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Up Topic Welding Industry / Technical Discussions / GTAW on a aluminum 6061 dip brazed fabricated part
- - By Ringo (***) Date 09-05-2008 12:56
Anybody out there have any experience GTAW over a dip brazed joint?We have a procedure in place from the manufacturer,1)Carbide burr to remove anodize coating,2)Clamp copper chill blocks,3)GTAW AC 10-20 amps balanced AC,argon shield,AMS 4248 wire4)blend ,5)Stress relieve 300F for 4 hours,5) FPI,6) re-anodize.
Parent - - By 803056 (*****) Date 09-05-2008 13:29
Good luck.

Aluminum filler metals used for dip brazing melt at temperatures on the order of 50 degrees less than the base metal. The braze will melt as you attempt to weld over it and it will alloy with your filler metal and base metal. In doing so, it can create eutectics that have a wide range between the liquidus and solidus which will likely cause cracking issues.

So little detail provided, so little we can suggest.

Best regards - Al
Parent - - By Ringo (***) Date 09-05-2008 13:35 Edited 09-05-2008 16:30
I can give some more detail,but it has'nt been attempted yet.The part is a core fan vane on a gas turbine engine,welding on a crack on a airfoil that extends thru wall,basically a t-joint.I figured there would be cracking issues,and I don't think there is any way to totally remove the existing braze
Parent - - By 803056 (*****) Date 09-05-2008 13:50
That's the devil of it, removing as much braze filler as possible.

Best regards - Al
Parent - - By Ringo (***) Date 09-05-2008 13:58
They figured it was worth a try,it's a 50k part.I'll let you know how it goes.
Parent - - By Lawrence (*****) Date 09-05-2008 15:34
Ringo,

It's a long shot but water blast might be a mild method to consider for removal. But that is going to take R&D programming for a shot in the dark if you have the equipment at all.

It is always problematic to weld with braze mateiral on or behind a thin component. Repair of cracks and wear near Honeycomb brazed to airseals are a common problem... But the solutions for your type of problem are going to be different with aluminum vs hastelloy that is far more common.

This might be a good time to have a peek at the Pratt, GE, CFM, Rolls, or Allison, standard practice manuals to see if they provide any insight..... Sometimes the research time is cheaper than trial and error.
Parent - - By Ringo (***) Date 09-05-2008 15:37
It's worth a shot,we have a few scrap parts to practice on.What PSI?
Parent - - By Lawrence (*****) Date 09-05-2008 21:36
Oh man I dunno that... I'm talking that super waterblast stuff they use for removing flame spray from super alloys and Ti.......  We had good succsess with it at UAL in the late 90's.  This stuff was so powerful that it was all robotic. The part was loaded in a fixture and the multi axis sprayer went to work in a closed cell...  Not your typical steam clean... This stuff would blast right through Inconel if left in the same spot too long... But would also do a beautiful etch after removing flamespray coatings.... a real thing of beauty when setup correctly.
Parent - - By Ringo (***) Date 09-09-2008 10:57
We'll give it a shot,thanks,man
Parent - By Lawrence (*****) Date 09-09-2008 17:16
Keep us posted... this is interesting!
Up Topic Welding Industry / Technical Discussions / GTAW on a aluminum 6061 dip brazed fabricated part

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