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Up Topic Welding Industry / Technical Discussions / Inconel 718 cracking
- - By Ringo (***) Date 02-08-2008 14:48 Edited 02-08-2008 15:10
We are welding some LP interstage seals that are made of Inconel 718,with Hast W wire (AMS5786)that we are getting some circumferential cracks on the build-up (3 passes).The process is GTAW (pulse),on a Sciaky 5 axis welder with a  Miller power source,argon shielding (20 cfm),about 80 amps,on .095 (approx.) thick material.The piece is basically grit blasted with aluminum oxide,and welded.

Any help would be greatly appreciated,
Ringo 
Parent - - By Lawrence (*****) Date 02-08-2008 16:03 Edited 02-08-2008 16:07
Ringo

I spent years running Sciaky's on LPT Seals etc.... However ours were on CF6-6,  JT8D's and JT9D's. 

I guess the typical process control quesitons are in order.

Inco 718 is a Percipitation Hardenable alloy so did you:
     Anneal?
     Post weld stress relieve?
     Does your welding fixture have pre-load expansion features?
             If yes are you sure the proper values were attained?
             If your fixture is solid did you need to heat the part to remove it?

Are you using a trailing shield to reduce oxides on multi pass welds or do you stop to remove surface oxides after each pass?
I belive you will find removing those oxides between each pass of a multi pass weld to be a standard practice or OEM requirement with all inco alloys.
On parts with a continuous rotation build up schedule, an integrated argon trailing sheld can make significant reductions in oxide buildup.

There are a number of further variables also in play, but I think this is good to start....  Has W for a filler for one....High/Low pulsation values  Wire feed/retract and R Axis speeds etc.  These are a bit above my paygrade. <although I know a guy who I could recommend who is literally the best in the world at this exact kind of stuff>
Parent - - By Ringo (***) Date 02-08-2008 16:22
Lawrence

Thank you for the very informative post (once again),and we have done none of the above that you mentioned.I got in on the last part of this repair qualification,in that it came to me for a visual and i rejected it.I will try to implement some if not all of your suggestions in order to rectify our problem.I'll be in touch.

Once again thanks,
Ringo
Parent - - By Lawrence (*****) Date 02-08-2008 17:35
Ringo

Also
Pay very close attention to the ID demensions pre- and post weld.....

You will most likely have to go deeper than the repair AR/RU doccuments to get these numbers.
Parent - - By Ringo (***) Date 02-08-2008 17:42
We have a pretty good fixture,Its made of copper,with holes for back-up gas.I noticed that the sciaky already has a flowmeter on it specifically for trail gas.Is there a specific trail gas rig that goes with the Sciaky?or can we just get one made for a manual rig? 
Parent - - By Lawrence (*****) Date 02-08-2008 18:06
Ringo,

We made our own custom trailing shields... We had a certified mad scientist as a tool maker who made argon trailing shields that looked suspiciously like a Porsche 911 Targa.

BTW  I worked for UAL.
Parent - - By Ringo (***) Date 02-08-2008 18:21
Lawrence

We may buy off the shelf for the time being,but I think it would be nice to have one that curved like the seal.We are getting some bad oxide on the backside of the seal,almost to the point of sugaring.We had this guy from Chicago (PWT) to train us on the machine(he actually built this one for Northwest),and they make custom shielding devices that should work.Its still in the development stage,but they have pletty out there that need this repair. 
Parent - - By Lawrence (*****) Date 02-08-2008 18:42
I worked with Gregg and Gary from PWT for years... Gregg was my boss and an important mentor in my career; he taught me everything I know about this kind of work and process control in general, and Gary is a certified mad scientist.

They have a trail of patents behind them that GE and Pratt covet.

If you depend on PWT they will meet your needs. 

There is absolutly nothing I can add to what they offer.
Parent - - By Ringo (***) Date 02-08-2008 19:33 Edited 02-09-2008 01:45
The guy who trained us was named Walt,but he spoke very highly of Gregg.I'm going to call him and get the trail gas shield.They have some custom ones in their brochure.Maybe he can give me some advice as well.I appreciate the help,and I don't know where you work now Lawrence,but you should probably go into consultingI think your leaving alot of money on the table.

Thanks buddy,
Ringo
Parent - - By Lawrence (*****) Date 02-08-2008 20:44
Walt is a cool dude as well....Expert in hardware and creative solutions, he has gotten way more out of some of that equipment that it was originally designed for.... When I worked for United and he worked for Sciaky we would meet at every welding Expo and Walt would take us all out to dinner.... Detroit/Winsor Canada was an especially memorable time... I remember drinking freely and eating alligator....

