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Dull looking welds

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Dull looking welds

Postby taydin » Sun Oct 01, 2017 10:11 am

Hi, I did some tig welding practice today on steel. The welds always look dull and as if they are covered with some dark gray, matt finish.

I used a square tube with 4mm wall thickness. A welding calculator told me to use between 120 - 150 Amps, so I set the machine to 150 A so that when the pedal hits the bottom, it will be 150. I selected DC, HF start, preflow is 0.2T and post flow is AUTO. No pulsing. The gas was set to 7l/min (from the calculator).

Torch had a 2.4mm gas lens with #7 nozzle and 2.4mm 1.5% lantanated (gold color code) tungsten. Rod was 2.4mm ER70S6.

I started the arc, pressed all the way down and then lifted the pedal a little to give roughly 135 Amps. When I started the arch, I kinda move the torch in circles to enlarge the puddle. Then I move the torch forward and again need to make circles to enlarge the puddle. When I don't make this circling movement to enlarge puddle, the rod mostly sticks to the work, or I need to bring it very close and it touches the tungsten. So I pushed the pedal all the way down to give 150A, but still same thing, moving forward, making circles to get puddle larger, dip rod every 2 seconds or so and move forward.

The result didn't look good. I was expecting shiny looking welds with brownish/bluish haze here and there, just like what I see in Jody's videos :D

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Last edited by taydin on Sun Oct 01, 2017 10:19 am, edited 2 times in total.
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Re: Dull looking welds

Postby taydin » Sun Oct 01, 2017 10:13 am

I cleaned the work with paint thinner beforehand and used grinder type sanding disk on the area to be welded.

I suspected that the gas isn't sufficient and cranked up the gas flow to 12l/min, but still, exact same result.
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Re: Dull looking welds

Postby Oscar » Sun Oct 01, 2017 10:23 am

This is what happens to steel when it is hot and not covered in a blanket of argon, it oxidizes and turns gray. It all has to do with managing heat input. You likely took too long and didn't use sufficient amperage. You should use enough amperage so that you can get an appropriate sized puddle established within about 3ish seconds, otherwise you're just unnecessarily heating up the part for no reason. Circling motion is not needed if everything else is in order. That will just be something else to distract you from focusing on the puddle. Also, dunno the2.4mm filler rod in favor of 1.6mm. You don't need 2.4mm filler until you're over ~6mm part thickness
Last edited by Oscar on Sun Oct 01, 2017 6:03 pm, edited 1 time in total.
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Re: Dull looking welds

Postby taydin » Sun Oct 01, 2017 10:30 am

Thanks for the response, that makes sense ... I have some experience OA gas welding steel and this kinda felt like I was doing OA welding :)

How close do I need to be with the tungten tip? I really needed to be very close. The tip was about 1 mm away from the surface and the arc umbrella was very small without any room for bringing in the rod.
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Re: Dull looking welds

Postby taydin » Sun Oct 01, 2017 10:48 am

I think part of the reason was that I never let the work cool. I just sanded it and continued welding on another untouched spot. I will cut pieces from another tube and practice on new pieces everytime. Hopefully that will make a difference.
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Re: Dull looking welds

Postby cj737 » Sun Oct 01, 2017 5:59 pm

taydin wrote:Thanks for the response, that makes sense ... I have some experience OA gas welding steel and this kinda felt like I was doing OA welding :)

How close do I need to be with the tungten tip? I really needed to be very close. The tip was about 1 mm away from the surface and the arc umbrella was very small without any room for bringing in the rod.


That will depend upon the taper you have on the tungsten, and how much stick out you’re using.
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Re: Dull looking welds

Postby Oscar » Sun Oct 01, 2017 6:09 pm

taydin wrote:Thanks for the response, that makes sense ... I have some experience OA gas welding steel and this kinda felt like I was doing OA welding :)

How close do I need to be with the tungten tip? I really needed to be very close. The tip was about 1 mm away from the surface and the arc umbrella was very small without any room for bringing in the rod.


Well there you go. It was your OA welding experience that you were trying to use when you shouldn't have been.

With a 2.4mm electrode, your arc length should be sufficiently large to bring in the filler rod, but then again, IMO your filler rod was un-necessarily large to begin with. 1.5-3mm would work well for beginning to TIG weld. Especially if you drop down to a 1.6mm filler rod. You are likely using (again IMO) too large of a filler because that might be what you are used to in OA welding, where the tip of the filler rod is melted with the OA flame, as opposed to TIG welding where the filler rod is to be melted by introduction to the molten weld puddle, which of course needs to be appropriately sized, by using the correct amperage in the first place. Time to go back and watch some of Jody's videos. :)
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Re: Dull looking welds

Postby robtg » Mon Oct 02, 2017 12:32 am

Introducing the filler rod to the puddle is the same with OA or tig. Either way you don't melt the rod in to the puddle.
The rod is dipped in the puddle.
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Re: Dull looking welds

Postby taydin » Mon Oct 02, 2017 5:57 am

Thanks for the helpful replies guys! Very much appreciated. Being a beginner, it sometimes happens that I make multiple mistakes, which compound each other and one mistake causes the next step to fail. But i'll keep at it. Luckily I have lots of scrap steel lying around :)

Here is another test I will do today: I want to see what the welder displays in terms of current/voltage while I do the welding. So i'll bring in my digital camera, mount it on a tripod and record the welder displays. I want to make sure that the current I have set is really flowing.
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