GB767855A - Nitrogen-bearing ferrochromium - Google Patents

Abstract

A method of producing low carbon nitrogen bearing ferrochromium comprises heating a compacted, uniformly porous aggregate produced by heating ferrochromium pellets containing 50-90 per cent Cr, 1-6 per cent Si, and more than 0.25 per cent C, the balance being iron, with an oxidizing agent and a binder under sub-atmospheric pressure and a temperature below the fusion point of any part of the pellets until the carbon content has been reduced to not more than 0.25 per cent, and then heating to 900-1400 DEG C. in the presence of nitrogen until the nitrogen-carbon ratio is at least 20/1. The nitrogen content may be between 0.5 and 7.0 per cent in an alloy containing 50-90 per cent Cr, 1-6 per cent Si, not more than 0.25 per cent C, the balance being iron. The decarburization may be carried out at a temperature below 1400 DEG C. under subatmospheric pressure, the reaction being considered complete when the pressure falls below 150 m.m. of mercury. Nitrogen is then introduced in sufficient quantity to give the required nitrogen content in the ferro-chromium. The alloy is stated to be suitable for addition to stainless steel alloys in which nitrogen and a very low carbon content is required.