Welding Tips and Tricks

Hi there,

Here a question from a "hobby" TIG welder from the Netherlands.

Recently I bought a new TIG welding machine. At the moment I'm figering out what good settings are, since there are a lot more options than my previous machine had.

Currently my problem is that the welds have a gray collor after welding. In my opinion this means overheating / "surface burning" of the material. The next picture shows an example (as you can see, no external material is added, tubes are 1,5 mm thick, argon backing gas is used).



Are there setting which I can change such that the weld shown above looks like the weld shown in the following picture? Such that the weld discolorations are more bright and shiny?



Extra info: Material used is stainless steel 1,5mm thickness.
Argon about 7 L/min.
Red 2.4 mm thick thungsten bar is used.
Gas lens is used.
Current about 50 to 60 Ampere (reducing the current would be an option, however at the end, the two materials must form one "new" part, good penetration is needed, using a to low amperage this is not the case.

Waiting on your response.

Thanks, Kn3rf

What size gas lens are you using? Just because you're using a gas lens doesn't mean it is helping you out. If you're using a teeny tiny #4 gas lens then you're just shooting yourself in the foot thinking it's helping you. So more actual information is needed. Of paramount importance is what is the torch angle and arc length that you are using?

Also what machine settings do you have available? We can sit here and recommend setting after setting after setting, and then only to find out that you may not even have the settings available. What exactly are the settings you can alter and by how much can you vary them??? Catch my drift?

Without knowing any of this, I would venture to say that you simply do not have enough argon trailing the welding cup because of the round tubing shape. Argon will naturally dissipate much much faster because of the convex curved surface compared to that picture you posted that has fillet welds like a "L" which will allow argon to linger around just a tad bit longer before diffusing in to the atmosphere. Therefore you need more argon coverage and or heat-sinking to happen so the metal cools sufficiently before it comes in contact with the oxygen in the atmosphere. So it's not the heat that is the problem really---it is that it is too hot when the argon shield dissipates and then oxidizes the instant oxygen comes in contact with the hot metal surface. Solve this and your welds will be shiner by way of not oxidizing.

Gas flow (any fluid, actually) has interesting properties. The gas flow that will give you those bright, straw-color welds on a fillet will turn a pipe weld black. Why? With good torch angle on a fillet, the gas is trapped and flows both directions from the cup, providing great coverage. On a round surface, though, the gas will tightly follow the contour, and Bernoulli's principle suggests the momentum and pressure differences will draw air in to the gas stream. Counterintuitively, a lower gas flow will give better coverage on pipe (with proper torch angle).

I always say, though, if the color will brush off to "shiny", no harm is done to the weld quality.

Steve S

By the way, kn3rf,

That's an excellent example of autogenous welding, and nicely done. I'd think a minute with a wire brush will make it fabulous.

Steve S

Kn3rf,
- How much do you adjust tungsten extension from a nozzle?
- How much is the distance between a tungsten tip and a pipe surface? What is the torch angle on a pipe during the welding process?
- Can you try to make a bead(without a filler rod) on any other detail(stainless steel plate or pipe)?
- Make sure of the quality of the gas you use. Was it the same gas for the both products in your post above? By the way, what is the exact material of the pipe you used? (I mean maybe just this material gives such color)
- Can you try to make the same bead(on a pipe) with a usual nuzzle(instead of a lens)?
- And in any case you can just try to increase the flow rate of argon through your torch.

Otto Nobedder wrote:Gas flow (any fluid, actually) has interesting properties. The gas flow that will give you those bright, straw-color welds on a fillet will turn a pipe weld black. Why? With good torch angle on a fillet, the gas is trapped and flows both directions from the cup, providing great coverage. On a round surface, though, the gas will tightly follow the contour, and Bernoulli's principle suggests the momentum and pressure differences will draw air in to the gas stream. Counterintuitively, a lower gas flow will give better coverage on pipe (with proper torch angle).

I always say, though, if the color will brush off to "shiny", no harm is done to the weld quality.

Steve S

Never even thought it that way Have to pay some extra attention and test different torch angles with different flow value.


