Steel

This chapter highlights some of the many uses of steel, explaining which material properties make steel an appropriate choice in each case. The disadvantages of relatively high density and susceptibility to corrosion are shown to be greatly outweighed by the good mechanical properties, extensive manufacturing base and low cost. An overview of the various different alloying elements present in steel is given. The way in which small amounts of carbon can have significant impact on steel properties is explained. The iron carbon phase diagram is explained at a basic level with a summary of the main different phases commonly encountered in steels. This is supplemented by a section explaining how the lever rule can be used to gain insight into microstructural development during cooling. The particularly high strengths achievable in high strength steels are highlighted and the underlying mechanisms explained.