|
Welding of Aluminium and its Alloys |
Welding of Aluminium and its Alloys - Aluminium is a silvery white metal and it possesses the following characteristics:
(i) It is light metal, with a density about a third that of steel or brass.
(ii) Aluminium is a very good conductor of electricity. On a weight for weight basis aluminium is a better conductor than copper.
(iii) Aluminium has higher resistance to corrosion than many other metals, owing to the protection conferred by the thin but tenacious film of oxide which forms on its surface.
(iv)Aluminium is a good conductor of heat.
(v) Aluminium is very ductile.
(vi)Aluminium is non magnetic.
(vii) Melting point of pure aluminium is about 659°C and the fusion range of most of the aluminium alloys varies between about 520 and 650°C.
Although pure aluminium is not particularly strong, it forms high strength alloys in conjunction with other metals such as Cu, Cr, Ni, Fe, Zn, Mn, Si and Mg.
|
|
(i) Some of these aluminium alloys are more than 4 times as strong as the same weight of mild steel.
(ii) They are malleable and ductile.
(iii) They exhibit toughness and become stronger at temperatures below the ordinary atmospheric range.
(iv)They do not work well at temperatures of the order of 300 to 400°c.
(v) Aluminium and its alloys can be
(a) Cast
(b) Forged
(c) Welded
(d) Extruded
(e) Rolled, etc.
|
|
|
Uses or Al and Al-alloys
The intensive demand for Al and its alloys arises chiefly from their attractive physical, mechanical and chemical properties. Aluminium and its alloys are frequently used for:
(i) Transportation industry structural framework, engine parts, trim and decorative features, hardware, doors, window frames, tanks, furnishings and fittings.
Trains, trucks, buses, automobile cars and aeroplanes use many component parts made up of aluminium alloys.
(ii) Overhead conductors and heat exchanger parts.
(iii) In food industry, aluminium alloys find applications as food preparation equipments (pans, etc.), refrigeration, storage containers, bakery equipment, shipping containers, etc.
(iv) Mangles and Wafflemolds.
(v) In architectural field, aluminium alloys find uses such as window frames, doors hardware, roofing, coping, sills, railings, fasteners, lighting fixtures, solar shading, grills, gratings, etc.
|
(vi) Cryogenic applications.
(vii) As heavy duty structures such as dragline booms, travelling cranes, hoists, conveyor supports, bridges etc.
(viii) In process industries, parts made up of aluminium and its alloys are used to handle organic chemicals, petrochemicals and drugs. Tanks, drums, pipes, heat exchangers, gratings, smoke stacks, drilling towers, precipitators, centrifuges, valves, fittings etc are produced from aluminium alloys.
|
|
|
