Classification of aluminium sheet defects (2)

Classification of aluminium sheet defects (2)

(6) sticky injury

Definition and characteristics: due to the plate or strip between the roll layer adhesion caused by the plate, with the surface is dotted, flaky or strip-shaped scars. Sticky injury is often produced when the upper and lower aluminum sheet (or volume layer) is symmetrical, sometimes periodic.

The main reason: annealing temperature is too high.

(7) flower face

Definition and characteristics: quenching the surface of the plate occurrence of gloss and colour uneven stains.

Main causes: quenching and cleaning with acid, alkali concentration is too low; quenching and cleaning with acid, alkali wash is not sufficient; quenching and washing is not sufficient.

(8) Oil stain

Definition and characteristics: oily stains on the surface of aluminium plates and strips.

Main causes: shear, straightening and other processes in the equipment lubricating oil pollution plate and strip material.

(9) Corrosion

Definition and characteristics: plate, strip surface contact with the surrounding media, chemical or electrochemical reaction occurs in the plate, strip surface local damage phenomenon. Corrosion of aluminium plate, strip surface loss of metallic lustre, serious when the surface of the corrosion products produced gray-white.

The main reasons: quenching and washing, the surface of the plate residual acid, alkali, nitrate salt; plate, strip production, packaging, storage, transport, due to the climate of moisture or water droplets infiltration surface; process lubricants contain water or alkaline; compressed air contains water.