__________ of grey cast iron produces white cast iron.

ANS:B - Rapid heating

Rapid heating refers to the process of quickly increasing the temperature of a material, typically a metal or alloy, to a desired level. This can be achieved through various heating methods such as induction heating, flame heating, or electric resistance heating. The key characteristics of rapid heating include:

1. Speed: Rapid heating involves heating the material at a fast rate compared to conventional heating methods. This allows for quick attainment of the desired temperature.
2. Uniformity: Efficient heat transfer mechanisms are employed to ensure uniform heating throughout the material. This helps to prevent localized overheating or thermal gradients within the material.
3. Energy Efficiency: Rapid heating methods are often designed to be energy-efficient, minimizing heat loss to the surroundings and reducing overall energy consumption.
4. Control: Temperature control is essential during rapid heating to prevent overheating and ensure that the material reaches the desired temperature without exceeding its limits.

Rapid heating is commonly used in various industrial processes such as heat treatment, forging, welding, and casting. It allows for shorter processing times, increased productivity, and improved material properties by optimizing the heating cycle. However, it requires careful consideration of factors such as material composition, heating rate, and cooling methods to achieve desired results without compromising material integrity.