High temp, abrasion resistant mesh material? 1

[kclim]

Hello all,

I'm looking to find a material I could use for a wire mesh. The mesh is to be used in a boiler furnace space (operating temperature 650-820 C, dry environment) to screen flyash particles.

Our most recent attempt at these screens consisted of a 316 SS wire mesh, which failed quite miserably - I haven't had the opportunity to look at the actual mesh but I've been told that it underwent excessive scaling.

The original drawing states that a 321 SS mesh should be used, although some questions have been raised regarding the suitability of this too.

Does anyone have any experience which such screens, or can someone recommend a material? I guess the main criteria would be:

- high temperature resistance
- good abrasion resistance
- low cost

Inconel has also been suggested, although I'm a little concerned at the cost.

Any insight would be much appreciated.

Regards

 

[arunmrao]

You can consider 310 or 321 material for high temperature application. But wear resistance from this material is poor. Perhaps consider some form of cladding on the belt which can be disposed or replaced.

 

[kclim]

Arunmrao - the screen is a static screen with mainly hot air blowing through it. But I'm starting to think that the austenitic stainlesses might be out of the running.

My initial concern with 316 was that we were operating in the temperature region where sensitisation can occur, although I have been somewhat assured that this is not a major operating concern, because it isn't really a corrosive environment.

Keep the comments coming... much appreciated

 

[NickE]

Nickel based alloys might provide the properties you'r loking for at those temps. I think tat the steels are out of their element. maybe one of the super duplex grades.



Nick
I love materials science!

 

[arunmrao]

I still feel that you can try with the suggested SS wire and then spray a wear resistant ceramic on the wire,like it is done on pump shaft sleeves for improving the wear resitance.

 

[mcguire]

The temperature here isn't extreme for certain stainless grades, but they must be resistant to the environment. As Arunmrao said 310 would be much better.
Spalling resistance is helped by minor amounts of rare earths. Avesta-Polarit makes grades based on this principle. Check out 253MA on their web page. If this problem weren't solvable we wouldn't have jet engines.

 

[rolledalloy]

820C (1508F)is certainly pushing the limits of 316 stainless steel from an oxidation standpoint. We generally suggest 1500-1600F as the limit for 316 plate. One would want to be more conservative with light sections like thin wires.

Stainless steels with greater chromium and nickel contents will raise your temperature capabilities. 309 (13Ni-23Cr, 1900F limit) stainless would be the least expensive upgrade followed by 310 (20Ni-25Cr, 2000F limit). RA 253 MA (11Ni-21Cr-Si-Ce-N, 2000F limit) is a good suggestion for abrasion. The cerium component helps the metal form a thinner scale that is less prone to spallation and less susceptible to damage and removal by abrasive particles. For this reason this alloy has been popular for pulverized coal burners adn fluid bed applications.

 

[rolledalloy]

One comment on superduplex. These grades of stainless are good for aqueous chloride environments in resisting corrosion and mild abrasion. They are not suggested for use at elevated temperatures. Most duplex and superduplex stainless steels should not be used above 600F because of their rapid formation of secondary phases that will severely embrittle them. 885F embrittlement at lower temperatures and sigma phase formation at higher temperatures.

 

[unclesyd]

At this temperature your are going to have to use a refractory alloy to have any strength. We used Alloy 230 screens slighty above your temperatures with good results. I would contact a wire cloth manufactuer, one that works with the alloys and use his knowledge. There is a lot of information, mesh size, width, unsupported area, and etc., needed for a recommendation

 

[kclim]

Thankyou everyone for your responses. I finally received a sample of the mesh today. My initial comment about the thick scaling still holds, and it snaps like a twig - probably a sigma phase/embrittlement issue.

The grid dimensions are
1000 x 700 mm
3.15 diameter wire
10 mm aperture
woven

It sounds like the 253 MA might be the go, and failing that probably 310.

 

[metman]

kclim,

Thanks for the feedback but you did not tell us which alloy you tried.

Jesus is THE life,
Leonard

 

[stanweld]

The 253MA alloy has proved effective for similar oxidizing/abrasion environments in your temp. range. Also recommend N06617 or N06007.

 

[Maui]

446 is a non-hardenable stainless grade that has among the highest corrosion and heat resisting properties of any of the stainless grades. I believe that it would be appropriate for your application, provided the abrasion resistance is acceptable. It scales at approximately 2000 F. For the temperature range that you specified it should not exhibit any significant amount of scaling.


Maui

 

[kclim]

Metman,

Made the final recommendation of 253 MA, and I believed the relevant store people have followed it though. Won't be put in service for some time though... We'll see how it goes.

thanks again everyone