Butt joint stick welding

[Lefty]

I'm a novice. I'm going to butt weld two pieces of 1/2" plate. They are 6" wide by 36" long. I'd like to join them to make a piece that's 12" x 36" for a top on a tool stand. I have some 1/8" 6011 and 5/32" 6013. I've never welded material of this size and am looking for some guidance. I'm guessing I'll need to bevel and am wondering if there should be a gap but like I said, this is a first for me. Will I need to make multiple passes? Will these rods work for the application? This is not critical as the tool I'll be putting on the table is not super heavy. I have a 200 amp machine. I have some 2" angle 0.25 thick that I was going to tack perpendicular to the joint to keep the joint stable and the finished product flat. I'm welding on top of a metal table, or at least that's my plan. I'm concerned about sticking the work to the table but I have some spatter spray I could coat the table with. Any guidance is appreciated.

Thank you

 

[Lefty]

Or maybe I can clamp down on my work and avoid the need for tacking the angle perpendicular?

 

[Lefty]

I also have some 1/8" 7018 that I picked up today.

Or now that I'm thinking about it, maybe I should weld the angle perpendicular and tack the weld joint and then move over to some saw horses to weld the joint?

 

[Gary Fowler]

To avoid warpage to the least amount, double V bevel (bevel equally from both sides) and alternate welding the front and back side of the joint. I would use the 7018 as you get much better ductility than with 60xx series rods. You can use a minimal gap if you grind the back side of the weld joint to clean and sound metal before adding the reverse side pass. Also joint gap allowance depends on how much "land "(look that term up is you dont know what it is) you have on the bevel. The thicker the land, the more gap you need in order to get maximum penetration.

 

[MrCreosote]

The first 2 questions are: 1) how much distortion can you tolerate and 2) do you need full penetration/full strength at the weld (what are the loads on the table? More welded material, more distortion.) The high aspect ratio of the pieces (long and narrow) is going to very distortion prone.

 

[tooler]

I would not weld the seam at all if I could avoid it. Just weld the two pieces to the base.

 

[Lefty]

Thanks. Sorry for the delay. My settings here must be such that I wasn't notified of the responses. I ended up clamping, tacking and moving around with short runs. The pieces did draw in significantly even while clamped. A couple of passes on the opposite side took care of about 90% of it. I was still left with a slight arch, which is acceptable for the application. The most important attribute for the table was weight and this thing is a rock.

My gap was probably a little tighter than it should have been given my landing size. But full penetration was not needed, which I knew going in. I thought about just tacking to the base but I was concerned due to the width. I was attaching these two pieces to a piece of angle running parallel at the seam leaving a significant cantilever on either side. In hindsight, it probably would have worked just fine with a couple of tacks on the top side along the seam. But then I wouldn't have gotten as much practice and experience. This was my first opportunity to weld a significant multi-pass. I didn't weld because I needed a table. I tabled because I needed to weld.

Thanks for the responses.

 

[Chuck1225]

I'm glad you got something to work. In the future, you would probably want to weld something like you describe with 6013 or 6014. The first number on the rod is the strength of the steel. The 60 is 60,000 psi. If you are welding hot rolled steel flat stock, it is normally 60,000 psi metal. Structural steel is typically 70,000. Pipe is 80,000 and there are many higher grades used in tool making. If you are welding 60,000 psi steel, there is no advantage to using 70,000 psi welding rod. Often, the higher the psi, the less ductile the metal is, though it is not always the case. The second number is the type of flux. A number 10 flux is typically used on rusty and dirty metal because the flux causes the metal to spray downward and it reacts with rust and sand to pull them out of the weld. Sand in the metal makes it brittle. Rust will often bubble as it gives up the oxygen tied to it due to the heat of the arc. 10 is the most aggressive flux. It gives deep penetration. The higher the number, the less the flux is able to spray downward and tie up contaminants. 10 is often used as the rod for a first pass on a weld to get good penetration and assure that any contaminants are reacted out. If the metal is ground before hand, such as when beveling, a higher number works better in that it does not spray sparks everywhere and is easy to weld with. On clean metal, I will often switch to 7014 to fill the gap. It is especially nice in that the flux left on top the weld comes off easily and the rod produces a very clean looking weld. I use a lot of 6014 for plate and 7014 for structural. If you do a lot of welding, higher flux numbers will mean more metal deposited on each pass and will fill your gaps faster than lower numbers. 6018 or 7018 are standards frequently used in construction. I have used 7024 on some projects.