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Aluminum Alloys


I am trying to find the material properties of two aluminum alloys that were used in the Avro Arrow: 1) 75S(T) and 2) 79S. Any ideas?

Mike Hildebrand
- Ottawa, Ontario, Canada


Mike, those sound like rather old designations within a particular specification: and my best guess would be the British Standard series of specifications that dealt with aluminum (or "aluminium"), BS 1470, BS 1471, BS 1474, etc. I don't find either of the ones you mentioned listed in my usual books of Equivalent Specifications so I likely won't be of help. My next step would be to contact a customer service metallurgist at Alcan or Alcoa in the UK, and see if they might remember those designations, and to what four digit Aluminum Association designation they might correspond.

Good luck!

Lee Gearhart
East Aurora, New York


75S is an Alcan notation which is equivalent to ISO Al-Zn6MgCu. Chemical cmposition in wt %.

Zn 5.1-6.1
Mg 2.1-2.9
Cu 1.2-2.0
Cr 0.18-0.35
Fe 0.50 max.
Si 0.40 max.
Mn 0.30 max.
Ti 0.20 max.
Other 0.05 max each - total 0.15

0 condition UTS 21.8 kg/mm2 - 0.2% Proof stress 12.7 kg/mm2
T6 temper UTS 54.9 kg/mm2 - 0.2% Proof stress 49.2 kg/mm2

I have no info on the other alloy.

Timur Ulucak
aluminum extrusions & finishing - Istanbul, Turkey


I believe UNS 7049 is a better suited equivalent to 75-S alloy.

Scott McClelland
- Victoria, BC, Canada

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