Hello, friends in this article I am going to tell you about ” The different techniques of heat treatment of steel” This principle is based on the fact that change takes place in the internal structure of steel at a specific temperature.
it is heating and cooling of metals at controlled afraid to get the desired improvement in mechanical properties.
Hard and brittle iron carbide doesn’t become fully combined with iron, however, a temperature reached about 800°c.
If the steel is heated further, there will be no change in temperature this is due to the fact heat applied is consumed to bring the structure and chemical change in the steel.
The carbon and iron form solid solution all the steel is well below the melting point and is known as decalscene point.
After this point, the temperature further rises again. If the steel is removed from heat and allowed to pull a point appears to be arrested and temperature even may rise slightly and such a point is called coalescence point.
Purpose of heat treatment
- Heat treatment is used to increase mechanical properties neck ductility strength toughness of metals.
- It is also used to increase machinability. Generally in cold working internal stresses are developed to relieve these internal stresses.
- Heat treatment is done after cold working. it is also used to improve properties like corrosion resistance and hardness.
Process of heat treatment
it consists of three steps, first, the metal is heated to a specific temperature and it is kept at that temperature for a specific period of time.
In this time the material rearranges its grain structure depending upon the temperature and after that material is cooled at a specific rate so as to get the desired improvement in its properties.
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The different techniques of heat treatment of steel are given below:-
1) Annealing- To make steel soft annealing is done. It is the process of heating steel to a temperature generally above the critical temperature.
2) Normalizing- It is the process of heating or heat treatment in which steel is heated up to 5°c above the critical temperature and allowed to pull in air. It improves the strength of medium carbon steel and reduces internal stress.
3) Quenching/hardening- The process of heating the steel above the critical temperature and along with cooling rapidly and plunging it into the liquid path. In this process roughness or ductility decreases but hardness increases.
4) Tempering- The process of heating the steel to some predetermined temperature between room temperature and critical temperature. During this process toughness and ductility increase but hardness decreases.
5) Surface hardening- In this process, the outer surface of the steel is hardened and the poor of steel is only refined.
So, friends, I hope this article on “Different techniques of heat treatment of steel” Remains helpful for you.