aluminum tig issue

[2000_SS]

Using a Dynasty 200DX, 4043 filler, and straight argon at 15-18cfh. Material is clean, freshly sanded and wiped with acetone.

I'm running 85 amps or less, 83% balance, and 130hz.

The weld i'm making is usually a butt weld on aluminum tubing, 16 gauge I believe. The problem is i'm getting a rough, grainy finish on the weld. I know the material is clean and if decent quality. I'm starting to question the filler rod. Gas is not believed to be the issue either.


Any thoughts?

[zapster]

You stated "Sanded"..
As in sandpaper?

All you need is the stainless brush and acetone with clean rags..
The stuff on top is the sand left over from sanding..It gets into the aluminum and you don't want that at all..

Other than that looks good and consistant..
You can take a die grinder and skim off the top and do it over and make it all nice again..


...zap!

[2000_SS]

Yeah yeah yeah no sandpaper I know, lol.

I actually have been using a dedicated wire brush on other joints and have had the same results.

[zapster]

Get the inside as well as the wall face as clean as possible in the weld area.

...zap!

[2000_SS]

I have been, that's why i'm kind of baffled. I've been trying all kinds of methods and techniques.I even switched gas suppliers. The only thing I haven't tried is using a different filler, but this isn't any special grade of material. The 4043 should be fine. I'm kind of stumped.

[dave powelson]

Originally Posted by 2000_SS

I have been, that's why i'm kind of baffled. I've been trying all kinds of methods and techniques.I even switched gas suppliers. The only thing I haven't tried is using a different filler, but this isn't any special grade of material. The 4043 should be fine. I'm kind of stumped.

4043 composition gives a more sandy top--than 5000 series. I think that's been
explained before with 4043 having a higher silicon content.

[jakeru]

I think that graininess can happen even when you have no contamination. (EG, perfectly pure alloys, welded in a totally inert environment, I do believe it could happen) It can be just "what happens" with a high silicon content aluminum alloy (namely, 4043 filler) when it cools slowly.

Try changing your alloy (try 5356 filler perhaps) or weld "hotter and faster" so it cools more quickly.

When you cool 4043 quickly enough, it will be entirely different and will be so shiny, that its almost like a mirror! 5356 usually leaves a slight frosted/hazy texture (but it still looks great, IMO).

I have yet to "master" 16 ga aluminum tubing for really nice aesthetics myself, but I have noticed these things, and believe I have a handle of what's going on. Once I welded a hypereutectic aluminum alloy (with way high silicon content) and noticed really strange puddle solidification behavior. It's the silicon content solidifying early on (at a relatively higher temperature than the rest.)

That does look like a nicely made weld though (in terms of structure and consistency of the weld deposit, etc.)

I really doubt that sandpaper is going to stick into your aluminum if you just sanded it by hand. If you used a power sander that somehow heated up the aluminum enough to 'smear' it in, that's one thing, but sanding it by hand there is no way you're going to be able to heat the aluminum up enough to do that. Just a solvent wipe with a paper or cloth towel (or, even just a quick rub with a clean, bare hand) will remove any remaining grit or contamination that is on the surface after sanding.

[2000_SS]

I'll try going faster and hotter and see what happens.

Thanks for the help and compliments guys. I'll post some pictures later of the project

[aevald]

Hello 2000_SS, in reference to "sandpaper" you may find the difference can be relative to whether it is a XXXXXXCarbide type or Aluminum Oxide type. The carbide types are not recommended for use on aluminum materials, mainly due to the carbide component utilized in the manufacture of that type of abrasive. This is very well not the issue for you here, yet for future considerations this may be worth considering. Likely, as others have stated, this could be due to silicon content and travel speeds and technique. Nice looking welds by the way. Good luck and best regards, Allan

[weldermick]

Do you notice any crud floating around in the puddle while you're welding? or does the pitting seem to appear as the weld freezes?

Even though your welds look great, they seem to be stacked pretty high, which indicated to me that you were using relatively thick filler rod, which leads you to have a longer arc length. That combined with the angle you feed the fill could be letting a bit of air into the weld, but given the shininess of your welds, I think this probably isn't it. In any case, I would personally use a smaller filler and dip more frequently to get a slightly flatter weld.

I notice some soot marks on the edge of the weld which usually comes from dipping the tungsten at some stage and deposition of some residual contamination (sometimes a number of welds later). So is your tungsten super clean?

Have you cleaned (scrub with scotchbrite and wipe with acetone) your filler rod? Not usually needed, but would remove this issue as a suspect.

