Plain carbon steel is an alloy of iron and carbon where the amount of carbon ranges from 0.015% to 2%. This material has great strength and hardiness which are essential for motor bodies, appliances, apparatus, ships, containers, and the structures of buildings.

Carbon steel is by far the most widely used kind of steel. The properties of carbon steel depend primarily on the amount of carbon it contains. Most carbon steel has a carbon content of less than 1%. Carbon steel is made into a wide range of products, including structural beams, car bodies, kitchen appliances, and cans. In fact, there are 3 types of plain carbon steel and they are low carbon steel, medium carbon steel, high carbon steel, and as their names suggests all these types of plain carbon steel differs in the amount of carbon they contain. Indeed, it is good to be precise that plain carbon steel is a type of steel having maximum carbon content of 1.5% along with small percentages of silica, sulphur, phosphorus and manganese.

Limitations of plain carbon steel:

Like everything, the plain carbon steels do have some appreciable properties but also consists of some limitations. These are:

1. There cannot be strengthening beyond about 100000 psi without significant loss in toughness (impact resistance) and ductility.
2. Large sections cannot be made with a martensite structure throughout, and thus are not deep hardenable.
3. Rapid quench rates are necessary for full hardening in medium-carbon leads to shape distortion and cracking of heat-treated steels.
4. Plain-carbon steels have poor impact resistance at low temperatures.
5. Plain-carbon steels have poor corrosion resistance for engineering problems.
6. Plain-carbon steel oxidises readily at elevated temperatures.