Research on Gear Forging Temperature Solution Engineering Scheme
Steel blanks are also difficult to meet the technical requirements of both the banded core 2 and the non-granular bainite. There is no specific requirement for the uniformity of the blank structure and hardness.
Conventional normalizing, after austenitizing the blank, the structural transformation is completed under continuous cooling conditions, and the cooling conditions at different positions of different parts and the same part are different, so the uniformity of microstructure transformation, hardness and stress distribution is poor. .
The difference in hardness on the same blank can reach 30-80HB, and the difference in hardness of different blanks will be greater. Thereby, the problem that the cooling rate of the parts is difficult to control and the parts are not uniformly cooled during the normal normalizing process is overcome.
The isothermal treatment temperature generally selects the temperature range near the "nose" of the pro-eutectoid ferrite and pearlite transformation in the austenite isothermal transformation curve according to the hardness, the band-like structure requirement, the size of the part, and the amount of furnace loading.
In order to effectively realize the control of the band structure, and avoid the isothermal temperature and time of the bainite should be based on the isothermal transformation curve and the appearance of the material, the appropriate cooling air volume should be selected on the equipment, the furnace volume and the effective thickness of the parts in the process. In addition, it is sufficient to ensure that the Aussie should reasonably allocate the cooling time and the cooling time, and to achieve as much time as possible for the full conversion of the fast body to the ferrite pearlite.
After the cold, the ferrite transformation is partially completed (the temperature of the simple test part for determining the isothermal time can be determined by infrared spectroscopy, and the temperature of the surface of the part after the quick cooling is generally effective and effective: from a batch of parts of the isothermal furnace Take out one piece, around 70 °C).
Do not choose too high a temperature to prevent the appearance of solid isothermal growth of the 5 isothermal normalized blanks and the general technical requirements.
In order to avoid the control of the stability during austenitizing heating, and according to the characteristics of the isothermal normalizing process, the microstructure and hardness requirements of the surface and the core can be consistent. Explore.
According to the formulation principle and technical requirements of the above process, we have been effectively used in the production of various transmission gear shaft parts and screw bevels, which not only solves the problem of machining difficulties due to unstable tooth structure and hardness, but also It also improves the stability of heat treatment deformation, reduces the trial production cycle of new products, and reduces the scrap rate of parts.
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