Interesting Explanation Heat Treatment Of “Four Fires”: Annealing, Normalizing, Quenching, Tempering

In the industrial field,

it should be known or heard about overheating treatment.

When it comes to heat treatment,

one has to mention the four industrial fires.

Thery are….

Annealing, Normalizing, Quenching, Tempering.

Today,

we are going to talk about the differences of?Annealing, Normalizing, Quenching, Tempering.

Annealing,

is to slowly heat the metal to a certain temperature.

keep it in warm for a while,

then slowly cool to room temperature.

Think about it,

You made a bowl of noodles but it was too hot.

So you have to put it aside,

Let it cool down before you eat it.

That’s what annealing is all about.

Normalizing,

that is to heat the metal to 30-50°C above the critical temperature.

Keep warm for a?proper?time,

and a heat treatment process that is cooled in air.

It sounds like,

normalizing and annealing are very similar.

Nothing but,

the cooling rate of normalizing is slightly faster,

and production cycle is shorter.

Because of normalizing,

Cooling like this.

↓↓↓

Noddles are often eaten faster,

that is to get the product faster.

So annealing and normalizing can also meet the performance requirements of parts.

Use normalizing whenever possible.

if we assume,

annealing and normalizing are cousins,

that quenching and tempering is a good partner who will never give up.

Quenching,

is to heat the metal above the critical point.

At this time,

The internal structure and state of the metal will change—Austenitizing.

We need to keep it warm for a certain time,

to make the metal undergo this change.

Then cool at a rate greater than the critical cooling rate.

To get the metastable martensite structure or lower bainite structure.

This quick cooling method,

Usually like this.

After quenching, martensite structure is obtained.

But the internal structure of this organization is extremely unbalanced.

Although the hardness is high,

but plasticity and toughness are poor,

and brittleness is big also.

Therefore,

the quenched metal will not leave the factory as a finished product.

After all,

this hardened metal cannot be processed again.

Metal that’s brittle than an Iphone 6s screen,

no one would like this.

As a result,

the effect of?tempering?is reflected.

After the metal has been hardened,

heat it to a temperature below the critical temperature.

Keep warm for a period of time,

so that the internal structure of the metal can be evenly distributed.

Then cool down to room temperature,

then a certain strength, hardness

and a certain plasticity, toughness of the finished product can be gotten.

We call this,

a perfect case of?1+1>2.

Said so much above,

on the difference between?annealing, normalizing, quenching and tempering,

?we may get the general idea.

In fact,

?“quenching” and “tempering” can also make the noodles crisp~

Thank you for reading.

If you have any question, please don’t hasitate to contact our team member below.