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Precision cold drawn steel pipe surface quality defects
Aug 23, 2018

1 External fold: a spiral-shaped sheet-like fold on the outer surface of the cold drawn steel tube, the spiral direction of which is opposite to the direction of rotation of the steel when perforated, and the pitch is large. This defect is called outer fold.

2. Crack: The inner and outer surfaces of the cold drawn steel tube show continuous or discontinuous fine hair, some of which have a y shape, and the direction of rotation is opposite to the direction of rotation of the steel when perforated and the pitch is large. This defect is called crack. .

3. Separation layer: A spiral shape or a block of metal delamination or crack or bulge appears on the inner surface of the cold drawn steel pipe. This defect is called a separation layer.

4. Inner fold: a spiral, semi-spiral, irregularly distributed zigzag fold appears on the inner surface of the cold drawn steel tube. This defect is called inward fold.

5. Scarring (including scales, skins, suede): On the inner surface of the cold drawn steel tube, there are angular scars, which are called scars.

6. Scratch (snap): The inner and outer surfaces of the steel pipe are cold drawn, and the grooves are regularly distributed in a straight line. This defect is called scratching (hairing).

7. Rolling: Wrinkles appearing in the longitudinal direction or the length of the tube wall, and the outer surface is strip-shaped. This defect is called rolling.

8. Correction (correction): On the surface of a cold drawn steel tube, a spiral depression is formed. This defect is called a concave (straightening), also called a thread (straightening angle).

9. Glitch: A full-circle or partial residual zigzag-like sheet appears in the circumferential direction of the end of the cold-drawn steel tube. This defect is called a burr.

10. Uneven wall thickness: Cold drawn steel pipes have different cross-section and longitudinal thickness. This kind of defect is called uneven wall thickness.

11. Trembling (also known as corrugated, bamboo-shaped, ring-shaped): On the inner and outer surfaces of the cold-drawn steel tube, there are continuous or semi-circular ring marks in the horizontal direction, which are continuous and intermittent. On the surface only, this defect is called wobble (also known as ripple, bamboo, and ring).

12. Pit (including indentation): There are local depressions with different areas on the surface of cold drawn steel pipes, some of which are periodic and some irregular. The surface of the defect has a flaw as a pit, and the surface has no damage as an indentation.

13. Pitting (also known as pockmark): A small, point-like depression on the surface of a cold-drawn steel tube. This defect is called pitting.

14. Straight track: Straight-line scratches with a certain width and depth appear on the inner and outer surfaces of the cold drawn steel pipe, distributed in the full length or part of the cold drawn steel pipe. This defect is called a straight track.http://www.skivingtubelw.com/


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