Our rod anchors are made of top-grade, ductile EN-GJS-400-18-LT spheroidal graphite cast iron, with guaranteed notched impact toughness at -20°C. In terms of safety, this material offers numerous advantages over cast steel, which is prone to cracking due to its extremely high shrinkage. One of these is the expansion resulting from the formation of graphite spheroids in the ferritic matrix, which offsets the – in any case inherently low – shrinkage for this material and thereby prevents cracking.
Grade EN-GJS-400-18LT also boasts a minimum elongation at break of 18% and, on account of this high ductility, is also suitable for low-temperature applications. The permissible stresses for spheroidal graphite cast iron were determined by Dr. Betschart as early as 1980 in his thesis entitled “Untersuchungen neuerer metallischer Gusswerkstoffe für Baukonstruktionen” (“Investigation into modern cast metals for structures”), Stuttgart University – see “Basic knowledge” – “Bibliography”. His comprehensive research was conducted at Daimler-Benz AG in Stuttgart and at various distinguished foundries.
Spheroidal graphite cast iron is used to produce safety components for cable cars and ski lifts in high Alpine regions, for example, but also for heavy-duty chassis elements, crankshafts and wheel hubs of motor vehicles. BESISTA® has not recorded a single failure during the 25 years in which it has used the material for its rod anchors.
Due to its many benefits, the “modern form” of cast iron with spheroidal graphite has largely superseded cast steel. Indeed, the use of cast steel is now largely confined to clearly defined applications where weldability is required, e.g. welded assemblies or cable structures.
BESISTA® collaborates only with foundries that implement a strictly controlled, state-of-the-art process for the manufacture of rod anchors. A key constituent of the starting material is the high-grade alloy Sorelmetal® from Canada.