Welding Titanium

[SiR_RB]

Just want to know if it's possible, or who can weld a either a stainless steel / mild steel muffler to a titanium cat back exhaust ?

Has anyone done had this done ? Is one easier to weld then the other ? (Stainless or mild )

Any info would be much appreciated

[Ben C34]

Why not use a flange? Then not joining different materials.

[SiR_RB]

That's an idea...but isn't that the same thing as the flanges are normal stainless/mild anyways ?

Would a slip joint work ?

[scotty nm35]

Ti won't weld well to mild or stainless, as Ben said keep the flange the same material as the tube. Even mild flanges with stainless tube is a bad idea, but that's what most shops use when making stainless systems.

[GTR-N1]

Whatever the interface is, whilst it be Ti-SS, there'll be no galvanic corrosion between them. So you're safe there.

http://www.ncbi.nlm.nih.gov/pubmed/15246296

[Daleo]

Whatever the interface is, whilst it be Ti-SS, there'll be no galvanic corrosion between them. So you're safe there.

http://www.ncbi.nlm.nih.gov/pubmed/15246296

Yep, I've got 2 Ti plates, and 12 SS screws in my arm;

No issues so far...

[mr_rbman]

Don't have Titanium welded by anyone who doesn't have experience with doing so...

You need to setup a tig torch with a trailing gas lens in order to protect the molten pool form atmospheric contaminants, Titanium requires the molten pool to be kept as cool as physically possible when being welded...

Ti to SS is another level up again and wouldn't be recommended by most, as a few of the guys have suggested I would get flanges welded and join that way.

[SiR_RB]

We decided on flaring the muffler ends and making a slip joint with the necessary step lap band clamps

Works a treat

Thanks for the Replys

[Darmanin10]

Im looking at modding my 3.5 inch tomei ti catback, to make it a full 3.5 inch setup, as it currently drops down to 80mm at the cat.

Would the above be the best way to go about it?

[Kustom20]

Good to see you got the problem sorted - just thought I would post this reply

Welding SS and Ti also needs purging on the rear of the welds to ensure no contaminants are drawn into the weld while cooling - if you get the amps correct and the FZ or freeze zone then you can run a continuous stainless weld and not have the dark grey or carbons being sucked in because it freezes before the shielding gas exits the weld and nice salmon or rainbow welds,

Some use a gas lens on the torch which disperses a more even gas shield on the top welds or they will use a trailing purge as well. With the rear of the weld You can either get someone to shield opposed side with a purge tube while you weld, or purge the complete inside tube with end caps and purge hose as argon is heavier than oxygen it will push it out the tubes it you get your setup correct with release holes, some even weld SS and Ti in purge chambers similar to a small sandblast cabinet.

As for Ti to SS I wouldn't bother - can be done but the process is very extensive and use a lot of Argon for shield to protect containment

I would just stick with SS to SS and Ti to Ti - some of the tig fillers they are making are getting better like the Ally to Steel

Welding titanium with other metals presents great difficulties due to embrittlement caused by the formation of intermetallic phases. Numerous tests to join titanium with molybdenum, tantalum, silver and vanadium by the TIG process without filler metal have resulted, with the exception of vanadium and silver and with niobium and hafnium, in welds of limited ductility.

Welding steel with titanium is very difficult due to the low solubility of iron in alpha titanium at room temperature. When titanium is welded with steel the intermetallic phases TiFe and TiFe2 form, which are very hard and brittle and prevent the production of technically useable welds.

One way to achieve ductile welds of steel and titanium is to use intermediate layers of materials capable of being welded with both titanium and steel, without brittle phases occurring. One such material is vanadium. Titanium/vanadium/steel joints have been produced successfully by resistance spot, electron beam and diffusion welding.

In the same way, initial plasma overlay welds using titanium grade 2 and grade 12 on HII boiler plate have been carried out successfully, with intermediate layers of copper.

Niobium is suitable for intermediate passes to produce serviceable copper-titanium welds, while silver has proved successful in the production of aluminum/titanium joints.

In most cases a loss of strength in the weld must be expected.

Slip joints can be annoying but work ok, if you don't need to remove exhaust too often.

Another option would have been to either source the flanges either bolt type or v band whichever suited your muffler, if they were not available in Ti off the shelf for your application then either machinist to spin some Ti or a lasercutter to cut the bolt style then you could simply have them tig welded in Ti to suit.