1. Raw material selection
To save costs, some seamless steel pipe manufacturers will choose round steel produced by small steel mills for processing, but the round steel produced by these small steel mills will contain many impurities, bubbles, interlayers, pores, etc., which are easy to cause cracking problems after later processing.
2. Inadequate control of heat treatment temperature
Small manufacturers do not have professional production experience and technology. Workshop workers cannot guarantee whether the heat treatment of steel pipes is in place based on heating temperature and duration alone, and heat treatment will change the mechanical properties of steel pipes. However, general manufacturers do not have clear indicators for different steel grades, wall thicknesses, and mechanical properties, nor do they have testing equipment to determine whether the pipes have reached the performance indicators required by customers.
3. Straightening strength
Straightening is equivalent to secondary deformation. Bidirectional force is applied during straightening. If the operator is inexperienced, the straightening force is too strong, and the thick-walled pipe does not control the force well, it will cause internal injuries and cracks in the steel pipe. In the later stage, there is no flaw detection and it is directly packaged and shipped. This is also the reason for the cracking of steel pipes in the later stage.
4. Drawing deformation
If the drawing deformation is too large, cracks will be formed in the steel pipe, causing the steel pipe to crack during the later processing. The elongation of the bright tube is low, generally 7-8%. The deformation is large and the elongation is low; the deformation is small and the elongation is high. Some small manufacturers cut corners and change three deformations to two to save the process, which increases the deformation and causes cracking due to excessive stress.
5. The old end of the steel pipe is not cut cleanly
Many manufacturers blindly pursue the yield rate, and only cut a few centimeters of the old end of the steel pipe. The hidden danger of cracking at both ends of the steel pipe is not cut cleanly, which is also one of the factors that cause cracking in later use.
Post time: Oct-11-2024