MIG shielding gas question

[twraska]

Trying to weld some new metal that was outside for and couple of years and rusted. 1/4" and 3/8" thick square tubing & flat plate. We ground the weld areas to bare metal but are still having issues with the welds having 'worm holes' in them, like if the gas was not on. Running 75-20 argon/co2, would straight co2 help? How about inner shield with gas? Or how about flux core or even flux core with gas.

I'm grasping for answers here, even tried a different welder and it was doing the same thing.

Could the grinding wheel be leaving something on/in the metal making it hard to weld?

Or,,,,, could I have gotten some 'bad' gas, or mis labeled gas?

Any help appreciated.
Tim

 

[jpfabricator]

Try using a torch to clean and preheat the weld area. Is the welder welding the same on diffrent metal? Im assuming the metal is "mystery", is it possible that you got leaded steel?

 

[Tony Wells]

If you were welding outside, and it was windy, that could cause it. CO2 will give a "sharper" arc and generally penetrate better than a mix, but if the metal is really rusty, it won't weld well with MIG.

 

[twraska]

Try using a torch to clean and preheat the weld area. Is the welder welding the same on diffrent metal? Im assuming the metal is "mystery", is it possible that you got leaded steel?

All was bought metal, mild steel. Don't know if it was US or south of the border mfg. Bought at different times from different suppliers.

Will try torch tomorrow.

- - - Updated - - -

If you were welding outside, and it was windy, that could cause it. CO2 will give a "sharper" arc and generally penetrate better than a mix, but if the metal is really rusty, it won't weld well with MIG.

We are inside, with a big door open but not much breeze. Have welded metal rustier than this before without any problems, at least not this bad.

Any idea on the different wire classifications and how much they help? i.e. E70S2 or E70S6 Tag is off the spool so don't know what it is. I'm ready and willing to try anything at this point.

 

[Tony Wells]

My memory says that the S6 has elements that help with dirty, rusty or oily steel. Manganese and silicon maybe. Not totally sure. S2 has that and some other elements, but I believe the ultimate tensile is lower, but that's desirable for some welds where no residual stresses are desired. I think both will do OK for less than pristine metals. And if you were grinding the weld areas, there should have been no issues with either of those fillers. Perhaps your gas flow was a little low. I tend to be stingy with the gas just because I am cheap, but it does bite me once in a while. Usually though, it's pretty consistent in the bead, not OK for a bit, and then act like the gas dropped out. Do you have anyone to watch the flowmeter while you're welding? You might try adjusting it up just a little if you're by yourself.

 

[sniggler]

Sounds like a gas problem check the gas diffuser (behind the tip), the whip connection to the feeder for the o-rings and that it is fully inserted and the regulator, sometimes a regulator left out will get a spider web or a cacoon in it an play havoc with flow. Gas flow rate need to match the nozzle diameter too much flow can cause turbulence and porosity. To much drag angle and can mess up the gas field. A power wire brush on the angle grinder should be enough to clean the steel but when in doubt grinding to bright metal is the way to go. Welding with the settings way out of parameters can cause issues as well. What machine are you using?

Bob

 

[Rbeckett]

ER70-S6, 75/25 or pure CO2. Make sure you are using the correct polarity and grind the joint about one inch back from the edges. You may also be using too much pressure and causing turbulence in the shielding gas so make sure your around 10 or so CFM. You should hear a slight puff when you trigger, but then it should be very quiet. Also check your nozzle for plugged gas ports, especially if you have used inner shield or flux cored wire recently. Slight pitting around the weld can cause some worming too, so make sure you use a good, clean flap disc to really get down and scrub off the rust at the joints. If that doesn't help snap a pic and I will get the Lincoln book out and we can see what else it says to do to eliminate this issue. Good luck and let us know how it works out and what you did to fix it..

Bob

 

[sniggler]

The rate is in feet per hour. Outside you should on the high end of typical.

​

 

[Rbeckett]

Snigglers chart is more accurate than my memory, just make sure it isn't too much because this is one of those more aint necessarily better things. I stand corrected on the CFM, goes to show what trying to work from memory will do for ya. Sorry.

Bob

 

[sniggler]

Yeah i always say cfm too until i think how much gas that would be. Stick out is also important. We use ESAB dual shield with co2 and change to a small nozzle for root passes and tight access so you have to drop the flow for that some guys use the root nozzle for everything but i hate it and change to the larger nozzle as soon as possible. Argon /Co2 is a little smoother to me but co2 has deeper penetration. We use co2 gauges they are not the same and have heaters to prevent freezing.

Bob