Tuesday, 29 January 2013

Aluminium Alloy 5083

Aluminium alloy 5083 contains 5.2% magnesium, 0.1% manganese and 0.1% chromium. In the
tempered condition, it is strong, and retains good formability due to excellent ductility. 5083 has
high resistance to corrosion, and is used in marine applications. It has the low density and excellent
thermal conductivity common to all aluminium alloys.

Typical Applications
require a weldable alloy of high to moderate strength, with good corrosion
resistance. Marine applications, unfired welded pressure vessels, TV towers, drilling rigs,
transportation equipment, armour plate.

Element                 %                            Element             %
Aluminium      Remainder                    Silicon           0.40 max
Magnesium       4.0 – 4.9                      Iron                0.40 max
Manganese        0.40 – 1.0                   Copper           0.10 max
Chromium         0.05 – 0.25                 Others, each   0.05 max
Others, total      0.15 max

Corrosion Resistance Alloy 5083 has excellent resistance to general corrosion, and is used in
marine applications. Resistance is excellent in aqueous solutions in the pH range 4 – 9.
The corrosion resistance of aluminium alloys relies on a protective surface oxide film, which when
damaged is readily repaired by the rapid reaction between aluminium and oxygen. However, the
high reactivity of the base metal can give rapid corrosion if the film cannot be repaired, so
aluminium alloys are not suitable for use with reducing media. Alloy 5083 can be anodised to
improve the corrosion resistance by thickening the protective surface film.
Alloy 5083 can be susceptible to exfoliation corrosion in severe applications. Material in the H116
temper is least susceptible, and passes the ASTM G66 Exfoliation Susceptibility Test (ASSET Test).
AS 1734 suggests alloy 5083 should not be used above 65 degree Centigrade.

Fabrication Aluminium 5083 is readily cold formable, as it is ductile. Forming loads and tool &
press wear are generally less than with carbon steel. For piercing and blanking the punch to die
clearance should be about 7% of the thickness per side for temper O, 7.5% for other tempers.

Welding Alloy 5083 is readily welded by the TIG and MIG processes using 5183, 5356 or 5556
filler alloys. Welding the H116 temper will reduce the tensile and yield strengths in the heat
affected zone to those of the annealed condition. Aluminium must be very dry & clean to avoid
contamination & porosity of the weld. It is essential that all traces of flux used in welding or brazing
are removed by scrubbing with hot water.

Heat Treatment Alloy 5083 is annealed at 350 degree Centigrade,time at temperature and cooling rate are unimportant. Stress relief is rarely required, but can be carried out at about 220 degree Centigrade. If loss of strength is of concern, stress relief tests should be conducted.

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