What is the difference between cold forging and hot forging of flange

　　Flange cold forging is in low temperature forging, flange size change is very small. Forging below 700 ℃ results in less oxide scale formation and no decarburization on the surface. Therefore, as long as the deformation energy is within the range of forming energy, it is easy to obtain good dimensional accuracy and surface finish by cold forging.

　　As long as the temperature and lubrication cooling are well controlled, the precision of warm forging below 700 ℃ can also be very good. Cold die forging, cold extrusion, cold upsetting and other plastic processing collectively. Cold forging is the forming process below the recrystallization temperature of materials, and it is forging below the recovery temperature. In production, forging without heating blank is called cold forging. Most of the cold forging materials are aluminum and some alloys, copper and some alloys, low carbon steel, medium carbon steel and low alloy structural steel with low deformation resistance and good plasticity at room temperature. Cold forging has good surface quality and high dimensional accuracy, which can replace some cutting processing. Cold forging can strengthen the 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 also permeating or replacing to cutting, powder metallurgy, casting, hot forging, sheet metal forming and other fields. It can also be combined with these processes to form a composite process.

　　The hot forging of flange is: during hot forging, large flange with complex shape can be forged due to small deformation energy and resistance. In order to obtain high dimensional precision flange, hot forging can be used in the temperature range of 900-1000 ℃. In addition, we should pay attention to improve the working environment of hot forging. The service life of forging die is shorter than that of forging in other temperature regions, but it has large degree of freedom and low cost.

　　The main purpose of hot forging flange is to reduce the deformation resistance of metal, so as to reduce the forging pressure required by the deformation of bad material and greatly reduce the tonnage of forging equipment; By changing the as cast structure of the ingot used for flange, the coarse as cast structure becomes a new structure with fine grains after recrystallization in the process of hot forging, and the defects of as cast structure are reduced to improve the mechanical properties of the steel.