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Discussion Starter · #1 ·
I'm fairly new to TIG so I have run into an issue that might have a simple answer...but I'm stumped. I am building a sheet metal brake for another project I thought I would make out of Aluminium I had laying around. I am attempting to attach the legs I made to the main base. I can't seem to join the two and was hoping someone could explain what is going on.

So here is the backstory The main base is 1/4in 6061 and the "legs" are 1/16in aluminum scrap(so I do not know exactly what it is). I thought if I could focus the arc on the thick metal , heat it knowing I am not going to get fantastic penetration, and just melt the thinner metal into the base I could join the two without blowing out the thinner metal. When I strike the arc the tungsten immediately eats away like it would if you struck it without and gas. I tried two different tungstens and both did the same thing. I cleaned the first time with non-chlorinated brake cleaner. I thought it might be something to do with surface prep so I scrubbed with a wire brush and then wiped it down again but no change. I then ran a bead on a scrap piece of aluminium I practiced on previously to check to see if the welder was malfunctioning and that bead was fine. Here is the list of specs and settings I am using:

Eastwood TIG 200 set to AC
3/32 grey tungsten
100% Argon is set at 20
foot pedal at 140amp
Clearance Effect set at -1 and then +1, no difference
#5 alumina cup
pre flow is .5 sec

Here is a shot of the tungsten that is thrashed. This happened immediately as the arc was struck. At least a few mm were lost as the tungsten just kind of dissolved before my eyes.


Here is the work Piece. On the left I got a little bead happening the first try but the tungsten was trashed and I was just trying to glue the pieces together.. I was forcing it. The right is the last attempt where you see the buildup of filler. As soon as the tungsten went the arc looked like a giant cone and immediately melted the thinner aluminium so I tried to get filler in to plug the hole. Ugly and wrong..I know.


I pulled out a practice piece and ran a bead that you will see circled in red. No settings were changed, same type tungsten but a different one since the original two were beyond use, didn't even adjust the pedal just feathered it. Tungsten was fine.


I have accidentally struck an arc without the gas on before and what happened to the tungsten then was exactly what I saw here but the gas was on. I know it has something to do with the workpiece since the welder was fine on the scrap.

Is this somehow because of the thick base plate I was working with? Also, I am a definite newbie to TIG so any comments on the bead on the scrap is welcome, my travel speed was all over the place I knew :(

Thanks so much for any help!
 

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I bang metal
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2,779 Posts
i would think (not completely sure) that your material is contaminated. Seeing as how the machine works fine on the scrap. What steps did you take to prep? The way i was taught was to use a stainless steel wire brush that has been used for no other purpose and brush that material then put a layer of soot on it (like you are annealing it) and brush all that off and then it should be ready to go. You could try using a green tungsten and that might help, just make sure you ball it.

beyond that i am really not sure, how was your scrap aluminum stored? If it was laying on a rack with steel or under steel it is for sure contaminated. Maybe try sticking a magnet to the scrap peices and see just how contaminated it is.

have you tried to weld on a spare peice of the scrap by its self just to see what happens?

edit: are you letting your material sit around for awhile before you weld it or do you prep it and use it pretty much right away?
 

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Pretty sure 6061 is not weldable.
Nope. 2011, 2024 and 7075 have poor weldability but 6061 is weld friendly.

From Speedy Metals, "6061 is a good, general purpose aluminum alloy with magnesium and silicon as its alloying elements. 6061 has the highest resistance to corrosion of all the heat treated aluminums, but strength is lower. 6061 has a wide range of mechanical properties and is readily machined and has good forming properties. 6061 welds easily, has excellent joining characteristics, and good acceptance to anodizing and other applied coatings. Electrical conductivity is 40% of copper. 6061 is widely used and has the largest size selection of all aluminums. 6061 shapes are available from sheet and plate at Speedy Metals utilizing our high definition plasma cutter."

Later, Doug
 

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sickboy
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Your settings should be pretty close except I would run a #8 cup. It could be your technique preventing proper gas coverage for a filet weld. How far is your tungsten sticking out of your cup? what angle are you welding at?
 

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sickboy
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3,544 Posts
One other thing I just noticed about your settings is your gas is set to 20, thats too high. For a #5 cup you should be around 13-15. Too much gas, especially in a filet weld like your trying to weld can create a lot of turbulence and cause major arc wandering and other problems.
 

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Discussion Starter · #9 ·
Cool, I feel like I have some good actionable information to figure this out.

Deathmetaldan - I did have the pieces stored above a rack of steel...

Seeing the posts I feel like I understand a little better. I see the black sooty look around the weld, the tungsten ate itself just like there was no gas...I'm going to head into the garage and play with gas flow and clean and re-clean and see where I'm at.

Thanks for the help.
 

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sickboy
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3,544 Posts
cool beans, sounds like you probably just didnt have enough gas coverage. Are you using a gas lens? If not id highly recommend it. Best money you can spend on your machine. It focuses the argon and takes the turbulence out of it so you get the direct coverage you need. Check Ali-express, lens kit with collets and cups is only like $20 or so.

gas lens vs no gas lens...
 
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