Rapid heat treatment by induction heating is characterized by increasing heat treatment temperature and shortening heat preservation time. In special cases, it is necessary to keep short heat preservation time, such as quenching and tempering treatment.
1. Determination of steel quenching and heat preservation time
When carbon steel and low alloy steel are quenched and heated, the carbon content in steel is higher. There are alloying elements with strong affinity to carbon and nitrogen in steel. In order to make the formed carbide and nitride fully dissolved in the heating process, it is beneficial to increase the temperature and increase the holding time at the same time, and it is also beneficial to homogenize the austenite content of carbon. When Hengyuan electric furnace studied the quenching process of 35CrMo steel tube by induction heating and quenching, the quenching and holding time was extended from 30s to 60s, and no change was found in the room temperature performance of the hardened steel. Thus, it can be seen that the induction heating quenching and heat preservation time of ordinary low alloy steel and carbon steel can be maintained at around 30s without affecting the properties of hardened steel. On the contrary, if the quenching and heat preservation time is too long, it will not only increase the burden on the process equipment, but also cause grain growth and reduce the quenching effect.
2. Method to extend quenching and heat preservation time
Under the condition of continuous rapid heating, the specific way to prolong the quenching and heat preservation time is to install the heat preservation device after quenching and heating the least inductor. The steel is kept at the quenching temperature in the unit. The insulation may be heated by induction, resistance wire or other means, but the temperature shall be kept constant.
On 2018-08-08 11:45:46
