Mechanical Engineering - Engineering Materials - Discussion

Tempering is hardening process.

Anealing is softening.

Annealing is a primary hardening process while tempering is a secondary hardening process. Tempering is done to increase the toughness of the steel by reducing the hardness of the alloy.

It is done after hardening the steel in order to remove the brittleness. Since it it mentioned that hardened steel, tempering would be the answer.

There is some confusion, we know that annealing is done for softening a piece of steel, but in question mentioned that what is done to soften a hardening steel?

That means after hardening, we must go for tampering, it is also done for the expanse of hardness.

The process of heat treatment of steel is in order of = annealing - normalizing (equilibrium condition) and hardening-tempering (non-equilibrium condition). So option D is correct.

Tempering: Tempering reduces the hardness in the martensite by transforming it into various forms of tempered martensite. Tempering is a heat treatment technique applied to ferrous alloys, such as steel or cast iron, to achieve greater toughness by decreasing the hardness of the alloy.

Annealing/Normalising: Annealing is a heat treatment process which alters the microstructure of a material to change its mechanical or electrical properties. Typically, in steels, annealing is used to reduce hardness, increase ductility and help eliminate internal stresses.

The correct answer is annealing.

Hardened steels here refer to martensitic steels, so tempering is the correct method of softening them i.e. improving the ductility by small amounts while reducing hardness and tensile strength by small amounts.

What is the correct answer? Please explain.

Answer is correct.

Annealing is used to relieve stress caused by rolling, extruding etc.

Though the final product is ductile and soft, it is not used for hardened steels.

Tempering is used to increase toughness of hardened steel. So the final product from tempering is soft and tough steel.

Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical point for a certain period of time, then allowing it to cool in still air.

So it is right answer.

Tempering is the Right answer.