EXACTLY which weld filler did you use?

Avesta 2205 filler metals, typically designated as 2209, are more highly alloyed with nickel relative to the base metal to assure a fusion zone with austenite-ferrite balance, toughness, and corrosion resistance similar to those of the base metal.

You must likely have different (apperently better corrosion resistant) mellurgy of the weld than base 2205.

You are correct. Our 2205 has 5.8 % Ni while the overlay is 2209 with a 9.5% Ni content.

I thought only Cr, Mo, and N were important in pitting.

Thanks

Thanks again for the reply. I still am struggling with trying to understand. The nickel content is higher in 2209 than 2205 (9.5 vs 5.8%) However, the nickel content of 317L SS is even higher (13 %) and it is by far the worse material in this service.

I should not have used the word "thinning". The corossion is highly localized. We had a hole through metal that was originally 0.75 " thick while two inches away the metal was 0.5 ".

Corrosion can be a weird thing - it may be due to the syngeristic effects of whatever the weld metal has wound up as, due to dilution. Perhaps the austenite content of the weld metal is around 75% (25% ferrite), where the duplex will be about 50% and this, combined with more nickel produces a more corrosion resistant hodge-podge.

It would be interesting to see if you welded a couple beads on a 2205 coupon to see how it fairs.

In any event, if you are looking for a more corrosion resistant alloy - I would propose that a 6-Mo stainless will perform very well (much better than either 2205, 317, or the crazy weld )

Would this be like a SSC-6MO or a AL6XN ? What is the cost multiple over a 317 SS ? A SAF2507 has been suggested. Any comment on that ?

Thanks again.

Yes, the brand names "SSC-6Mo" and "AL6XN" are part of the 6-Mo(ly) - the original brand was from Avesta called "254 SMO"; there are other 6-Mo's too, for example 1925 HMo. They all have slightly different metallurgies but all perform essentially the same.

The cost will most likely be greater than 317 - HOWEVER, due to the recent surgance in the availability/acceptance of duplex stainlesses (eg, 2205 & 2507) and the superiority of duplex over 317 in practically all applications - has made (at times) depending on mill quantities and demands, the price of 317 even more than duplex (people aren;t using as much of it as before - the whole supply and demand thing)

The 2507 will be more than the 2205 - but will perform better.

A 6-Mo is probably around the same price as 2507 (maybe slightly more), almost for sure more than 2205, and, as said before due the "rarity" of 317 most likely more. 15 years ago or more it would have been a no brainer - 6Mo WOULD DEFINITELY been much more than 317.

It is a toss-up to which may perform better in your application: 2507 or 6-Mo, depending on the actual "pitting" tests performed on them - they can be too close to call. See figures: http://www.sandmeyersteel.com/images/2507-Spec-Sheet.pdf

I would get some recent pricing for 2507 and a 6-Mo (because the metals markets have been ALL OVER the map/spectrum in recent years) and base your decision on more of a cost basis with a slight preference given to 6-Mo to perform better.

The best thing would be to get coupons of 6-Mo and 2507 and see how they stand up to your real world conditions.

Corossion data from a sister plant may help the answer to the question. The rate for 317L, 316L, and 2205 was 30 mpy, 254-SMO was 18, C276 was <1 , and titanium grade 2 was <1. We would like to use something more inexpensive than the last two metals.

I figured that cost was an issue (isn't it always) and did not mention the nickel alloys or titanium - but yes, they would be the best.

..... You may even want to look into a 7-Mo stainless - the original brand being Avesta 654 SMO

Hi all!
I've just visited this forum. Happy to get acquainted with you. Thanks.
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Guest,

I assume it is the same guest in replies 1-3-5-7 etc - if not already a member, please join. It is good to hear from someone knowledgeable and lucid. GA's all.

Hi Prof - thanks for the offer (again)

I took a little hiatus after some frustration with posts (a little "argument" over piping design where a well-wisher did not understand the ramifications of what was being discussed, including not understanding that what he was proposing, if the supports were not designed right (nor were they even discussed) could impose forces upwards of 750,000 lbs on structures and/or vessels).

It just left a bad taste in my mouth.

I have had the odd little interjection into discussions, over the last few months - because CR4 seems to be an addiction.

should have "guest"

i think that the point is the "quality" of the weld overlay.. in order to get the resistance of a "solid" 2205 you nedd to have the same chemical composition and ferrite/austenite balance.. you should review the wps or weld overlay procedure and make chemical and ferrite test..

Welding practice for the Sandvik duplexstainless steels SAF 2304, SAF 2205 andSAF 2507

s

corrosion protection