Chapter 5 - Production of Steel

Abstract

Steel making is an ancient process and numerous developments have taken place in the technology over the many years of its use. The two processes that are now commonly used for the production of steel are the Basic Oxygen Furnace (BOF) and the Electric Arc Furnace (EAF); they use variety of charge materials and technologies. The EAF process uses virtually 100% old steel to make new steel. EAFs make up approximately 60% of today's steel making in the US. This chapter illustrates the operational details of EAF and BOF processes. The electric arc furnace operating cycle is called the tap-to-tap cycle. The EAF has developed as an efficient melting apparatus, with designs focusing on increased capacity. In modern EAF operations, especially those operating with a ‘hot heel’ of molten steel and slag retained from the prior heat, oxygen is often blown into the bath. This technique allows for the simultaneous operation of melting and refining in the furnace. The Basic Oxygen Furnace process uses 25 to 35 percent old steel to make new steel. The iron-iron carbide phase diagram is a good basis for understanding the effect of temperature and components on the properties of steel.