I have used heat to camber beams and straighten many shapes over the past 48 years, but I have never used heat on AR400. Is the 1200 deg. soaked temp the same as for mild steel? Is there a difference in the process that I should know about. I have been called on, as one of the last tough jobs before retirement, to repair a heat warped weldment. It is a rectangle box with a 1"plate bottom. A circle is cut in the 1" plate to match a pipe flange. Then the box is cut in half so that it can be installed around a pipe and bolt to the flange. When cut in half through the circle margins the halves spring. Because I'm the "Old Guy" I get to fix a young guys poor fit up and weld procedure. I built and supervised the welding of two of these items and they were fine. The two that the smarter and younger guy built sprang open. I am heating "V" shapes around the circumfrence, starting at the outside edge moving to the center. For this material what is my upper heat limit?
Any help will be dandy! I go back to play on 1/2/2013
Thanks Dennis
Dennis,
You know better than me that straightening steel shapes, beams and heavy castings by applying heat and subsequent quick cooling is an art based on experience rather than a science based on theories. Many years ago, I saw a 3 meters ( 10 feet) inside diameter spur gear being straightened using this method.
If you have 48 years experience in doing so, does someone in this Forum know more than you on this matter?
The only thing I can tell you, as I don't know the chemical composition of AR 400 steel, is to be careful about the possibility of the material developing martensitic structure upon cooling after having been heated.
Happy New Year, Dennis!
Giovanni S. Crisi
Sao Paulo - Brazil
Mr. Crisi,
I feel honored that you would answer my inquiry. My 48 years has been in general fabrication and welding. The heat straightening has been with mild steel, and only occasional. My need is to know the upper heat limit where if I go beyond that point no shrinkage will occur and the lower limit that I must heat beyond so that shrinkage will occur. I know a little and come to the forum often to learn.
Thank you,
Dennis
Hi Dennis,
Just a quick word of caution since I have to run...
The steel makers of AR400 will all give a maximum interpass temp and/or heat input . Too much heat into the steel will soften it, thereby destroying the hardness and abrasion properties of the material. I don't know off hand what's the max temp. (the internet is your friend), and I don't have experience with shrinkage temp.
Tyrone
By Alexa
Date 01-04-2013 17:23
Dschlotz. Q&T plate it seems. I recommend running this by your tech that wrote the welding procedure and/or the responsible engineer. If your corrective action is outside spec, you should attach a note of explanation in the final docs, so the Buyer(s) know the thermal history of the work pieces. Alexa
