[Danosoar64]

Hi Guys,

Just joined the forum as I need some help with TIG welding some .035" wall 4130 tubing. I ran a two inch bead joining two 3/4 inch tubes together and from under the hood all looked well until I took the hood off and found something that looked closer to Fido's butt then the nice bead I expected. Have a look at the attached pictures to see what I mean.

These are all the settings I can think that would have some affect on the weld...let me know if I'm missing something:
Everlast 210EXT
Max amps set to 37 - no pulse
Argon gas @ 13 CFPM
.5 second pre-flow and 5 second post-flow
CK Worldwide Flex-Loc w 25' hose
2% lanthanated 1.6MM Tungsten
Gas Saver LENS
#5 Cup
ER70S-2 filler rod @ .045"

I would start the puddle with 100% pedal and quickly back off and use 50 to 85% to keep from blowing through the metal. Any thoughts would be greatly appreciated.

Thanks,
Dan

Welds 4- small.jpg (227.87 KiB) Viewed 1981 times

Tig Tourch - small.jpg (213.91 KiB) Viewed 1981 times

[Otto Nobedder]

Danosaur64,

You need a little more heat. That's a cold weld, and I'd set the max amps at 50. #5 cup is small for tube work, and I'd build argon dams from foil and set the preflow longer even if I could use a larger cup (with the gas-saver lens, you can do a #12 cup and much more stick-out). I'd move to 20 CFH with a #12 cup.

If you're building an airframe, you should go to E80-S2. The finished weld will more closely match the parent metal properties without PWHT. (Per any number of EAA references.)

Jody is a member of EAA, as are a few others here. Even if you're building a racecar, rather than an airplane, their knowledge will be valuable.

Steve S

[michialt]

Dan;

Let me start, I am a beginner, and I haven't worked with 4130 yet. Please don't take my experience as anything more than a beginner experimenting and teaching himself how to do this stuff

I am working on steel angle iron right now, but that weld looks just like a lot of my welds on mild steel in the beginning. I had watched several videos on TIG, and they all did the same thing, they looked like they were pushing the torch in a straight line, and simply dabbing/tapping the filler rod into the bead as needed. I couldn't for the life of me get a bead that looked anything close to the videos.

Finally I was working on a long but joint, and I started using this method: I would place the filler rid in the joint about 1/8" ahead of the arc. Then I would start the arc on one edge of the two pieces, and then I would massage the pool back and forth across the two pieces using small circles. As the pool formed between the two pieces, the circles were close enough to the filler that it also melted, and then you would see the melted filler get sucked into the pool. I kept this pattern up as I moved along the joint. Sometimes I would need to move the filler a little further away, and sometimes closer to keep the bead consistent, but when I was done my beads looked a lot better. I also found that I had better and more consistent penetration.

I am at the office right now, but here is a picture of an old weld, still far worse than yours, but you can see the similarities between mine and yours. When I get home I will take a picture or two of my more recent work to show you the differences.

[zank]

Can you post up some pictures of some of your welds on flat plate? The reason I ask is it looks to me like you are trying to melt the filler with the arc rather than the puddle. It's also hard to tell if you cleaned off the scale and cleaned it to bright shiny metal. I can see what looks like a little sooting around the toes that indicated to me that the scale was left on the 4130.

Small diameter tubing is tough because you are constantly and dramatically changing your torch angle relative to the work piece. It looks to me like you are trying to jam a lot of filler in in fear of blowing a hole. I suggest sneaking up on heat when you light up rather than pounding the pedal. Light up easy, give it a little more juice until you start to see a small puddle, move the heat to the adjacent tube and heat that in the same way, get the two tubes to fuse (the same way you would do a tack), and then add some filler to the puddle to get the width you want. Then start pushing the puddle and adding filler to the leading edge. It's hard to explain, but easier to show. Take a look at Jody's videos on the bicycle frame. The tubes I cut for him on that were close to the thicknesses you are dealing with.

http://www.youtube.com/watch?v=is0BP39XZLw
http://www.youtube.com/watch?v=yT108iL-vMw

Here is a shot of a recent frame I made with similar wall thicknesses. These are a little thinner (0.028" and 0.032" wall) but larger diameter. I might suggest trying some bigger diameter tube to practice on since you don't need to adjust the torch angle quite so dramatically. Have fun!


Bryan F by Zanconato Custom Cycles, on Flickr


Bryan F by Zanconato Custom Cycles, on Flickr

[TamJeff]

^ Very nice!

[Otto Nobedder]

Zank makes a great deal of sense...

Feeding the rod into the arc, rather than the puddle, will make the same boogers as way-low heat. (Actually, in low-heat, the only way to melt the rod is to feed it to the arc, as it will glue itself to the puddle.)

Steve S

[Danosoar64]

Thanks for the feedback and advice...

Mike hit the nail on the head as I was jamming the filler into the arc trying to avoid a blowout. I did have the metal cleaned down to bright metal, used a flapper wheel, but I do see the sooting he is talking about.

I don't have any flat metal practice pictures to post but I did cut up some more tubes and did some more practice with them. Getting better but after looking at Mike's welds I think I'm going to cry.

Thanks again,
Dan

[Otto Nobedder]

The welds in your last post are looking better! If this is scrap, put 'em in the band-saw, and see what it looks like on the inside. I wouldn't be surprised if these are a "pass", despite not being "pretty" yet.

It's like the old joke, "How do I get to Carnagie Hall?"... "Practice..."

Steve S