[NoShopSkills]

Other than the learning curve, I have never really had much of a problem getting both structurally sound and reasonably aesthetically pleasing welds in the past. After some pretty major recent surgery, I headed out to the shop today, just to run a few strands of weld & help get my mind off the recovery. I think the bottle is a 75/25 mix (which I didn't specify last time I exchanged it) rather than pure argon. I grabbed my favorite .094 tungsten and planned to encapsulate a 3" steel cube I'd machine too much of the corners from while perfecting my milling machine prowess.

This block of metal started out as a project my son had welded together in high school shop class. I'm 100% certain that it's just plain old carbon hot rolled flat steel most likely 3/16 or 1/4" 1018, it certainly machines like it is. Back when I had it in the mill vise, I had trued it into an accurate cube first, then beveled each of the 12 edges. Each bevel is about 3/8" wide. Because it needed to be taken down on some dimensions more than others, a few of the bevels got through the parent material and showed a fine crack, from when he'd originally joined it all together. The material was clean as a whistle, but cutting oil had been used when I was milling it. I brushed and wiped it down prior to striking up on it.

I choose ER70S-2 for filler rod. Using a WP20 with a #8 gas lens set at about 22 cf/m next proceed to try to run a bead on each of the 12 edges. My plan was to build up and eventually just fill each of the faces of the cube with one bead after another like a certification card. I got RUST, I got spatter all the way up into the gas lens! I got blow outs like when your completing the last weld on a 4130 tube structure and it blows out on you. I got improper parent metal penetration that cratered and spattered. I got deep undercuts and uneven heat distribution. Arc wandered all over the place. What a mess!

I know someone will ask: Dx200 straight DC, lift arc, no pulse, 2 second pre and 8 second post flow. 110 Amps using finger tip control in RMT standard configuration. Sitting at my weld table as comfortable as one can be. Shop door closed - no breeze.

Is it the gas? I don't know how I ended up with the mix, but I did... not to mention that it cost more. I don't see a mix recommended for mild steel in any charts but didn't think it would make a hill of beans, but man what an embarassment! Thoughts and pointers greatly appreciated.

[Braehill]

NSS,
75/25 Mixed gas will not work for steel with a Tig welder as you have found out. All your symptoms seem to be about right for trying to use 75/25. Straight Argon should clear this up.

Was the cylinder mis-marked? Or do you also have a Mig welder with another cylinder for it?

Len

[NoShopSkills]

No it's clearly marked... I think I've been bent over by the counterman once again. This marks the 4th time I've either gotten home with empty bottles or the wrong shield gas. Thanks for you validation.

[WJH]

Not that it matters, but 1018 is usually Cold Rolled. Hot Rolled will have a mill scale, and the dimensions are not as true.

[NoShopSkills]

It does matter and you're right. This was hot rolled, so it likely isn't 1018.

[Boomer63]

I have a bottle in my shop right now that swears it is 75/25; it is hooked up to the Miller 252 wire feed. I get such a weird reaction out of it I am convinced it is >85% or pure argon. The bottle doesn't change it's story, the label continues to read 75/25. I think I am going to change bottles, and find out once and for all if the sum-bitch is a liar or not. Not the first time this has happened to me!
Gary

[Braehill]

Cylinders are not analyzer after filling when you buy industrial grade gases unless it comes with a Certificate of Analysis or a Certificate of Conformance, each of which cost money, and usually about double.

If you own the cylinder and get it filled while you wait some places don't take the time to replace your neck label and it can get mislabeled that way. Sometimes it's just moisture in the cylinder from not being evacuated properly. Most owned cylinders don't ever get a vacuum pulled on them to get rid of moisture. I think it might be worth it to buy one of the cheap HVAC vacuum pumps from Harbor Freight to pull your own down before taking it for refill. Just put it on the vacuum pump for a couple hours or overnight and it would be good to go in the morning. An inline desiccant filter helps but nothing beats a vacuum.

They fill hundreds of cylinders in a day and they're all hand sorted so you can see where sometimes things don't end up in the right group. Labels get put where they don't belong. It's not rocket science but it's a little more involved than them just filling your cylinder when you pull up. Not making excuses for it, just have seen it happen. Always be suspect of the gas if you start having problems right after changing cylinders.

Len

[Otto Nobedder]

I recently watched one of my co-workers try an unusually long time to dial in a MIG before giving up, reporting it defective, and grabbing another machine.

