1. Heating calculation.
When the infinitely long cylindrical forgings are uniformly heated, if there is no temperature difference before the heating, the temperature t of each point on the section of the heating process is a function of r. It is generally considered that the forgings having a length three times the diameter can be regarded as an infinitely long cylinder. .
2. Cooling calculation.
When forgings are cooled, the important problem is to know in advance the cooling of different diameter forgings in different quenching media, including: (1) the cooling time required for the forging center to cool to a certain temperature; (2) for The cooling curve of the center of different diameter forgings with different quenching temperatures; (3) the cooling rate at the center of the forging; (4) the relationship between the cooling time of any part of the forging and the diameter of the forging. Now make an introduction based on the calculation method:
The cooling time required for the forging center to cool to a certain temperature. Since the forging determines the final cooling time based on the temperature of the core, a more reliable cooling time relationship with the forging diameter is required. Since the cooling time of the same diameter forgings to a certain temperature is also related to the quenching temperature, a series of cooling curves at different quenching temperatures are required.
Second, it is suitable for the cooling curve of different diameter forgings at different quenching temperatures. According to the existing measured data and heat transfer theory, the cooling curve of the center of the forgings not exceeding 2m and the diameter of the different quenching temperatures is cooled in water, oil and air.
Third, the cooling rate of the center of the forging. The hardenability of the steel is usually determined by the cooling rate at 700 ° C, which requires a relationship between the cooling rate and the diameter.
Fourth, the relationship between the cooling time of any part of the forging and the diameter of the forging. Forgings are usually sampled at 1/3R from the surface for mechanical property testing. Some particularly important parts are also required to take the core and surface specimens. Therefore, it is necessary to understand the relationship between the cooling of different parts of the forging and the diameter of the forging.
3. Calculation of the final cooling time of forgings.
In production, it is often used to calculate the cooling time per millimeter of cooling time. Especially for the quenching medium with strong cooling capacity, there will be a disadvantage that the small core temperature is too low and the large part is not cold enough.