(1) definition and characteristics of peeling: local peeling on the surface of strip. The layers are thinner and break up. The main causes: Heating time is long, surface serious oxidation. 

(2) definition and characteristics of crack: surface cracking of plate and strip. The main reasons are as follows: the heating temperature of the casting is too high, and the pass processing rate is too high. 

(3) definition and characteristics of SPLIT EDGE: the edge of plate and strip is broken and serrated when serious. The main causes are as follows: low temperature of casting block and poor plasticity of metal; improper control of Roll Profile, resulting in tensile stress at the edge of plate and Strip; incomplete aluminum coating at the side; excessive pass processing rate; improper roll edge technology; improper coiling tension adjustment during cold rolling. 

(4) the definition and characteristics of delamination: A crack on the Cross section of a sheet which is parallel to the surface of the sheet and extends in the direction of calendering. The main reasons are: improper distribution of hot rolling pass reduction, excessive reduction, uneven heating or high or low heating temperature of INGOT. 

(5) definition and characteristics of scratch: A bundle (or group) of marks on the surface of a plate or strip caused by debris or aluminum powder in contact with the surface of the plate, edges and surfaces between the materials, or relative slippage or dislocation between the surfaces after contact. The main causes are: Friction between plate and Strip when they come into contact with guide and equipment in the process of production; irregular end face of cold rolled coil, which causes dislocation between layers during annealing turnover in vertical furnace; interlayer dislocation during uncoiling; loose coil. 

(6) definition and characteristics of a scratch: a single strip of damage caused by a sharp object (such as a corner, a metal chip, or a sharp object on a piece of equipment) in contact with the surface of a plate during relative sliding. The main causes: Hot Rolling Mill Roll Table, guide plate on the sticky aluminum; Cold Rolling Mill Guide, Flatten Roll and other prominent sharp objects.

 (7) definition and characteristics of indentation: surface defects, such as scratches, scratches, and sticky aluminum, which have been rolled by rollers. 

(8) definition and characteristics of EMULSION MARKS: The marks on the surface of plate and strip are milky white or gray-black. The main causes: High temperature emulsion, the emulsion did not blow clean; emulsion temperature is too high, the emulsion sintering on the plate. 

(9) definition and characteristics of METAL INDENTATION: metal chips or metal fragments are pressed into the surface of plates or strips. The surface of the plate and strip is broken because of the different size of the indentation after being scraped off. The main causes are as follows: The roll side has less passes, the metal chips or strips of the cracked side fall on the plate surface and are rolled in; after the roll sticks aluminum, its aluminum is rolled in the plate surface; The quality of the cutting edge of the disc is poor, resulting in burrs falling on the Strip and being rolled in. 

(10) definition and characteristics of non-metallic indentation: Indentation Plate, non-metallic inclusions with surface. The non-metallic impactor has a point shape, a long strip shape or an irregular shape, and the color varies with the impactor. The main causes are: The production equipment or the environment is not clean; the Rolling Process Lubricant is not clean; non-metallic Foreign Bodies Exist in the billet; the surface of the slab is scratched, and the sludge and other non-metallic foreign bodies remain in the dent; during the production process, non-metallic foreign bodies fall on the surface of plate and strip.

(11) definition and characteristics of impression (roll impression) : There are single or periodic depressions or protrusions on the surface of plate or strip. A smooth depression or projection. The main causes: Roll, Work Roll, packaging coating roll and plate, strip surface with metal debris or dirt; other process equipment (such as: calender, straightening machine, feeding roll, guide roll) surface defects or adhesion dirt; The surface of the sleeve is not clean, not smooth and there is a smooth bump; when winding, Aluminum Plate, with adhesion foreign body. 

(12) definition and characteristics of ADHESIONS: Marks on the surface of a plate or strip caused by adhesion between sheets or coils. The upper and lower plate (or coil layer) is symmetrical and sometimes periodic when the adhesive damage occurs. The main causes are as follows: The plate and strip are subjected to local pressure under hot condition; the tension is too high during cold rolling and coiling, which is produced by annealing; the tension is too high during hot rolling and coiling. 

(13) definition and characteristics of oil stains: Oily stains on the surface of plates and strips. The main causes are: Residual Rolling oil on the surface of plate and strip mixed with dust, aluminum powder or impurities; high viscosity lubricating oil mixed in the rolling oil. 

