Forgings and castings are common metal forming processes, but forgings are superior to castings in many ways. This article will introduce in detail the reasons why forgings are better than castings from several aspects.
Microstructure density: Due to a series of complex processes such as heating and forging, the forging makes its crystalline structure more compact and the grains smaller, thereby improving its mechanical properties such as strength and toughness. The casting grain is large, and it is easy to produce defects and holes in the solidification process, and its performance is more unstable.
Uniform stress distribution: After the forging is hammered or pressed, the internal stress distribution will be uniform, which further improves its strength and toughness and other properties. However, due to the non-uniform structure and defects in the castings, it is easy to produce stress concentration, resulting in low tensile strength and compressive strength.
Good plasticity: The production process of forgings can be repeatedly hammered or pressed according to the need for processing operations, so that complex shape and size requirements can be achieved, and the plasticity is better. Due to the limitation of the solidification process, castings can usually only get a simple shape and size, which is not easy to meet the complex use needs.
Performance under high temperature dynamic load is better: After high temperature processing, the internal grains of forgings become smaller, and the grain boundary energy is also improved, so that it has better performance under high temperature dynamic load. However, due to defects, holes and other reasons, castings are prone to damage or rupture under high temperature dynamic load.
High precision: the forging can be shaped and levelled by a certain die at the same time of processing, so as to achieve higher accuracy requirements. Due to the shortening and abnormity of the casting during the solidification process, secondary processing is usually required to meet the accuracy requirements.
In short, forgings have become one of the most widely used metal forming processes in many fields because of their good structure density, uniform stress distribution, good plasticity, good performance under high temperature dynamic load and high precision.