[shovelon]

As the others have stated, it is a result of the 4043 filler.
Switch over to 5356. You will surpised.

[2000_SS]

Originally Posted by weldermick

Do you notice any crud floating around in the puddle while you're welding? or does the pitting seem to appear as the weld freezes?

Even though your welds look great, they seem to be stacked pretty high, which indicated to me that you were using relatively thick filler rod, which leads you to have a longer arc length. That combined with the angle you feed the fill could be letting a bit of air into the weld, but given the shininess of your welds, I think this probably isn't it. In any case, I would personally use a smaller filler and dip more frequently to get a slightly flatter weld.

I notice some soot marks on the edge of the weld which usually comes from dipping the tungsten at some stage and deposition of some residual contamination (sometimes a number of welds later). So is your tungsten super clean?

Have you cleaned (scrub with scotchbrite and wipe with acetone) your filler rod? Not usually needed, but would remove this issue as a suspect.

The pitting seems to appear after it freezes. the puddle is usually pretty clean.

i was switching between 3/32 and 1/16 fillers to see if maybe one batch ran better than the other, hence the excess reinforcement on some of the welds.

the tungsten is kept clean, but i have made some tack welds with some light contamination. i keept it clean during welding and if i get it dirty, i stop welding and clean it off.

Originally Posted by shovelon

As the others have stated, it is a result of the 4043 filler.
Switch over to 5356. You will surpised.

I'm going to get my hands on some and give it a try

[2000_SS]

Here's the project by the way...Turbo kit for my buddy's '67 Camaro It's still a work in progress, but should be done this evening or tomorrow. Once the turbo piping is complete, we're building a chromoly core support for it and then HOPEFULLY making some shakedown passes in Tulsa saturday night.

[2000_SS]

I had an uneven gap to fill in the downpipe, but it turned out pretty nice. I cranked the machine up to 160amps if memory serves and just feathered the pedal the whole time as i traveled a little faster. The end result was a much cleaner looking weld, but i also wonder if it helped having that super clean, machined flange to weld to? Either way, turning up the heat made a little difference, but i'm still going to get some 5356.

[SundownIII]

Several comments (many already covered)

1. You fu fued Zap about the "sanding" comment, but, depending on the material used, can be a factor in "grainy beads".

2. Technique (moving too slow and overheating the filler) is most likely the culprit.

3. 5356 (if the part will not be subjected to heat >165 deg F) would be a better choice.

4. Prep shows a degree of inconsistency. For mill finish material, the SS brush is generally a better prep than sanding.

5. Don't know what's with the indentations (markings) on one half of your tube. If they're pipe wrench/vice marks, then impurities could be embedded in the indentations.

6. As mentioned, the soot marks would indicate "dipping the tungsten". When this happens, the tungsten needs to be "refreshed" all the way past the contaminated section (not just regrinding the tip). The area affected needs to be brushed to remove the soot before starting a new bead.

7. For that joint configuration, you don't really need such a "focused arc". Dropping the frequency back to about 100HZ may "soften the arc" a bit and help with puddle. A "less focused" arc will allow the heat to spread out slightly reducing the height of the bead using the same size filler.

8. You didn't mention cup size, but for that weld, I'd be using a 7-8 cup with a gas lens.

9. Make sure the puddle's melting the filler, not the heat from the arc. Moving the filler too far back from the covering gas will also allow the filler to "oxidize slightly" and will introduce impurities into the weld puddle.

[chimmike]

No intercooling eh?

He doing low boost or chemical intercooling? (methanol injection)

One more question: aluminum for exhaust piping? Interesting coming right off the turbo....i'd probably not do that myself but eh

[2000_SS]

Originally Posted by SundownIII

Several comments (many already covered)

1. You fu fued Zap about the "sanding" comment, but, depending on the material used, can be a factor in "grainy beads".

2. Technique (moving too slow and overheating the filler) is most likely the culprit.

3. 5356 (if the part will not be subjected to heat >165 deg F) would be a better choice.

4. Prep shows a degree of inconsistency. For mill finish material, the SS brush is generally a better prep than sanding.

5. Don't know what's with the indentations (markings) on one half of your tube. If they're pipe wrench/vice marks, then impurities could be embedded in the indentations.

6. As mentioned, the soot marks would indicate "dipping the tungsten". When this happens, the tungsten needs to be "refreshed" all the way past the contaminated section (not just regrinding the tip). The area affected needs to be brushed to remove the soot before starting a new bead.

