Welding Tips and Tricks

Is anyone in a production environment MIG welding stainless steel?

I am having a hard time getting good looking beads with the following setup:

Trimix gas ( He, Ar, Co2) about 20 CFH
0.035" 308L and 309L( 309L when doing stainless to mild)
Millermatic 350p

Experimentally found a 'pushing' technique was the best.

Recently I have been doing some 11G 304 SS tubing to 1/4" A36 plate and boy
is it hard to get a nice bead. I am finally geting the hang of it, but it seems like
your technique has to be PERFECT. It seems to me the puddle doesn't flow as nice
as mild steel.

If anyone is doing this a lot or has in the past, please let me know your thoughts.

Thanks!

Elliot

Ehart4130.

Gday.

It would be helpful if you could attach a couple of photos.
Being able to see the 'non good looking beads' would give the members so more information with which to work.

Tanks.
Alexa

ps: Just in case it helps, I have attached the link that gives instructions to attach a photo at this site.

http://forum.weldingtipsandtricks.com/v ... =25&t=2466

Hey,

Dont beat yourself up too much, solid wire stainless mig, in my experience , just doesnt lay down a "nice " bead. I have been exposed to ss/ss ss/mild and quenched and tempered steel using ss wire, they all seem a little ropey, passable but dont try to compare it to mild steel.

Mick

Are they requiring uphill progression? This is especially challenging w/ 308 & 309.

If downhill is permitted, it's much easier, once you get the feel for it.

Steve S

Here are some pictures of what I am working on now.
Its 2" x 4" x 11G 304 SS tubing welded to some 1/4" mild steel plate.

My first stab at it with a wave went real bad: Big holes from the weave not fusing in, and some incomplete fusion on the toe of the fillet.

Here is what I have down now: This one I did with almost just a straight push
at 25V and 310 imp, with the trimix gas and 309L wire.

I am pretty happy with the straight push. I almost never do this technique on mild
steel but it seems to be working good here. Pretty much looks like a stick weld done
with a 7018 or something!

Otto Nobedder wrote:Are they requiring uphill progression? This is especially challenging w/ 308 & 309.

If downhill is permitted, it's much easier, once you get the feel for it.

Steve S

Luckily I have the luxury of doing these welds in the horizontal position.
I did however do some samples with vertical down. I cut and etched them and
didn't see much penetration so I decided to do them in the horizontal positon.

I have it cranked way up at 25V 310 imp and I think this is a good spot. The splatter is
way down and it looks like its burning in real good.

Do you have any sample pics of your SS MIG work? What have you found is a good technique? Push, Pull, wave?

Elliot

Ehart4130.

Tanks for the follow up explanation and photos.

Alexa

weldin mike 27 wrote:Hey,

Dont beat yourself up too much, solid wire stainless mig, in my experience , just doesnt lay down a "nice " bead. I have been exposed to ss/ss ss/mild and quenched and tempered steel using ss wire, they all seem a little ropey, passable but dont try to compare it to mild steel.

Mick

I hear ya Mick! To me stainless mig always feels like you have to wait for it. For me I found that if I do the little circular motion slowly with tight circles I
get much nicer results.

Yeah, MIG Stainless does not like a weave, and when it's needed it must be fast and close.

For 310 IPM, I'd be closer to 23.5V on our Lincoln CV305, and 22.8V on any of our Miller 251's. It's a little more spatter to deal with, but it lays down nicer due to the higher current. I do prefer a "push" in flat, horizontal, and overhead, because the bead lays flatter and doesn't look like "cold lap" from buildup behind the puddle. I do a lot of vertical down, using these high current settings, and that's where I prefer to "drag", with a step-pause to increase penetration. Despite what is said regarding penetration in vertical-down, it can be done. I weld heavy suspension systems this way. If the joint is designed for the weld and the weld has been tested for the joint...

I'll have a couple SS MIG welds tomorrow I'll take pics of.

Steve S.

"Spatter Spray". Use lots!

'nuff said.

Otto Nobedder wrote:Yeah, MIG Stainless does not like a weave, and when it's needed it must be fast and close.

For 310 IPM, I'd be closer to 23.5V on our Lincoln CV305, and 22.8V on any of our Miller 251's. It's a little more spatter to deal with, but it lays down nicer due to the higher current. I do prefer a "push" in flat, horizontal, and overhead, because the bead lays flatter and doesn't look like "cold lap" from buildup behind the puddle. I do a lot of vertical down, using these high current settings, and that's where I prefer to "drag", with a step-pause to increase penetration. Despite what is said regarding penetration in vertical-down, it can be done. I weld heavy suspension systems this way. If the joint is designed for the weld and the weld has been tested for the joint...

I'll have a couple SS MIG welds tomorrow I'll take pics of.

Steve S.

Thanks for the info, I can't wait to see some of your pics. Could you offer a sketch or picture of a joint that is designed to be welded with vertical down?
I would really like to know because its a really nice, easy weld to do in most cases.

I design many of our connections and joints and I would like to squeeze in some vertical down.

Thanks!

A vertical down is typically overdesigned, meaning for the structures I build the material is mostly 3/8", mix of stainless and carbon steels, and require exlusively fillets. The fillets, done uphill, would only need to be 3/16" minimum. Done downhill, the welds are 3/8", doubling the weld interface area, and done with relatively high wire speed for the voltage, resulting in a higher current at the puddle. The step-pause method with a strong (15-25*) drag angle seems to help.

The welds I'll do tomorrow are repairs, and don't fit this pattern, but we have a "bogie", or trailer subframe in the works I'll take a pic ot two of (though it's all CorTen carbon steel).

Steve S

Here's a couple of shots of 1/4" stainless to 1/2" stainless, a tee joint, where I replace a section I had to remove to repair stress cracks that resulted in a vacuum leak.

Here's the "flat" 1F (the slope is about 30* at this location). And here's the opposite side, 4F, at the same 30* Outside the MIG weld in both are TIG welds used to fill where I ground out stress cracks.

Oddly the most difficult weld all day was small. I had to TIG it left handed, almost standing on my head to feed the rod, with the shortest cup and back-cap I have on a WP-20 torch. This was the bottom side of a stop-drill hole I needed to localize the vacuum leak that led to the repair. Steve S

NIce work. Looks like some really tough positioning.

I have definitely be there with the difficult positions for TIG. I have had to sit or use my shin on the foot
pedal to get a few jobs done. Sometimes thats what it takes.

Nice work!

Elliot

Elliot,

I finally realized where I can get a pic of a structural joint designed for downhill MIG... It's on the "wall of shame", pictures of what not to do... There's a sloppy spot with no tie-in in the worst possible place... The end of a gusset where it makes a stress riser... I'll get a copy tomorrow.

Steve S

The wall of shame is the title of my resume . lolol

Shizz....

I forgot to copy the pic!

Just compleated ,a ton of 304 ss stacks i believe they where all 10 gauge,used 308l and 98% %2 sprayed it all at about 25.5 v don"t remeber exact ipm low though maybe 2.25 good starting point but try it on scrap first you barely want to hear a little crackel now and then.Used a slight push ran about 18" beads with no spatter ,after weld brush right away with ss brush comes out clean enough to skip the passivating!Skip the spatter spray its a real bitch to clean,hope that helps.From the pictures i saw i would definitely use spray transfer on those.SORRY FOR BUTCHERING THE ENGLISH LANGUAGE!