Heavy Haul Rails
Microalloyed steel rails can be an excellent choice for severe traffic conditions, they constitute a very attractive alternative to head-hardened rails for heavy transport
Heavy Rails (Head Hardened Rails)
Heavy Haul Rails: Technological properties
The poor performance results of carbon-manganese steel rails at the points in rail tracks characterised by extremely harsh service conditions –low radius curves, axle loads of over 30tonnes, etc.– have led to the development of new rails with improved Mechanical properties.
Head Hardened Rails
ArcelorMittal Americas (Steelton) and ArcelorMittal Europe – Long Products (Gijón) have integrated in the rolling mill a head hardening system (HH), based on controlled cooling by water jets. More than one million tonnes of top-quality head hardened rails have already been produced using this advanced technology.
Constructed originally in 1994, the present rail head-hardening system is a result of technological evolution. This cooling method, based on a meticulous design that has been verified mathematically and subjected to industrial tests in real production conditions, is an efficiency-proven application and is a clear example of the quality that ArcelorMittal brings to the steel industry.
This system uses controlled water jets to dissipate the heat in the steel in successive stages in order to obtain a fully pearlitic structure, perfectly suited to the metallurgical properties of these type of rails. The entry and exit temperatures determine the optimum range to ensure a fully pearlitic structure over the entire length of the rail.
Moreover, the latent heat generated during rolling allows reducing the energy consumed in the process. As it is integrated in the production line, the rail head-hardening system involves minimum handling requirements. It also brings about greater flexibility for future modifications to the production process, such as the production of longer rails.
ArcelorMittal has based on the experience producing 1.500.000 tons of HH rails in Steelton (Arema Standard) and HH rails in Gijón, up to 75 metres in any standard (Euronorm, Arema, UIC, Australian Standard etc.).
To sum up, this head-hardening process based on water-jet cooling and designed to optimise the properties of the rails, has resulted in an overall improvement in product performance, allowing the company to respond to the present and future challenges of the railway industry. The ability to efficiently obtain a deep hardened layer in each rail produced is a crucial factor when considering possible future increases in axle loads and in the tonnes transported on railway infrastructures, as it allows hardness values of over 380 on the Brinell scale to be achieved. Whether the rails are used for passenger or goods transport, safety is at all times ArcelorMittal's top priority, in addition to the manufacture of products of the highest quality with the longest possible service life.