The principle of medium frequency induction heat treatment for LSAW steel pipe is a rapid heat treatment method. The use of high/medium frequency electric current and general flame heat treatment in steel has many advantages over the fine grain microstructure of metal. The rapid heating of steel tube to austenite temperature before quenching can form fine horse-quenched structure, which can be formed when the fine grain ferrite E pearlite structure is normalized. Due to the short tempering time of induction heating and the uniform distribution of small particles of carbide precipitation in fine martensite matrix, this structure is particularly conducive to casing corrosion protection.


If the steel is quenched and tempered, its mechanical properties are superior to those of other methods except high temperature thermomechanical treatment. After high strength steel perforator seamless steel tube, medium frequency induction heating heat treatment and conventional heating heat treatment, the mechanical properties of induction heating after quenching are better than that of ordinary heat exchange index on quality. Conventional heating and quenching, such as cooling medium pipe, can not easily crack. In addition to induction heating, the inner and outer surfaces of cracked pipes have never occurred with water as cooling medium. This is because when the heat comes from the phenomenon of induction quenching and tempering, it helps to eliminate the quenching stress and easy to produce quenching cracks. The performance of the canal is very uniform, and the quality and appearance of the whole root canal are very good. In the process of heat treatment, the heating time of induction heating pipe is different, and the heating time of different kinds of pipe is the shortest. The temperature is very fast, and there is only a small amount of iron oxide in a given time, basically no decarbonization.


After the induction heat treatment of steel pipe, the ship also bends, but its curvature is less than that of many traditional roller hearth furnaces or walking beam furnaces. Among them, straightening is very advantageous, especially for casing corrosion and high strength steel in API standard. It has low straightening stress, high corrosion resistance and crack resistance. After induction heat treatment, the curvature of steel pipe depends on the original curvature, diameter, heating mode and cooling conditions. Usually, steel pipe is heat treated before bending. The smaller the diameter, the more flexible it is after heat treatment.  Therefore, it is necessary to maintain a certain smoothness before heat treatment of steel tubes. The straight forward way of steel tube tends to bend during heating, while the forward way of spiral steel tube is not easy to bend. The cooling of bending effect is also great, the cooling is not uniform, and the bending of pipeline can also be changed.