EnglishViews: 234 Author: Julong Publish Time: 2023-10-11 Origin: aluminum panel systems manufacturer
According to the standard estimation approach, the direct economic loss caused by corrosion in China amounts to around 3% of GDP (gross national product) each year, and the steel used due to corrosion accounts for approximately 1/3 of annual output, which accounts for approximately 1/1 of overall output. The number ten is not recyclable.
Pitting corrosion, intergranular corrosion, stress corrosion cracking, and layered corrosion are the most common types of corrosion in aluminum and aluminum alloys. Among the deformed aluminum alloys, the 6000 series alloy has the highest production. Although its corrosion resistance is not as good as that of the 1000, 3000, and 5000 series aluminum alloys, it is far superior to that of the 2000 and 7000 series aluminum alloys. The intergranular tendency of 6000 series alloys is also relatively high, and the intergranular corrosion susceptibility of 6000 series aluminum alloy materials utilized for essential structures should be assessed. Click here for Aluminum-plastic Composite Panel.
Aluminum corrosion can be split into two types based on the appearance of the corrosion: general corrosion and local corrosion. The former is known as uniform corrosion, sometimes known as general corrosion, and it signifies that the material's exposed surface is uniformly eroded and destroyed.
Metal corrosion in an alkaline solution is typical uniform corrosion, such as alkaline washing; the corrosion consequence is that the metal surface thins at roughly the same pace, reducing quality. It should be mentioned. However, consistent corrosion does not exist, and the thickness loss varies from location to location. Localized corrosion refers to corrosion that occurs only in a specific area or component of a structure and can be classified as follows:
Pitting corrosion occurs in relatively localized areas or parts of the metal surface, expanding caves or pits and even generating perforations. Pitting corrosion occurs when the diameter of the pit opening is less than the depth of the pit; pitting corrosion occurs when the diameter of the pit opening is greater than the depth of the pit. There is no clear distinction between pitting and pitting.
Aluminum pitting corrosion in chloride-containing aqueous solutions. Pitting corrosion is the most prevalent type of aluminum corrosion, and it is caused by the potential of a specific area of aluminum being different from that of the substrate or by the presence of impurities whose potential is different from that of the aluminum substrate.
This is a type of corrosion that happens at the grain boundaries of metals or alloys when the grains or crystals themselves are not significantly corroded, drastically lowering mechanical characteristics and leading to structural damage or accidents.
The grain border is particularly active under specific situations, such as impurities at the grain boundary or an increase or reduction of an alloying element at the grain boundary, which causes intergranular corrosion. That is, there must be a thin layer of aluminum on the grain boundary for the remainder of the metal. Corrosion occurs preferentially in a portion of the electronegative area. In hydrochloric acid and high-temperature water, such corrosion can occur in high-purity aluminum. Intergranular corrosion affects Al-Cu, AI-Mg-Si, Al-Mg, and Al-Zn-Mg alloys.
Galvanic corrosion is another type of aluminum corrosion. Galvanic corrosion occurs when a less reactive metal, such as aluminum (anode), comes into contact with a more reactive metal, such as copper (cathode), in the same environment or when conductors are linked, producing a galvanic couple and inducing current flow.
Bimetallic corrosion and contact corrosion are other terms for galvanic corrosion. Aluminum's natural potential is extremely negative. Aluminum is always anodic when it comes into contact with other metals, and corrosion is hastened. Almost all aluminum and aluminum alloys are susceptible to galvanic corrosion. Galvanic corrosion is more severe when the potential difference between the two metals in contact is higher. It should be mentioned that in galvanic corrosion, the area factor is extremely essential, and the most unfavorable pairings are a large cathode and a small anode.
The coexistence of tensile tension and particular corrosive media causes stress corrosion cracking. Stress can be external or internal, and it can be induced by deformation during processing, significant temperature changes during quenching, or volume changes caused by changes in internal structure.
Residual tension is also created by riveting, bolt tightening, press fit, and shrink fit. tension corrosion cracking occurs when the tensile tension on the metal surface approaches the yield strength Rp0.2. Aluminum alloy-thick plates from the 2000 and 7000 series are available. When processing airplane components, residual stress will be formed during quenching and should be reduced by pre-stretching before age treatment to minimize distortion or even carry into the parts.
Debonding is sometimes referred to as delamination, exfoliation, and layered corrosion. It is a particular corrosion form of alloys from the 2000, 5000, 6000, and 7000 classes. Extruded materials are more prone to it. When it happens, it can look like mica. Layer by layer, peel away.
It is a type of corrosion that can develop in a worm-like form under aluminum paint film or other coatings, although no such corrosion has been seen under anodized film, which is commonly used to coat aviation aluminum structures and architectural or structural aluminum parts. Material composition, pre-coating pretreatment, and environmental conditions all influence filiform corrosion. Temperature, humidity, chlorides, and other environmental conditions are examples.
