SS For Blister Cu Launder

[HEC]

Here is a challenge, I am looking for a material suitable for handling molten blister copper. Blister copper is 97% copper with sulphur and oxygen impurities. We currently use a "HP" grade stainless steel for the Anode grade copper launders with great success. The Anode grade copper is 99.6% purity copper.
Cheers


Mark Hutton

 

[EdStainless]

So, these are cast parts? I presume since HP is a cast grade.

What do you use now with BC? What problems do you have?

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Corrosion, every where, all the time.
Manage it or it will manage you.

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[arunmrao]

A new potential application for my castings. HP grade is from ASTMA 297 35Ni/25Cr grade.
As per Steel Castings Handbook pp 22-12 in the temperature range of 1093-1177 C,HP has a stable austenitic structure . Grade HP and its modifications have high long term strength and good resistance to thermal cycling and carburization.

 

[HEC]

EdStainless

We currently use the HP cast grade stainless steel with the Blister Copper (BC). The problem is short life due to erosion/corrosion/melting(?). In essence it is quickly consumed in the BC application. Blister Copper temperature is around 1200 - 1280 Centigrade, just to add a degree of difficulty. I believe the Anode Copper (AC) is at around the same temperature.


Mark Hutton

 

[EdStainless]

I think that you need an alloy with NO Ni in it. A high Cr ferritic stainless would work. A CC (not that any exist) or HC with little to no Ni. It may become very brittle with time, you sure will get a lot of grain growth.

You need to avoid Ni because of low melting point compounds formed with both S and Cu.

I have see wrough 26-1 used with molten copper.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[arunmrao]

Ed How about 27%Cr CI? This is basically a wear resitance alloy,but no harm will be done if a few trials are made with this. I hope I get some day an opportunity to serve this industry!!

 

[EdStainless]

But CI is also 15% Ni. I don't think that you would see any improvement.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[arunmrao]

Sorry if I have confused. By CI I meant cast iron and 27% grade has no Ni.

 

[EdStainless]

OK, that is better. Would be a white iron? You might have some thermal shock issues because it is so brittle. Once you got it hot it shouldn't be a problem. Just don't cycle it.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[HEC]

Edstainless, what are the characteristics of the wrought 26-1 grade. Do you know of teh equivalent UNS number. I am interested in your comments in relation to Ni and Cu/S compounds being formed. Is this a possible cause of failure on the BC but not the AC application. A better understanding of the cause of failure will get us closer to a solution!

Arunmaro, the Cast Iron option sounds interesting.

Mark Hutton

 

[EdStainless]

26-1, E-Brite, S44627
It is a high puity super ferritic. It is a pain to weld. It must be quenched hard from anneal. The thickness is limited to about 0.100" (due to heat treating). Like all super ferritics it suffers from 885F Embrittlement, but you are hot enough that that won't matter. You are above the temp range.
At room temp it has limited ductility, and the DBTT isn't too far below room temp.
On the other hand, it cannot be chloride stress cracked. Being a high purity grade it has almost no grain boundary phases so IGA isn't an issue either. It is the workhorse in hot, concentrated caustic, esp if there are chlorides. It is more corrosion resistant than Ni200 and it will resist erosion.

To be honest, alloys like HR-120 and HR-160 would prob work better. A cast Co-Cr would be great, but you prob can't afford it. Some aircraft alloys might come close, like L-605.
Some Ni doesn't hurt too much, but in order to keep a 25-35% Cr alloy austenitic you need a lot, unless you use some Co instead.
High Si also helps.

How about R30023 (Stellite 23) or R30031 (Stellite 31), maybe as an overlay. Other similar alloys are R31233.
The more that I think about it the more that I like the idea of a weld overlay.

The kinetics of sulfidation are well defined. There are low melting eutectics formed with the metals and S. If the sulfide is liquid or gas, you get rapid corrosion. If it is solid then corrosion is slower. Each alloy has limits were you go from slow predictible corrosion to rapid attack. The breakaway is usually defined in terms of both time and temp.


= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[HEC]

EdStainless,

Thank you for all the information, it sounds like the 26-1 would be best applied as a cover sheet over a structural base. A the temperatures we are considering are there any issues with contamination from say a mild steel structural base. Also is the 26-1 easy to form over such a base?

The sulphides would mainly exist as copper sulphides, I would therefore expect that the nickel sulphide is more likely to form than the copper sulphide, i.e. the copper sulphides are reduced to copper and the nickel picks up the sulphur. I will do some more research on this.


Mark Hutton

 

[EdStainless]

Don't bother looking for 26-1. There is only one source (Allegheny Ludlum), and it is very difficult to work with.

I think that using a Co-Cr weld overlay sounds like a good idea. Apply Stellite 31 weld overlay over a new casting of your existing material and test it out. There are many good shops that can do weld overlay work.

= = = = = = = = = = = = = = = = = = = =
Corrosion, every where, all the time.
Manage it or it will manage you.

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[HEC]

EdStainless,
Thanks for your advice I will let you know of how we proceed and the results.


Mark Hutton