Introduction

1. Steel is a term given to alloys containing a high proportion of iron with some carbon. Other alloying elements may also be present in varying proportions. 

2. The properties of steel are highly dependent on the proportions of alloying elements so that their levels are closely controlled during its manufacture.

3.  The properties of steel also depend on the heat treatment of the metal. Steel is by far the most important metal, in tonnage terms, in the modern world, with the annual global production of over 700 million tonnes dwarfing the approximately 17 million tonnes of the next most prolific, aluminum. 

4. The low price and high strength of steel mean that it is used structurally in many buildings and as sheet steel, it is the major component of motor vehicles and domestic appliances. 

5. The major disadvantage of steel is that it will oxidize under moist conditions to form rust.