ELECTRODES FOR SUPER DUPLEX SS (25% Cr)

Date 06-28-2004 10:28

Hi everybody,

For Duplex SS, 22 Cr % (P no: 10 H), E 2209 electrode is used. Now we have Super Duplex SS 25 % Cr (P no 10H), another electrode & filer rod to be used. As I rsourced these electrodes, which ESAB OK68.53 Basic-Rutile (E 25 9 4 NLR 3 2 with 30-50 Ferrite content) AND ESAB OK. 68.55 Basic type (E 25 9 4 N L B 4 2 with 70-100 Ferrite content) may be suitable for Super DUPLEX SS.
As a Filler Rod ESABOK Tigrod 16.88 (W 25 9 4 N L) seems ok.

So, could you advise any other electrodes & Filler Rod for Super Duplex SS , if you had already experience on these kind of welding process and electrodes. .
In addition that, as per Asme sec IX it seems there is no re-qualification welding procedure test required for Super Duplex SS (we have existing PQR for Duplex SS), Since there are no Essentil variables.
For info : Duplex SS (UNS no: S31803), Pipe
Super Duplex SS (UNS no: S32750), Pipe
Regards..

Gokhan

By GRoberts (***)

Date 06-28-2004 16:27

Metrode also has a selection of super-duplex electrodes, both in 2507 type and Zeron 100 type. Those are the main two types of superduplex filler metals available. The ESAB ones you mentioned are of the 2507 type. I would caution though, that the last few batches of ESAB OK68.55 we have used here have had porosity problems, which was confirmed by the manufacturer, but they didn't offer a solution. Another alternative, if you can find a manufacturer that will make it for you, is to order 2553 with the additional, requirement of PREn over 40. It is not the most desirable route though as ferrite tends to be high in these type of electrodes, which is detemental to toughness. We have done this before, but not on 2507 type base metal.

By Niekie3 (***)

Date 07-18-2004 20:13

Hi Gokhan

We have used Sandvik fillers when welding these steels with great success. Seeing as they developed these materials (SAF 2205; SAF 2507) I believe they should be making good electrodes.

Regarding the qualification, just make sure that the electrodes are in fact supplied to a relevant specification that can be classified an F number. Then also make sure that the A number is the same. If all OK, then you do not have to re-qualify. Obviously, if you are performing a critical job (very probable when using these materials) I would perform the tests in any case, because you want to be sure that you are ending up with the correct microstructure.

When welding duplex S/Steel, having a ballanced heat input is important.

Regards
Niekie Jooste
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