Can superduplex 2507 stainless tubing be welded with superaustenitic 254 SMO tubing material? 4

[AnsAvi]

Hi,
Can the welding of superduplex 2507 material with 6 Mo material be considered as an option? I am aware that 2507 can be a tricky thing to weld even on its own, but would welding with 254 SMO grade lead to potential corrosion or mechanical issues? Are there any precautions that one must keep in mind when trying to do this? Or is it strictly not-advisable?

Also, is this combination more or less advisable than say....welding 316L to 2507?

 

[metengr]

https://link.springer.com/article/10.1007/s40194-016-0408-7

 

[EdStainless]

Yes, either use a 6%Mo filler or better yet a Ni alloy filler.
The use of Ni filler (C276 type) will help suppress secondary phases and will give you weld corrosion resistance that is closer to the super-duplex.

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P.E. Metallurgy, Plymouth Tube

 

[AnsAvi]

Great. Thanks a lot Metengr and EdStainless!

 

[pradipgoswami]

Hi,
In addition to the above suggested links I hope you'll find the contents of this document as helpful. If the design requirements calls for Pitting Corrosion test @40 Deg C or more one has to be very careful & specific on selection of welding consumables.
Usually Alloy 625 (ER-NiCrMo-3) is the default choice while welding 254SMO to same.
In case of dissimilar combination as above this link suggest use of Hastelloy C-22 consumable.
Use this info at your discretion.
Thanks.

http://www.nickelalloys.com.br/Metr... stainless steel/6Mo superaust ss profile.pdf

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[EdStainless]

Without reading the link I'll add that for best corrosion resistance the high performance Ni alloy fillers (C22, 686, 59) all have proven to work very well with superduplex.

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P.E. Metallurgy, Plymouth Tube

 

[AnsAvi]

Thanks Pradip. Your article was very informative.

EdStainless - Your advice agrees with the paper and the link provided. Thanks.

 

[moltenmetal]

Is this also an option for 2205 and 31803 duplexes?

 

[EdStainless]

You could use Ni-'C' filler, but it overkill.
These are more typical:
Welding 2205 to 2205 uses 2209 filler to get the correct phase balance.
Welding 2205 to a 300 stainless could be done with a 6%Mo superaustenitic.

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P.E. Metallurgy, Plymouth Tube

 

[moltenmetal]

If the "overkill" gets rid of the paranoia on the part of our welding staff on hitting ferrite numbers in the resulting welds, I'm all for paying for a more expensive filler metal- we're not using that much filler anyway since we're welding small stuff all the time.