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The lamination of seamless steel pipes
- Jun 05, 2018 -

The lamination of seamless steel pipes. 

The inner lamination of seamless steel pipe is divided into two kinds of billet lamination and operation lamination. 

The inner surface of seamless steel tube is irregularly distributed and spirally folded, and the defect edge is mainly serrated. The laminatin is generally caused by residual shrinkage and intermediate porosity of the billet. 

2 Operation lamination is form of a mesh, point shape, flake, spiral and so on. The regular helical defect is usually caused by serious head wear or mandrel defect, in addition to regular distribution of defects, the edge of the defect is more tidy than the steel defect. 

The irregular network, dot shape, flake and other internal folding defects are generally caused by the following reasons. 

1)Under the pressure of the top of mandred is too large, resulting in the inner folding caused by the premature formation of the hole cavity in the tube. 

2)The billet is not uniform and the heating temperature is too high, so it is easy to cause inner folding. 

3)Perforation appeared after the "Big Ear" did not cut, pre-piercing mandrel will be "big ear" into the capillary caused by the fold, which is a flake, generally appear in the tail section.