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Up Topic Welding Industry / Welding Fundamentals / Help on TIG welding Brass
- - By ajclay Date 07-28-2007 13:39
I seem to get involved into some odd projects for the all mighty dollar. I've been TIG welding yellow brass ( 70% copper & 30% zink ) with limited success. Material is .062 thick sheet metal. I've been putting the edges together and seaming the pieces. Filler rod is same material sheared down to long point used only every now and then. Machine is set to AC. I have to be carefull not to put to many amps into the material because it will "sizzle" for a lack of words and get a bunch of small pin holes.

I was hoping that some of you has had some experience with similar material and have a real filler rod that will work better. I've got a couple of other projects that I'm not going to be able to just seam the edges. I'm getting by; but only barely. Thanks in advance for the pointers.
Parent - - By DaveBoyer (*****) Date 07-29-2007 04:46 Edited 07-29-2007 04:49
I have no direct experence but offer this: Keep the heated area under protection with the argon untill it cools enough that the zink doesn't burn. Overheated [boiling] zink is probably what is causing the sizzle and pin holes. Have You tried brazing rod? How important is color match?
Parent - - By ajclay Date 07-30-2007 02:16
Thanks for the advice. I'll have to give the brazing rods a try the next day or so. I wouldn't think they would be alloyed the same, but they just might work. The color isn't an issue, the pieces will not be polished. Thanks.
Parent - - By MDG Custom Weld (***) Date 07-30-2007 15:58
We use bare brazing rod, A/C, 2.5Mhz, and move the balance around depending on the material thickness.  It can be done with D/C too, but that "Sizzling" is very hard to control on thin material.  Since we started using the new tig welders  (i.e. Miller Dynasty & Fronius Magic Wave), A/C with very high pulse Hz has increased our brass efficiency by 50%.  We have even been successful welding as thin as .025 polished fire place trim plates, and as thick as .200 sheet for other applications.
As with any Zinc or Brass alloy, wear a respirator!
Parent - By 357max (***) Date 07-30-2007 18:43
On a Dynasty AC output, unbalance to 95-99% time at negative also.
Parent - By ajclay Date 07-31-2007 03:06 Edited 08-05-2007 13:21
MDG, Thanks for the suggestions, but I have to say you lost me on the 2.5Mhz suggestion. I guess you're taling about the AC frequency, but that goes from 20hz - 400hz on my machine. Dynasty 700. Or maybe the pulse? If you have another minute, I guess you're going to have to spell it out for me... As for the rods, you mean the oxyfuel "low fuming bronze" rods? https://weldingsupply.securesites.com/cgi-bin/einstein.pl?Next::1:UNDEF:OR:terms::PF

Updated: 8/5/07
There is no doubt that going up to 95% on the balance made the biggest improvement. The regular old style brazing rod worked just fine too. .062 thick material, AC / 100-125 amps, 30cfm argon. Thank you to everyone for the suggestions.  Aj
Attachment: brass.jpg (45k)
Parent - - By UNI Date 05-04-2008 00:16 Edited 05-04-2008 00:25
Brass welding is tricky
I personally use tig when welding brass.  I have never tried to weld brass in AC(always dc).  You want to bevel atleast 2/3 the gauge of your sheet. Bevel width would be a 45 from bevel depth.  Keep your argon high I keep mine around 35 but I don't pay for it my employer does.  If you have pre flow and post flow crank them up also.  My preflow is in miliseconds so i keep it around 4.  My post flow is in second I keep it around 6.  You will notice the bronze puddle gets bigger as you move.  I personally use a pedal as my remote.  You can let off much faster then any hand remote. 
Penetration is always an issue this is why we bevel brass.  Some people preheat brass.  That all depends on how thick the brass is. If your using thin gauge material like that you wont need to preheat.  Preheating will warp your sheet especially if it has bent flanges from the break. 

Back your welds.
Always clamp something behind your weld in the event of blow through.  I use aluminum to back brass welding.  Backing your welds will also act as a heatsink an minimize warping.

Pits:
Pits need to be ground or drilled out and filled correctly

If you have the luxury of having a pulser this is ideal for brass welding.  Pulsers in general have 4 settings 1. Pulses Per Second (PPS) 2.Peak Time 3.amperage 4.Background amperage.
amperage would be the high point of the pulse
background amperage would be the low point of the pulse
pps would be how many times a second it goes high low high low etc
peak time is how long the pulse is at the high point.

This is good for a few reasons
1.Puddle size will stay consistant because the weld is hot cold hot cold etc
2.Color will stay CLOSE to matching because its not burning out all of the alloys
3.Pulser will automatically coin welds if configured right.

I use 2% thoriated tungston but thats up to you I wouldn't use anything less then 3/32 since brass burns so hot

See the puddle connect then add wire other wise you will wind up with pits.
Light gage material like that can even be fused.

Keep your max penetration on the plus side

A Smoke eater and a respirator will become a requirement the more often you weld brass

I dunno I'm sure I left something out but at this point i'm rambling off topic.
I've done all sorts of brass tig welding.
Here is my employers website you can see some things I have done with brass.
http://crescentmichaels.com/

Its hard to have a structurally sound weld that matches
I say its hard because its tricky to get both color and strength
Good Luck
Chris
Parent - By ssbn727 (*****) Date 06-18-2008 01:07
Nice work there Chris!!! :) :) :)

Respectfully,
Henry
Parent - - By Ringo (***) Date 05-15-2008 16:54
I've always used TIG ,DC electrode negative,with silicon bronze filler (CU-SI) 100% argon.I welded some custom made precussion drums and had slightly different color match,but it welded very well.
Parent - - By wolfewelding Date 06-12-2008 01:00
I would agree that this is the best method for welding brass. I prefer to keep the heat on the filler material (silicon bronze) and let the filler fuse to the base mat. and with somewhat of whip motion smooth the weld out for cosmetics. Getting the filler to stick to the base mat. with minimal heat to the base mat. will minimize or eliminate the "sizzling" and the pinholes. Does this make sense? It does to me but I can see where someone reading this would think I have breathed way too many fumes.
Parent - By arrowside (**) Date 06-18-2008 22:47
Wolfe nailed it. Where i work we make water tight ship doors, hatches, flood panels, etc. The " dogs" on some of the larger doors are some kind of brass, bronze combination, and they get welded to steel.

   When I first attempted this, I was muddereffing, and WTEffing everything in sight.

   At a loss, i tried the " whip ", motion described above, adding the filler when bringing the puddle back forward. For whatever reason, everything evened out and I ended up with some decent looking welds.

   You will also be at the mercy of the quality of your base metal. I was taught that the higher the zinc content, the more difficult it will be.
Up Topic Welding Industry / Welding Fundamentals / Help on TIG welding Brass

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