12CrlMoV steel pipe (wall thickness > 40mm) for power transmission and distribution construction is heated. There have been cooling, low speed and low hardness of steel pipe. For example, air cooling, water spraying or oil immersion cooling, there are technical problems, large equipment investment and environmental pollution. Therefore, the heat treatment test of 12CrlMoV steel pipe in medium frequency induction heating furnace is carried out and applied to production practice, and practical results are obtained.
12CrlMoV steel pipe specimen is heated and austenitized and cooled in water at about 20 ℃. The heat treatment test of medium frequency induction heating equipment shows that in actual production, the immersion termination temperature can be controlled according to the wall thickness and the corresponding immersion time. The microstructure of 12CrlMoV steel pipe sample after immersion in water and air cooling is characterized by high content of pearlite and granular bainite, which is conducive to improving the high temperature endurance strength. The organization meets the requirements of technical conditions. At the same time, after treatment, the mechanical properties such as hardness meet the technical requirements and have excellent properties.
The effects of immersion cooling time, cooling rate and water temperature of steel pipe were studied. The results show that the heat emitted by the sample per unit time is directly proportional to the temperature difference between the sample and the cooling medium, and the cooling rate of the sample is inversely proportional to the temperature of the cooling medium in a certain range.
The heat treatment characteristics of medium frequency induction heating equipment for 12CrlMoV steel pipe are as follows:
1. 12CrlMoV steel pipe heat treatment process can improve the cooling rate of high temperature section (higher than 600 ℃ ± 50 ℃); Increase the content of granular bainite and pearlite and improve their properties.
2. The immersion temperature can be controlled by controlling the immersion time, so as to control the occurrence of martensite and avoid the cracking of pipe fittings. After water immersion treatment, no martensite structure and crack are found, and the metallographic structure and performance indexes fully meet the technical requirements.
3. Using the heat treatment process of medium frequency induction heating equipment, the defect of low hardness in the production of 12CrlMoV steel pipe with wall thickness greater than 40mm is well solved, and the production application is good.
4. In production, the corresponding immersion time can be determined according to the test curve according to the steel pipe wall thickness, and the immersion time can also be adjusted according to the change of water temperature.
Overseas manager: Tom Wang
Email:tom@foreverfurnace.com
Phone: 0086-13303078975(whatsapp, wechat,line)
Post time: 12-31-2021