(1) In air i and oxidizing aqueous medium, the surface of aluminum is more likely to produce a dense alumina passivation film, and it has good corrosion resistance in some oxidizing media. In high temperature concentrated nitric acid, the corrosion resistance of pure aluminum is better than that of stainless steel. Aluminum is often used as a corrosion-resistant container material.
(2) For some media that are not very corrosive but require iron pollution prevention, such as chemical fiber production media, alumunium foil has good corrosion resistance, and there is no iron pollution material. Karena itu, aluminum materials are often used as iron pollution prevention materials. material of the container. Other non-ferrous metal containers are also resistant to iron contamination, but aluminum is the cheapest.
(3) The minimum design temperature of aluminum foil container can reach -269℃. Aluminum is often used as a material for cryogenic containers. When the magnesium content in the aluminum-magnesium alloy is high, the intermetallic compounds Mg2Al3 and lMg5Al8 will be precipitated between the products, which will make the aluminum-magnesium alloy sensitive to stress corrosion in some media. Corrosion, so the specified design temperature of aluminum-magnesium alloys with magnesium content exceeding 3% does not exceed 65 °C. Excessive precipitates will also reduce impact toughness, so aluminum-magnesium alloys and their welded joints with magnesium content exceeding 3% should be tested for impact toughness. Impact toughness testing is not required for other aluminum and aluminum containers, including cryogenic aluminum containers.
(4) Due to the high strength, good plasticity and good weldability of the aluminum-magnesium-silicon alloy in the solid solution aging state, the welded joint can still maintain a high strength after welding, so it is often used as a high-strength aluminum alloy for containers. The specified non-proportional elongation stress of aluminum, especially pure aluminum, is very low, and plastic deformation occurs under small loads. When using and transporting aluminum containers, attention should be paid to collision and deformation.
(5) In order to obtain good plasticity, the deformed aluminum materials of pure aluminum, aluminum-manganese alloy and aluminum-magnesium alloy are only used in the annealed state or the hot working state, and the cold working state is not used. For the welded joints of aluminum in the hot working state, the welding heat has an annealing effect on the heat affected zone, so the allowable stress is only the allowable stress of the aluminum in the annealed state. Only aluminum-magnesium-silicon alloys and aluminum-copper alloys are in solution aging state to ensure their high strength.