Why does the seamless steel pipe fold?
Posted by zora li on December 6th, 2022
Inward bending is a common quality problem in the production of seamless steel pipes. It is irregularly distributed sheet folds and spiral folds on the inner surface of the steel pipe, and the edges of the defects are mostly jagged. There are two main reasons for inward folding defects: the quality of the continuous casting billet (internal cause) and the piercing process system (external cause).
In addition, improper operation will also cause the steel pipe to fold inward. The inward folding forms in operation mainly include net shape, point shape, sheet shape and spiral shape. Regular spiral defects are generally caused by severely worn plugs or defective mandrels. In addition to the regular distribution of such defects, the defect edges are more neat than steel defects. Inward folding defects such as irregular mesh, dots, and flakes are generally caused by the following reasons.
1) The amount of depression before the top is too large, resulting in premature cavity formation of the tube blank during piercing, resulting in inward folding.
The specific reasons for inward folding during piercing are as follows:
1) Influence of perforation deformation parameters on inner folds
2) Influence of piercing temperature on inward folding
3) The influence of the centering hole on the inward folding
To improve the quality of the inner surface of the steel pipe and reduce the occurrence of inward bending defects should start from the following methods
1. Ensure the uniformity of the structure during casting, reduce segregation, and prevent excessive concentration of non-metallic inclusions;
Like it? Share it!
About the Authorzora li
Joined: August 16th, 2022
Articles Posted: 85
More by this author