Mechanical Engineering - Engineering Materials - Discussion

@Dinesh.

Quenching is the process where a material is cooled after the heat treatment process under control atmosphere.

Quenching is done by three methods:-.

1. Air quenching: where the material is cooled under the atmospheric air. Here heat transfer rate is low.

2. Water quenching: where a material is cooled with the help of water. Here heat transfer rate is quite high as compared to air quenching.

3. Oil quenching: This technique generally used by a blacksmith for manufacturing blades and knifes.

Quenching may be fast or slow it depends on medium i.e.air, water, oil brine etc. And here it is about normalizing in which quenching (air cooling) and then fine grain size formed.

Quenching is a rapid cooling process. The grain size formed is a function of cooling rate. Higher the cooling rate, finer will be the grain size.

The grain size may not change in quenching. If the quenching is fast, martensite will form. This transformation is diffusion less.

Sudden cooling does not allow the grains to grow, so they remain in a smaller size (fine grains).

Quenching is the rapid cooling process in this 1st step is heating, 2nd step is soaking.

Because finer grain gives better mechanical properties(strength).

@dinesh.

Quenching means rapid cooling.

Why the finer grain size is desirable?

What is quenching?