Annealing Treatment of Precision Tube

Precision tube is a high-precision, high-brightness seamless steel pipe produced by cold drawing or cold rolling processes. They have excellent mechanical and physical properties such as high strength, high toughness, high wear resistance, and high temperature resistance. Therefore, they are widely used in petroleum, chemical, aerospace, aviation, nuclear engineering, heavy-duty vehicles, mechanical equipment and other fields. The production process of precision tubes is very strict, requiring precision machining and heat treatment of multiple processes, among which annealing treatment is a very important step.

Principle of precision tube annealing

Precision tube annealing refers to a heat treatment process in which the precision tube is heated and kept warm for a period of time within a certain temperature range and then cooled to room temperature. Its main purpose is to eliminate the residual stress inside the material, improve its texture structure, improve the plastic deformation ability of the material, and reduce its hardness, so as to achieve better mechanical and physical properties.

Necessity of precision tube annealing

During the manufacturing process of precision tubes, due to the influence of rolling, stretching and other processes, certain internal stresses and tissue defects will be generated, which will affect the mechanical properties and stability of precision tubes. For example, in the oil drilling industry, if the drill pipe, casing pipe and other pipes used in deep well operations are not properly annealed, they may fail due to fatigue due to stress concentration.

Annealing is a method of heating and heat preservation to make the internal structure and stress of the precision tube reach a relatively balanced state, thereby eliminating tissue defects and reducing internal stress. After annealing, the mechanical properties of the precision tube are more stable and can better meet the use requirements.

Common annealing methods

According to the material and use requirements of the precision tube, the commonly used annealing methods include complete annealing, spheroidizing annealing and stress relief annealing.

1. Complete annealing

Complete annealing is to heat the precision tube above the critical temperature, keep it warm for a certain period of time, and then slowly cool it to make the structure completely uniform.

2. Spheroidizing annealing

Spheroidizing annealing is to heat the precision tube to a temperature slightly higher than Ac1, keep it warm for a period of time, and then slowly cool it to make the carbide spheroidized and evenly distributed.

3. Stress relief annealing

Stress relief annealing is to heat the precision tube to a lower temperature, keep it warm and then slowly cool it, which is mainly used to eliminate internal stress.

Effects after annealing

The organization and performance of the precision tube after annealing have been significantly improved.

1. Eliminate residual stress

Annealing can eliminate the residual internal stress inside the precision tube and reduce deformation and cracking caused by stress concentration.

2. Improve the texture structure of the material

During the annealing process, the grains in the material will be rearranged and combined again, and the structure with a relatively high defect density will be optimized, so that the overall texture of the material is more uniform, the size of the grains is controlled, and the performance indicators of the material are improved.

3. Improve mechanical properties

Annealing can also improve the mechanical properties of precision tubes, such as strength, plasticity and toughness, making them more adaptable to complex and changing working environments.

Summary

In short, annealing of precision tubes is an important step to improve their performance and extend their life. By selecting appropriate annealing methods and process parameters, the quality and performance of precision tubes can be ensured to be optimal, providing a strong guarantee for the normal operation and service life of the equipment.