Filler Metal to join 2205 to C276..? 1

[qcrobert]

We have qualified WPSs to join 2205 to 2205 with 2209 filler metal and C276 to C276 with ERNiCrMo-10 filler metal. I believe the correct filler metal to join 2205 to C276 is ERNiCrMo-10 filler metal however the 2205/C276 will be subjected to a variety of atmospheric harsh acids and am concerned about the corrosion resistance of the duplex stainless.

Fe% lift off test revealed no ferrite in the weld metal when 2205/C276 was joined with ERNiCrMo-10 and very low ferrite (10% max)when joined with ERNiCrMo-10. Of course the grain boundary between the two base metals is also a concern.

May I ask what filler metal you would propose to qualify a procedure that would provide the best corrosion resistance to 2205/C276?

Thank you in advance of your comments,
Robert

 

[EdStainless]

Have you corrosion tested the two welds?
You will be limited in application by the 2205, so use a test that you know that good 2205 will pass.
A moderate temp ferric chloride pitting test would be common, unless your application is a lot different.
I have seen people do this type of weld successfully with 2209, 2507, and "C" (C22, 59, 686).
The real key is to not form intermetallics in the 2205 or the weld.

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[qcrobert]

Good information Ed!

Yes I have two 1/4"x2"x2" samples ready to send off to the lab for testing to ASTM A 923 Method C. Question is, at what temp do I wish the samples to be subjected to?
I've attached the temp chart.
Robert

 

[EdStainless]

I presume that the 2205 was precured with A923 testing.
I would use 30C as a starting point.
When welding with the duplex filler did you use N2 in the weld and shield gas?
How were the samples prepared? I presume that they are full thickness with both the face and edges of the welds exposed.
It looks like you have ground the weld caps off, I hope that you didn't take much metal.
I also hope that these were not acid cleaned after grinding.
You may need to run many more samples to get a good idea.
I would start at 30C, and then run 35C, 40C, and so on until I get pitting.
Then go back to a safe temp (maybe 3-5C below pitting) and run a few duplicates to show that you have it well defined.
The corrosion test can become part of your PQR and welder qualification.

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P.E. Metallurgy, consulting work welcomed

 

[qcrobert]

I presume that the 2205 was precured with A923 testing. Ordered standard as ASTM G 28-02 (Reapproved 2015) Methods A & B.
I would use 30C as a starting point. Unfortunately we do not have the luxury of numerous testing and are limited to testing the two samples at either the higher or lower temperature. (But I will run it up the flagpole)
When welding with the duplex filler did you use N2 in the weld and shield gas? Used TriMix (90%He/7.5%Ar/2.5%CO2)
How were the samples prepared? I presume that they are full thickness with both the face and edges of the welds exposed. Correct
It looks like you have ground the weld caps off, I hope that you didn't take much metal. Ground only to base metal and will be prepared by lab.
I also hope that these were not acid cleaned after grinding.No acid cleaned, sending as is to be prepared by lab.
You may need to run many more samples to get a good idea. I agree
I would start at 30C, and then run 35C, 40C, and so on until I get pitting. If possible will do so.
Then go back to a safe temp (maybe 3-5C below pitting) and run a few duplicates to show that you have it well defined.
The corrosion test can become part of your PQR and welder qualification. On previous 2205 to 2205 with ER2209 w/ TriMix it was required by Customer and was successful.

Ed
You've given me valuable insight and a starting point for further testing.
Thank you
Robert

 

[EdStainless]

I have never welded duplex without N2 in the gas.
You could cut those samples into thinner strips, you won't need much weld to tell you if it works.
We used to test sample about postage stamp size, plenty of material.

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[qcrobert]

The tip on small sample size will be used in the future when qualifying procedures.

Re-reading my original post, I found an error and wish to correct it by striking "ERNiCrMo-10" and replacing with "ER2209".
Fe% lift off test revealed no ferrite in the weld metal when 2205/C276 was joined with ERNiCrMo-10 and very low ferrite (10% max)when joined with ER2209.

Regards
Robert

 

[EdStainless]

That makes sense, the FN.

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Ni alloy filler is a must for basic metallurgical compatibility in this DMW joint. Ferrite is not relevant for a Ni alloy weld deposit, and you can assume its corrosion resistance is superior to the 2205 (the design objective).

The weak link for corrosion resistance will be the 2205 HAZ, and that depends entirely on the welding conditions and not the filler metal alloy. Use the same parameters you would in joining 2205 to itself. Too much heat for too long a time develops various precipitates as well as sigmatization, which seriously compromise corrosion resistance of duplex SS. Either your client's tech spec will tell you to do corrosion testing (ASTM A923) or you may want to do it in your own self-interest, given you mention some nasty potential operating conditions.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

I have never welded duplex without N2 in the gas.

UNS S32205 (overlapping with S31803 composition but with N and some other elements nearer the upper end of their respective ranges) was developed to eliminate the need for supplemental N2 in the shielding gas.

I only ever see dual certified 2205 SS nowadays. On a major 2015 qualification campaign I was able to pass A923 requirements for GTAW and GMAW deposits without supplemental N2. But I would agree it is good practice to do so.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[EdStainless]

Up until a couple of years ago it all had to be dual cert, ASME hadn't added S32205 to the Code yet.
The fab shops that I work with all use 2%N2 in the gas, just to help.
When welding duplex use high power and high speed.
And the universal truth of welding SS and Ni alloys, worry about the HAZ.

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P.E. Metallurgy, consulting work welcomed

 

And the universal truth of welding SS and Ni alloys, worry about the HAZ.

Just not for the reasons you worry about it in carbon and low alloy steels.
I should clarify: I don't worry about it, but all my non-metallurgist coworkers worry too much about it.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."