Several common aluminum plate deformations, what are the causes of aluminum alloy plate defects?
At present, alloy aluminum sheets are widely used in construction, industrial manufacturing, transportation, hardware accessories and many other industries.
However, due to the influence of external force or welding stress during the processing and manufacturing process, the aluminum plate usually produces a certain degree of deformation, and these deformations can usually be corrected to meet the product quality requirements.
Common deformation phenomenon of aluminum plate
1. Non-metallic press-fit
Definition: Non-metallic pressed into the surface of the strip
Features: There are obvious dot-like or long yellow-black defects on the surface
reason:
The conditions of the rolling process equipment are not clean
Rolling process lubricant is not clean
Process oil spray pressure variable
Slab surface scratches
2. Metal press-in
Definition: Metal shavings or metal fragments pressed into the surface of the strip
Features: Press the object to scrape off large and small depressions, and destroy the continuity of the surface of the board and strip
reason:
The number of hot-rolled coils is small, the edge of metal chips is cracked, and the strip falls into the plate surface after pressing
The quality of the disc trimming process is poor, resulting in burrs falling off after the rolled strip is pressed in
Rolled aluminum-bonded rolls, which are bonded to aluminum and pressed onto the slab.
The hot-rolled guide ruler was clamped too tightly, and chips fell on the slab after pressing in.
3. Start from scratch
Definition and characteristics: Where sharp things (such as plate corners, metal chips or sharp objects on equipment come into contact with the plate surface, the single-distribution scars caused by relative sliding are called scratches.
Causes: The guide plate or the flattened tape protrudes or sticks to aluminum; scratches caused by the shearing process; improper hoisting by manual inspection.
4. Scratches
Definition and characteristics: The distribution of a bunch (or group) of scars caused by the relative sliding or dislocation between the prism and the object and the contact surface of the strip surface, called scratches.
Cause: Mechanical or artificial dislocation between the layers of the aluminum plate.
5. Bruises (dents)
Definition and characteristics: The scars produced on the surface or end face of the plate, strip, etc. after the collision of objects such as aluminum plates and coils. The defect occurs on the surface or end face of the aluminum sheet, aluminum coil, and most of the metal present at the edge of the depression is extruded.
6. Sticking
Definition and characteristics: strips caused by excessive pressure between plates or strips, the surface of the strip is point-like, flake-like or band-like scars. Sticking often occurs when the upper and lower plates (or roll layers) are symmetrical, sometimes periodically.
7. Stamping (Rolling)
Definition and characteristics: There are periodic depressions on the surface of the strip. The depressions are relatively smooth.
8. Water marks
Definition and characteristics: The surface of the quenched sheet after rolling shows light white or light black irregular water marks.
9. Surface stains (flower surface)
Definition and Characteristics: Sheets with glossy and uneven color stains on the surface.
10. Surface bubbles
Definition and characteristics: irregular round or strip-shaped cavity protrusions on the surface of the strip. The raised edges are rounded and smooth. The plate is asymmetrical up and down, and the distribution is irregular.
11. Corrosion
Definition and characteristics: Defects that occur after the surface of the plate and belt is in contact with the surrounding medium, and the chemical or electrochemical reaction occurs on the surface of the plate and belt. Corrode the sheet, and the strip loses its metallic luster. In severe cases, gray-white corrosion products are produced on the surface.
12. Trace nitrates
Definition and characteristics: Nitrate medium residues and scars on the board surface after heat treatment. Nitric acid marks are irregular white patches with rough surface and no metallic luster.
13. Oil spot
Definition and characteristics: There is oil residue on the surface of the plate, and different degrees of yellow-brown spots are formed after quenching.
14. Cracks (surface cracks)
Definition and Characteristics: Cracks on the surface of a sheet or strip at right angles to the rolling direction.
15. Cracked edges
Definition and characteristics: The edges of plates and strips are fractured, and in severe cases, they are serrated.
16. Slider
Definition and characteristics: Stretch the board surface, and the stretching direction is a regular dark line at an angle of about 45°.
17. Sidebend
Definition and characteristics: The longitudinal side of the sheet, the strip presents a non-linear state that is bent to one side.
Cause: The pressure at both ends of the mill is different; the thickness of the material on both sides of the plate and strip is different.
18. Ripples
Definition: The sum of various uneven phenomena formed by uneven deformation of plates and strips.
Features: It is called edge wave at the edge and medium wave at the middle. Both are called complex waves. Both in the middle and at the edges are called double bars.
19. Dislocation of composite aluminum layer
Definition: Surface defects of strip steel formed by offset or lateral swing of hot-rolled clad aluminum sheet.
Characteristics: The defect is a neat dark band along the edge of the board. Dark yellow strip marks after heat treatment.
20. Layering
Definition and Characteristics: Due to uneven deformation. The crack layer parallel to the plate surface generated at the central end and edge of the plate is called delamination.
21. Slag layering
Definition and characteristics: Strip cracks parallel to the surface of the plate are generated in the cross section of the plate, extending along the rolling direction and distributed irregularly.
22. Stick aluminum
Definition and characteristics: rough sticking damage on the surface of the sheet and strip caused by poor lubrication performance between the roll and the surface of the sheet and strip.
23. Overburning
Definition: Heat-treating a metal at a temperature that reaches or exceeds the low-melting eutectic temperature and produces a unique microstructural phenomenon called overfire.
Features: The surface is obviously oxidized (gray or light yellow), and it is over-burned when rough or dense small bubbles. In the microstructure, thickened grain boundaries or intergranular eutectic triangles or eutectic spheres appear in the crystals.
24. Folding
Definition: Creasing, where the crease is at an angle to the direction of the curl.
Features: The pleats have bright patterns.
25. Lotion marks
Definition and Characteristics: Milky white or gray-black dotted or striped marks on the surface of a plate or strip.
26. Press Scratch
Definition and characteristics: Surface damage, such as friction, scratches, sticking, etc., pressed by a roller.
27. Bend (crease)
Definition and Characteristics: Creases of a sheet after bending and deformation.
28. Oil stick
Definition and characteristics: The residual process lubricant and other oils in the coil are oxidized during the annealing and heating process, and polymerize to form viscous asphalt, which affects the smooth unwinding of the coil.
29. Shear waves
Definition and characteristics: corrugations across the surface of the strip in the vertical calendering direction.
30. Light and dark stripes
Definition and characteristics: The structure is uneven, or there are coarse grains and the same light and dark stripes parallel to the rolling direction.
31. Copper Diffusion
Definition and characteristics: Due to the inappropriate heating system, the copper atoms in the base material of the composite aluminum plate diffuse to the grain boundaries of the composite aluminum layer to form whisker-like grain boundaries.
32. Penetrating porosity
Definition and characteristics: The surface of the board is a projection of a circular, edged or elongated cavity that runs through the full thickness of the board, with symmetry. The distribution of such bulges is irregular.
33. Friction injury
Definition and characteristics: quenching in which adjacent plates rub against each other to produce scars. The friction strips are irregular and round, destroying the natural oxide film and coating.
34. Pine branch pattern
Definition and Characteristics: Slip Lines During Rolling
35. Edge warping
Definition and Characteristics: Warping of strip edges due to rolling or shearing.
In addition to the above reasons, the deformation of aluminum plates during processing will also cause many problems in actual operation, storage, transportation, cutting and processing, so each step of the operation is very important.