Flange cold forging is low temperature casting, and the flange size changes little. When casting below 700℃, there is less scale on the surface and no decarburization. Therefore, as long as the deformation energy is within the range of forming energy, cold forging can easily obtain excellent dimensional accuracy and surface smoothness. As long as the temperature is well controlled and cooled smoothly, the warm forging below 700℃ can also obtain excellent accuracy. Cold die forging, cold extrusion, cold upsetting and other plastic processing. Cold forging is a forming process below the recrystallization temperature of materials, and it is a casting below the recovery temperature. In production, it is customary to call the casting of unheated blanks cold forging. The data of cold forging are mostly aluminum and some alloys, copper and some alloys, low carbon steel, medium carbon steel, low alloy structural steel and other materials with less deformation resistance and better plasticity at room temperature. Cold forgings have good surface quality and high dimensional accuracy, which can replace some cutting processes. Cold forging can strengthen metal and improve the strength of flange.

The development of cold forging technology is mainly to develop high value-added products and reduce production costs. At the same time, it is constantly infiltrating or replacing cutting, powder metallurgy, casting, hot forging, sheet metal forming technology and other fields, and can also be combined with these technologies to form composite technology.

Flange hot forging is: when hot forging, because of the small deformation energy and deformation resistance, large flanges with messy shapes can be cast. In order to obtain the flange with high dimensional accuracy, hot forging can be used in the temperature range of 900- 1000℃. In addition, attention should be paid to improving the working environment of hot forging. The service life of forging dies (hot forging 2000-5000, warm forging 1-20000, cold forging 20000-50000) is shorter than that of casting in other temperature ranges, but it has great freedom and low cost. The main purpose of hot forging flange is to reduce the deformation resistance of metal, thus reducing the forging pressure required for the deformation of bad materials and greatly reducing the tonnage of forging equipment; By changing the as-cast structure of flange ingot, the coarse as-cast structure can be recrystallized into new fine-grained structure during hot forging, which can reduce the defects of as-cast structure and improve the mechanical properties of steel.