Rail Steels

The development of rail steels has been determined by the interplay between the demanded characteristics and the currently available production technology. A rail is a product with a long life-cycle. The average service time is 15 years.

Even though the development cycles have become ever shorter starting in the last third of the twentieth century, the time between the introduction of a new rail steel into the market and its establishment still spans several year, since the railroads and public transport companies have to test its characteristics in the field through rail tests lasting several years.

The rail steels of voestalpine Schienen GmbH are produced according to the specifications of our customers. We have been ready for the European Standards for Rails EN 13674-1since 1998.

In addition, we take into account the special demands of our customers and supply them with rail steels defined by their applications. This also includes our extensive research and development program.

An important characteristic for new and advanced rail steels is their weldability. Newly developed rail steel would be completely useless for railroads if the continuous track could not be produced using regular welding techniques. This is why we conduct welding experiments early on during our R & D projects.

Damage of Railway Rails

The new European Standard for rails defines seven steel grades that cover a hardness spectrum from 200 to 400 BHN (Brinell Hardness Numbers). voestalpine Schienen produces even more steel grades, especially harder ones.

This leads to the question, which steel grade is the appropriate one for the actual conditions. The answer starts at the damage characteristics, which depends both on the loads applied and the steel grade used.

The influence of the load is described by the curve radius and axle load. In tight curves, wear is the dominant failure mode. The rails must be replaced frequently in highly stressed area, sometimes at annual intervals.

Starting at a radius of approximately 700 to 1000 m, rolling contact fatigue becomes the prevalent mode. The rail repeated loading fatigues the surface by the high local pressure combined with reasonable slip, so that cracks are formed. They appear typically close to the gauge corner and are named as Head-Checks. A worldwide study shows that the damage is quickest and worst at radii between 1500 and 3000 m.

For safety reasons, but also in order to increase service life, the fatigued surface area is ground or machined off. In wider curves and tangent, other rolling contact fatigue damage becomes more prominent, such as corrugations, Belgrospies and Squats. These defects shall also be removed by grinding.

The influence of the axle load and the total annual tonnage is evident: the larger they are, the earlier will the damage occur. Consequently, rail service is reduced.

The rail grades from voestalpine Schienen offer the optimum solution for all the different loading conditions. This is based on RAMS- and LCC-analyses, which put economical considerations into the centre of the material choice.

Rail Grade Choice

The new European Standard for rails defines seven steel grades that cover a hardness spectrum from 200 to 400 BHN (Brinell Hardness Numbers). voestalpine Schienen produces even more steel grades, especially harder ones.

This leads to the question, which steel grade is the appropriate one for the actual conditions. The answer starts at the damage characteristics, which depends both on the loads applied and the steel grade used.

voestalpine Schienen does approximately 20 track tests, worldwide and in parallel, together with infrastructure companies of the railroads.

New and advanced rail steels are tested at different conditions, and the actual “best solution” is taken as the sparring partner. The results show consistently that only high-quality products ensure the highest customer value added.

The starting point is based on RAMS- and LCC-analyses, which put economical considerations into the centre of the material choice.

The rail grades from voestalpine Schienen offer the optimum solution for all the different loading conditions. This result is shown graphically – in the same way like the damage characteristics – in the attachment.

Our wide range of steel grades makes us – again - One Step Ahead.

Information on the European Standard EN 13674-1

After more than ten years of work, the first part of the European Standard for rails was released by the end of 2003 from the European Comitee for Standardisation (Comité Européen de Normalisation – CEN). The part 1 applies to Vignole rails with a mass per metre of more than 46 kg/m and is the most recent international specification for rails. Parts two to four describe requirements for tongue rails, check rails and Vignole rails from 27 to 46 kg/m and are in the final stage of publication.

The EN 13674-1 specifies seven rail grades by their hardness, because hardness correlates directly with the wear properties of the particular steel grades. In contrast to the codex UIC 860-O from the International Union of Railways, which was the most common rail specification until now, the new standard is a performance based product standard. In order to fulfil safety requirements, two types of tests are applied:

Qualification tests Qualification tests must be done including fracture toughness and fatigue testing. Acceptance tests verify that each rail delivered complies with the specified requirements.

In contrast to UIC 860-O, non-destructive tests are specified in detail as part of the acceptance tests. All rails must be tested by ultra-sonic and eddy current on a 100 % level to ensure freedom from detrimental defects. As European Railroads move towards high-speed transportation, testing of surface flatness is an additional requirement so far not specified in other documents.

Additionally, where product properties are difficult or impractical to test, details of the production processes are specified. For example, a vacuum treatment of the liquid steel is mandatory for all steel grades to ensure that no shatter cracks will develop in the finished rails. Throughout, state-of-the-art production technology must be applied to meet all requirements.

The attachment summarizes on the most important differences between the EN and the UIC-codex. If you have additional questions on these specifications, please do not hesitate to make contact to the Technical Customer Service.