Repair of Forming Cracks in Structual Steel
Repair of Forming Cracks in Structual Steel
(OP)
Can anyone tell me where I can find something to document the recommended repair for stress cracks in 5/8" A36 grade structual steel. The parts were formed and are showing stress cracks on the outside radius of the bend. I know that I have been told that you can repair these areas by welding the affected areas, but I have not been able to find any documented evidence that this is considered an acceptable method.
Thanks,
Mike Hiser





RE: Repair of Forming Cracks in Structual Steel
Are the cracks running the length of the part along the radius or simply across the end of the formed section? If it cracked the length of the bend I would not use that part. Cracks across the thickness on the end of the part are normally not considered a problem.
A36 shouldn't crack along the length unless you are using a too small male punch .625 radius or smaller, or an undersize vee die smaller than 5", or higher strength material has been use such as a 50-60 ksi material, or the parts are formed along the grain instead of across the grain. It could be a combination of the conditions.
RE: Repair of Forming Cracks in Structual Steel
Thanks for your reply. The cracks are not the entire length of the bend. They vary in length from 1/8" to 1" in length, but are well represented along the surface. The punch radius used was indeed identified as being small. The issue that we are faced with is more to repair the surface so that there are no questions from our customer with regards to the strength or integrity of the part. We just want to be sure that welding to cover the cracks is an appropriate method.
Thanks.
Mike
RE: Repair of Forming Cracks in Structual Steel
Cosmetically you can fix the problem with welding the cracks closed and grinding flush then when its painted nobody knows. Structurally I would like to know that the stresses in the corners are well within design limits as you will not know the penetration of the weld unless you completely grind out the crack and weld. If you have past experience with this particular part then let that be your guide.
The real question is how do you avoid this in the future. If this has been a recurring problem stronger measures should be used. Someone not changing the punch to improve time performance or not having the correct radius punch available due to the cost of the tool are both examples of people not wanting to do a quality job. Quality is built in not inspected in or repaired.
Bill
RE: Repair of Forming Cracks in Structual Steel
RE: Repair of Forming Cracks in Structual Steel
RE: Repair of Forming Cracks in Structual Steel
RE: Repair of Forming Cracks in Structual Steel
You can not do anything else than welding for those cracks on formed parts, additionally you can not be sure whether you copmpletely removed or it remains over there provided you completely remove the crack as BillPSU said.
The important thing is to build up a system to prevent the future problems. This is a general problem if you are using a small punch to form the parts. I suppose you to bend the parts at a temperature to prevent cracking step by step (for ex. you start with 90 degree and increasing)
RE: Repair of Forming Cracks in Structual Steel
There are rolled radius limits for different steel thicknesses in ASME. I forget the paragraph number. You can use this information as a guide.
If the material cracks are from forming procedures you may want to use a thinner metal or increase the radius.
I would need more information about the geometry to make a conclusive evaluation.
RE: Repair of Forming Cracks in Structual Steel