Basic types of corrosion of aluminum and aluminum alloys

Basic types of corrosion of aluminum and aluminum alloys

(1) Pitting corrosion Corrosion, also known as pore corrosion, is a localized corrosion pattern in which a needle tip, a dot, or a hole is formed on a metal. Pitting corrosion is a unique form of anodic reaction and is an autocatalytic process in which the conditions created by the corrosion process in the pitting hole are both sufficient and sufficient to sustain corrosion.

(2) Uniform corrosion of aluminum In a solution of phosphoric acid and sodium hydroxide, the oxide film thereon is dissolved, uniform corrosion occurs, and the dissolution rate is uniform. The temperature of the solution increases, the concentration of the solute increases, and the corrosion of aluminum is promoted.

(3) Crevice Corrosion Corrosion is a type of local corrosion. The metal component is in the electrolyte solution, because the metal forms a gap between the metal or the metal and the non-metal, and the width thereof is sufficient to make the medium immersed and the medium is in a stagnant state, so that the corrosion inside the gap is intensified, which is called crevice corrosion.

(4) Stress corrosion cracking (SCC) SCC occurs under certain conditions: they are: a certain tensile stress or residual stress inside the metal. The SCC of aluminum alloy was discovered in the early 1930s. A type of failure of a metal under the combined action of stress (tensile or internal stress) and corrosive media is called SCC. SCC is characterized by the formation of corrosion & mdash; mechanical cracks that can develop along grain boundaries or through grain extension. Since the crack propagation is inside the metal, the strength of the metal structure is greatly reduced, and sudden damage occurs in severe cases.