constrained joints

[Anti-GMAW]

go to www.weldit.com click on products, then alloy steels, then polaris aaa. I've used this wire & stick rods for welding 4140 plate to mild steel plate many times. I pre-heat, weld then let it cool on it's own. Never had a problem. Or www.rockmountnassau.com (same place)

Very impressive site. They've got alot of uniqe fillers, thats for sure.

[st333v]

I'm welding a four inch solid shaft from an 18-wheeler hub to a half inch mild steel plate. There is a hole in the plate, and it's a butt weld around. This thing lasts about two months before the cracks are visible again. It keeps breaking at the interface with the steel plate. I'm welding it with 7018, preheating it to death, etc. My vote is that the geometry of the joint is causing the cracks to start as soon as the material starts to cool and has no place to loose tension. It's obviously not lamilinear tearing because the stress is in the direction of the grain in the plate. Anyway, is there any good info on contrained joints on the net? I know pipe flanges are welded all the time all day long without cracking, and its a very similar joint. Any ideas?

QT-100 plate steel, bend on break press,diamond shape holes with rounded angles. stitch weld.....don't look back, ur good 2 go now.

[welder_one]

when is the last time you tried to bend T1 on the brake??? (qt100 = T1)

[hockeyguynick]

I used to work at a tractor trailer repair shop. We had a guy come in and weld replacement axle stubs on all the time when the truck blows out a bearing. This was before I really got into welding so I didnt pay a whole lot of attention to what he was doing. But I do remember him preheating, and weld a little, then let it cool a bit. When it was all done, he pointed a torpedo heater at it and let it cool very slowly. He would go nuts if we opened a garage door in the winter while he was working.

[seattle smitty]

Do you weld clear around the shaft in one pass? In school they told us to divide the circle into eight segments, and make the root pass with eight sequenced (opposite sides) welds. It's a lot more trouble, and you have to make nice clean starts and stops (and grind out bad ones as best you can), but it is supposed to reduce the stress accumulation. That said, maybe slow-cooling solves your problem without resort to this method.

I'm always interested in reading about these problems; glad you posted it.