The carbide segregation level of forged flange does not meet the requirements
The forged carbide segregation grade of forged flange does not meet the requirements, which mainly occurs in ledeburite tool and die steel. The main reason is that the carbide in the forged flange is unevenly distributed, which is concentrated in large blocks or distributed in a network. The main reason for the defects of this forged flange is the poor carbide segregation level of raw materials, coupled with insufficient forging ratio or improper forging method when changing the forging of forged flange. Forgings with this defect are prone to local overheating and quenching cracks during heat treatment and quenching. The cutting tools and moulds are easy to collapse when used.
Uneven grains of forged flanges
The uneven grain of forged flange means that the grain of some parts of the forging is particularly coarse, but some parts are small. The main reason for the uneven grain of forged flange is that the uneven deformation of the blank makes the degree of grain breakage different, or the deformation degree of local area falls into the critical deformation zone, or the local work hardening of superalloy, or the local grain coarseness during quenching and heating. Heat resistant steels and superalloys are particularly sensitive to grain inhomogeneity. The uneven grains of forged flanges will significantly reduce the durability and fatigue performance of forged flanges.
Cold hardening of forged flanges
During the forging deformation of forged flange, due to low temperature or too fast deformation speed, as well as too fast post forging cooling of forged flange, the softening caused by recrystallization may not keep up with the strengthening (hardening) caused by deformation, so that the cold deformation structure is still partially retained in the forging after hot forging. The existence of this structure improves the strength and hardness of the forged flange, but reduces the plasticity and toughness of the forged flange. Severe cold hardening of forged flanges may cause forging cracks.