I consult a little through the college as time permits, less money that way but far fewer hastles...Thats one of the biggest benefits of teaching at the College, I have December, June, July and August to consult, write, do committee work or just go up north, read Russian novels and snag bass with my wife.... But I have enough work to do as it is (more on that in a few months).... Beside it's not all about money.
Parent - By Ringo (***) Date 02-09-2008 01:43
Right on Lawrence,I know it's not all about the money,but you only live once brother.You sound like you have a great life,and I'm happy for you.Once again man,thanks for the advice.I put an email into Walt this afternoon,for the trail gas lens,and in conclusion,I hope to meet this guy Gregg from PWT some day,It seems that he is a weld god of sorts.

Later,
Ringo 
Parent - By Ringo (***) Date 02-08-2008 17:40
Lawrence

Did you used to work for Northwest?The reason I ask is,we bought the  Sciaky from Northwest,and there are some seal programs already on the data base.This is the first repair we have attempted with this welder,and with your help hopefully we can make it a successful one. 
Parent - - By js55 (*****) Date 02-08-2008 16:13
This could turn into a good discussion, and perhaps Lawrence can get in on this one.
Now correct me if I'm wrong, because I'm no expert on blast media, but wouldn't using Al oxide (your mentioning of this is conpicuous)as a blast media have a tendency to increase Al content in the weld metal and possibly transition the precipitation hardening mechanism of 718 from its intended slower precipitating y" (Ni3Nb) to th efaster precipitating y' (using Al/Ti) which is more susceptible to strain age age cracking?
Although we need more details on the cracking.
Parent - By js55 (*****) Date 02-08-2008 16:14
Like I said, Lawrence should weigh in on this one, and beat me to the punch.
Parent - - By Ringo (***) Date 02-08-2008 16:24 Edited 02-09-2008 01:52
I'm afraid the prep (grit blasting with aluminum oxide) is trapped in the book repair by Rolls-Royce,and we can't deviate,even the PSI of the grit blast is controlled,but what you said is worth exploring.
Parent - - By js55 (*****) Date 02-08-2008 16:33
Well, it may certainly be interesting but I'm guessin if RR has it as an SOP your probably going to have more success looking elsewhere. Maybe a quote from Emily Litella is apropos at this point.
Parent - - By Lawrence (*****) Date 02-08-2008 17:49
JS

It's true that all the majors (aerospace wise) are just dandy with alum oxide grit blasting media for air seals etc... I know we used it for A286, Has X, Inco 718, inco 625. Incoloy 901, waspalloy and a few of the weird cousins..

By the way... What's all this I hear about Eagles Rights?
Parent - - By js55 (*****) Date 02-08-2008 17:59
Lawrence,
Nevermind.
Parent - - By Tommyjoking (****) Date 02-09-2008 01:46
js55   I got the same thing....the AL oxide is listed in the repair station manuals...therefore it might as well be written in stone.  IT is a good point tho......
Parent - - By Ringo (***) Date 02-09-2008 01:56
Tommy

We are stuck with that.If we try to change a medium or something along those lines,We are told not to deviate from the controlled book repair.It's the FAA-those guys are tough to deal with.
Parent - - By Tommyjoking (****) Date 02-09-2008 03:13 Edited 02-09-2008 03:16
RIngo---  tell me about it......anytime you involve the govmt whether its defense contracting or what have you...it can be painfull to get real world changes going.   We have to do procedures per repair manuals period or ya get busted and it gets expensive quick.  I get into a lot of arguments over things like preheat etc.   There is quite a bit more leeway in the manufacturing side tho...as all you got to do is go get the FAA to buy off the change...still takes time and money...but its nothing like say trying to deviate from a GE standardized process...thats practically impossible it seems.  Its all because they manufactured it and you did not I rekon.....so from my point of view either they have to change it or thru business relations you communicate and get them to go thru the expense of a rider or change order on the manual...that probably directly relates solely to how big a customer you are.  LOL!!  no matter as those decisions are above my pay grade...I give them what they ask for no more and no less.  At any rate I understand your pain in dealing with it....its a long slow road when you see errors.....but in the end its probably for the best,  cause I don't see too many planes dropping out of the sky in these parts.  I am pretty lucky where I am in that I have a few contacts in engineering that are not afraid to stand up and say " Guess what we were wrong"....even on qualified drawings.

