Heat Treatment Process

The process of heating and cooling for changing the structure of metal or alloy and thus obtaining the required properties is called heat treatment. It can also be said as a process of heating and cooling of ferrous metals especially various kinds of steels in which some special properties such as softness, hardness, tensile strength, toughness, etc., are induced in these metals for achieving the special function objective. 

The heat treatment process consists of three main phases namely

(i) Heating of the metal

(i) Soaking of the metal 

(ii) Cooling of the metal

In any heat treatment operation, the rate of heating and cooling is important. A hard material is difficult to shape by cutting, forming, etc. The shape of metal depends upon the structure of different types of the molecules and quantity of carbon present in it.

For making soft, weak, and ductile steel, it must be heated to a suitable temperature and then slowly cooled. On the other hand, for making hard and brittle steels, it must be heated to a suitable temperature and then rapidly cooled. Many types of furnaces are used for heating steel in the heat treatment process. In this chapter, we will study the various methods of the heat treatment process and heat treatment furnace, etc.

Methods of Heat Treatment Process

The heat treatment process of steel is classified as

1. Equilibrium Heat Treatment 

All the heat treatments which produce equilibrium conditions are called equilibrium heat treatments.

There are two types of such heat treatments 

(i) Annealing

(ii) Normalising