Specialty aluminum panels are mainly aluminum-manganese series and aluminum-magnesium series alloys. As their age-hardening effect is not obvious, they are not suitable for strengthening by heat treatment, but their strength and hardness can be improved through work hardening.
The main performance characteristics of this alloy are moderate strength, good plasticity and corrosion resistance, so it is known as rust-proof aluminum with good weldability - the most widely used aluminum alloy in welded structures.
Specialty aluminum panels are collectively called rust-proof aluminum, because the alloying elements in them increase their corrosion resistance. Aluminum-manganese alloys include 3003, 3004 and 3A21: the first is widely used, the second is commonly used for can bodies, and the latter is used where high conductivity requirements apply, such as wires. Aluminum-magnesium alloys, ranked by magnesium content, include 5005, 5252, 5251, 5050, 5052, 5754, 5083, 5056, 5086, etc., which are respectively used in industries with high corrosion resistance and strength requirements, such as shipbuilding, containers and metro high-speed trains. High-pressure machined aluminum alloys have good corrosion resistance in atmosphere, water and oil.
Specialty aluminum panels mainly include aluminum-manganese and aluminum-magnesium series alloys that cannot be strengthened by heat treatment. Rust-proof aluminum alloys with manganese content of 1.0%-1.7% have high corrosion resistance. However, the magnesium content in aluminum-magnesium rust-proof aluminum alloys generally does not exceed 7%. As magnesium content increases, the strength of the alloy increases - sigma-0 up to 400 MPa - while plasticity decreases. This rust-proof aluminum alloy is usually used in the annealed, cold-work-hardened or semi-cold-work-hardened state. With low strength, good plasticity, easy pressure processing, good corrosion resistance and weldability, it is especially suitable for manufacturing deep-drawn parts and welded parts under low loads, and parts working in corrosive media such as oil tanks and pipelines. Another rust-proof aluminum alloy is the aluminum-zinc-magnesium-copper alloy, which can be strengthened by heat treatment. It has high tensile strength, excellent seawater corrosion resistance, good fracture toughness, low notch sensitivity and good formability. Because it contains manganese, aluminum-manganese alloy has higher corrosion resistance and strength than pure aluminum, good weldability and plasticity, but poor machinability. Due to the effect of magnesium, aluminum-magnesium alloys have lower density than pure aluminum, higher strength than aluminum-manganese alloys, and better corrosion resistance.
The age-hardening effect of specialty aluminum panels is very weak, so they can only be hardened by cold deformation, but plasticity will decrease significantly. Aluminum-manganese alloy is one of the most widely used rust-proof aluminum alloys. The alloy has high strength, especially high fatigue strength; good plasticity and corrosion resistance; cannot be strengthened by heat treatment; semi-cold-hardened state has good plasticity, cold-hardened state has low plasticity; good corrosion resistance and weldability; but poor machinability and polishability.
