Question

Q4.WHAT IS THE MECHANISIM WORKING HAREDING?

.Q5.EXPLAINTHEMARTENZITIKTRANSFORMATION?

Q6.EXPLAIN THE TEMPERING HEAT TREATMENT AND ITS BENEFITS?

Answer 1

Mechanism of work Hardening

work hardening is also called strain hardening, is cold working process.Strain hardening is a process of making metal harder and stronger through plastic deformation.when a metal is plastically deformed, dislocation move and additional dislocation are generated.The more dislocation generated In metal the more they will interact and become tangled consequences decrease in mobility of dislocations and strengthening of material.This type of strengthening in material is called work hardening.

Example:

As you are aware with the phenomena of bending a piece a wire when we bend a piece of wire one time we cannot bend the piece of wire again at that place because of that area is strain hardened and formation of dislocation become tangled.But by continuous bending of wire back and forth several times it breaks due to fatigue cracking.

Martensitic transformation

Martensitic transformation is a diffusionles transformation in this type the change in phase involves a definite orientation relationship because the atoms have to move in a coordinated manner.There is always a change in shape which means that there is a strain associated with transformation.

TEMPERING PROCESS

Tempering is a low heat treatment process which is performed after neutral hardening ,double hardening, carburising to reach a desired hardness to toughness ratio.

Benefits

Tempering process can reduces the hardness in the material and increase the toughness of material.