Aluminium high strength

Fig. 1.10 Grain structure of a wrought high-strength precipitation-hardening aluminium alloy showing potential crack growth paths...

Fig. I.I2 Curves showing the relationship between strength, stress-corrosion susceptibility and heat treatment for a high-strength precipitation-hardening aluminium alloy...

Composites of aluminium alloy with a thin cladding on one or both surfaces of a more anodic aluminium alloy or pure aluminium, enable sheet, plate and tube to be produced with special combinations of strength and corrosion resistance appropriate to service conditions. Although originally applied to high strength aircraft alloys, this principle of cladding is now utilised in several important industrial applications. 

Sandoz, G., In Stress Corrosion Cracking in High Strength Steels and in Titanium and Aluminium Alloys, Ed. B.F. Brown, Naval Research Laboratory, Washington, pp. 79-145, (1972)... 

Stress-corrosion cracking occurs in certain aluminium alloys which have been developed for medium and high strength by employing variations in composition, cold work and heat treatment The main alloys are based upon Al-Mg, Al-Mg and Al-Cu, but stress corrosion also occurs in Al-Ag, Al-Cu-Mg, Al-Mg-Si, Al-Zn and Al-Cu-Mg-Zn alloys. It has... 

Three broad classes of aluminium alloys will be considered here the heat-treatable high-strength aluminium-copper 2000 series and aluminium-zinc-magnesium 7000 series alloys and the non-heat-treatable lower strength aluminium-magnesium 5000 series alloys which are used extensively in marine applications. 

The main application of sprayed aluminium is for the protection of structural steel, and the process can also be utilised to protect high-strength aluminium alloys. The process has the important advantage that it can be carried out on site. 

Recommended practice for examination and evaluation of pitting corrosion Test method for determining susceptibility to stress corrosion cracking of high-strength aluminium alloy products Test method for pitting and crevice corrosion resistance of stainless steels and related alloys by the use of ferric chloride solution Recommended practice for preparation and use of direct tension stress corrosion test specimens... 

The discussion so far has been limited to the structure of pure metals, and to the defects which exist in crysteds comprised of atoms of one element only. In fact, of course, pure metals are comparatively rare and all commercial materials contain impurities and, in many cases also, deliberate alloying additions. In the production of commercially pure metals and of alloys, impurities are inevitably introduced into the metal, e.g. manganese, silicon and phosphorus in mild steel, and iron and silicon in aluminium alloys. However, most commercial materials are not even nominally pure metals but are alloys in which deliberate additions of one or more elements have been made, usually to improve some property of the metal examples are the addition of carbon or nickel and chromium to iron to give, respectively, carbon and stainless steels and the addition of copper to aluminium to give a high-strength age-hardenable alloy. 

Alclad a composite in which a thin layer of aluminium, or an aluminium alloy of good corrosion resistance, is bonded metallurgically to a high-strength aluminium alloy (of lower corrosion resistance) to provide a combination of these two properties. 

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