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7XXX series alloys contain zinc as the main alloying element, usually in combination with magnesium and copper. Alcoa's range of high strength 7XXX alloys are widely used in aerospace structures and are approved by the world's leading airframe builders. For engineering applications these alloys are generally used in the T651 or T652 temper in order to provide maximum strength.

Strength:

These materials offer the highest levels of room temperature strength attainable in rolled aluminium alloys.

Stress relieved:

7XXX plate alloys are stress relieved by controlled stretching, designated T651 or cold compression designated T652. See table overleaf for details.

Machinability:

7XXX are easy to machine, especially in the T651 temper.

Polishability:

7XXX alloys can be polished to a high finish.

Corrosion resistance:

7XXX alloys are susceptible to exfoliation corrosion and stress corrosion cracking in the T651 temper. This can be improved by over ageing. 7XXX alloys often require protection against general corrosion and a wide range of commercial protective coating systems are available.

Welding:

7XXX alloys with more than 0.2% copper are not considered weldable by fusion welding. 7XXX alloys with less than 0.2% can be welded.

7XXX Applications:

7XXX is superseding steels in structural load bearing applications where the benefits of lightness, specific stiffness and high strength-toweight ratio can be exploited.

Machined components

Load bearing structures, e.g. cargo
containers

7XXX alloys, with excellent machinability and wear resistance are widely used for mould applications.

7xxx series alloys technical data

STANDARD DIMENSIONAL AVAILABILITY

Alcoa Europe only supplies plate that
exceeds the requirements issued by
the major specifying authorities e.g.
European Standards.

1. These dimensions show only the range of

capabilities and cannot necessarily be
provided in every combination of these sizes.
Other sizes may be available, subject to
enquiry.
2. The above alloys are only available in Mill
Finish
3. * denotes maximum width decreases with
increasing thickness
4. ** denotes wider widths may be available
on request

TYPICAL PHYSICAL PROPERTIES

7020 T651
7075 T651

7020 offers a combination of good ductility and levels of

strength which are higher than 6XXX series alloys.

7020, with less than 0.2% copper is weldable. Heat affected
zones will recover part of the fully heat treated strength
through naturally ageing.

7075 in the T651 temper is one of the strongest of

the general engineering alloys. The T7351 temper
has greater resistance to surface corrosion and
stress corrosion cracking than the T651 condition,
but at the expense of strength, which is

approximately 12% lower

Good quality welded joints can only be achieved by strict attention to welding

technique and good joint design. Postweld corrosion protection maybe required.

We advise our customers to consult Alcoa before designing welded

structures in 7XXX.
7075-T651 is commonly used for the production of highly

stressed machined components.