Does aluminium degrade over time?

[jez-4-bikes-max]

Just wondering this?

 

[stew-b]

over a few million years yes.in real time you may get a light later of oxidisation,same as surface rust on steel but thats it,nothing structual.

 

[SLIM]

short answer , yes

long answer , something to do with the white powdery stuff that appears on it

like when you anodize it , the process uses this to coat it , the powdery stuff is drawn to the surface and is coloured

over time it is drawn to the surface , weakening it

there is a chemical name to the process ??

or that is my understanding of it anyway

 

[jez-4-bikes-max]

Well I understood that Aluminium oxidises just like that of steel - again as you say its a powdery white dust that collects on the surface. This can make paint come off an alloy frame but if treated in time isnt a traumatic issue.

However I was also infomed (wrongly maybe) that Aluminium turns brittle with age...

Any material engineers confirm this?

 

[SLIM]

i did read somewhere that some manufacturers of aluminium parts , leave the " kegs " as they are called , on the roof of their place for years before using them

something to do with the aging/weathering process drawing most of the stuff out , so maybe it isn`t detrimental ????

 

[Ziggy]

Very much doubt it, but you're not thinking of fatigue life are you? Ie aluminium has a fixed fatigue life - meaning an ally frame will eventually fail if ridden normally where steel might last 'forever'...

Maybe of use to someone but I'm sure you knew that!

Aluminium does oxidise though, just not as easily as steel. It's saving grace is that aluminium oxide protects the 'good' metal underneath, wheras rust doesn't! This means that if your ally frame gets scratched or whatever it will oxidise, but only in a thin layer. You'd have to keep scratching the oxide off & allowing it to form again, to make it spread...

 

[jez-4-bikes-max]

I was wondering, if it say for example, it was a frame that was just left alone and not used. Would this become brittle with age or would it be as usable as a frame fresh from the manufacturers?

 

[Ziggy]

I'd go for it being fine. Obviously that assumes 'alone' is in a relatively benign environment... Fatigue wouldn't be a problem, & nor should oxidation (& that'd probably be obvious anyway).

I'm not a materials engineer though, so I can't remember much materials stuff - any experts please feel free to correct me!

The amount of money that people are willing to spend on old aluminum frames does surprise me sometimes though - the fatigue issue means I wouldn't want to ride one regularly & hard... but if it's been a garage queen its whole life, it'll be fine!

 

[SLIM]

interesting really because ...

two frames , both aluminium

one NOS , one used for 10 years

the used one would have 10 years of fatigue put into it ,

but both would be equally brittle ??

which would break first ??

what actually breaks frames , fatigue or brittleness ??

 

[jez-4-bikes-max]

I think fatique would break it obviously.

However my question was whether alloy "naturally degrades without use over time"