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MIGging thicker metal

I have a Lincoln 175SP+ with .030 wire and Ar/CO2 mix gas.

I am getting ready to weld some 2" x 2" x 1/4". It will be welded at right angles, and some flat bar welded here and there to complete the item.

I have a guide on my welder that says the settings to use on this thickness/gas mix/wire size, which would be at the max.

I will clamp it all down to keep warpage down.

My question is:

Should I weld it with several smaller passes, or should I maintain one large puddle, and pause on each wall longer to melt more of the base metal? Also, should I put a root space in there of 1/8"+, or butt them right up? Or should I do like pipe - a small hot root pass, then a hot cover pass?

I want to really burn it in and get good fusion all around. But am not sure if one big pass, or more smaller ones is the best way.

What would you do?

If I had a stick welder, I would do it with 7018, and not think twice about it. But this is what I have to work with.

(Hah! Maybe this is a reason/excuse to get that stick welder...............)

Steve

Reply to
Steve B
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I would grind a taper on the angle and space it about 1/16th. Make a root pass, two stringer beads, and a cover pass. However if Ernie or Randy says different, I would pay attention to them.

Dan

Reply to
dcaster

Yeah. Waiting for them to weigh in. My main concern with doing multiple pass is the HAZ, heat input, and warpage, although I will have it clamped down. But, it would look nice with a good figure 8 weave cap on it.

Steve

Reply to
Steve B

Reply to
RoyJ

I think you get smaller HAZ and less warpage with multiple passes of smaller stringer beads. If you have a large puddle, then there is more metal cooling and shrinking.

Dan

Steve B wrote:

Reply to
dcaster

It seems that everyone has a handle of the problems with small welders. Many here have more experience with 110 volt units than I have. I have run a small mig for about 20 minutes total. The only thing that I have to contribute is on distortion control. The general rule is that if you put in the maximum weld material in the minimum time distortiom will be reduced. That means a large hot bead is better than multiples. The problem is that the rule is too absolute. Yes it will reduce distortion. Mulitiple beads refine the grain structure of the initial beads. Multiple passes also prevent cracking of welds when they are ridiculously too big. Distortion is not a bad thing if you anticipate it. What is embarrassing is when it suddenly appears. One instance comes to mind from several years ago. We tried to straighten an assembly with multiple powered jacks. We gave up at 500 tons and finally gouged out the welds, straightened it, then welded it back together. Randy

"Steve B" wrote in message news:Jj7Kf.677$_87.256@fed1read06...

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Yeah. Waiting for them to weigh in. My main concern with doing multiple pass is the HAZ, heat input, and warpage, although I will have it clamped down. But, it would look nice with a good figure 8 weave cap on it.

Steve

Reply to
R. Zimmerman

Reply to
dcaster

Reply to
Steve B

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