Bolts quenching by high frequency induction heating machine

A bolt is a mechanical part specially matched with a nut. It has a threaded shape and is cylindrical. It is a kind of fastener. It consists of a head and a screw. If it is divided according to the shape of the head of the bolt, it has a round head. , square head and so on. Bolt has a wide range of uses, and it can be seen in both mechanical manufacturing and daily necessities. Due to the working characteristics of the bolt, it will be affected by friction, tensile stress, alternating stress and environmental corrosion, which will shorten its service life for a long time. Therefore, when we produce bolts, we must use alloy steel with higher toughness and better quality. In the process of processing, we use high-frequency heating machine for quenching heat treatment process to further improve the internal structure, so that qualified bolts have enough Excellent tensile strength, yield strength, good toughness and wear resistance, high fatigue strength and other advantages.

The heat treatment process of the bolt is forging and forming the blank, then cleaning, and finally quenching, tempering and heat treatment. When heating in the equipment, the temperature should be controlled at 860-870°C, so that the granular pearlite can be transformed into austenite structure and fully play its role. The tempering temperature after quenching is 520-550°C. The bolts should be kept at this temperature for 90 minutes and then cooled with water, which can effectively avoid the occurrence of secondary tempering brittleness and obtain tempered sorbite structure. The hardness after quenching and tempering treatment is in the range of 30-38HRC, which ensures the mechanical properties of the bolt. If conditions permit, one step of normalizing can be added before the bolt conditioning treatment, which is beneficial to improve the overheated structure that may be generated inside the bolt during hot punching, and eliminate its processing stress, and better prevent the bolt from cracking during the quenching process. It must be noted that during the heat treatment of the bolts by the high-frequency induction heating machine, the operation sequence must be strictly followed to control the heating time and temperature to avoid early failure.