GB832666A - Improved ferrous metal and methods of producing the same - Google Patents

Abstract

A ferrous metal, having in the "as-cast" condition a microstructure with carbon in the form of compacted graphite, contains C 1-2.5%, Si 1.5-3.2%, B 0.001-0.05%, the composition of the ferrous metal being such that the metal would solidify as a white cast iron in the absence of boron. The metal may also contain one or more other elements such as Cr, Ni, Cu, P, Ti, Al, V, Mo, Sn in amounts normally used in cast irons. One or both of Te up to 0.01 and Bi up to 0.02% may also be present, these two elements, if used together not exceeding 0.02% in total. The metal may also contain Mn up to 1.15% and S up to 0.5%. The metal may be produced by melting together steel and white cast iron in quantities such as to give the required C and Si contents, tapping the melt into a ladle at a temperature in the range 2700 DEG F-3000 DEG F, inoculating with B and either Te or Bi or both and pouring at a temperature in the range 2600 DEG F-2750 DEG F into a mould. B may be added in the form of ferro boron, boron carbide, calcium boride, nickel boron, borax or as the element; Te is added as ferro-tellurium, copper-tellurium or as the element, and Bi is added as the metal. Ductility of the cast metal can be improved by heat treatment e.g. at 1300-1350 DEG F for 3 hours. The tensile strength is improved by normalizing at 1500-1600 DEG F.