5 Common Heat Treatment Processes for Steel Pipes

What are the 5 common heat treatment processes for steel pipes, seamless steel pipes, and precision steel pipes? There are many types of steel pipes, and the steel grades (types) used are also different. The chemical composition of the same type of steel pipe may also be different, but after heat treatment, the steel pipe can meet the relevant technical requirements.

There are mainly 5 types of heat treatment processes for steel pipes:
1. Quenching + high temperature tempering (also known as quenching and tempering): The steel pipe is heated to the quenching temperature to transform the internal structure of the steel pipe into austenite, and then rapidly cooled at a rate greater than the critical quenching rate to transform the internal structure of the steel pipe into martensite, and then combined with high temperature tempering, the steel pipe structure is finally transformed into a uniform tempered troostite structure. This process can not only improve the strength and hardness of the steel pipe, but also organically combine the strength, plasticity, and toughness of the steel pipe.

2. Normalizing (also known as normalization): A heat treatment process in which the steel pipe is heated to the normalizing temperature to completely transform the internal structure of the steel pipe into austenite, and then cooled with air as the medium. After normalizing, different metal structures can be obtained, such as pearlite, bainite, martensite, or their mixed structures. This process can not only refine the grains, uniform the composition, and eliminate stress, but also improve the hardness of the steel pipe and improve its cutting performance.

3. Normalizing + tempering: After the steel pipe is heated to the normalizing temperature, the internal structure of the steel pipe is completely transformed into the austenite structure and then cooled in the air, and then combined with the tempering process. The steel pipe structure is tempered ferrite + pearlite, ferrite + bainite, tempered bainite, tempered martensite, or tempered troostite. This process can stabilize the internal structure of the steel pipe and improve the plasticity and toughness of the steel pipe.

4. Annealing: After the steel pipe is heated to the annealing temperature and kept warm for a certain period, it is slowly cooled to a certain temperature with the furnace and then taken out of the furnace for cooling.
The role of this process:
① Reduce the hardness of the steel pipe and improve its plasticity to facilitate subsequent cutting or cold deformation processing;
② Refine the grains, eliminate organizational defects, make the internal organization and composition uniform, improve the performance of the steel pipe, or prepare for subsequent processes;
③ Eliminate the internal stress of the steel pipe to prevent deformation or cracking.

5. Solution treatment: Heat the steel pipe to the solution temperature so that carbides and various alloy elements are fully and evenly dissolved in austenite, and then cool it quickly so that carbon and alloy elements have no time to precipitate, and obtain a heat treatment process with a single austenite structure.
The role of this process:
① Uniform internal organization of the steel pipe and uniform composition of the steel pipe;
② Eliminate hardening during processing to facilitate subsequent cold deformation processing;
③ Restore the corrosion resistance of stainless steel.


Post time: Oct-30-2024

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