End crack of forged flange
The end cracks of forged flanges are caused by internal stress, but they often appear within a few hours after cutting. When the material hardness is too high, the hardness is uneven and the material segregation is serious, it is also easy to produce shear cracks of forged flanges. For billets with end cracks of forged flanges, the cracks will further expand during forging.
Blank end face depression of forged flange
When loading and unloading in the shearing machine, because the gap between the scissors is too small, the upper and lower cracks of the metal section of the forged flange do not coincide, resulting in secondary shearing. As a result, some end metal is pulled off, and the end face is concave. Such blank is easy to cause folding and cracking of forged flange during forging.
Gas cutting crack of forged flange
The gas cutting crack of forged flange is generally located at the end of the blank, which is caused by the lack of preheating of the raw materials of the forged flange before gas cutting and the generation of structural stress and thermal stress during gas cutting. For the blank of forged flange with gas cutting crack, the crack will further expand during forging. Therefore, it should be removed in advance before forging.
Cracking of convex core of forged flange
When the lathe for forging flange is used for blanking, a convex core is often left at the center of the end face of the bar. In the forging process, because the cross-section of the convex core of the forged flange is very small and the cooling is very fast, its plasticity is low, but the cross-section of the blank matrix is large, the cooling is slow, and the plasticity is high. Therefore, the abrupt junction of the section becomes the part of stress concentration, and the plastic difference between the two parts is large, so the surrounding of the convex core is easy to crack under the action of hammering force.
