How Heat Treatment works ? The basic concept of Heat Treatment
Every metal or alloy is made out of atoms and microstructures. These micro structure plays a very crucial part in mechanical properties of metal. Properties like strength , Ductility, brittleness, Hardness , toughness, strength, machinability and weldability . Now, every metal or alloys when it is manufactured it gets a metal structure based on how it is cooled.
It is the main reason behind every mechanical properties of metal.
Now we will mainly discuss steel as most of the metal that we use in heat treatment is steel.
As soon as man kind started making weapons and tools of steel we started using heat treatment. In anciant time when blacksmith started making steel they realized when we heat up steel and then quickly cool it down with liquid steel becomes stronger and harder. no one knew how it worked. But they ended up making strong weapons and tools. Only thing they knew was If you heat Steel until it gets red then you quickely cool it down it becomes stronger.
Unknowingly they were actualy applying one of the heat treatment process to the steel.
Now to understand how heat treatment works you need to understand how metal structure works.When most metal solidify normaly as the temperature falls below melting point they start forming crystalibe structure .These structures have gaps and defects in the bonds. Now if you look at these uniform metal balls you will see that even if they are all round when they come together they create some sort of structure / pattern in organizing. If you look at these patterns closely you will realize that this is because of imperfection / defects in the structure. When metal is workd on with different operations like forging, heating or hammering. it changes its structure and these defects starts moving in the body.
Now if we look at the metal structure normally the steel structure look like this. So in normal case these metal atoms with do movement like this and next structure will do movement like this. Blocking each other at different rate. When we apply heat to the same structure these gaps and atoms get settels down and creats a uniform structure which can take more load and distrulibuted evenly which affects the mechanical proporties of metal.
Now to explain you the same concept look at this metal balls which are trapped into a wall like structure to explain this. When we first put the metal balls into it it settles in very random pattwrn which is simmilar to metal setteling down initially. Now when we heat it up or apply energy to it will start having vibration and they will form a better structure removing defects from the body and settle down.
In my next video I will explain different types of Heat Treatment methods.
Book of Metallurgy for the Non-Metallurgist : https://amzn.to/3LyLmNu
references
https://www.tec-science.com/material-...
https://www.tensilemillcnc.com/blog/t...
https://www.generalkinematics.com/blo...
https://www.quora.com/What-is-the-mic...