65% of railroad wheel failures are caused by shattered rims, a form of subsurface initiated rollingcontact fatigue rcf. Wheel and rail wear understanding the effects of water and. Grinding and milling are essential for rail quality global. Effect of wear on surface crack propagation in railwheel wet. Wheel damage wear wear occurs from sliding between the wheel and rail, typically in the flange root area benign slow process. According to the union pacific railroad wheel fracture database, 65% of railroad wheel failures are caused by shattered rims, a form of sub surface initiated rollingcontact fatigue rcf. Experiments have proven that an increase in surface hardness improves its wear resistance8, 9. Thermal load effects on fatigue life of a cracked railway wheel.

The test discs were analyzed to verify the superficial conditions and wear mechanisms using sem scanning electron microscopy and roughness measurements. The tool can predict a surface crack length or crack depth. Rolling contact fatigue rcf defects such as squats or surface shellings. As is known, friction plays a vital role in wheel and rail wear 2,3,9,10 and investigations and applications have indicated that lubrication of the wheelrail contact is an effective method for. Repeated, alternating mechanical stresses lead to the formation and propagation of cracks under the stressed surface, which is thus destroyed. Initiated cracks are in this case worn off and will not be able to propagate deep beneath the surface of the rail or wheel. Too high wear is monitored by geometry measurements. Longer wear lives, higher speeds and larger loads have made fatigue the new main cause of railway wheel replacement and reengineering. Rail surface inspection systems international engineering. Jan 04, 2014 surface irregularities short, medium and long wavelength corrugations, surface defects and material flaws such as head checks, squats, cracks or crushed areas impact rail and wheel wear and vehicle track performance. Classical wheelrail wear has been extensively studied under dry. For instance, kassa and nielsen 5,6 used the commercial multibody system mbs software, gensys, to model the dynamic interaction between the railway vehicle and turnout. Surface irregularities short, medium and long wavelength corrugations, surface defects and material flaws such as head checks, squats, cracks or crushed.

Jan 08, 2014 cracks that propagate on the rail surface go deeper, faster in dirty, poor quality rail steels than in clean steels, kalousek told delegates at the first wheelrail mostly rail seminar sponsored by advanced rail management. This suggests a need for methods that can effectively predict the occurrence of rcf cracks. Damage mechanisms such as surface cracks and wear on a rail can reduce the service life of a railway track. The main research application is the wheelrail maintenance of korea highspeed train. Study on the performance of highspeed rail damage of four. In the present paper, a evaluation of surface defects of wheel and rail for korean highspeed railway. The first area is for the motion of straight lines and the conical coefficient, which is defined as the ratio of half the difference between left and right wheel rolling radius of an axis to movement of transverse axis, is often designed from 0. Calculation of minimum crack size for growth under rcf.

Effect of laser cladding on wear and damage behaviors of. Macroscopic examinations of radialtangential sections from shelled areas have indicated that shelling is caused by cracks that form at angles of 30 to 50 deg to the tread surface. Allowable speeds mentioned below are not to exceed the prevailing track speed limit. Jan 25, 2018 the interaction between wear and rolling contact fatigue in wet contact was investigated by means of experiments on a twodisk test bench. All these environmental factors influence wheelrail wear. Wear lateral wear occurs primarily on the gauge face due to highwheel fl ange force rail is located on the high side of a curve. The tester is composed of two rollers served as a wheel roller lower specimen and a rail roller upper specimen. The total weight of all the trains is the total load. Simulation and measurement of wheel on rail fatigue and wear.

The tribofatigue damage transition and mapping for wheel. In this research, we analyze one of the most important phenomenon. This is not always disadvantageous, since natural wear is able to remove material containing very small cracks before these become dangerous. Two frequent rail surface defects caused by the wheel rail contact are rolling contact fatigue cracks in the gauge corner socalled head check and squats. Nowadays, the railway is considered as a means of fast, aggregate and secure transportation.

The wheelrail contact is an open system contact, which is subjected to various environmental conditions, such as temperature, humidity, water, and even leaves. During the process of crack growth the contact stress at the rail wheel interface is almost always driving wear of the surfaces as well as initiating and possibly propagating cracks. How to ensure train track security and keep it stay away from steel rail wear. Fatigue wear prevention must be a consideration in planning and design phases. Mar 21, 2006 as wheel or rail wear or surface damage takes place the contact patch size and shape will change. Development of gcc beyond the first few millimetres into the rail requires the presence of a liquid, in particular water. Due to the solidity of the contact surfaces of the rail and wheel, small.