Welding aluminium alloys

Two pieces of work-hardened 5000 series aluminium alloy plate were butt welded together by arc welding. After the weld had cooled to room temperature, a series of hardness measurements was made on the surface of the fabrication. Sketch the variation in hardness as the position of the hardness indenter passes across the weld from one plate to the other. Account for the form of the hardness profile, and indicate its practical consequences. 

Aluminium alloys Sensitive to contaminants requires very clean welding attacked very rapidly in concentrations near 100% or with excess acetic anhydride... 

The selection of materials for high-temperature applications is discussed by Day (1979). At low temperatures, less than 10°C, metals that are normally ductile can fail in a brittle manner. Serious disasters have occurred through the failure of welded carbon steel vessels at low temperatures. The phenomenon of brittle failure is associated with the crystalline structure of metals. Metals with a body-centred-cubic (bcc) lattice are more liable to brittle failure than those with a face-centred-cubic (fee) or hexagonal lattice. For low-temperature equipment, such as cryogenic plant and liquefied-gas storages, austenitic stainless steel (fee) or aluminium alloys (hex) should be specified see Wigley (1978). 

In the last decades, aluminium and aluminium alloys have received an increasing interest in cryogenic applications [5-7], Pure aluminium is used in the building of superconducting heat switches (see Section 4.3) because of its high switching ratio [8,9] and convenient critical field. Satisfactory procedures for welding have also been found [10,11],... 

Various investigations have been carried out on steels and aluminium alloys, in particular on the following materials AISI 316, AISI 316 L, AISI 304, Fe 410, P-A1 Mg 4,4 UNI 5452, and 08H18N10T austenite stainless steel. The investigated samples belong to base plates as welded or to vessels plates before and after exercise. 

Roberts D K and Wells A A Fusion welding of aluminium alloys, Pt V - A mathematical examination of the effect of bounding planes on the temperature distribution due to welding, Brit Weld] 1 (12) 1954 553-60. 

Aluminium alloys retain the corrosion resistance properties of pure aluminium with an increase in strength. The alloys are cast into cylinder heads and gearboxes for motor cars, and switch-boxes and luminaires for electrical installations. Special processes and fluxes have now been developed which allow aluminium to be welded and soldered. 

It has been shown that in comparison with spot welds, rivets and a variety of selfpiercing mechanical fastenings, toughened structural adhesives may yield single lap shear joints of superior energy absorption when used to bond aluminium alloy sheet the findings were confirmed in tests on full-size bonded vehicles (see Toughened adhesives, Structural adhesives). 

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