The heat treatment process of steel pipe mainly includes the following 5 categories:

1, quenching + high temperature tempering (also known as quenching and tempering)

The steel pipe is heated to the quenching temperature, so that the internal structure of the steel pipe is transformed into austenite, and then cooled faster than the critical quenching speed, so that the internal structure of the steel pipe is transformed into martensite, and then tempered with high temperature, finally, the steel pipe structure is transformed into uniform tempered sopranite.This process can not only improve the strength and hardness of steel pipe, but also organically combine the strength, plasticity and toughness of steel pipe.

2, normalizing (also known as normalizing)

After heating the steel pipe to normalizing temperature, the internal structure of the steel pipe is completely transformed into austenite structure, and then the heat treatment process is cooled with air as the medium.After normalizing, different metal structures can be obtained, such as pearlite, bainite, martensite, or a mixture of them.This process can not only refine grain, uniform composition, eliminate stress, but also improve the hardness of steel pipe and its cutting performance.

Normalizing + tempering

The steel tube is heated to the normalizing temperature, so that the internal structure of the steel tube is completely transformed into austenite structure, and then cooled in the air, and then tempered.The structure of steel pipe is tempered ferrite + pearlite, or ferrite + bainite, or tempered bainite, or tempered martensite, or tempered sortensite.The process can stabilize the internal structure of steel pipe and improve its plasticity and toughness.

4, annealing

It is a heat treatment process in which the steel tube is heated to annealing temperature and kept for a certain time, and then cooled down to a certain temperature with the furnace.Reduce the hardness of steel pipe, improve its plasticity, to facilitate the subsequent cutting or cold deformation processing;Refine grain, eliminate microstructure defects, uniform internal structure and composition, improve the performance of steel pipe or prepare for the subsequent process;Eliminate internal stress of steel pipe to prevent deformation or cracking.

5. Solution treatment

The steel tube is heated to the solution temperature, so that carbides and alloying elements are fully and uniformly dissolved in austenite, and then the steel tube is cooled quickly, so that carbon and alloying elements have no time to precipitate, and the heat treatment process of single austenite structure is obtained.Function of the process: uniform internal structure of steel pipe, uniform composition of steel pipe;Eliminate hardening in the process of processing to facilitate the subsequent cold deformation processing;Restore the corrosion resistance of stainless steel.