What is the reason for the cracking of cold-drawn seamless steel pipes
Date: 2024-10-29
What is the reason for the cracking of cold-drawn seamless steel pipes
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. Each batch of steel pipes produced by steel pipes has clear temperature and speed indicators for normalizing, annealing, and tempering, and tensile tests will be carried out to determine whether the products meet the performance required by customers.
3. Straightening strength
Straightening is equivalent to secondary deformation. During straightening, bidirectional force is applied. If the operator is inexperienced, the straightening force is too strong, and the thick-walled tube is not well controlled, it will cause internal damage and cracks in the steel pipe. In the later stage, it is directly packaged and shipped without flaw detection. This is also the reason for the cracking of the steel pipe in the later stage.
4. Drawing deformation
If the deformation of the drawing is too large, cracks will also form in the steel pipe, causing the steel pipe to crack during later processing. The elongation of bright tubes is low, generally 7-8%, with large deformation and low elongation; and small deformation and high elongation. Some small manufacturers cut corners and changed three deformations to two to save technology, which increased the deformation and caused 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 leading to cracking in later use.
Post time: Oct-29-2024
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