Welding Inconel??

Date 12-07-2008 15:09

from what little i had had with inconel it welds pretty much like sst hope this helps try some beads on sst to get the fill
thanks
mac

By Jenn

Date 12-07-2008 16:34 Edited 12-07-2008 17:02

Rob I weld with inconel ALL the time at work.... pretty much it handles exactly like stainless steel does. It is a little more finiky about how aggressive you have to be about getting in and out of the puddle (so the end of the rod doesn't ball up on you), and it likes LOTS of argon shielding. (I use a purge box whenever possible on smaller items). I use RED tungstens with this, of course, and sharp sharp points on them. Best to keep that tungsten as clean as possible too.

Sometimes the puddle with inconel may not look as super "clean" as stainless does with that one defined fish eye, this may take a little getting used to, there may be little tiny and more than one piece in there. This is WAY the case if you have the amps down too low (I do allot of buildups and have to do it this way anyways). It looks very mukky, but turns out ok in the end. As long as it's nice and shiny when you're done, or whatever color is on there brushes off easily, you're ok.

I don't know what else you'd like to know about this metal.... I'm rather fond of working with it :) But the "colors" do show any lack of shielding, or if you let off at all. AND by the way, I am certified with inconel....

Jenn

EDIT < here's a tidbit from an article that describes what I'm talking about as far as the puddle not being as "clean looking" :

"Inconel 625 can be welded using conventional stainless steel TIG welding techniques. Inconel Filler Metal 625 rod is used to weld Inconel to Inconel as well as to dissimilar metals including stainless steel. Inconel weldments are high strength and are highly resistant to corrosion and oxidation. Many welders describe that welding Inconel as "dirty". In other words, the weld pool appears to be under a "skin" and is not well defined. In addition, the weld pool is somewhat "sluggish" as compared with steel or stainless steel. These characteristics tend to result in a "coarse" appearing weldment as compared to stainless steel. Welding Inconel is not necessarily more difficult to weld than stainless, just different. "

END EDIT<

By Rob Wade Date 12-07-2008 17:50

Thanks for the info everyone. Jenn, its funny you posted that. I just finished reading that on the Burns Stainless website, before finding this site. Thanks again.

By Jenn

Date 12-07-2008 18:20

Welp, it's true, but mostly only when you're a little on the low side of the amps, it gets cleaner the hotter you weld with it. But you can't always do that ;) Lemme know if there's anything else you need with it, I think those are the major particulars on it.... really.

By ZCat

Date 12-07-2008 22:35

As long as you're not butt welding pipe, you shouldn't have any trouble. That's where it seperates the welders from the wannabes.

By Jenn

Date 12-08-2008 00:31

Technical sheets on it if you want, may be more info on the metal than you really care for:

http://www.specialmetalswelding.com/products/inconel/inconelfm625.htm

By js55

Date 12-08-2008 14:01

Inconel is a Brand name for general group of alloys. Whether or not you use 625 depends upon the base metal you are welding too. Know which 'Inconel' you are dealing with. Alloy 625 (E/ERNiCrMo-3) is a Cb stabilized Ni Cr Mo alloy that can be slightly more crack sensitive than some other Ni base alloys, though tons and tons of it are welded every day. Its a good all purpose wire for many applications but is not the only Ni base alloy available. Not by a long shot.
If your GTAW welding I more commonly recommend ERNiCr-3. Its generally cheaper and is a good all purpose wire as well, and is good to temps of 1100degF.
Cleanliness is an absolute. Use wider bevels, and knife sharp feather edges. Keep amps and volts down. Cranking up the heat won't make it run any better. Keep torch more perpendicular than with other alloys. And don't get in a hurry.

By Lawrence (*****)

Date 12-08-2008 17:06 Edited 12-08-2008 17:47

Along with the good data from js and Jenn there are just a couple of pointers that require special attention with many of the alloys in the inconel family..

Weld terminations are a big key. When a foot pedal is available it is a good practice to slowly "tail off" your welding current and actually watch your puddle "freeze flat" (meaning no crater in the termination). This may require an extra dab of filler. This technique is one reason seasoned inconel welders will often select a smaller wire diameter for manual filling than with a stainless filler. That dab will help to cool the puddle and fill any crater. Those craters are stress risers and often under magnification will display cracking. Many of those seasoned welders also employ a smaller diameter tungsten (.040 for example on inconel up to .080) in order to have greater control on weld terminations.

Starts, stops and tacks.
Oxide coatings on these alloys, if not removed may result in lack of fusion (lof) even when running over a tack. RT indications are often caused by a lack of surface prepration on multi pass, or sequenced welds that are employed to control distortion. So when you are tying together passes or running over tacks, be careful to remove all surface oxides just prior to welding. :Edit: These oxides are present on weld faces even if the color of the weld appears perfect,,,, still remove them on multi-pass or run overs.

These techniques are best thought of as "habbits" and can be a benefit on inconels, stainless, or any precipitation hardenable super alloy. They can't hurt and can only make for superior craftsmanship.

By Rob Wade Date 12-08-2008 23:42

Thanks for the information everyone. Since I don't do a ton of tig welding, some of the terminology is a little over my head, but most of it,I can defenately use. Thanks again.

By Shane G Date 12-09-2008 03:24

I have to agree on the comment on weld termination. Most of the nickel alooys we run across 617,625,Hast-x,Haynes 230 are really bad about crater cracking if you do not taper off your stop really slow and add some wire to it.

They also as mentioned above are not nearly as fluid as mild and stainless steels and alot of times depending on material and even brand of wire you will see some crap floating around on your weld puddle almost like a cloudy dark color which will solidify along the toes of the weld alot of times.Really make sure the material is clean as possible.Running it hotter trying to make it more fluid will not help much either it wil discolor badly.

Also if it is thin material or tube to make sure you back purge because it will be a real mess on the burnthru side,actually it would probably suck back and go very deep if you needed to backgrind.

By Jenn

Date 12-09-2008 03:44

NICE :)