How to straighten cold rolled section

They will only distort even more if you heat them, IE: start to curl. once SS has gone cold and work hardened it is impossible to correct as you require. I bet some one differs on this. There are some really dumb people out there.

Observational evidence suggests that you are 100% correct. (I just tried an oxy acetylene torch on one) Many thanks.

Dumb is only related to closed minded people that think they know it all

Straightening by stretching would be possible for a simpler rolled section if the item was worth the set up, but your form is to complex with to many variables.

I am afraid you will have to come up with a better forming method.

Re: How to straighten cold rolled section

The Section you have shown ,seems to have not been properly rolled,I wonder whether it is done by roll forming or initially pressed and subsequently (improperly)rolled.You can attempt Re rolling the same section again or alternately hold it by clamping with thick plates(properly contoured to hold the section firmly) at either ends and then stretch it so that the section is straightened.

Its my guess work ,I would tend to experiment that way though I have no experience of such works.

'The Section you have shown ,seems to have not been properly rolled,I wonder whether it is done by roll forming or initially pressed and subsequently (improperly)rolled.'

Correct, the material comes on a roll, is de coiled, cut and radiused, and fed into the rollers. The de coiler is OK, but the rolling machine was picked by the accountants, and has about 6 rollers to few. The quality was deemed acceptable by the powers that be for 4 years, but now some product has gone to Germany, and quite rightly, has been questioned.

Update. As a result of advice obtained from this thread, I have been able to demonstrate to the required people the impracticalities of trying to straighten them, and a new machine is being sourced. Mission accomplished, thanks people.

If I understand the problem correctly, there is a very slight curvature along the length of the piece...you can hardly see it in the picture, but it can't be more than a centimeter. A dip along the top of the piece.

I would rent a shot peen setup and gently hit the inside of the curve all along the length of it with a hard media, like steel bb shot. This should stretch the metal on the inside surface, causing it to straighten out. It won't take long. Go carefully, check often, results start out slowly, and then suddenly you realize "hey, its straight!"

This procedure works when I straighten out swords and hand saws, and they are not only work hardened but heat treated as well! Though mind you, I use small hammers instead of shot...but thats just me.

This material has a nasty habit of cracking when so treated.

As do hardened steel knives. This method works.

Ok if you say so. Time will tell.