What causes a grey colored TIG weld?

atomicjoe23

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While I was in TIG class I was all worried about aluminum, but once I started it I thought it was easier than stainless!

You just have to be prepared to move fairly quickly. . .which boils down to feed technique and I don't even have a great feed technique yet as I'm still a beginner. One thing that P'd me off more than antying else though was forgetting to switch the machine back to AC after putting in DC+ to create the ball on the end of my tungsten. . .I hate ruining a fresh tungsten because I forgot to switch the machine back!!!
 

mikeyfrombc

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While I was in TIG class I was all worried about aluminum, but once I started it I thought it was easier than stainless!

You just have to be prepared to move fairly quickly. . .which boils down to feed technique and I don't even have a great feed technique yet as I'm still a beginner. One thing that P'd me off more than antying else though was forgetting to switch the machine back to AC after putting in DC+ to create the ball on the end of my tungsten. . .I hate ruining a fresh tungsten because I forgot to switch the machine back!!!

i,ve been playing with some 304 ss with 316filler and it,s hard stuff to weld , it,s .065" 600grit scraps from a job we,re doing . it sure heats up quick gotta watch the puddle shine and it,s size and it,s not to bad , pulse is the bomb for ss , just gotta get the helmet dialed in for pulse mode
 

atomicjoe23

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One other thing that I noticed for both SS and aluminum is filler rod size selection. . .with SS it seemed best to go with a smaller filler rod, it was easier to keep a uniform bead size with a smaller filler rod and to add more filler than to try to melt the larger filler rod without adding to much heat to the medal and getting the grey beads previously discussed.

With aluminum it was just the opposite. . .I like to use a much larger filler rod for aluminum because the aluminum melts much faster, with the larger filler rod I don't have to feed as much rod into the puddle to achieve the correct size puddle and to cool the weld enough to keep from blowing a hole in the aluminum.

These are just things that I picked up and my personal preferences. . .there are without a doubt people on this forum who have much more experience than I do welding aluminum. . .and that's a fact!
 

Chase 2

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I welded nothing but stainless for a couple of years and personally I find it easier, being more predictable (to me at least). When welding thinner gauge stainless (16 down to 32) predicting and preventing warpage is the biggest issue, not running a bead. I agree with the the pouring lots of thin rod in to the puddle in many little dabs with stainless as opposed to big huge very deliberate "add rod assimilate into the puddle and move on" technique of aluminum. I've never used the pulsed technique, but I do tend to use a lighter setting on the lens with stainless and get in real close and "bear down" on the whole process, you really have to be able to see exactly whats going on for maintaining that iddy biddy puddle.
 

atomicjoe23

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That's something I noticed as well Chase2. . .I run my lens pretty light compared to a lot of people. I like to be able to see what's going on. . .I was told as long as I don't get headaches, don't have to squint, and don't see any spots that I'm not running the lens too light. . .I generally run between a 9-10 for MIG and usually no more than a 10-10.5 for TIG. . .any darker than that and I'm having to concentrate too hard to try and see what's going on that the weld suffers.

For stainless using a small tungsten was helpful as well. . .I used 1/16" w/a #8 gas lens for SS and a 3/32" w/#8 gas lens for aluminum.

I really need to get a TIG here at home, but I think I should get a plasma cutter first.
 

mikeyfrombc

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That's something I noticed as well Chase2. . .I run my lens pretty light compared to a lot of people. I like to be able to see what's going on. . .I was told as long as I don't get headaches, don't have to squint, and don't see any spots that I'm not running the lens too light. . .I generally run between a 9-10 for MIG and usually no more than a 10-10.5 for TIG. . .any darker than that and I'm having to concentrate too hard to try and see what's going on that the weld suffers.

For stainless using a small tungsten was helpful as well. . .I used 1/16" w/a #8 gas lens for SS and a 3/32" w/#8 gas lens for aluminum.

