Development of High-Strength Alloyed Rail Steels Suitable for Heavy Duty Applications

Abstract

In the first section of the paper, a summary will be given of the various defects which can develop in rails subjected to high axle loads, such as corrugations, gross plastic deformation and abrasive wear of the railhead, checking and spalling, shelling and transverse defects. The second section of the paper will cover in detail the developmental work on high-strength alloyed rail steels conducted at Broken Hill Proprietary Co. Ltd. Melbourne Research Laboratories. An essential part of the work has been the development of techniques for laboratory simulation of industrial rail production and on-site welding procedures. Various other material properties have also been used in assessing material types. The major emphasis of the work has been directed to optimizing the mechanical properties of three rail steel types, namely: chromium-columbium-vanadium steels, chromium-vanadium steels, and chromium-molybdenum steels. Fully pearlitic steels exhibiting yield strengths greater than 900 MPa have been developed without adversely influencing other mechanical properties. The steels can be flash butt welded using modified procedures.

Investigation of the influence of rail hardness on the wear of rail and wheel materials under dry conditions (ICRI wear mapping project)

“…A British Rail full-scale test program, however, showed that wheel wear reduced with rail hardness increases [6]. This lack of a consistent pattern was backed up by research carried out in other laboratories (for example [7] and [8]). However, while no clear trend in wheel wear emerged, it was noted that rail hardness increases almost always led to a drop in overall system wear.…”

“…In the work reviewed, few potential mechanisms were proposed to explain the observations made, except for in the work by Marich & Curcio [8]: it was hypothesized that a reduction in wear of the rail would reduce the amount of wear debris within the interface which may lead to less abrasive wear on the wheel. This highlights another deficiency in almost all wheel/rail interface studies: wear debris analysis is rarely included.…”

Influence of Microstructure on Mechanical Properties of Bainitic Steels in Railway Applications

“…Most rails are made of steels with pearlitic microstructure, which is an alternating lamellar structure of ferrite and cementite. The mechanical behavior of different pearlitic rail steels in relation with their microstructure has been widely investigated in the literature [7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The pearlitic rail steel grades offer appreciable wear resistance due to their hardness values ranging from 260 to 400 HB [21].…”

“…The hardness values can be further increased by increasing the carbon content in pearlitic grades, which results in higher wear resistance in the steel microstructure [7], but this comes with the cost of reducing fracture toughness and producing poor weldability. The wear resistance of the pearlite steels can be further improved by refining the microstructure [13,14] using accelerated cooling or by using high concentrations of Mn, Cr, V, Si and Mo in the alloy composition [15][16][17]19]. Increased concentrations of these alloying elements shift the continuous cooling transformation curve towards longer times (decrease the critical quench rate), and fine pearlitic microstructure can be achieved with low cooling rates [20].…”

Wear Enhancement of Wheel-Rail Interaction by Ultrasonic Nanocrystalline Surface Modification Technique

“…There have been many studies on rail damage and maintenance in order to secure safety on the railway [ 5 , 6 ]. The wear resistance of the rail-wheel interface was studied earlier using a tin disk testing method, which is a simple way to evaluate the wear characteristics of materials [ 7 ]. It has been also reported earlier that the wear rate of the rail-wheel interface can be reduced with an increase in hardness [ 8 ].…”