During a storm one of my tent poles that used to be straight, became bent. Is there a way to straighten the aluminium pole again? Or is it a bad idea to try straightening the pole because is would likely snap anyhow and is replacing the pole the way to go? (There is already a question about finding replacement poles)
As a clarification, a picture of the bent pole. It shouldn't bend at all.
Aluminum has a crystal structure and can be hardened using a process called "work hardening." Long story short, you've hardened your pole by causing dislocation movements in the crystal structure of the aluminum. If you compare your bent pole to your other poles, you'll notice that it doesn't flex as much as it used to, that is because it is now a harder alloy than the rest. Any attempt to bend it back now that you've somewhat work-hardened it will cause fractures in the alloy. The only way to soften the aluminum is to anneal it, which involves heating the aluminum almost to it's melting point and then letting it cool slowly, but if you try to do that then your pole will be so soft that it won't flex, it'll just bend like welding wire. You would have to know how to re-harden the aluminum after you annealed it and bent it back, not a simple process, and not that cheap to get a metal worker to do it for you.
You're best option is to either replace your pole, or deal with it being bent, unless you have a friend who is a millwright and knows how to anneal and harden alloys. Bent poles aren't that bad, I've been using bent poles in my MSR Hubba Hubba for years. Your pole is still strong, it's just not as straight and flexible as it used to be, annoying, but still functional.
You won't be able to get your pole back to what it was, but if you wanted to attempt to get your pole straight and see how much longer it lasts, my recommendation would be to use a pipe or tube straightener.
Just don't expect results, and expect a struggle, like I said, that hardened bend won't bend back easy, if you take the pole to a hardware store then you might find some plumber guy that'll be convinced he could get it straight for you. But don't be surprised after he breaks it or puts stretch fractures in it from trying. You can be surprised instead if he actually gets it straight and it doesn't bend right back the first time you try using it again.
Your likely out of luck. Aluminium is used in tent poles because it is stiff, strong and light. The trade off is that because it is less dense and more stiff it is less forgiving to being "manipulated". When steel fails it fails slowly, aluminium simply breaks.
You could bend it back and see what happens, who knows it might hold. But bending it back is likely only going to stress it more. Also what harm does it do if it breaks when you don't want it to and can't replace it?!
I think you'll be after a new pole.
This mountain biking site summarises the properties quite well
No matter how you bend it back, you will be weakening it more (it's already been weakend by bending it). You could try and warm it slightly to decrease the stress (hair dryer on high) or use a plumbers bending spring:
But these are for soft copper pipes not aluminium ones so it may still break.
You say that the tent is held up by a single straight pole. That pole looks pretty minimal for the job, so if you make a straight replacement you'll likely face the same issue again.
If you walk with trekking poles, you may have the option of using one as a tent pole if you use a little ingenuity. Much stronger. I've been doing this for years.
Alternatively, replace with a stronger pole - as others have explained, this one will never be right again.
