GB653382A - Production of chromium-nickel stainless steel - Google Patents

Abstract

A process of producing stainless steel of low carbon content comprises melting in an electric arc furnace having carbonaceous electrodes a charge consisting principally of chrome ore, base steel scrap, stainless steel scrap, and nickel oxide to form a chromium rich and iron rich bath having a low carbon content and a supernatent slag thereon including chromium and nickel oxides and adding to the slag a silicon-containing reducing agent of low carbon content for recovering the metallic chromium and nickel from their oxides. The reducing agent used is preferably crushed ferrosilicon relieved of fines. In charging the furnace chrome ore may be disposed along the banks of the furnace with base steel scrap on the furnace bottom, the oxidizing material in the middle of the furnace and on the scrap and the stainless steel scrap over the chrome ore. Further amounts of chrome ore may be added during the melting while maintaining the melted metal at a boil. The chromium and iron rich bath and the final stainless steel may contain less than 0.03 per cent of carbon. Additions of ferro-chromium, ferromanganese, electrolytic manganese and nickel, copper, tungsten, vanadium, aluminium, titanium, niobium, molybdenum or zirconium may be added after the reduction step. Specifications 437,186 and 649,023, are referred to. The Specification as open to inspection under Sect. 91 comprises also the replacement of nickel oxide as oxidizing material wholly or in part by other oxidizing agents such as iron ore, iron oxide, rolls or mill scale. This subject-matter does not appear in the Specification as accepted.