Bending steel/I overheated it

[Boltbreaker]

I did the dumb newb mistake while welding a piece of 2"X3" 1/8" wall tubing. I bent it while welding it.
I cut a small section horizontally out of the center and then boxed it. Well I clamped it down to the table while welding it at the boxed area, but when I flipped it over to weld the top rail area I didnt clamp it down. I know it was dumb. So now it is slightly bowed . The piece is 60 inches long and it is noticeable and a problem.
How do I straighten it out?
Should I get it back onto the bench, reclamp it and heat it with a torch? Or will that mess with the characteristics of the metal and weaken it?
Advice would help.
Thanks,
Brian

 

[Sniper]

Without seeing it, I would guess that it has shrunk at the immediate weld area. Not much chance your going to get that section to grow out again.. so the other alternative is shrink the opposite side to bring it back. Heat up a two inch area opposite the weld sites, ( just a slight dull red will be plenty enough) and wipe it down with a wet cloth. It will surprise you how much it will move. Pick the next worst spot, and give it another go. If you just do a two inch wide section at a time, you'll keep some control on the situation. Try doing to big an area at a time, and it will get away on you and you won't get it back. It might be wise to do a little test run on a piece of scrap, anything will do. Your just going to educate yourself on how far to go, and how much it will take. Just don't over do it with the heat. Sniper

 

[Bonehead]

Sniper is right, and it is hard to tell you what to do for sure without seeing it. In that 60 inch length, how far is it out of straight? 1/4 inch? If you have a solid work table you can bring it around cold with two clamps and a short piece of 1/2 thick steel. Just clamp one end down and lay in the scrap at the worst part of the bend, then start clamping down the other end. When you reach the table with the tube, let it all loose. and check to see if it was enough. If you need more, us 1/8 inch scrap added to your stack at a time until the tube is straight. This requires a strong work table, or beam.
It is generally more forgiving than heat, because you can go too far really fast with heat.

 

[Boltbreaker]

Without seeing it, I would guess that it has shrunk at the immediate weld area. Not much chance your going to get that section to grow out again.. so the other alternative is shrink the opposite side to bring it back. Heat up a two inch area opposite the weld sites, ( just a slight dull red will be plenty enough) and wipe it down with a wet cloth. It will surprise you how much it will move. Pick the next worst spot, and give it another go. If you just do a two inch wide section at a time, you'll keep some control on the situation. Try doing to big an area at a time, and it will get away on you and you won't get it back. It might be wise to do a little test run on a piece of scrap, anything will do. Your just going to educate yourself on how far to go, and how much it will take. Just don't over do it with the heat. Sniper

Thanks Sniper.
I am going to practice on a scrap piece first. I am afraid of it getting away from me the first time. I get a little over jelous at times.

 

[Boltbreaker]

Sniper is right, and it is hard to tell you what to do for sure without seeing it. In that 60 inch length, how far is it out of straight? 1/4 inch? If you have a solid work table you can bring it around cold with two clamps and a short piece of 1/2 thick steel. Just clamp one end down and lay in the scrap at the worst part of the bend, then start clamping down the other end. When you reach the table with the tube, let it all loose. and check to see if it was enough. If you need more, us 1/8 inch scrap added to your stack at a time until the tube is straight. This requires a strong work table, or beam.
It is generally more forgiving than heat, because you can go too far really fast with heat.

Yep I am about a 1/4" off total if I clamp one end to my welding table. So I think I will try it cold first and then practice on a scrap piece with heat. I have a couple hours already invested into this piece with all the boxing and I want to avoid ruining it.
Thanks for your help!
Brian

 

[T2T]

It's agood idea to weld short (1.5") sections and move around on the piece to avoid over heating. I like to make lots of tack welds to hold everything in place before making the short welds. Sounds like you are not too far out of wack, good luck.

 

[rustbucket49]

I know this is an old thread, but I had to share a stupidity moment with you regarding bending hot steel. Back when I was a teenager I was working on a drilling rig during my summer break. We had to do some fabrication work and I was using a O/A torch to heat some metal to bend. I was flapping my piehole to somebody else while I was heating this metal, right? So after I heating I proceeded to bend it - while I was still flapping my piehole, right ?? So I proceed to GRAB the RED HOT metal w/ my BARE hand to bend it..... PSSSTTTTTTTTTT - holy mother of kingfish - that was not a good idea..... I was working one-handed for a few weeks.

Moral of the story, don't flap your piehole when you're holding a cutting torch.