Performance processing of small diameter precision seamless steel pipe

1. The original state of steel, that is, the delivery state of steel pipes, can be divided into (codes in brackets): cold working/hard (BK), cold working/soft (BKW), stress relief annealing after cold working (BKS), tempering (GBK) ), normalizing (NBK). The commonly used state is the annealed state, which facilitates subsequent processing. The performance and general application of steel pipes in various states are as follows:

2. Cold-worked/hard (BK) steel pipes are produced through cold processing of normal or large deformation finished product passes without heat treatment. They have high dimensional accuracy, high tensile strength, and low elongation coefficient. Generally used to make motorcycle parts, such as shock absorber struts.

3. Cold-processed/soft (BKW) steel pipes are produced through cold processing of finished products with small deformation, without heat treatment, and have high dimensional accuracy, high tensile strength, and a certain elongation coefficient (10-15%) . Generally used to manufacture automobile parts.

4. Steel pipes subjected to stress relief annealing (BKS) after cold working are subjected to low temperature and rapid heat treatment after cold working. They have higher dimensional accuracy, slightly higher tensile strength, and a certain elongation coefficient (more than 15%). Generally used to manufacture various mechanical parts.

5. Annealed (GBK) steel pipes undergo normal and complete heat treatment after cold working, and have normal dimensional accuracy, normal tensile strength, and elongation coefficient (more than 20%). It is a commonly used state and has a wide range of applications.

6. Normalizing (NBK) is a complete heat treatment followed by controlled cooling after cold working. It has normal dimensional accuracy and slightly higher tensile strength and elongation coefficient (more than 20%). This is the state of oil well pipes. In addition, the selling price of steel pipes in steel pipe factories has little correlation with the delivery status. It mainly depends on specifications, accuracy, and length requirements.