What are the common forms of corrosion on Aluminum Die Casting?

1. Chemical corrosion: Some of the well-known problems related to Aluminum Alloy Die Casting include chemical corrosion when the product is directly exposed to acids, alkalis, and other chemicals. It is found that aluminum reacts with this chemical to produce soluble salts or compounds and suffers from material loss and /or performance detrimentation.

2. Electrochemical corrosion (bimetallic corrosion): When the metal aluminum comes into contact with other metals with dissimilar electrochemical potential (such as iron or copper and so on) in a moist climate, an electrochemical cell is created and the aluminum will be corroded as the anode of the battery. This phenomenon is quite conspicuous in the die-casting of aluminum and the assembly of various other metallic parts.

3. Pitting corrosion: The oxide film on the surface of aluminum may be simply damaged at some point in time in some environment: seawater containing Cl-ions or salt spray environment, such that small corrosion pits form there. These pitting corrosion pits will continue to become deeper thus leading to localized thinning and cracking and consequently loss of strength.

4. Crevice corrosion: When the Aluminum Casting Die surface there are crevices, cracks fasteners, and other structures, the crevice may accumulate moisture and corrosive substances, form of local electrochemical corrosion environment, and accelerate the corrosion process.

5. Stress corrosion cracking (SCC): In a given corrosive environment, such as in automotive applications, if an Aluminum Die Casting is exposed to tensile stress the material may crack even if the stress is less than the material’s yield strength. Depending on the nature, of the alerts, cracking can happen along the grain boundaries or within the grains and result in abrupt failure.

6. Environmental corrosion: In high humidity, salt spray, industrial atmospheres, or marine environments, aluminum die castings may suffer accelerated corrosion. The combined effect of salt and moisture can break down the protective film of aluminum and accelerate the corrosion process.

To avoid or reduce these types of corrosion, various precautions can be taken such as the application of anticorrosive coatings, anodizing, plating, and other surface protection treatments; the use of aluminum alloys with improved corrosion resistance; the minimization of the number of crevices or concentration of stress; and control of conditions such as dryness or use of inhibitors if necessary. Other preventive measures include constant checking of the Aluminum die castings and management of minor corrosion that may develop.