spray arc disaster.

running a lincoln power mig 350. the wire is 0.045 Mil spec 70S2 hardwire. the gun is a magnum 400. shielding gas is 98%argon with 2%Oxygen at 42cfh. I'm trying to run a testing coupon of 3/8" thickness with a 30 degree bevel (60 degree total for both sides) with a 1/8" root gap. using 1/4" backing plate. I have the machine on setting "21" for 0.045 argon mix welding. the procedure per the PQR says that I should be using 3/4" plate with the same bevel and a 3/16" root gap running 27 volts and 300 amps. Cannot seem to get it to work what so ever. I've already tried 4 tests and each one has linear cracks down both sides of the root which carry thru the entire weld sequence. I've tried preheating the plates and postheating the plates. I've tried a ton of different amperages and wire speeds to no avail. it seems like the spray just wants to suck into the sides instead of getting down into the root on my initial pass.

Does anybody know exactly what settings or parameters I should be running for these conditions? I've always run fluxcored wire at my old job and this spray arc hardwire mig is really pissing me off. also, any idea why i keep getting cracks/porosity? it's carbon steel so I cannot understand why this is so difficult especially running in the flat position! I've run fluxcore 0.045 vertical up tests that were over an inch thick and a foot long with absolutely no problems and they passed RT, PT, and VT testing so I can weld believe it or not this is just a totally new procedure for me. any advice or suggestions are much appreciated because my boss is about to kick me out the door even tho he's told me to use 3 different shielding gases already so he has no clue.

Yahoo/answers doesn't really have a category for this so if anybody knows where I can find the info that'd be great too.

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my gut tells me you are experiencing center line cracking from excess heat input and fast travel speed creating an alignment of solidification grain boundaries down the center line of each bead.

i would recommend using the bottom end voltage settings to achieve spray to decrease heat input..and cheat toward the high side on wire speed to prevent the cracking.

mikec

by mike
(warner robins, ga, usa)

laid a bead with one of the combo units tig torch at fabtech in atlanta last year. ran great! for a low duty cycle air cooled combo.

Cracking in stainless welds

A friend of mine recently had a set of stainless turbo headers built for his car by a local fab shop. After only a few hours of use we noticed that almost all of the welds had a crack right down the center. After closer inspection it looks like they pulsed over the original welds to make them look cleaner. The welds look pretty good and I am just puzzled on why they cracked in the first place. Was it the pass on top that did it? improper back purging? to much heat? wrong filler? wrong type of stainless for the heating and cooling of an exhaust manifold? I'm fairly new to tig and am trying to educate myself as much as possible. Your site has been by far the best one i have come across so far and i greatly appreciate you taking the time to share your all of your knowledge on here. You kick ass!

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the cracking could be caused by all kinds of different things.

using 303 free machining stainless.

excessive stress

inadequate filler and cross sectional thickness of welds.

if the cracks appeared that quickly, it is possible they already existed and that is why they were welded over.

that seems most likely. cracks welded over by washing leaves a cosmetic weld pass that is very thin.

the crack underneath propagates quickly.

help with welding uphill with flux core on the outside corner of a box

When I run uphill on the outside corner on the box its like im too hot and i gouges out the metal it under cuts it real bad I've always welded stick and im having trouble figuring flux core out.any help would be appreciated.

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Just like with stick welding, you have to set the machine to the right settings for the application.

Whatever amperage worked on the stick, would be pretty close for flux core welding.

trouble is, most mig and flux core machines dont have amperage settings...only voltage and wire speed.

one suggestion is to get the spec of the wire, like E71-t1 and go to the manufacturers web site and pull up the spec sheet with recommended settings.

here is a link to lincoln electric flux core wire spec sheet where you can get some really good settings for flux core wire.

click here for the settings

sanitary weld - inside corner.

by RJ (shopdog)
(DePere, WI)

I TIG'ed some stainless salt pans for a food service company and I backed the corners with aluminum angle. Turned out real nice. Even though the job didn't require it yet,I would like to be ready to provide a nicely finished (NFS sanitary type) inside corner. I have a feeling they will be asking for it in the future. I run a Synchrowave 250 and use 2% lanthanted and 2% ceriated.
BTW smokin' site!

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you can convert your aluminum angle to backing plates by drilling a bunch of holes to provide a path for argon. and then use some tubing on the back side also with a bunch of holes drilled on the back side along with some jb weld or devcon putty.

Couple of quick questions

Gday, brand new to tig welding and teaching myself, I have noticed porosity at the end of a lot of my beads. Any suggestions? I have purchased a uni-mig 180 amp DC, HF inverter, I had to sacrifice the aluminium option for my budget. Do you have any experience with this machine or have you heard any feedback about them?

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I dont have any experience with that brand.

as far as your porosity issue goes, make sure you are using er70s2 or 3 or 4 or 6 tig wire and not rg45 gas welding wire.

they look the same. but the gas welding wire does not have the ability to scavenge impurities.

also, if you are practicing on mild steel, it could be that it just gets so oxidized that porosity happens.

you may need to stop to let cool more often, and cool the metal in water, and then grind clean before restarting.

best of luck

jody

bare wire mig and flux core .045" diameter--differences

by greg
(wisconsin)

how does flux core wire welding differ from regular .045 bare wire.

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Settings and techniques differ.

There can be a lot of difference depending on welding position, thickness of metal , and whether a self shielded fire or a flux core wire that also needs gas shielding (dual shield)

Below are 2 links to Millers welding calculator for both bare wire and flux core settings.

these are good resources for a starting point.

mig bare wire settings

flux core wire settings