Metallurgy Question:

Actually, you asked a question, which requires a very long-winded answer. In summary, actually, you asked a question, which requires a very long-winded answer. In summary, metallurgy i.e., science of metals, is used to get metals with higher quality and higher in-service performance.

Casting is a forming method based on melting metals and pouring them into molds with desired shapes, so that after solidification desired properties are achieved.

Forging is a solid state forming method, which means it involves no melting. Forging stock is heated up to the appropriate temperature (it is usually so hot that appears red or white) and then application of pressure leads to plastic deformation of stock. Therefore, stock takes on the negative shape of die. Heating facilitates forming, i.e. makes possible forming at a smaller load.

Forging products usually are of higher quality and have a higher manufacturing cost compared to castings. Some parts cannot be used in the cast form because of the defects inherent to casting (most grades of steels) while some other metals are so brittle that they cannot be forged (e.g. cast irons). Indeed, there are some metals, which can be produced by either of the methods. The standard applicable to the part determines which form must be used.