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Several aspects for seamless Steel tube quality
- Dec 08, 2017 -

1) Chemical composition

The requirements for the content of hazardous chemical elements such as As Sn Sb Bi Pb and gas N,H,O are proposed, in order to improve the uniformity of chemical composition and purity of steel, reduce the non-metallic inclusions and improve the distribution in Tube billet, the molten steel is often refined by the refining equipment of the furnace and even the electroslag is used to remelting the billet.

2) Dimension precision and shape

The geometrical dimension of seamless steel tube mainly includes the outer diameter, wall thickness, ellipse degree, length, bending degree, bevelling and root face.

3) Surface Quality

Common surface defects are: crack, hair lines, internal folding, external folding, rolling broken, off the layer, scar, concave pits, convex bags, hemp pits (pock), scratches (abrasions), internal Spiral press, outside the Spiral press, concave, roller printing. Among them cracks, internal folding, external folding, rolling broken, off layer, scar, concave pits, convex bags,pock, Green Line, abrasions, slight internal and external straight, slight internal and external spiral, concave, roller printing as a general defect.

4)Mechanical properties

It includes mechanical properties at ambient temperature and at a certain temperature (thermal and Low-temperature properties) and corrosion resistance (e.g. antioxidant, water erosion, acid and alkali resistance, etc) These propertis are generally dependent on the chemical composition of steel, microstructure and the purity of steel and heat treatment methods of steel. In some cases, the rolling temperature and deformation degree of the steel tube will also affect the performance.

5) Process Performance

Expansion of steel pipe, flattening, curling, bending, ring-pull and welding performance.