What is quenching?
In order to increase the hardness of the raw material, the raw material is heated to a high temperature (about 800 °C) and then cooled quickly. It can be divided into different cooling methods basing on different cooling medium, such as oil cooling/water cooling/jet cooling and the so on. The material will become hardenability easily and it will lead to the material easy broken. In order to increase the toughness of the steel, it needs to be tempered again. Pure iron will not become harden even though it has been quenching. If the carbon content of the raw material is more than 0.35%, it may cause quench hardening.
What is quenching and tempering?
Quenching and tempering is the heat treatment that combine quenching with high temperature tempering to adjust the hardness, strength and toughness of steel or steel parts. Since the material and products that after quenching need to have mechanical processing, the hardness is not high as after quenching.
What is high-frequency quenching?
Carbon steel with a carbon content of more than 0.35% like 45# steel or 40Cr/42CrMo needs to be hardened on its surface. It should be noted that after the high-frequency treatment of the gear, the hardness of the tooth surface and the tooth top will meet the requirements for use, but the tooth root part will not reach the quenching hardness. Therefore, the hardness is generally lower than the hardness of the carburizing and quenching treatment. And after the gear is high-frequency hardened, the accuracy will decrease. If it needs to be used as a high-precision gear, it is necessary to increase the subsequent process to grind the gear.
What is carburizing and quenching?
Carburizing and quenching is a heat treatment method in which carbon is infiltrated into the surface of low carbon steel to make it into a state of high carbon content. This method is a heat treatment method that only hardens the steel surface.
The hardness of the surface and core (C = 0.15%) that penetrate the carbon continuously changes from soft to hard. The core hardness is lower than the surface hardness. Similar to high-frequency hardening, the gears that have undergone carburizing and hardening are prone to deformation (such as increased size) and distortion, which will lead to a decrease in gear accuracy. In order to improve the gear accuracy, it is necessary to increase the subsequent process to do the grinding of the gear.