Main Points Of Forging Heat Isothermal Normalizing Process

1. Temperature control of wheel forgings after forging

After forming, the temperature of the wheel forging must be above a fixed value. When the temperature fluctuation of the forged part is small (the forging heating and forging process can be continuously and stably controlled), the direct quenching method can be used; when the temperature of the forging of the wheel after forging is large or the wheel forging is large When the cross-section changes greatly, the temperature equalization process must be increased, that is, after the wheel forging is forged, it enters the temperature uniform heat treatment furnace for a period of time to uniformize the temperature of the wheel forgings before quenching, otherwise the temperature of the wheel forgings after quenching will be different. Large, producing abnormal structures (granular bainite or bainite structure).

2.Cooling cooling speed control

Quenching is a key process of forging waste heat isothermal normalizing process. The quenching process requires sufficient cooling speed of the wheel forgings, and the air volume, wind speed, wind temperature and wind direction can be adjusted and controlled to ensure the rapid cooling of the wheel forgings. The temperature of the same batch of wheel forgings is uniform (or similar). The purpose of quenching is to reduce the amount of pre-eutectoid ferrite or inhibit the production of pre-eutectoid ferrite by rapid cooling. Too much ferrite will cause the hardness of the wheel forging to be low after isothermal normalization. The quenching speed must be controlled. Too fast quenching speed will produce Weiss structure in the wheel forging structure. Generally, the quenching speed is controlled at 30 ° C / min ~ 42 ° C / min.

3. Isothermal temperature control after quenching

After quenching, the temperature of the wheel forging must be in the pearlite transformation zone, which cannot be lower than the starting temperature of bainite transformation, that is, the temperature, otherwise the bainite (or granular bainite) structure will appear in the structure; at the same time, such as isothermal after quenching If the temperature is too high, the amount of pre-eutectoid ferrite increases, and the pearlite lamellar spacing is large after the structural transformation, resulting in low hardness of the wheel forging. After quenching, the isothermal temperature of the wheel forging is generally controlled at 50 ℃ ~ 100 ℃ above the material temperature. The temperature of the wheel forging is measured by an infrared thermometer or a handheld infrared thermometer set on the production line.