7. For that joint configuration, you don't really need such a "focused arc". Dropping the frequency back to about 100HZ may "soften the arc" a bit and help with puddle. A "less focused" arc will allow the heat to spread out slightly reducing the height of the bead using the same size filler.

8. You didn't mention cup size, but for that weld, I'd be using a 7-8 cup with a gas lens.

9. Make sure the puddle's melting the filler, not the heat from the arc. Moving the filler too far back from the covering gas will also allow the filler to "oxidize slightly" and will introduce impurities into the weld puddle.

I don't know what those marks are on the tubing, they came like that from the vendor.

This is a high heat application, exhaust side of a turbo.

I played around with the frequency, both up and down, and didn't really get any satisfying results either way.

Cup is a #7 with a gas lens.

i am going to get a new stainless brush...i now suspect my current brush has been use for other cleaning jobs when i wasn't around

[chimmike]

Might want to watch that then, especially with the exhaust directly hitting the weld.......I'm not sure it's gonna hold up to that kind of heat under extreme conditions like drag racing. He might want to consider some SS since it looks like the exhaust isn't running that far.

[2000_SS]

Originally Posted by chimmike

No intercooling eh?

He doing low boost or chemical intercooling? (methanol injection)

One more question: aluminum for exhaust piping? Interesting coming right off the turbo....i'd probably not do that myself but eh

intercoolers are illegal in his class when running ethanol or alcohol. he'll be running E85 at first, but we're thinking methanol may be in the future. Boost this weekend will be under 10psi, running off the wastegate. In the very near future when the boost controller arrives and the setup is dialed in closer, we're turning it up around 20-24psi.

Aluminum is light weight. The heavier gauge tubing used at the turbo has been proven effective before. it IS new to us, but we've seen it done by multiple cars running under 5 second 1/8 miles ETs, so there must be something to it.

This is NOT a street car...but it will see some street duty

[2000_SS]

Originally Posted by chimmike

Might want to watch that then, especially with the exhaust directly hitting the weld.......I'm not sure it's gonna hold up to that kind of heat under extreme conditions like drag racing. He might want to consider some SS since it looks like the exhaust isn't running that far.

Yeah, but like i said above, there are MUCH more powerful cars out there utilizing aluminum exhaust, so we're giving it a try.

[Zmechanic]

Originally Posted by 2000_SS

Yeah, but like i said above, there are MUCH more powerful cars out there utilizing aluminum exhaust, so we're giving it a try.

Some of the guys have gotten away with aluminum exhaust, and some of them have opened everything up after a run to find the tubes sagging.

As for your problem with the grainy finish, my opinion would be that Sundown's #2 point is probably exactly it. I generally find that appearance when the metal is borderline overheated. Travel speed is most likely your culprit..

Here's a similar setup I'm working on. Pics aren't the greatest. It's running dual water-to-air intercoolers in the dash. Welded with a syncrowave, with balance at about 58% DCEN @60Hz . 2% 3/32" thoriated. 1/16" 4043 filler.

[SundownIII]

2000,

5356 filler IS NOT suitable for that application. Forget we mentioned it.

[2000_SS]

Yep, I was starting to gather that. I'm still going to get some and see how it runs, I've never used it.

I suspect the people with sagging downpipes weren't using a heavy enough tubing. We used a little thicker tube for the split coming off the turbo. The ones that melted might not have had their tune up right on and got the egt's higher than expected.

[gatehead]

I have the same problem on my dynasty. I just turned the cleaning action up until it went away, I think I am around 58%.

[chimmike]

Originally Posted by 2000_SS

intercoolers are illegal in his class when running ethanol or alcohol. he'll be running E85 at first, but we're thinking methanol may be in the future. Boost this weekend will be under 10psi, running off the wastegate. In the very near future when the boost controller arrives and the setup is dialed in closer, we're turning it up around 20-24psi.

Aluminum is light weight. The heavier gauge tubing used at the turbo has been proven effective before. it IS new to us, but we've seen it done by multiple cars running under 5 second 1/8 miles ETs, so there must be something to it.

This is NOT a street car...but it will see some street duty

Ahh, okay.

I was considering building an aluminum exhaust (downpipe-back) for my street car, but keeping the stainless downpipe. Heat isn't as much a concern for me as the hangar mounts for the exhaust itself...too much stress/movement in the exhaust would rip the hangar right off, so I'm doing SS.

e85 should work well for fueling...I'd imagine you could reach mbt on e85 without any problems.