This steel contains iron, carbon and small amounts of other elements. About 95% of the total world, Crude-steel output belongs to this class. It is plain carbon steel is further classified as follows:‑
a) Low Carbon Steel in which carbon content is bellow 0.2%.
b) Medium Carbon Steel with carbon content from 0.2 to 0.5%.
c) High Carbon Steel with carbon content above 0.5%.
The plain carbon steel is used for structural shapes, plates, tube pipes. rods and bars, tools, wheels, axles and rails.
(2) ALLOY STEEL
The steel, in which different elements are added to get a desired alloying effect. Is called alloy steel. Some important alloys of steel are:
It has the composition.
Iron = 73 to 79% Chromium = 14 to 18 % Nickel = 7 to 9 %
Stainless steel is a corrosion resistant alloy and is used in making cutlery, automobile Parts, food manufacturing machinery, surgical instruments etc.
The composition of invar is Iron = 64% and Nickel 36 %. It has low co-efficient of expansion and used for making pendulum rods, meter scales, measuring instruments. •
(iii) NICKEL STEEL
It has the composition, Iron = 96.5 %, Nickel = 3.5 %. Nickel steel is hard and resistant to corrosion. It is used for making cables, automobiles and aeroplane parts.
(iv) SILICON STEEL
The composition of silicon steel is Iron = 96 to 99%, Silicon F 1 to 4%. Silicon steel is hard and highly magnetic and is used in making magnets and transformers.
(v) MANGENESE STEEL
It has the composition: Iron • = 85 to 88%, Manganese = 12 to 15 %. This alloy steel is extremely hard and tough. It is used for making safes and rock-drilling tools.