bullet1 Metallic Materials

bullet2 Ferrous (plain carbon Steels)

From this selection of steels an engineer who requires a plain carbon steel which can be cold formed into a certain shape e.g. a car body panel, would select a low carbon steel, as this material has the desired property i.e. Ductility . 

An engineer who requires a plain carbon steel which can be used to cut other metals, including steel, e.g. a cold chisel, would select a medium carbon steel as this can have the desired property of hardness.

Plain carbon steels are those alloys of iron and carbon which contain up to 1.7% carbon.  However in practice, most ordinary steels also contain up to 1.0% manganese, which is left over from a de oxidation operation carried out at the end of the steel making process.  This excess manganese dissolves in the solid steel, slightly increasing its strength and hardness.  Medium and high carbon steels can be hardened and tempered (toughened) all steels can be softened (annealed).  See the chart below for some uses of steels

Composition of plain carbon steels
Common Name
% of Carbon
Common uses
Mild Steel (or low carbon steel)
0.1 to 0.25
General purpose, used throughout engineering.
Medium carbon steel
0.25 to 0.7
Hammers and bolts and high stress components
high Carbon steel (or tool steel)
0.7 to 1.7
Metal cutting and forming tools