Welding Tips and Tricks

Hi,

I'm having trouble welding 0.065" wall SS304 square tubing. I'm using a Lincoln EZ MIG 140 with 308L wire and 2.5CO2/7.5Ar/90He gas without much luck. I've been all over the ABCD voltage settings and up and down wire feeds using 0.023 and 0.030 wire. Welds beads are all pretty much just sitting on top of the material. In contrast, I have a lid to a pressure cooker which I believe it stainless of some kind (it is not magnetic), and without any trouble can lay a bead down that really melds in at almost any setting on the welder.

The weld sounds pretty good (maybe a little more muddled than I'm used to with mild steel), it's not porous, the arc is consistent. Just when I pull away, it's laying mostly on top of the metal. It appears there isn't enough heat, but even with the welder on highest voltage and moving slowly, to the point where there's a glowing white mass of base metal and filler metal, still, the filler metal is mostly globbed on top.

Any advice would be much appreciated!

Thanks,
Greg

P.S.- Is it the ground?

The lid may be some kind of cast SS. Not sure with out pictures. SS pipe or tube needs an internal purge if you want perfect shiny beads. And junk on the backside of the metal( including oxidation from an unpurged backside will be pulled through the molten puddle up to the surface. Sounds like from your description that you need a lot more heat.

Try bevelling the joint. Make sure it's a tight fit up if you're not purging. Have no experience with that mixture of gas, might be alright. Not sure if that much helium works with mig/mag.

https://www.lincolnelectric.com/en-us/s ... etail.aspx

"Short-Circuiting Transfer
Power supply units with slope, voltage, and inductance controls are recommended for the welding of stainless steel with short-circuiting transfer. Inductance, in particular, plays an important part in obtaining proper puddle fluidity.

The shielding gas recommended for short-circuiting welding of stainless-steel contains 90% helium, 7.5% argon, and 2.5% carbon dioxide. The gas gives the most desirable bead contour while keeping the CO2 level low enough so that it does not influence the corrosion resistance of the metal. High inductance in the output is beneficial when using this gas mixture."

if i remember right transformer machines don't have variable inductance.
you may need to change your machine or the gas.