Aerospace grade Aluminiums

[noisy]

Can anyone point me in the direction of a web page containing the properties of aircraft grade aluminiums? I don't want to have to pore over obscure documents in dusty libraries and hoped someone might have put the info up on the web. Specifically I'm interested in the corrosion of the material. If you want really specific then I'm interested in the corrosion of aluminiums in fresh water, although I understand that it largely depends on the Ph of the water.

I wrote a paper on this very subject at Uni - and then lost it!

Cheers,

N

[DubTrub]

Noisy,

try a search on google...

I had the same situation a year or so back.

Wilsons (http://www.wilsons.plc.uk/f-alu.htm) was one result, Aircraftmaterialsuk (http://www.aircraftmaterialsuk.com/data/aluminium/ukusaspec.html) was another

Regards
DT

[Genghis the Engineer]

In the UK the standard reference is the "Aluminium Federation Handbook", which pretty much anybody dealing with the issue has on their desk. It covers all the current, and many of the older, alloy designations, with the main properties and conversions between alloys. I'm afraid that I'm not aware of an electronic resource as useful, and the Aluminium Federation's website at http://www.alfed.org.uk/ seems to be down for maintenance at presence so I can't say if there's anything there.

G

[mono]

It may not be exactly what you are after but it's a start

Corrosion (http://www.airbus.com/pdf/customer/fast03/corr.pdf)

[noisy]

Thanks for the replies guys, although it looks as if it's back to the ASM materials books in that dusty library.

What do people think of using Deoxidine and Alochrom as a basic treatment for the corrosion of Aluminium? After this treatment, followed by paint, will corrosion pits continue to erode into the surface of the metal?

I know the only real answer is to cut away the corrosion and rivet in a repair, but that's unfortunately not an option for me. How is Corrosion actually dealt with on airworthy aircraft?

[wrenchbender]

You guys are spelling it wrong..... it's "aluminum".

[mono]

Noisy,

The simple treatment of corrosion with deoxidine and/or alochrom (at least in aviation) is not a sufficient treatment for corrosion.

Firstly minute traces, etc may be left behind which will continue to corrode.

Secondly and more importantly, the corrosion pits create stresses within the material which can reduce the structural integrity of the componant.

To this end, when treating corrosion, all evidence of corrosion must be removed, plus a little extra for good measure. The depth of material removed is then checked against the maintenace manual (actually called a structural repair manual) to check it is within limits. Some form of NDT will be carried out to confirm there are no undetected cracks, pits or other damage. The damaged area is blended to ensure there are no sharp edges or gouges where further stresses may develop. the blended area will have a contour which is within the limits stated in the manual.

If after the NDT there is no sign of further damage and the depth and contour are within limits the area is reprotected and released to service.

If, however, the damage is out of limits or NDT detects damage within the componant then it is replaced. I am not aware of ANY aviation practice which allows the damaged area to be removed and a repair "riveted" in.

Certain types of corrosion will almost always require componant relacement. A good example is intergranular corrosion, as by the time this form of corrosion is visible at the material surface, the damage is done.

Perhaps if you explain what your specific problem is someone may be better able to help.

[noisy]

Oh dear.

The a/c I am interested in is not airworthy. She's in a static museum collection. I have got severe intergranular corrosion and corrosion pitting all over the airframe. I read in one of my old notebooks the horrifying prospect that corrosion pits are self perpetuating.

Removing skins from the airframe is a no-no. The museum is not a workshop environment and she's still got her original paint on. Besides, some of the ribs & stringers are not in great condition either. Oh, and there's not much of a budget.

The plan was to use deoxidine and alochrom to stabilise the metal, followed by silver paint and waxoyl. (This is only for the internal conservation - the exterior has to be left alone)

I fear that this is not truly effective, although if I can arrest the corrosion to the slowest rate possible I will be satisfied.

Is there a better treatment? :sad:

[Terraplaneblues]

I find the information on this site useful
aluminum tempers (http://www.engineersedge.com/aluminum_tempers.htm)

edited 8 times to do the url thing!

[noisy]

Terraplaneblues

Thanks, this is really helpful.

Cheers,

N