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.

Tuesday, 4 December 2012

Aluminium Welding in Marine Industry

Aluminium Welding in Marine Industry

Marine industry Or Shipbuilding industry using Aluminium as an alternate for steel for manfacturing of ships.

Aluminium is of 1/3rd of weight to steel, ease of welding, faster production, lighter ships resulting fast ships or fast patrol vessels.

Generally  AA5083, AA 5086, AA 5383 & AA6082 used in marine industry with different heat temper & grade as per requirement.

Mig & Tig welding is used in Marine industry frequently.

Automation of welding at some extent is possible by use of robots.

For Mig welding 5556 & 5183 filler wire is used  with Helium- Argon (80%-20%)  gas shielding. Gas flow will be in the range of 16-25 lpm (litre per minute).

For Tig Welding 4043 filler wire is used with Argon (99.999 %) gas shielding. Gas flow will be in the range of 6-14 lpm (litre per minute).

Aluminium welding Needs Special Precautions. Few of them are:-

1. Edge prepared should be cleaned just before welding by buffing wheel & acetone both.
2. Correct current & voltage settings must be choosed according to plate thickness.
3. Gas flow will be according to reuirement & positon of welding.
4. welding should be avoide in very moist & windy condition,
5. It must be protected from direct wind draft.

Aluminium Uses in Real World

Aluminium Uses in Real World

Aluminium is the most widely used non-ferrous metal. Global production of aluminium in 2005 was 31.9 million tonnes. It exceeded that of any other metal except iron (837.5 million tonnes).Forecast for 2012 is 42–45 million tonnes, driven by rising Chinese output.

Aluminium is almost always alloyed, which markedly improves its mechanical properties, especially when tempered. For example, the common aluminium foils and beverage cans are alloys of 92% to 99% aluminium. The main alloying agents are copper, zinc, magnesium, manganese, and silicon (e.g., duralumin) and the levels of these other metals are in the range of a few percent by weight.

1.   Transportation (automobiles, aircraft, trucks, railway cars, marine vessels, bicycles, etc.) as sheet tube, castings, etc.
2.    Packaging (cans, foil, etc.)
3.    Construction (windows, doors, siding, building wire, etc.).
4.    A wide range of household items, from cooking utensils to baseball bats, watches.
5.    Street lighting poles, sailing ship masts, walking poles, etc.
6.    Outer shells of consumer electronics, also cases for equipment e.g. photographic equipment.
7.    Electrical transmission lines for power distribution
8.    MKM steel and Alnico magnets
9.    Super purity aluminium (SPA, 99.980% to 99.999% Al), used in electronics and CDs.
10.   Heat sinks for electronic appliances such as transistors and CPUs.
11.  Substrate material of metal-core copper clad laminates used in high brightness LED lighting.
12.  Powdered aluminium is used in paint, and in pyrotechnics such as solid rocket fuels and thermite.
13.  Aluminium can be reacted with hydrochloric acid or with sodium hydroxide to produce hydrogen gas.
14.  A variety of countries, including France, Italy, Poland, Finland, Romania, Israel, and the former Yugoslavia, have issued coins struck in aluminium or aluminium-copper alloys.
15.  Some guitar models sport aluminium diamond plates on the surface of the instruments, usually either chrome or black. Kramer Guitars and Travis Bean are both known for having produced guitars with necks made of aluminium, which gives the instrument a very distinct sound.

Aluminium is usually alloyed – it is used as pure metal only when corrosion resistance and/or workability is more important than strength or hardness. A thin layer of aluminium can be deposited onto a flat surface by physical vapour deposition or (very infrequently) chemical vapour deposition or other chemical means to form optical coatings and mirrors

What is Aluminium

What is Aluminum (Al) : A Quick glance

Atomic weight : 26.981
Atomic Number : 13

Physical Properties

It is a relatively soft, durable, lightweight, ductile and malleable metal with appearance ranging from silvery to dull gray, depending on the surface roughness. It is nonmagnetic and does not easily ignite. A fresh film of aluminium serves as a good reflector (approximately 92%) of visible light and an excellent reflector (as much as 98%) of medium and far infrared radiation. The yield strength of pure aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel. It is easily machined, cast, drawn and extruded.

Chemical Properties

Corrosion resistance can be excellent due to a thin surface layer of aluminium oxide that forms when the metal is exposed to air, effectively preventing further oxidation. The strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is also often greatly reduced by aqueous salts, particularly in the presence of dissimilar metals.
Owing to its resistance to corrosion, aluminium is one of the few metals that retain silvery reflectance in finely powdered form, making it an important component of silver-colored paints. Aluminium mirror finish has the highest reflectance of any metal in the 200–400 nm (UV) and the 3,000–10,000 nm (far IR) regions; in the 400–700 nm visible range it is slightly outperformed by tin and silver and in the 700–3000 (near IR) by silver, gold, and copper.