The ways of heat treatment for seamless and precision pipe
The heat treatment of pipe normally have five ways as below:
1.Quenching+high temperature tempering
The steel pipe is heated to the quenching temperature, so that the internal structure of pipe can be transformed to austenite, then cooled faster than the cirtical quenching speed, so that the internal structure of pipe is transformed to
Martensite, and then tempered with high temperature. Finally the steel pipe structure is transformed to uniform tempered sopranite. This process not only improve the strength and hardness of pipe, but also can combine the strength, plasticity and toughness of the steel pipe.
The steel pipe is heated to normalizing temperature, so that the internal structure of the steel pipe can be completely transformed to austenite structure, and then cooled in the air and tempered. The structure of pipe is tempered ferrite+pearlite, or ferrite+bainite, or tempered bainite, or tempered martensite,
Or tempered sortensite. This process can stabilize the internal structure of pipe and improve its plasticity and toughness.
The steel pipe is heated to the annealing temperature and keep for a certain time, and then cool down to a certain temperature with furnace. Reduce the pipe hardness, improve its plasticity in order to do the subsequent cutting or clod deformation process. 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 pipe to
Prevent deformation or cracking.
The steel pipe is heated to the solution temperature, so that carbides and alloying elements are fully and uniformly dissolved in austenite. And then the steel pipe 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 and compostion of steel pipe. Eliminate hardening in the process to faclitate the subsequent cold deformation processing. Restore the corrosion resistance of stainless steel.