316/316L versus 316Ti 4

[BobUXL]

I have read a few threads about the benefits of a titanium stabilized 316 and that 316Ti has better corrosion resistance than 316L. What are the pros and cons for these two alloys. If 316Ti has better corrosion resistance, why isn't 316Ti not more mainstream. I am looking for when I should use 316L and when I should use 316Ti

Thanks,

Bob

 

[metman]

BobUXL,
Could you please post the other thread numbers so we can catch-up with you? I am very interested to hear some replies, especially from the S.S. guru (what's his moniker) whom TVP sometimes defers to.

Jesus is THE life,
Leonard

 

[NickE]

-mcguire is our local SS info guru...

nick

 

[CoryPad]

mcguire seems to be on a (hopefully) short sabbatical from Eng-Tips. He has not logged in for almost one month, so others should respond if they can help.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[BobUXL]

Hi everyone,
Sorry I took so long to respond. Being on the road and having to put up with dial-up, well you know.

Here are some threads I have read about some of the differences. 330-82054, 794-64209, & 338-58971. These talk about some of the details, but would like to get more detail with 316L is the best choice and 316Ti is the best choice. I am looking for some side by side comparisons.

Thanks,

Bob

 

[kclim]

I would say 316L and 316Ti have pretty similar corrosion properties. The whole point of reducing carbon (L) and adding Titanium (Ti) is to reduce chromium carbide precipitation and the subsequent occurance of intergranular corrosion.

The Ti grade would be more desireable in a high temperature environment where strength would be better retained than the L grade (low carbon reduces high temperature strength).

On the other hand, I imagine the L grade would be easier to get a hold of - especially given that there is a dual certification 316/316L grade available, which covers a lot of applications. 316L would probably be cheaper than 316Ti too.

There would be less restriction in the welding too - could use 316Ti consumable to weld 316L, but not the other way around (can't verify this, need an expert to back me up here).

 

[mcguire]

Sorry to be gone so long. 316Ti should perform the same as 316L by conventional metallurgical thinking, but recently we have learned that Ti ties up more than carbon. It is a powerful deoxidant( stainless usually is only Si/Mn deoxidized to about 100 to 200ppm O) and a more poweful de-sulfurizer. It is now thought that oxygen and sulfur cause the de-chromization around inclusions that causes pitting.
This makes 316Ti much more pitting resistant than 316L.
The critical pitting temperature of 316TI is over 20C. For 316L it is 10 to 15C. The difference is even greater in welds wwhere 316L drops off to about 5 to 10 C whereas 316Ti hardly changes.
316Ti is hard to find in the USA, but is common in Europe.

 

[TEV]

As McGuire states, 316Ti is common in Europe. The European version also generally has a minimum of 2.5% Mo, compared to the American versions of 316, which are typically about 2.1% Mo. This will also improve pitting resistance.

 

[BobUXL]

I would like to thank all for their contributions.

Bob

 

[rmw]

mcguire,

What does the ti do to the weldability of 316ti, and is this a plate material as well as a tube material??

rmw

 

[rmw]

bobUXL,

See my post in thread 391-92907 for a link to ask for an e mailed version of a paper by Dan Janikowski of Trent tube. This has a lot of data about SS materials, among others.

rmw

 

[BobUXL]

mcguire,

First off, I do not know whether this is available in tube or plate form. I do know it is available in bar form from Ugitech (Previously known Ugine Savoie Imphy)through Ugine Stainless & Alloy here in the US. I would imagine that the plate could be purchased through Industeel (a sister company) if quanities are sufficient.

The 316Ti that Ugine supplies is not AISI 316Ti. The Ti is balanced a little differently to enhance corrosion resistance.

My main reason for starting this post is to get an idea of the differences between this grade and 316L and why 316Ti is not more prevanent in the US. It does seem to have some advantages over the typical 316L.

As far as weldability, I do not detect any differences between 316 (check out the Ugitech data sheet at

http://www.ugitech.com

under Ugima 4571).

RMW - Thanks for the lead. I will check this out.

Bob

 

[mcguire]

Bob
The Ti can hurt weldability in two ways. It can cause welds to have a intermittant slag clump, e.g. every few feet. This applies mainly to the manufacture of tubing. Whether this occurs depends on some other chemistry factors.
It can also lower the sulfur level. The absence of sulfur causes TIG welds to have poorer penetration. Allegheny Ludlum makes a grade of 316L for Rath Tubing which has a sulfur-bearing, titanium-modified chemistry, which gives all the corrosion benefits of 316Ti without the poor weld penetration. Try contacting Dave O'Donnell, technical director at Rath, to try to get some. It is proprietary.
I used to work with Ugine research. They are quite good, but sometimes it is like having a root canal to get them to give you what you want. Their specialty is making high machinability products. You would have to go to Ugine for plate or tubing. They are also very French.

 

[BobUXL]

mcguire,

Thanks for the tip. This will be very helpful.

Bob