Best Regards
Tommy
P.s. I love my job because even as a welder I can effect change that makes people safer, the company more profitable or my job easier to take.
Parent - - By Ringo (***) Date 02-09-2008 03:42
Great post Tommy

I spent alot of years in the manufacturing and construction industry,and there is a little more leeway in PQR and WPS qualification.but since I have gotten back into the aviation industry in 2000,(I am a former Marine who was in avaition back in the mid to late '80's),it's a little frustrating trying to get parts overhauled on manufacturing principles.I enjoy coming on this forum an interacting with great welding minds.As I once read,"you should learn and study about everything important in your life",this is a great place for welders and inspectors like ourselves to share our experiences with everybody who's interested.

Keep it real,
Ringo 
Parent - - By Ned CHS Date 01-20-2011 04:09
Hi Ringo: I'm a Chinese new graduate with a mechanic design major.I teached myself ENGLISH therefor there may be some mistakes in my writing.
The company I work for is a sales agent of Sciaky in Shenzhen ,China.
We have not enough technical informations about EBFFF.
So everything about Sciaky or Fabrications is important. and this is why I interesting in your problem.
what is PWT? is that short for Propulsion Wind Tunnel or what?

BTW,I'm 21 years old.what you had said is very useful for my views toward life .Thanks
Parent - - By Lawrence (*****) Date 01-20-2011 04:42
Welcome the the forum Ned!

Your English is *very* good for a beginner..  I could understand you perfectly!

"PWT"  in this conversation stands for "Percision Welding Technologies"  They are a group of consultants and experts on GTAW, PAW and EBW and have probably about 90 years of combined experience doing work with Sciaky equipment.   Programming, Process control, set-up, repair, metallurgy, procedure qualification to DOD, Pratt, GE, Rolls Royce, Allyson and more.

They are the best in the world at what they do.

Here is a link to their official contacts and website.
http://www.pwt-online.com/

If you contact them, please give them Larry's best regards..
Parent - By Tommyjoking (****) Date 01-20-2011 05:37
Dang Law u r a great ambassador for the AWS....they should give you some free books or something.
Parent - By Ned CHS Date 01-20-2011 10:23
thank you very much!I'm really appreciate for what you had done for me.
I had sent some email to Pat Lee /Megan Paja/Lori Dick/ Kim Farrugia /Kenn Lachenberg (to mention just a few) before.
but without feedback,they are busy or in their new year vacation maybe ,i think.
give them Larry's best regards means say hello to them and mention Larry,right? i wonder Larry is short for Lawrence or another person?it is Lawrence right?
it is interesting ,still i may not contact PWT because they are busy too.but you are different since you gave me feedback. U are very kind .
what attract me most is the EBFFF. can you give me some advice on EBFFF?
beside that i had download every *PDF on the website of Sciaky.com about EBFFF or close technology.
i can understand the articles well despite the time i had used on them is costly.
Parent - - By Ned CHS Date 01-21-2011 06:29
thank you Lawrence.
the website about PWT you had offered yesterday is useless at the first sight.
but through carefull reading ,i find it deadly useful.A lot of EB welding components i can find there.I can not thank you more.
i'm really sorry,my perception of english is not very good,so i can not find important informations immediately.
BTW. Regis,an export manager  from Climats company visited China as a guest of our company .We eated Chinese food together.he used chopsticks skillfully which is very amazing.
our company is a sale agent for Sciaky/Climats/Qualmark/Reliasoft.
so this is why Regis come to our company.
i do not think he was full after dinner,because Chinese food is cut into small pieces.
Ned
Parent - - By James Kelly Date 04-17-2011 22:18
This is sort of a dumb comment, and I don't want to offend anyone, but is there any chance of copper pickup from that copper fixture?
Parent - By Ringo (***) Date 04-18-2011 13:08
Its possible,but we seem to have the problem rectifed (no more cracking).
Parent - By Lawrence (*****) Date 04-18-2011 14:59
James,

It's not a dumb comment at all... The OEM's and the Filler metal manufacturers all have cautions or prohibitions on copper contact with many of the members of the Inconel family as well as Haynes 25 and Haynes 188 cobalt based superalloys.

That being said, I have seen copper backups that were plated and backups that were not plated used on projects at OEM, Tier 1 suppliers and numerous repair facillities... Haven't ever seen cracking linked to copper backups. (will not mention names to protect the guilty  :) )

*Most* airseal buildup repairs are repaired in such a way that the base metal that reaches transformation temps will not be in contact with the backup...   Now there are plenty of other types of repairs that do have molten or high temp contact with argon backups...

What I don't know is whether the copper/superalloy contact might leave traces that could migrate interstitially over time with all the hot section cyclic activity and cause problems down the line that might not show up on post construction/repair work...  What do you think?
Up Topic Welding Industry / Technical Discussions / Inconel 718 cracking

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