FOUNDRY MATERIAL FOR ROLLERS OF UNDEFINED TYPE WITH SHIRT AND PROCEDURE FOR MANUFACTURING.

摘要

Procedure for the manufacture and preparation of an alloy casting material for the working part of rollers of indefinite type, which contains the elements carbon, silicon, manganese, chromium, nickel, molybdenum, vanadium, possibly other elements of group 5 of the periodic system , aluminum, residual iron, accidental elements and impurities due to manufacturing, according to which A. a casting is established that has the following chemical composition, in% by weight: as well as residual iron and impurities, and B. vanadium is added, which dissolves therein, in a weight percentage of more than 0.5 to a maximum of 5.9, said vanadium content being able to be partially substituted by a content of other elements of group 5 of the periodic system, that is, niobium and tantalum, in a dimension of less than 0.6% by weight, and C. the composition of the laundry is adjusted, from the point of view of the alloy, determining the concentrations of carbon and silicon io in the presence of nickel, as well as the sum of the actions of the carbide generating elements, such that during its solidification a microstructure is formed, containing 1.0 to 3.0% by volume of graphite with the condition determining that there are more than 20, but less than 100 graphite particles per mm2 of observation surface on a metallographic polished surface and that the rest is substantially formed by martensite, 8 to 35% by volume of eutectic carbides and at least 1% by volume of finely dispersed vanadium carbides, and then, D. the melt is poured into a mold, preferably in a centrifugal cast iron shell, and allowed to solidify forming a body, preferably a working body of a roller, and, eventually, said casting body is formed, for example, as a combined casting roller, said body or said roller, which has been formed in this way, E. subjected to a heat treatment consisting, at least, of a heating at treatment temperature, a maintenance at said temperature and a cooling at room temperature.