(14) the definition and characteristics of corrosion: the surface of plate and strip is in contact with the surrounding medium, and the surface of plate and strip is locally destroyed after chemical or electrochemical reaction. The surface of corroded plate and strip loses metal luster and produces gray corrosion product on the surface when it is serious. The main causes are: improper production, packing, storage and transportation of plates and strips due to humid weather or water dripping on the surface; moisture content in process lubricants or alkaline; Moisture Content in Compressed air and thickness gauge. 

(15) definition and characteristics of oil stain: residual oil stain on plate and Strip, Pale yellow, brown and Yellow Brown stain formed after annealing. The main reasons are: The physical and chemical index of the rolling oil is not suitable, the cold rolling is not clean, the residual oil is too much, in the annealing process, the residual oil can not completely volatilize, the high viscosity oil such as the mechanical lubricating oil drops on the surface of the plate and strip, have not been cleaned up. 

(16) DEFINITION AND CHARACTERISTICS OF ALUMINIUM CLADDING DISLOCATION: surface defect of aluminium clad plate or strip caused by deviation or transverse swing of aluminium clad plate during hot rolling. The defect is a dark strip along the edge of the plate, which is dark yellow after heat treatment. The main causes are as follows: The aluminum clad plate is not put straight; the roll edge is too large when welding the aluminum clad plate on the side, which causes the aluminum clad plate to shift; when hot rolling, the feeding of the cast block is not correct; when trimming, the shearing width on both sides is not equal, and the shearing quantity on one side is small; Unsoldered. 

(17) definition and characteristics of adhesive aluminum: Adhesive aluminum powder on the surface of plate and strip. Sticky Aluminum Plate, strip surface rough, non-metallic luster. The main reasons are as follows: High Ingot temperature during hot rolling, improper rolling process, large pass reduction and high rolling speed, poor performance of process lubricant, improper brush roll process. 

(18) the definition and characteristics of transverse wave: the ripple on the surface of plate and strip in the vertical rolling direction, the thickness of the ripple changes suddenly. Main Causes: rolling process in the middle of the shutdown, or faster adjustment reduction.

 (19) the definition and characteristics of the pattern of pine branches: The ripple on the surface of transverse plate and strip in the direction of vertical calendering, and the sudden change of thickness at the ripple. The main causes are poor lubrication, excessive pass reduction during cold rolling, and low tension, especially low post tension.

(20) definition and characteristics of small black strips (black spots) : Black Linear or dotted defects on the surface of a plate or strip distributed along the direction of rolling. The main causes are: Poor Lubrication of the process; dirty lubricant; scratch on the surface of the plate and strip; dirty guide way through the plate and strip; segregation on the surface of the cast-rolled strip or incomplete milling of the hot-rolled cast-block; inclusion in the metal; Produce a large number of alumina powder, and pressed into the metal, further rolling to produce black strip; brush roll process is not appropriate. 

(21) the definition and characteristics of bright and dark stripe: Because of the uneven roughness of the surface of the plate and strip, the width and width of the bright print on the surface of the plate and strip are different. The main reasons are as follows: Poor grinding quality of Roller; Poor Lubrication of process; rolling narrow material first and then wide material.

 (22) definition and characteristics of holes: Holes or holes in perforated plates or strips. The main reasons are as follows: There are stick, scratch and hole before rolling, and the pressed objects fall off after rolling.

 (23) definition and characteristics of wave: A general term for various unevenness of plate and strip due to non-uniform deformation. The waves generated at the edges of a plate or strip are called edge waves, the waves generated in the middle are called middle waves, and the waves neither in the middle nor on either side between the middle and the edge are called second rib waves, smaller, usually circular waves are called breaking waves. The main causes are: unbalanced adjustment of roll gap, unreasonable control of roll profile, uneven lubrication and cooling, uneven deformation of plate and strip, unreasonable distribution of pass reduction, poor shape of incoming material plate, uneven use of coiling tension. 

(24) definition and characteristics of warping: After rolling or Shearing, the edge of the Strip is warping. The main reasons are: too much reduction during rolling and uneven distribution of lubricating oil during rolling.

 (25) definition and characteristics of raised edge: surface creases produced during the CRIMP of Strip. Main Causes: Thick Head; Bad Underlay; improper crimp tension; sleeve is not round or has edges. 

Source: Al Bao

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