Head-hardened rails enable trains to travel faster, at greater frequencies and with heavier cargo
As a transport lifeline, railways have to continually innovate. And steel is playing a pivotal role in helping networks carry people and goods faster and further.
ArcelorMittal Steelton is one of only three rail producers in North America, and was the first plant built specifically for the production of steel rails in the US, having been established in 1867.
Steelton has produced more than 1.5 million tonnes of head-hardened steel rails over the past 15 years.
Head-hardened rails can withstand increased wear from trains travelling faster, at greater frequencies and with heavier cargo. With hardness levels of more than 380 on the Brinell hardness scale, these rails have a longer lifespan and are safer.
These rails are used for tracks that carry heavy loads, for acceleration and deceleration sections of railway lines, for railway switches, crossings or expansion joints, and in small-radius curves.
What makes head-hardened rails different? First, higher resistance to wear is made possible with greater hardness of rail head, which is the upper part of a rail and supports the wheels of railroad cars. Second, by making longer rails, fewer joints are needed on the track.
Innovation in production process
These strong metallurgical properties of head-hardened rails are achieved through a unique production system. At Steelton, high-temperature steel from the rolling mill is cooled with controlled water jets, creating a structure ideally suited for high-strength rails.
This process for making longer, harder rails, will also be used for the railway network in Europe. A production line for head-hardened rails has been built at the rail mill of ArcelorMittal Asturias, Spain. Engineers from Steelton worked closely with the project team at the Gijón factory, and their expertise helped start production at an industrial level three months ahead of schedule, in November 2011.
The production system at Gijón is state of the art, making it possible for each rail to be up to 75m long.
“The long length of the rails is achieved with a new process and equipment, all of which make the Gijón project unique in Europe, both within and outside the company.”
Juan Antonio González Rico, head of the project
The production line at Gijón also uses a proven technology for the heat treatment of the rail head, which was developed and improved by Steelton and ArcelorMittal’s global research and development centre in Asturias, in collaboration with other research centres and universities, including the Center for Research in Metallurgy (CRM), the Materials Technological Institute (ITMA), and the Universities of Oviedo and Bucharest.