Question

What is hardening and quenching of steel ? Explain.

Answer 1

Hint: Hardening and quenching of steel is a process in which steel is hardened and strengthened. In this the material is heated to a specific temperature, depending on the material.

Complete step by step answer:
- Let’s discuss about hardening of steel:
- Hardening of steel is done by heat or mechanical means to increase the hardness of the outer surface of steel . During this, the core remains relatively soft.
- The combination of a soft interior and hard surface has much value in modern engineering because it is found that it can withstand very high stress and fatigue, this is a property that is required in items such as anti-friction bearings and gears.
- Carburizing is the oldest surface-hardening method in which steel is placed at a high temperature in a carbonaceous environment for several hours. Then it is found that the carbon diffuses into the surface of the steel, and makes it harder.
- We can see that various techniques of carburizing have been developed which can increase efficiency and also reduce cost.
- There is also another method of surface hardening which is called nitriding, which utilizes nitrogen and heat. There are various fuel injection pumps that are typically hardened by this process.
- Now let’s discuss about quenching of steel:
- Quenching is a process in which heating of steel is done to a temperature above the critical temperature, heat is preserved for a period of time, it is basically associated with tempering at different temperatures.
- This method is found to improve the steel toughness, rigidity, fatigue strength, hardness, etc. Which enables the steel to meet various requirements of different mechanical parts and tools.
- Nowadays, the quenching technology is widely used in the modern machinery industry. The various important parts in machinery, especially that are used in airplanes, rockets, and in automobiles, are almost quenched.

Note: As we know that quenching is actually a very rapid cooling process, whereas hardening might include one or several processes that are found to increase the strength of the material.