1. The original state of steel, that is, the delivery state of small-diameter precision seamless steel pipes, can be divided into (codes in brackets): cold processing/hard (BK), cold processing/soft (BKW), stress relief annealing after cold processing (BKS), tempering (GBK), normalizing (NBK). The commonly used state is the annealing state, which is convenient for subsequent processing. The performance and general applicability of small-diameter precision seamless steel pipes in various states are as follows:
2. Cold processing/hard (BK) steel pipes are produced by cold processing of finished products with normal or large deformation, without heat treatment, with high dimensional accuracy, high tensile strength, and low elongation coefficient. Generally used to manufacture motorcycle parts, such as shock absorber sliding columns.
3. Cold processing/soft (BKW) steel pipes are produced by cold processing of finished products with small deformation, without heat treatment, with high dimensional accuracy, high tensile strength, and a certain elongation coefficient (10-15%). Generally used to manufacture automotive parts.
4. The steel pipes that are stress-relieved and annealed (BKS) after cold working are subjected to low-temperature and rapid heat treatment after cold working, and have higher dimensional accuracy, slightly higher tensile strength, and a certain elongation coefficient (more than 15%). They are generally used to manufacture various mechanical parts.
5. The steel pipes that are annealed (GBK) are subjected to 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 with a wide range of applications.
6. Normalizing (NBK) is controlled cooling after complete heat treatment after cold working, and has normal dimensional accuracy, slightly higher tensile strength, and elongation coefficient (more than 20%). Oil well pipes are in this state. In addition, the price of steel pipes in steel pipe factories is not closely related to the delivery status, and it mainly depends on the specifications, accuracy, and length requirements.
Post time: Jun-24-2025