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Aluminium, wrought alloys other than 2000 series aluminium, cast alloys of the silicon type: −0.90 Aluminium, cast alloys (other than silicon type); cadmium, plated and chromate: −0.95 Hot-dip-zinc plate; galvanized steel: −1.20 Zinc, wrought; zinc-base die-casting alloys; zinc plated: −1.25 Magnesium and magnesium-base alloys; cast or ...
High strength aluminium alloys, especially when extruded or otherwise subjected to high degree of working, can undergo exfoliation corrosion (metallurgy), where the corrosion products build up between the flat, elongated grains and separate them, resulting in lifting or leafing effect and often propagating from edges of the material through its ...
Galvanic corrosion of an aluminium plate occurred when the plate was connected to a mild steel structural support.. Galvanic corrosion occurs when two different metals have physical or electrical contact with each other and are immersed in a common electrolyte, or when the same metal is exposed to electrolyte with different concentrations.
Stress corrosion cracking (SCC) is the growth of crack formation in a corrosive environment. It can lead to unexpected and sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. SCC is highly chemically specific in that certain alloys are likely to undergo SCC only when exposed to a ...
The unshaded bars indicate the location on the chart of those steels when in acidic/stagnant water ( like in the bilge ), where crevice-corrosion happens. Notice how the *same* steel has much different galvanic-series location, depending on the electrolyte it's in, making prevention of corrosion .. more difficult.
In metallurgy, exfoliation corrosion (also called lamellar corrosion [1]) is a severe type [2] of intergranular corrosion that raises surface grains from metal by forming corrosion products at grain boundaries under the surface. It is frequently found on extruded sections where grain thickness is not as thick as the rolled grain.
In brief, corrosion is a chemical reaction occurring by an electrochemical mechanism (a redox reaction). [1] During corrosion of iron or steel there are two reactions, oxidation (equation 1), where electrons leave the metal (and the metal dissolves, i.e. actual loss of metal results) and reduction, where the electrons are used to convert oxygen and water to hydroxide ions (equation 2): [2]
In the aluminum industry, the process is also called chemical film [13] or yellow iridite, [13] Commercial trademarked names include Iridite [13] and Bonderite [14] (formerly known as Alodine, or Alocrom in the UK). [15] The main standards for chromate conversion coating of aluminium are MIL-DTL-5541 in the US, and Def Stan 03/18 in the UK.