Forging waste heat normalizing is after the wheel forging is formed, when the temperature is higher than a certain value, it enters a normalizing furnace, cooling box or annealing furnace for normalizing or controlled cooling to obtain a normalizing structure.
Due to the high forging heating temperature, the grains of wheel forgings processed by this method are relatively coarse. They are generally used for preliminary heat treatment, and are not suitable for wheel forgings with higher requirements on grain size. At the same time, the microstructure obtained after the treatment is a pearlite + ferrite equilibrium structure. The coarse grains do not have microstructure inheritance during subsequent heat treatment, and the grains can be refined again.
Forging waste heat isothermal normalizing is after the wheel forging is formed, when the temperature is higher than a certain value, it is rapidly cooled. After cooling to isothermal temperature, it is kept for a period of time and then air-cooled to room temperature.
After the forging of the wheel is formed, the temperature is generally in the range of 900-1000 ° C, the quenching speed is generally controlled in the range of 30-42 ° C / min, and the isothermal temperature is generally in the range of 550-680 ° C (specifically determined according to different materials). Quenching is the key step of this process. The cooling air volume, wind speed, wind temperature, and wind direction can be adjusted to ensure that the temperature of the wheel forgings is uniform after cooling. The isothermal temperature is determined according to the type of material and the required hardness. Generally, it is selected on the nose of the pearlite transformation curve to shorten the isothermal holding time.