Product Delivery Timeblack Annealed Tube Is One Of The Most Common Steel Pipes

If the cold-rolled steel is heated to the annealing temperature, the surface color becomes black due to high temperature contact with the air, it is called black annealing steel.  Its surface has not been polished so it is black.  The physical properties become soft and easy to further weld into steel pipes.  Common hardness 57HRB, can also be retreated to different hardness according to need.  

The black annealed tube is a treated A3 material tube in order not to rust.  After the treatment of the black annealed tube in welding, if the treatment is not good, there will be tears, of course, this situation is relatively less, there are many reasons for tearing, such as water on the surface of the welding matrix, rust on the surface, and the welding rod selection is wrong. 

Aim

(1) Reduce hardness and improve machinability;

(2) Reduce residual stress, stabilize size, reduce deformation and crack tendency;

(3) Refine the grain, adjust the structure, eliminate the structure defect;

(4) Uniform material structure and composition, improve material properties or prepare the organization for later heat treatment.

In production, annealing process is widely used. According to the purpose of the workpiece requirements of annealing, there are many kinds of annealing process specifications, commonly used are complete annealing, spheroidizing annealing, and stress relief annealing.

The Role Of Steel Pipe Annealing

Removing stress: Steel pipes may have internal stress during manufacturing, processing and welding, resulting in deformation, cracking or other quality problems.  Annealing  by heating and cooling, the internal stress of the steel pipe can be released and eliminated, reducing the risk of deformation and cracks.  

Improve toughness: annealing makes the grain of the steel pipe grow and reshape again, so that it has better toughness and ductility.  Toughness is the ability of the material to resist fracture, so that the steel pipe is not easy to break when it is subjected to impact or tensile force.  

Softened material: During the annealing process, the steel pipe will undergo a process of high temperature heating and gradual cooling, which reduces the hardness and strength of the steel pipe, thus making it easier to process and deform.  This is very important for subsequent processes such as cold working, cutting and welding.