Thermally Size Inconel 718

[TiGuru22]

I have an aerospace part currently being manufactured to a typical aerospace process plan. Three details two are Inco 718 and one is Rene 41. All three are GTAW welded to typical aerospace standard. After welding the assembly is put on an expander to bring back into drawing tolerance due to welding and maching stress up to this point. At this point the manufacturer sends the part out for a full Solution Heat Treat along with a Precipitation Hardening cycle. The part is laid down in the vacuum furnace for the heat treat, no fixturing to retain flatness or roundness of datums. What I am interested in developing is a heat treat tool to restrain or size the part during heat treat to ensure the part meets flatness and roundness requirements. Does anyone have any experience with designing such a tool? What metal would you pair with the Inconel 718/Rene 41 weldment? I have designed many other tools like this, but never for Inconel 718?

Please lend a hand if you can, I would appreciate it very much,
John Monsees

 

[Sparweb]

I don't have enough experience with this to help you directly, but I do question the cold-working between welding and heat treatment. Can you tell us more about why that is done? Surely the inspection that follows the precip. hardening is the one that counts.

STF

 

[WKTaylor]

TiGuru...

Metal & Metallurgy forum

http://www.eng-tips.com/threadminder.cfm?pid=330

is probably the better place for this question.

NOTE.
I am uncomfortable welding I-718 & Rene-41 together... then doing a SHT/PHT on the weld assy. I couldn't ID a compatible weld-filler alloy.. and Rene 41 requires higher SHT & PHT temps than the I-718... for starters.

Pneumatic planishing can-be used to cold-crush some welds smooth and straighten some parts [annealed]... but I haven't heard of it used for 'working' nickel/cobalt alloy welds.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[TiGuru22]

Dear WKTaylor, Actually in the aerospace industry GTAW, EBW and LBW of this material combination is fairly common. Where a filler is required we generally us AMS 5832. The Solution Heat Treat and Precipitation Hardening generally follows that required for Inconel 718. I have seen the customers, usually the jet engine builders, have their own heat treating specs to cover this combination too. It just depends I guess on what you favor for the actual application. Just as a matter of FYI on my original inquiry, I have gotten quite a bit of response from the heat treating industry. It seems that a 300 series stainless steel is favored with consideration given to the difference in CTE. On the question of planishing the welds, I have never done that on this combination before. I have performed this process on other high stress welds, just not this one.

Thank you for your help.