Reheating furnaces in the steel industry

The term steel is applied to iron-carbon (Fe-C) alloys containing up to 1.7% carbon, but most steels contain less than 1%. Other elements such as manganese (Mn), chromium (Cr), nickel (Ni), molybdenum (Mo), etc., are usually also present.

Steel is produced in two processes:

• reduction of ore (iron oxides) in blast furnaces and removal of excess carbon from liquid pig iron (3 to 4.5%) in oxygen converters;

• melting scrap (recycled steel) in electric furnaces.

The product obtained by these two methods is processed in refining plants, where it is brought to its final chemical composition by final adjustment of the carbon content and addition of the elements that will give the steel the desired characteristics. This operation is known as grading.

The liquid steel obtained is solidified in continuous casting machines from which it emerges in the form of blanks called semi-finished products, whose typical dimensions are :