The BASIC OXYGEN STEEL (BOS) - making Process
This can be described via the following steps:
The process occurs in a furnace which is a specially designed steel vessel that may be rotated through 360 in a vertical plane.
The vessels are lined with heat resistant (refractory) materials eg.dolomite (MgCO3/ CaCO3) and magnesite (entirely MgCO3). These last for up to 2 weeks before they have to be replaced.

Types of Steel

In general, steels can be divided into 2 groups:

Carbon Steels
small % of C (0.03 to 1.5%),
residual amounts of other metals
comprises 90% of all steels produced

At high temperatures, 907-1400 C, Fe is cubic close-packed (ABCABC) and can hold 1 C for every 12 Fe atoms.
This form of steel is called 'austenite'.

With excess carbon, an interstitial steel is produced called 'cementite' which has a precise composition of Fe3C.

'austenite' is stable down to 690 C where it converts to:
a body centred form called 'ferrite' which has less carbon and also 'cementite'.

It is possible to retain the 'austenite' structure below 690 C by adding Mn.

Alloy Steels
contain C and controlled amount of other metals; eg Mn, Cr, Ni, Mo.

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Copyright © 2005 by Robert John Lancashire, all rights reserved.

Created and maintained by Prof. Robert J. Lancashire,
The Department of Chemistry, University of the West Indies,
Mona Campus, Kingston 7, Jamaica.
Created July 2000. Links checked and/or last modified 20th October 2005.