for the root, i would use a weave and hold the rod right underneath the root of both plates w/ about a 1 second pause at each side. and i can actually feel the rod's flux touching the plate sometimes...that's how short of an arc I like to use.
for the rest of the beads I like to hold a short arc, move steadily along and do a short backstepping motion to the side. not a whip, not a weave, just a short 3/32" diagonal motion away from where you're running the bead, no pause, and then move back to where you were running straight. this seems to work very well in overhead 'cause it helps spread out the puddle w/o building up too large of a puddle and causing it to drip and sag. all you're doing is looking for a way to spread out the heat so the metal you're depositing has somewhere to flow instead of onto you!
i also like to weld overhead w/ the rod 10 degrees pointing away from me if i'm welding from the farthest point toward myself when looking down the length of the weld. it seems to put a little more heat onto the puddle, and if anything drips it won't fall onto my hands so easily.
and yes, a concave bead is alright. ya gotta start out small w/ the root sometimes so you don't get slag inclusions and to make sure you have complete fusion. if the bead is concave, you can just run another bead right over the top of the last one but w/ a slight weave w/ pauses.
I GUESS I DIDNT WORD IT CLEARLY. I'M HAVING NO PROBLEMS WITH GETTING A NICE FLAT WELD FACE AND FULL PENATRATION. YOU KNOW HOW IF YOU DO A GOOD 7018 VERT UP GROOVE, IF YOU LOOK FROM THE BACKSIDE OF THE WELD, IT [THE ROOT] LOOKS LIKE A NICE TIG WELD? MY PROBLEM IS THAT INSTEAD OF THE ROOT BEING FLAT, IT IS CONCAVE, SO IT SINKS INTO THE PLATE A LITTLE.
PS, I KNOW WHAT YOU MEAN ABOUT TOUCHING THE PLATE, I DO THAT ALMOST ALL THE TIME.
oh, you're running an open root w/ 7018 in 4G?
I am not a welder, so I can not give you much advice on the finer points of welding technique. What I can say however is that concavity in the root when welding overhead is largely due to the weld metal being too hot and or heavy. The surface tension is not able to overcome the gravitational effects. The solution therefore lies in reducing the size of the puddle while getting the weld metal a bit cooler.
I would suggest trying to speed up your weld when you get to the bottom of the pipe, or possibly putting a bit more heat into the sides of the pipe rather than the middle of the weld puddle.
Let me know if you found any improvement, or otherwise.
Regards
Niekie Jooste
there was a post in here a few months ago by somebody who was trying to weld an open root w/ 7018. i don't remember how they finally accomplished it, but i do know that he got a lot of good advice from people who have done it before.
One think to consider is modifyng your joint design and welding parameters to allow the end of the electrode to be as close as possible to the root. I have welded open root 7018 on vertical and horizontal welds with acceptable RT results. This was done using 5/64" and 3/32" electrodes.
When I weld the bottom of a pipe with 6010 I actually push the tip of the electrode against the joint and sometimes it extends through. When I do this, I seem to get more reinforcement. 7018 freezes much slower than 6010 but it may help.
In most situations, a concave root surface is acceptable provided it blends in smoothly with the base metal and the resultant cross sectional area is not less than the material thickness.
I hope this helps
Gerald Austin
http://www.weldinginspectionsvcs.com
Forum
