Silicon nitride tools for hot rolling of high-alloyed steel and superalloy wires

摘要

For hot rolling wires of high-alloyed steels or superalloys tools are nowadays made of cemented carbides. In service they suffer from roughening of the surfaces and severe wear, which deteriorates the surface quality of the wires and restricts the lifetime of the tool. Due to their high hardness and good high-temperature properties, improvements in tool behaviour can be expected by the use of silicon nitride tools. Experiments with several types of rollers were performed in commercial rolling mills. At modest and medium severe loaded positions (e.g. in the case of guidance rolls) silicon nitride rolls show superior performance to conventional steel or cemented carbide rolls. At the most severe loaded positions silicon nitride rolls were also superior to conventional rolls when rolling high strength steel wires. But for rolling superalloy wires, cracks, which limited further applications of the rolls, appeared in the roll surface profile (calibre).