Describe the process of case hardening. Give an example of the application of case hardeningand state why it is suitable for that application

Case hardening is a heat treatment process that is used to increase the hardness of the outer surface of a material, while maintaining a soft and ductile core. This process is also known as surface hardening.

Here are the steps involved in case hardening:

1. Carburizing: The first step in case hardening is carburizing. In this process, the metal part is heated in a furnace in the presence of a carbon-rich environment. This allows the carbon to diffuse into the surface of the metal, increasing its carbon content.

2. Quenching: After carburizing, the metal part is quickly cooled or quenched. This rapid cooling causes the carbon in the metal to form a hard, wear-resistant layer on the surface of the part.

3. Tempering: The final step in case hardening is tempering. This involves reheating the metal part to a lower temperature. This reduces the brittleness of the hardened surface and increases the toughness of the metal.

An example of the application of case hardening is in the manufacturing of gears. Gears need to be hard on the outside to resist wear, but they also need to be tough on the inside to resist the impact forces that occur during operation. Case hardening is suitable for this application because it provides the necessary hardness on the outside and toughness on the inside.