cladding C276 to HY 80 steel - iron dilution issue

[eknuds01]

Hello -

We are cladding C276 to HY 80 and it seems that a common practice is to ensure that that the iron levels, in the welds, are below 10%. Does anyone have a reference for this rule? Any texts that mention this threshold?

Any help would be appreciated.

thanks,
Erik

 

[stanweld]

Iron dilution is realy not a problem with regard to weld overlay cracking; however, if you intend to overlay with only one layer, you will need to control dilution to provide effective corrosion protection.

Specialty Metals/Inco & the NDIC provide literature on dissimilar metals and overlay welding.

 

[eknuds01]

Thanks, Stanweld!

What is the NDIC? Also, our concern is corrosion, not necessarily cracking (though that is obviously important).

Erik

 

[metengr]

Nickel Development Institute.

 

[SJones]

The 5 mass% and 10 mass% iron content limits can be found in API 6A, sub-clause 6.5.1.2.2 and apply to 625 only; but arguments will rage about whether they are valid limits for corrosion performance and the only real way to settle them is to corrosion test in a simulated service environment. Shell in the US used to be happy with up to 20% Fe in their 625 weld overlays.

If I wanted to avoid corrosion testing, I would be looking for a maximum Fe of 7 mass% and to hit the rest of the ERNiCrMo-4 filler composition at a minimum 1 mm below the final surface of the overlay.

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[strider6]

The iron dilution limit is not clearly defined but usually i've seen a value of 5-10%. this article suggest a 5% limit:

"The results support a general recommendation that iron content should be below 5% for optimum performance, although corrosion behaviour was determined not by the iron level per se but by the bulk composition and the minimum alloy content developed in the solidification structure.
Iron Dilution of Weld Metals"

http://cat.inist.fr/?aModele=afficheN&cpsidt=2619364

this is another article on this issue:

"During overlay welding on steel and welding of alloy clad steel plate iron dilution of the alloy weld metal is of
concern. Iron dilution can significantly reduce the corrosion resistance of welds made with low iron alloys like
alloy C-276."

http://www.specialmetals.com/docume...ing Products Solve FGD Corrosion Problems.pdf

hope this help

S

Corrosion Prevention & Corrosion Control