Contents of annealing process in high frequency quenching heat treatment
In the application of high frequency quenching heat treatment, there are often tempering and annealing processes after quenching. We know that there are many different methods for quenching, and the annealing process is also different, mainly including complete annealing and stress relief annealing. The main reason is that the desired effect of the workpiece is different. According to the requirements, we can manufacture the annealing process.
The so-called annealing means that after the metal is heated in a high-frequency furnace, the heat preservation is slowly cooled to obtain a certain required structure. Regarding the content of complete annealing, the temperature of heating the workpiece is above AC3, and the stress relief annealing is heated to below AC1. However, both need to be kept warm for a certain period of time and then slowly cooled. The main difference is the purpose of the two anneals. The main purpose of complete annealing is to reduce the hardness of the workpiece, improve the machining performance of the workpiece and remove the internal stress, which is suitable for medium carbon steel. The main purpose of stress relief annealing is to remove residual stress.
Complete annealing can put the workpiece directly into the annealing furnace. The holding time is the time from the workpiece to annealing and heating to cooling in the furnace. The workpiece needs to be cooled down to 500 ℃ in air. Different workpieces in stress relief annealing have different process parameters. The temperature is lower than the tempering temperature.