I really need to get a TIG here at home, but I think I should get a plasma cutter first.

buy the tig 1st i have all 3 and my plasma sits 99% of the time mig and tig are getting used equally most of the time all thou i practise my tig more then mig LOL
 

tomahawkracefab

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Now, since you all have been so very helpful...
Any advice or good threads on the "magical and mysterious" [AL]?:D

now ya talkin ! i did 20/30 hrs a week torchtime for 4 yrs on ally tig.. its actually easier than s/steel or 4130 , postflow or purging is not as important , if your short on gas you'll get a small 'grey skin' floating in the middle of your weld pool , infact , postflow serves mostly to shield your electrode while it cools down ( electrode should be a bluey / gold color ) i protrude the electrode about 2-3 mm but if your learning keep it flush , 15 cfm of gas is plenty , you'll see a greater temp variation in your weld from start to finish , so a pedal helps to get up to heat/pool quickly ( important ) then back off amps for the rest of the weld , dabbing the filler rod helps to spread/move the weld pool , it also helps to amp down slowly at the end of weld ( without moving ) if weld pool cools too quickly you'll get a pinhole that will leak if containing fluids...CLEAN your ally ! if its new extrusion no need , ally ages/oxidizes on the shelf , do your linishing / shaping then acid etch and flush 100% with water for best results , a quick wipe with acetone helps , even sharpie marks will do your head in ..your weld pool should look like a clean pool if 'quicksilver' ? at all times

hope this helps !, Anth
 

Chase 2

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So how many of you guys use a "keyhole" technique for 110% penetration with Al??
 

blueeyeddevil

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keyhole?? 110% penetration???:D

Ok. I'm over the "that's what she said" list of jokes I just told my monitor.
keyhole, is it like an oblong C?
 

atomicjoe23

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No. . .the keyhole technique is used a lot in OFW. . .I'm not sure how to describe it, but picture an old-school keyhole in a door that required a skeleton key. . .round hole on top of a rectangle. In welding the the round hole would be directly in front of the weld puddle that you just formed. . .you heat the metal enough that you are actually melting a portion of it away and then you quicly add filler metal to fill the keyhole. . .that's where you get the 100% penetration.

I'm pretty sure 110% is just to get the point across. . .I've never used "110%" before. . .but I knew what he meant.
 

Chase 2

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110% penetration is when you have a fillet built up on both sides of the joint. When done in a fixture and have the backside purged, about the only way you can tell the top form the back side is that the top will have a higher fillet. To get a keyhole there needs to be a gap between the 2 pieces being joined and then you melt both sides of the joint out so its like described above.
 

atomicjoe23

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Yeah. . .you generally have anywhere froma 1/16" to 1/4" gap depending on the thickness of plate being used.

When I was welding 3/8" test plate for qualifications it was 1/4" gaps. . .when I was learning to butt weld plates with MIG I started on 1/16" gap and moved to 1/8" as we moved up in plate thickness.
 

mikeyfrombc

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i remember doing 100% stick welds and we always set the gap the width of the rod being used , typically it was a 1/8" rod or 5/32" rod
 

atomicjoe23

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I used 1/4" gap for 1/8" 7018 for 3/8" plate for face bend and root bend tests. . .per AWS & the Washington State welding spec's.
 

blueeyeddevil

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Same here for setting gap on full pen stick welds. When I passed my unlimited test I set the gap at 3/16" - 1/4" or so. That was on 1" plate though. I just never heard it called "keyholing".
 

atomicjoe23

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The term "keyholing" isn't referring to the gap. . .it's referring to the method of welding where you melt the base metal enough to create a "keyhole" shape at the leading edge of the weld puddle as you progress across the weld when you are doing a push weld (not exclusively for push. . .but I have never used a keyhole technique for a drag weld. . .I think it would be a bit awkward to use the keyhole technique for a drag weld).

Washington state cert's use a 1" plate w/a 1/4" gap as well Blueeyeddevil.
 
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