As the guy these reports come to, I tried it for about two inches of weld, grabbed a fresh bottle, and fixed it. Best I can tell, this bottle labeled tri-mix was actually nitrogen.

Steve S

[Orestis]

P9200012.JPG (63.82 KiB) Viewed 860 times

Other than the learning curve, I have never really had much of a problem getting both structurally sound and reasonably aesthetically pleasing welds in the past. After some pretty major recent surgery, I headed out to the shop today, just to run a few strands of weld & help get my mind off the recovery. I think the bottle is a 75/25 mix (which I didn't specify last time I exchanged it) rather than pure argon. I grabbed my favorite .094 tungsten and planned to encapsulate a 3" steel cube I'd machine too much of the corners from while perfecting my milling machine prowess.

This block of metal started out as a project my son had welded together in high school shop class. I'm 100% certain that it's just plain old carbon hot rolled flat steel most likely 3/16 or 1/4" 1018, it certainly machines like it is. Back when I had it in the mill vise, I had trued it into an accurate cube first, then beveled each of the 12 edges. Each bevel is about 3/8" wide. Because it needed to be taken down on some dimensions more than others, a few of the bevels got through the parent material and showed a fine crack, from when he'd originally joined it all together. The material was clean as a whistle, but cutting oil had been used when I was milling it. I brushed and wiped it down prior to striking up on it.

I choose ER70S-2 for filler rod. Using a WP20 with a #8 gas lens set at about 22 cf/m next proceed to try to run a bead on each of the 12 edges. My plan was to build up and eventually just fill each of the faces of the cube with one bead after another like a certification card. I got RUST, I got spatter all the way up into the gas lens! I got blow outs like when your completing the last weld on a 4130 tube structure and it blows out on you. I got improper parent metal penetration that cratered and spattered. I got deep undercuts and uneven heat distribution. Arc wandered all over the place. What a mess!

I know someone will ask: Dx200 straight DC, lift arc, no pulse, 2 second pre and 8 second post flow. 110 Amps using finger tip control in RMT standard configuration. Sitting at my weld table as comfortable as one can be. Shop door closed - no breeze.

Is it the gas? I don't know how I ended up with the mix, but I did... not to mention that it cost more. I don't see a mix recommended for mild steel in any charts but didn't think it would make a hill of beans, but man what an embarassment! Thoughts and pointers greatly appreciated.

i also have a problem on mild steel and somebody told it could be a problem with the gas cylinder been used on other than straight argon

P9200012.JPG (63.82 KiB) Viewed 860 times

I use 1/16 2% lanthanated tungsten, 1/16 ER70S-6 filler, a gas lens with number 7 cup, 20 cfh of argon (2,5 secs preflow and 12 secs postflow), 80 amps dc on a 3mm thick mild steel
plate and the weld turns blue before I complete an inch...its frustrating to think that it might be the gas that is not pure!

[Otto Nobedder]

Blue on mild steel is normal.

Welcome to the neighborhood.

Steve S

[Oscar]

yea the beads look nice and clean and shiny. The rest of the steel will discolor due to the outside atmosphere reacting with hot steel. It happens. Unless you use a large/jumbo cup.

[Orestis]

Blue on mild steel is normal.

Welcome to the neighborhood.

Steve S

thank you
What do you mean it is normal ? if i weld like 10 cm there is something like dark blue crust and only if I wirebrush it, it looks ok

[Otto Nobedder]

Mild steel will discolor in air well below it's critical temperature. In a 10cm weld, your cup may only be shielding 2-3cm of it. The weld just outside that shielding may still be 400*C, and will turn blue in exposure to air.

Normal. Harmless.

The choices are to wire-brush it, get a bigger cup, or set up a trailing shield.

With mild steel, just brush it. It's cheap, and the color has not affected the weld.

Steve S

[Orestis]

Mild steel will discolor in air well below it's critical temperature. In a 10cm weld, your cup may only be shielding 2-3cm of it. The weld just outside that shielding may still be 400*C, and will turn blue in exposure to air.

Normal. Harmless.

The choices are to wire-brush it, get a bigger cup, or set up a trailing shield.

With mild steel, just brush it. It's cheap, and the color has not affected the weld.

Steve S

Thank you for explaining in such detail! It is good to learn from someone "who knows what he is saying ". So no harm if its blue, wire brushing fixes it.