Common steel defects and related terms
Keywords: steel defects
Common steel defects and related terms are introduced by seamless pipe manufacturers as follows:
1. Roundness: the circular section of the rolled material, such as the cross section of round steel and round steel pipe, the degree of diameter difference in each direction
2. Due to unreasonable mold design or manufacture, improper extrusion process, mold and extrusion cylinder, lubrication, etc., the metal flow velocity difference at each point is too large, resulting in deformation of the profile, due to excessive internal stress or traction force. Excessive size leads to dimensional deviation of profile tensioning
3. Bending: the degree to which the rolling piece is not straight in the length or width direction, and is curved
4. Sickle bending: the phenomenon that the length direction of the steel plate (or steel strip) bends to one side on the horizontal plane
5. Curvature of gourd and scoop: The steel plate (or steel strip) has undulations in the length or width direction at the same time, making it a "wave" or "boat"
6. Out of square and out of distance: the material of square and rectangular section is the edge range or the diagonal range of the section
7. The reverse side: the strip is twisted into a spiral along the longitudinal axis
8. Marking (row): straight groove shape, the phenomenon that the bottom of the groove is distributed on part or all of the length of the steel can be seen by the naked eye
9. Cracks: generally linear, sometimes Y-shaped, and most of them are in the direction of stretching, but there are also other directions, generally the opening is an acute angle
10. Scar: one is sticking to the steel body, and it is not easy to fall off when it sticks to the surface; the other is not sticking to the steel body, but it is easy to fall off when it sticks to the surface
11. Folding: There are obvious folding lines on the surface of the steel.
12. Corrosion: rust on the surface, color from apricot yellow to black red, rust removal, severe corrosion pitting
13. Hairline: The surface hairline has a very shallow depth, a small width, and a very fine hairline, which generally extends along the rolling direction to form fine lines.
14. Delamination: The local metal structure of the section steel is obviously separated, and in severe cases, it is divided into 2-3 layers, and inclusions can be seen between the layers
15. Bubble: a convex surface with irregular distribution of the surface size, the outer circle is relatively smooth, most of them are called, and some are not called. After pickling, the surface is smooth and shiny, and the shear section is layered
16. Pocks (pits): There are local or continuous rough surfaces on the surface of the profile, with pits of different shapes and sizes distributed, which are seriously similar to orange peel, larger and deeper than the pits
17. Oxidation color: the surface of the steel plate (or steel strip) after annealing is light yellow, dark brown, light blue, dark blue or bright gray, etc.
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