GB447580A - Improvements relating to iron-chromium alloys - Google Patents

Abstract

In a method of making iron-chromium alloys, a charge comprising iron scrap, iron oxide, and a material rich in chromium, which may be high-carbon ferro-chrome, or chrome ore, or both, with or without chrome-iron scrap, is melted in an electric arc furnace for the production of a bath of low-carbon iron-chromium alloy and an overlying blanket of slag; the bath of alloy is withdrawn from the furnace for refining in a second furnace, and the oxides of iron and chromium in the slag are reduced, for example, by silicon, for the production of a second alloy rich in chromium. After the withdrawal of the first product from the melting furnace, some iron scrap may be melted on the slag to form a bath for the reception of the iron and chromium afterwards reduced from the slag. The method is particularly applicable for the utilization of scrap containing chromium and one or more metals such as nickel, copper, molybdenum, tungsten, cobalt, &c., less readily oxidizable than chromium, in which case the first alloy withdrawn from the furnace contains substantially all the nickel &c. The electric arc melting furnace used may have a chromite bottom, and the refining furnace may be an electric arc furnace with a magnesite lining. In some cases the second product of the first furnace may be added to the metal bath in the second furnace prior to the refining operation. The production of two products containing respectively (1) 8-10 per cent of chromium, 8-10 per cent of nickel, and 0,7 per cent of carbon, and (2) 12-14 per cent of chromium and 0,7 per cent of carbon, from a charge of chromium-nickel rustless iron scrap, low-carbon steel scrap, high-carbon ferrochrome, chrome ore, and roll scale, is described.