Classification of Aluminium Alloys

Aluminium alloys are further subdivided, depending on whether or not an alloy can be hardened by the addition of alloying elements, as is the case with 

The addition of further alloying elements will always cause hardening, but not all elements have the same hardening effect. Hardening will also depend on whether the solute atoms are present in solid solution or as particles. Alloy hardening can be divided into 

It should be noted that age-hardenable alloys can be strengthened by the use of a suitable heat treatment whereas the same heat treatment of alloys which are not age-hardenable leads to a loss in strength. 

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In addition to examining pre-exposure effects, the slow strain-rate testing technique has been used increasingly to examine and compare the stress-corrosion susceptibility of aluminium alloys of various compositions, heat treatments and forms. A recent extensive review draws attention to differences in response to the various groups of commonly employed alloys which are summarised in Fig. 8.57. The most effective test environment was found to be 3 Vo NaCl -F 0.3 Vo HjOj. The most useful strain rate depends upon the alloy classification. 

Standard classification of resistance to stress-corrosion cracking of heat-treatable aluminium alloys... 

A decree of the French Home Secretary from June 30, 1983 on the classification of construction materials according to their fire resistance and on the definition of test methods has rated common metals such as aluminium alloys and steel MO , which means that under the conditions of a fire, these materials are considered to be incombustible. 

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