As Steve already said, that grey is not allways bad. It's just thick oxide layer that is formed in really high temperature.
I would recommend to try pulse welding. It will help with colour as your welding energy is lower, but in the same time you are able to get same penetration. Of course all depends of pulse settings...

Markus wrote: As Steve already said, that grey is not allways bad.

I would say it isn't always bad if it isn't overheating, but stainless steel is the capricious thing anyway .

First of all, thanks a lot for all the input given! I really appreciate it, in specialty the level of the response.

The weld shown in the first picture (see opening post) is made by my old Kemppi machine. Since a week I am the happy owner of a EWM Tetrix 230 Comfort 5P TM. This machine has a lot of more settings (sometimes simplicity makes life easier, however it will be allright ). Using my new machine, the same results i.e. gray surface are obtained as when I used my old welding device.

What I'm gone do is make some new welds and write down all parameters that are asked accurately. Using this information reinforced with some pictures we are able to investigate the problem better.

Thanks, kn3rf

Hi,

I just make a new weld. The "surface burn effect" i mentioned earlier is gone. The weld beneath is made using pulse function on a 2mm thick piece of stainless steel tubing. No use is made of additional material. There is no fully penetration of the weld through the material. Probably someone can give me some tips to optimize it further (the bump's/ oscillation in the weld is due to some movement with the torch).



Settings:
Peak amperage: 50
Pulse amperage: 15
Peak amperage time: 0.09 Sec
Pulse amperage time: 0.03 Sec
Gasflow: 7,5 Liter/min
Torch with small gaslens and cup #7 is used.

kn3rf wrote: Probably someone can give me some tips to optimize it further (the bump's/ oscillation in the weld is due to some movement with the torch).

You can use for example the walking the cup technique.

For what's its worth on .065" wall 316L stainless at 45amps, 10cfm purge, 15cfm flow with a 1/16" tungsten, gas lens, #7 cup I achieve full penetration on my sanitary stuff. I keep a tight arc length (almost looks like I'm in the puddle..lol) 80-90 degree to the surface...watch for the small black spot in the middle of the puddle some call this the devils eye. Travel speed is slow I can do it making a slow steady pass or by making small circles, weld is about 1/8"-3/16" wide Miller Maxstar 150sth

Like Otto...if it brushes off shiny you should be fine. Make sure you clean it well and make sure the joint is tight and square. Can you get a pic of the back side?

Today I welded an angle piece for a motorcycle exhaust linkpipe. Any comments about the quality?

kn3rf,

That technique is common on "sanitary" welds, in food services and beverages. If you use the search for the forum with "sanitary" as your keyword, you'll find tons of posts on how to get full penetration with an autogenous (no filler added) weld.

If you don't find what you're looking for, report back, and we'll find some references for you.

Edit: I just realized Rick H gave an excellent answer before I typed this...

Steve S

kn3rf wrote:Today I welded an angle piece for a motorcycle exhaust linkpipe. Any comments about the quality?

Looks fine to me! That's commonly called "lobster-back", because the progression of welds look like the carapace of a lobster's tail.

Nice color, showing good heat control.

Any additional effort would be for "decorative" purposes.

Well done.

Steve S

Thanks Otto!

Starting the welding process at the same location e.g. inside of the corner would indeed result in decorative more stationary result.

I might just make a dumb suggestion an im sorry if it is....your welds look good btw...but I've noticed when i weld with the pulse per second that if u use a higher pulse (id say 30+) I have sometimes doubled my normal amperage or heat to get the same penetration. It was tricky for me to get used to anyway is why i say something. Otherwise I like everyone's comments about how the shielding gas reacts to the shape ur welding against....Totally relevant i think...Argon travels toward the ground if i remember right so on your first pic in ur opening statement i definitely could have seen that as a problem. Anyway good luck

That's a good point. Argon has an S.G. of 1.38 meaning it's heavier than air and will therefore tend to disperse 'downwards', although with a proper shielding gas supply, this is unlikely to normally be a problem.

Neat welds

Try these pulse settings:

50 A / 0.1 second
25 A / 0.3 second

Remember to keep close arc.