Rails are a steel product of a high complexity, both as regards its technical design and manufacturing process, and the ever-greater demands made on them in their service conditions. Shorter train intervals, higher speeds, greater axle loads, shorter maintenance times, escalating demands on availability – all that requires of the rails all they can muster.
The new demands are complex and frequently even divergent. It’s simply impossible to meet these demands suitably with the traditional rail steel qualities, which have been in use for more than 60 years now. What is required at present is maximum durability against wear and material fatigue due to stresses unknown up to now and caused by escalating train frequencies, speeds and axle loads. And all this at the lowes possible maintenance expenditures and longest possible life span.
The hardest rails with an extreme resistance to abrasive wear and the lengthiest possible maintenance-free life spans are just good enough to master these ultra heavy haul demands.
In Europe, the further development of rail freight traffic is, within the framework of the available options, of eminent importance. Voestalpine is a supplier for such users, with its head-hardened alloyed rail steel grades 350LHT or 370 LHT or the hypereutectoid, head-hardened rail steel grade 400UHC.
The avoidance of as many welding joints as possible in modern railways is a prerequisite not only for economic reasons, but also from a technical standpoint with respect to travelling comfort. Wherever there is a weld, the smoothness of the wheel-rail system is interrupted and there is an increase in wear of the materials. The faster the trains are and the heavier the weight per axle becomes, the more this effect becomes noticeable.
Voestalpine come with the longest weld-free rails in the world. In view of the development perspectives of railways, the market share of ultra-long rails will further continue to grow.
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 30 tonnes, etc.– have led ArcelorMittal Steel to the development of new rails with improved mechanical properties.
Traditionally, alloyed steels, with Brinell hardness values of over 320 HBW and a tensile strength of around 1,100 MPa, were used for this purpose. These properties were achieved by using high levels of manganese, chromium and molybdenum, alloys that reduce the pearlite interlamellar spacing.
Microalloyed steel rails can be an excellent choice for severe traffic conditions. With equivalent properties but lower costs for the railway companies, they constitute a very attractive alternative to head-hardened rails for heavy transport.
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