Disassembling a 17-4ph part, nickel alloy braze
Disassembling a 17-4ph part, nickel alloy braze
(OP)
I need to disassemble a 17-4 ph part, it assembled with nickel alloy braze. I want to dissasemble this using acid strips to remove the braze and leave me with pieces, that i can then repair, then put back together using the nickel braze. I have looked and found that an initial strip of a water soluable alkali cyanide and a nitro-substituted aromatic compound in an 185 degree bath for 20-30 minutes. Then a rinse, and the acid strip of 50% nitric acid, small amount of hydrocloric acid for about 30 seconds to 5 minutes. My question is , does this seem right? What else do we need to know, do? Thank you
mjohnsonaero
mjohnsonaero





RE: Disassembling a 17-4ph part, nickel alloy braze
"gently, gently; catchee monkey"
RE: Disassembling a 17-4ph part, nickel alloy braze
RE: Disassembling a 17-4ph part, nickel alloy braze
wait for will talyor to reply, he'll set you straight !
RE: Disassembling a 17-4ph part, nickel alloy braze
1. Joint info... Devil is in the details.
17-4PH in what condition(X) [SHT, H1000, H1100, etc]? Heat treated to condition(X) before or after brazing?
What braze alloy? What braze process? What braze class [A, B, C]?
Joint design? Thick or very thin details?
Engine or airframe part?
Operating environment?
Why is it so crucial to disassemble and reassemble... as opposed to replacing?
Regards, Wil Taylor
Trust - But Verify!
We believe to be true what we prefer to be true.
For those who believe, no proof is required; for those who cannot believe, no proof is possible.
RE: Disassembling a 17-4ph part, nickel alloy braze
17-4PH in what condition(X) [SHT, H1000, H1100, etc]? Heat treated to condition(X) before or after brazing?Has been heat treated and final aged, 1922 deg ht and then the final age.
What braze alloy? What braze process? What braze class [A, B, C]?BNi-2, AMS 4777, Hi-Temp 820
Joint design? Thick or very thin details? thin, .080 thick
Engine or airframe part?Engine
Operating environment? flying
Why is it so crucial to disassemble and reassemble... as opposed to replacing? Trying to come up with a repair for the part, my job. I'm development Eng here. Right now we are burning the old vanes out, EDM, but it is many steps to get this done, if I could seperate by this means, it would be a bit faster.
RE: Disassembling a 17-4ph part, nickel alloy braze
The part being salvage, does it meet the original dimensional criteria.
Playing with fire my Friend.
Mfgenggear
RE: Disassembling a 17-4ph part, nickel alloy braze
RE: Disassembling a 17-4ph part, nickel alloy braze
-Kirby
Kirby Wilkerson
Remember, first define the problem, then solve it.
RE: Disassembling a 17-4ph part, nickel alloy braze
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Disassembling a 17-4ph part, nickel alloy braze
my apologies
Just that when used parts that are tac welded, brazed have very close fitting requirements for brazing. "I been there done that."
& are very close tolerance components. it is very difficult to salvage.
a brazed unit to my experience is an inseparable assembly. in other words it would destroy it to disassemble it.
with out knowing the details of it's fit form & function. I would guess this will not be a successful salvage.
if you have bridged that then I tip my hat to your facility.
OK I got that out of my system.
what is the brazing temperature. are there any close tolerances that will be affected.
sometimes some dimensions are finished after braze. I have done that.
so that is the question of braze temperature, and are the parts not distorting after braze.
"when there is way there is a will". although I don't agree with salvaging parts of this nature
it is probably done more often than not.
Masking of all areas that are not be etched is mandatory. you must work with a supplier who is willing do it.
etch only the braze joints of the parts that are to be scraped.
this is not any easy task.
ultimately machining is probably the best choice.
Mfgenggear
RE: Disassembling a 17-4ph part, nickel alloy braze
RE: Disassembling a 17-4ph part, nickel alloy braze
your best bet is to take a scrap assy & work with it.
you are breaking new ground and you will develop the best method.
I forgot to mention berksire idea of using ammonia. it eats copper with out attacking the base material.
it may work. It "ammonia" is used often to strip copper plated parts.
Mfgenggear
RE: Disassembling a 17-4ph part, nickel alloy braze
Please keep the ideas coming!!!!
RE: Disassembling a 17-4ph part, nickel alloy braze
NOTE.
I believe that this question would be better addressed in the metals and metallurgy forum [ http://www.eng-tips.com/threadminder.cfm?pid=330 ] or welding, bonding and fastening forum [ http://www.eng-tips.com/threadminder.cfm?pid=725 ].
NOTE.
You gave such low-grade answers to my questions, I hesitate to get involved. In my opinion You need to do a LOT of basic braze process research prior to going forward. There are many tricky elements to high temp/strength brazing You need to be aware of before proceeding. You also need to understand the exact environment these parts see [temperatures, gas flow, vibrations, etc] before proceeding. Then there is the element of qualification testing to verify all aspects of a process in real world environements. ETC, ETC...
NOTE.
Major engine manufacturer's, such as PW, GE, etc, usually have detailed process manuals for every significant operataion. I checked a PW manual used by DoD and found NO references for brazed assembly tear-down for rework, much less tear-down after thousands of hours in-service use. In this case it is obvious Your company has no such Brazing process manual system and is hunting for one.
A few useful starting documents may be as follows.
AWS [Americamn Welding Society]
AWS A2.4 Standard Symbols for Welding, Brazing, and Nondestructive Examination
AWS A3.0 Standard Welding Terms and Definitions Including Terms for Adhesive Bonding, Brazing, Soldering, Thermal Cutting, and Thermal Spraying
AWS A5.8 Specification for Filler Metals for Brazing and Braze Welding
AWS A5.31 Specification for Fluxes for Brazing and Braze Welding
AWS B2.2 Specification for Brazing Procedure and Performance Qualification
AWS C3.2 Standard Method for Evaluating the Strength of Brazed Joints
AWS C3.5 Specification for Induction Brazing
AWS C3.6 Specification for Furnace Brazing
AWS BRH Brazing Handbook
ASM [American Society for Metals/Materials] Books on "Brazing"
http://www.asminternational.org/portal/site/www/Go...=
NOTE. ASM has an excellent forum for members to technical questions of ASM experts/members.
Also, suggest You get Your engine manufacturer's (or any other reputable manufacturer's) general processes manual(s) if they are available.
Regards, Wil Taylor
Trust - But Verify!
We believe to be true what we prefer to be true.
For those who believe, no proof is required; for those who cannot believe, no proof is possible.
RE: Disassembling a 17-4ph part, nickel alloy braze
I would also be careful about Hydrogen pick-up after the disassembly soak. Generally you should be OK, but I not sure after in service exposure and if I am on the aircraft I would want to be sure.