Does forging have no impact on the organization?

Does forging have no impact on the organization?

1. Forging can generally refine the structure, break down dendrites, and promote tissue homogenization. When there are second phases distributed on the matrix, they will be elongated into 

strips, and the plastic phase will become longitudinally distributed bands, while the brittle phase will fracture into longitudinal chains; Forging can also weld the pores or microcracks inside 

the steel, improve the loose grain boundary structure, and make the steel denser. The primary purpose of forging is to make the steel reach the size and specifications of the blank. 

That is to say, forging is one of the important means of forming mold blanks. Another important purpose of forging is to improve the microstructure and properties of steel, such as 

crushing large carbides to obtain a uniformly distributed microstructure, improving the flow direction of carbides inside the steel, eliminating or reducing metallurgical defects, 

such as welding porosity, improving grain boundary microstructure distribution, making the steel denser, and so on. However, due to these functions being 

invisible and intangible, they are often overlooked.

2. Overheating is a structural defect caused by excessive heating temperature and prolonged heating time at higher temperatures, resulting in severe growth of austenite grains. The temp

erature at which grains begin to grow rapidly is called the overheating temperature. Overheated tissue can be eliminated through appropriate heat treatment or processing. Steel grades with 

phase transformation recrystallization are classified into "stable overheating" and "unstable overheating" based on recent research. The so-called 'unstable overheating' is caused by the 

overheating formed solely by the coarsening of austenite grains at high temperatures. This overheating can be eliminated by general heat treatment methods. The so-called "stable over

refersto the precipitation of a large number of second phase particles or thin films (including compounds composed of impurity elements such as sulfides, carbides, nitrides, etc.) along the 

austenite grain boundaries (or twin boundaries) after steel overheating, in addition to the coarsening of the original high-temperature austenite grain boundaries (or twin boundaries, 

etc.), as well as other factors that promote the stabilization of the original high-temperature austenite grain boundaries (or twin boundaries, etc.) or other overheated structures. This 

overheating cannot be easily improved or eliminated by general heat treatment methods. The research results indicate that not only alloy structural steel is prone to stable overheating, but it 

also frequently occurs in carbon steel, 9Cr18 stainless steel, GCr15 bearing steel, 60Si2Mn spring steel, high-speed steel, etc.

3. Overheating, also known as melting or burning, is mainly due to the high heating temperature, which not only causes severe growth of austenite grains, but also the appearance of molten

 liquid metal and easily melted eutectic oxides at grain boundaries. Due to the destruction of intergranular bonding caused by overburning, the strength of the steel is greatly reduced, and 

it can be shattered with a single blow. Therefore, overburning is a fatal heating defect, characterized by a crocodile skin like surface and coarse fracture grains. It is caused by prolonged 

heating at excessively high temperatures during rolling, forging, and heat treatment. Once the steel 

parts are burnt, they can only be scrapped.