Its likely in the heat treating, not the alloys of the shell. I doubt Campy changed the aluminum alloys much over time, probably using the equivalent of 6061 because it is obviously a high strength alloy and few, if any, corrosion problems are reported. A 6061 alloy would typically be heat treated to a T6 condition. If it missed the heat treat or was subjected to a period of temperature above say 350 degrees F (its a time at temperature deal), the material will go toward the annealed, soft T0 condition. I'm sure the occasional person heats an aluminum part to break free a pedal, crank or freewheel, but it is not a good idea.
Trivia: A pure aluminum ring placed on edge will not support its own weight! I worked out the math once while doing a paper on the properties of pure materials. Alloys are wonderful things.
More trivia, but more practical for users of old alloy parts: It is a wonderful thing that most bike parts are 6061 alloy. It is very corrosion resistant. If you have 7075 or 2024 alloy parts, check them very carefully for corrosion over time. I had an amazing degree of corrosion in a 7075 seat post once. Also, early aluminum parts may be of unproven (and unknowable) alloys.
Joe Bender-Zanoni Great Notch, NJ
Harvey M Sachs wrote:
> I've owned a Campy record hf road hub with a crack in the web.
> resulted from an overshift into the spokes.
> Not uncommon, I expect. So, I assumed that they are made of a hard
> alloy.
>
> But, wait. Recently, a list buddy and swapped some parts. I wound up
> with a Campy Record HF track hub with a flange bent in maybe 10
> degrees around about 90 - 120 degrees of the circumference. No
> prolem, this had been fully disclosed by the Honorable List Member,
> and I figured I could lace it up for a rider/commuter and not worry
> about it. Just on a whim, I put the brass jaws in the vise, clamped
> down on the flange, and bent it back. Worked just like on soft
> aluminum. Yielded smoothly. No cracks found. I'm pleased, of course,
> and this sort of fits in inutitively with the common experience of
> deformation around spoke holes, but I'm having some trouble
> reconciliing my mental metal models. Eh?
>
> harvey sachs
> mcLean va