5xxx Al-Mg alloys are deformed aluminum alloys mainly composed of Mg elements, among which 5454 aluminum alloy is one of the typical grades. 5454 aluminum alloy has many advantages such as medium strength, good welding performance, excellent processing and forming performance and good corrosion resistance.
It has been widely used in the fields of automobile manufacturing, canning industry, electronic communication and light industrial building materials, and it is also one of the potential main materials for structural parts of seawater desalination devices in future marine engineering. What is its annealing process?
With the increase of annealing temperature, the yield strength and tensile strength of 5454 aluminum alloy gradually decrease, and the elongation gradually increases, but when the annealing temperature is ≤90 ℃, there is only a slight change.
When the annealing temperature rises to 120-150 ℃, the yield strength decreases greatly, the change in tensile strength is small, and the elongation increases to 13% at 150 ℃. When the annealing temperature rises to 180-240℃, the properties change slowly.
When the annealing temperature reaches 270 ℃, the yield strength decreases greatly and the elongation increases greatly, but the change in tensile strength is small; at 300 ℃, the yield strength and tensile strength sharply decreased, the elongation increased sharply, and the performance reached the required value of the 5454-O state standard (Rp0.2≥85 MPa, Rm is 215-285 MPa, A≥17%).
At 330 ℃,the yield strength and tensile strength decreased slightly, and the elongation increased slightly; at 360-570 °C, the properties changed slowly, but when the annealing temperature reached 600 °C, the yield and tensile strength decreased slightly , while the elongation rapidly decreases to 15.5%.
When the annealing temperature is less than or equal to 90 °C, the properties change little, and the grain size does not change significantly, indicating that this temperature range does not have much influence on the properties of the 5454 aluminium.
In the range of 120-270 ℃, with the increase of annealing temperature, a large number of dislocations formed in the cold rolling process can move or disappear, part of the internal stress is released, so that the yield strength and elongation have a large change. However, the tensile strength and grain structure of 5454 aluminum change little, and slight recovery and recrystallization occur.
At 270-300 ℃, the internal structure of the alloy begins to nucleate and grow, the fibrous structure basically disappears, the small-angle grain boundaries are swallowed, the grains recrystallize, and the performance meets the O state standard requirements.
At 330℃, the strength is further reduced, the elongation is further increased, and recrystallization is basically completed; at 360-570 °C, the performance changes little, the grain grows slightly, and the residual small-angle grain boundaries are completely swallowed; at 600 ℃, the performance is abnormal, the crystal grains are re-spheroidized to form equiaxed crystals, and remelted balls are formed in some areas, and overburning occurs.
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