Alloy for blades & turbine disc

[Corgas]

I need to select new materials for blades and turbine disc for a gas turbine with 5ppm sulfur present @ temp 1300 °F.

A vendor is recommending UNS S66286. I have three questions :

1.- Will Sulfidation be an issue?
2.- How can I estimate service life (hours) based on operating temp only ?
3.- Can creep damage be present after 70,000 hours @ that temp.?

Thanks,
Corgas

 

[metengr]

Corgas;
Why don't you go back to the vendor and discuss these questions, since the technical recommendation is from them? This is what I would do on first cut.

 

[metengr]

Corgas;
One other suggestion, try to get your hands on a copy of the Aerospace Structural Metals Handbook - Ferrous Alloys, there is good technical information with associated references on A-286 material (UNS S66286).

 

[Corgas]

metengr :

This particular vendor is not recommending any type of TBC. Even though, plant location is not in marine environment, I'd expect type II (hot corrosion) due to the presence of sulfur.

Also, after reading a paper titled "Intermetallic Compounds in Titanium - Hardened alloys" by H.J.Beattie and W.C.Hagel another concern is aging.

Thanks,
Corgas

 

[TVP]

Corgas,

I am by no means an expert on gas turbines, but using alloy A-286 is questionable for this application. The temperature is very high [A-286 is usually recommended for temperature < 650 C (1200 F)] and the presence of S makes sulfidation resistance a significant issue, but this will also depend on the oxygen potential of the environment as well. In general, Fe-based alloys with > 25% Cr content are recommended for resistance to sulfidation. I suggest reviewing some authoritative references on this subject (ASM HANDBOOKS, NACE documents, EPRI recommendations, etc.) as well as alloy data such as that provided by Cartech:

http://www.cartech.com/news.aspx?id=1340

 

[metengr]

Corgas;
A 286 is a common gas turbine disc material and not necessarily for blades. You can do your own research to confirm this and evaluate other gas turbine alloys for this environment.

 

[Corgas]

TVP :

I totally agree with you. Those are the same issues that I mentioned to the vendor.

Excelente link, thanks.

metengr : What materials will you recommend for blades?

Thanks again,

Corgas

 

[metengr]

http://iweb.tms.org/forum/messageview.aspx?catid=194&threadid=277&enterthread=y