Corrosion Potential of Certain Alloys

[CobusvanJ]

Hi,

Can someone please advise on the galvanic (corrosion) potential between 16Mo3 and 15NiCuMoNb5 in feedwater?

Can somone also advise where I can find a table listing material galvanic corrosion potential values specifically with regards to EN (European) materials?

 

[mrfailure]

I do not know any standard reference tables including these alloys, but the difference between their potentials should not be meaningful in my opinion. Both are considered low alloy steels. The nickel in the 15NiCuMoNb5 would be the primary differentiating factor in potential if there were one. However, tables show a fairly narrow range of potentials within the low alloy steel category (at least in seawater).

Aaron Tanzer

http://www.lehightesting.com

 

[TVP]

I agree with Aaron-- there should be no meaningful difference between the two in terms of galvanic corrosion.

 

[CobusvanJ]

mrfailure, are these tables you are referring to available for reference on the net somewhere?

 

[TVP]

ASTM G82

http://www.astm.org/Standards/G82.htm

 

[EdStainless]

What type of water? In water with lower conductivity the galvanic differences are insignificant. The tables are all in seawater, if you take two alloys with 0.5V difference in seawater and put them into Lake Michigan you will not get galvanic corrosion in any reasonable time.

If you are talking boiler feedwater then there is no galvanic interaction since it is a very weak electrolyte.

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Plymouth Tube

 

[mrfailure]

CobusvanJ,

The chart I am referring to has been reproduced in many places. If you do not have ASTM G82 as TVP referenced, then you can find it in various corrosion or materials reference books. I looked in ASM Metals Handbook Desk Edition (2nd Edition) p. 1228 when I answered your question.

Aaron Tanzer

http://www.lehightesting.com

 

[CobusvanJ]

Thanks for all the input. The medium is boiler feedwater so therefore it seems there is no real concern.