Bright annealing of stainless steel seamless pipes

Bright annealing of stainless steel seamless pipes is a heat treatment process that heats the stainless steel pipe to a certain temperature, keeps it for a certain period of time, and then slowly cools it to change its internal structure and improve its mechanical and physical properties. The main purpose of annealing is to eliminate the internal stress generated during processing, improve the plasticity and toughness of the material, improve the surface finish, and improve the cutting performance of the material.

The bright annealing process of stainless seamless pipes has the following advantages:

1. Improve corrosion resistance

Bright annealing can improve the surface of steel better, improve the surface finish, thereby greatly reducing the surface roughness and greatly improving the resistance to chemical corrosion.

2. Guarantee service life
Because bright annealing can release the retained stress inside the crystal, the hardness of the steel is more uniform, and the concentration of local pressure is avoided, so the wear resistance and durability of the steel pipe are better.

3. Improve the aesthetics
After the bright annealing process, the color of the stainless steel annealed tube is brighter, showing texture and luster. Compared with other stainless steel products, it is more glorious and can better meet the customer's requirements for the appearance of the steel tube.

‌4. Improve the surface quality‌
During ordinary annealing, oxidation and decarburization will occur during the heating and cooling process, resulting in metal loss and increased costs. Bright annealing is carried out in a protective atmosphere or vacuum to prevent oxidation and improve the surface quality of the workpiece.

‌5. Eliminate work hardening‌
Bright solution treatment can restore the distorted lattice, eliminate internal stress, reduce the tensile strength of the steel pipe, and increase the elongation.

‌6. Restore corrosion resistance‌
Cold working will cause carbide precipitation and lattice defects, reducing the corrosion resistance of stainless steel pipes. After bright solution heat treatment, the corrosion resistance of stainless steel seamless pipes is restored to the best state.

Effect of annealing on the performance of stainless steel seamless pipes:

Annealing has an important influence on the performance of stainless steel seamless pipes, which is mainly reflected in the following aspects:
1. Hardness and strength of materials: Stainless steel pipe materials with different hardness and strength can be obtained through different annealing processes.
2. Toughness and ductility of materials: Annealing can make stainless steel pipe materials soft, improve their toughness and ductility, and make them more adaptable to complex processing contours.
3. Internal stress of materials: Annealing can eliminate the internal stress in stainless steel pipe materials and improve the stability and service life of materials.

Steps of bright annealing treatment of stainless steel seamless pipes:

The bright annealing process of stainless steel seamless pipes mainly has the following key steps:

1. Heating treatment
Place the steel pipe in a bright annealing furnace with a temperature range of 1040~1120℃ for a period of time to allow it to fully and evenly absorb heat. The heating time depends on the specifications and requirements of the steel pipe.

2. Hydrogen atmosphere treatment
Bright annealing adopts hydrogen atmosphere treatment, and the bright annealing furnace is filled with hydrogen atmosphere with a purity of more than 99.99% to heat the steel pipe.

3. Cooling treatment
After a certain period of bright annealing treatment, the steel pipe is taken out of the bright annealing furnace and placed in a rapid cooling tank for cooling treatment.

4. Water washing and drying treatment
After the above treatment, the steel pipe is washed with water and air-dried or dried with a dryer to ensure that the surface of the steel pipe is clean and pollution-free.

The bright annealing process of stainless steel seamless pipe is a delicate and cumbersome processing process. The heating temperature, atmosphere, cooling speed, etc. will affect the bright annealing effect of the steel pipe. Only in the process of refined management and operation can the best bright annealing effect be achieved.

Read more: Carbon steel pipe vs stainless steel pipe or Stainless steel pipe implementation standards