The recent trend is toward heavier axle load and higher speed is railway transportation. Such being the situation, development of a higher quality rail is being actively pursued. Also large production capacity of heat-treating rails is necessary. In-line heat-treating facility is most suitable for large volume production. At the time of construction of the in-line heat-treating facility, we studied the basic characteristics required for high quality rail. And to get the quality, we researched the cooling method and manufacturing process. NKK's new head hardened rail (NHH rail) and low alloy head hardened rail (AHH rail) have been in service in heavy haul railways throughout the world. NHH rail and AHH rail have characteristics of good was resistance for long life with fine pearlite structure at the rail head. An AHH-rail maintains good hardness after flash-butt welding, with controlled chemical compositions. But on the other hand, productivity of NHH rail and AHH rail is low because of off-line heat-treating process. Now we have had a new in-line heat-treating facility at a rail mill in Fukuyama works in last year. By this facility we produce a new type of heat-treated rails, called NKKs thicker head hardened rails (NKK-THH rail).
In-line heat-treater THH-rails
In-line-Wärmebehandlung von Schienenstählen
1993
6 Seiten, 12 Bilder, 3 Tabellen, 5 Quellen
Conference paper
English
Eisenbahnschiene , unlegierter Stahl , Wärmebehandlung (Materialbearbeitung) , niedriglegierter Stahl , Wärmebehandlungsofen , Härten (Metall) , kontinuierlicher Vorgang , Verschleißwiderstand , Perlit (eutektoid) , Werkstoffgefüge , Stumpfschweißen (Metall) , Härte , Japan , kontinuierliches Verfahren , Mikrogefüge , Abbrennstumpfschweißen
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