[MW:14510] RE: 14502] MW-14496-root causes for failing Pitting test in Duplex SS

Dear Pro,

Thanks you for your sharing,

in the welding part most importance is metallurgical part.

Regards,

Vu Duc Thuan

Email: dthuan117@gmail.com

Mobile: +84 983 017 936

Sky: vdthuan_vtau

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of pgoswami
Sent: Sunday, June 10, 2012 10:40 AM
To: nids01dme011@gmail.com
Cc: materials-welding@googlegroups.com
Subject: [MW:14502] MW-14496-root causes for failing Pitting test in Duplex SS

Hi Ankit,

ASTM G48 testing in ferric chloride solution allows a quick assessment of pitting corrosion resistance of stainless steels. The t effective ways of improving pitting performance and hence increasing the likelihood of passing the test as follows:-

Remove the weld oxides, improve surface finish, such as by pickling, grinding, brushing.
For 22%Cr duplex stainless steel, use superduplex filler as an alternative to a matching 22%Cr duplex.
Check the Nitrogen content in the SMAW electroede MTR and Test pad. Any Nitrogen loss from the weld pool may be problematic and would definitely impair the pitting resistance. Nitrogen is the "singlemost" important element to improve or lower the pitting resistance.
Monitor the welding parameters, such that heat imput (1.2-1.5 KJ/mm) and the IPT (125-150 Deg C Max) is just withinn the recomemnded range -as per the best practices followed for this metal.
Ensure the Ferrite/Astenite balance is claose to 50:50 or 60:40 or 55:45 range.

If the process is SMAW as per the description below, what's the value of Oxygen content in the arc environment or on the root side? Higher oxygen in the weld would affect "notch toughness" and may cause lowre pitting resisatnce also.

Hope the clarifications above and the atatchements would help to you to make the test pass , next time.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario, Canada.
Email-pgoswami@sympatico.ca,
pgoswami@quickclic.net

-----Original Message-----
From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of khatri ankit
Sent: Friday, June 08, 2012 2:56 AM
To: Materials & Welding
Subject: [MW:14496] root causes for failing Pitting test in Duplex SS

Dear Expets,

What will the root causes for failing the pitting corrosion resistance test for duplex SS (22% Cr grade).

What should be the remedies or how to improve my welding or welding quality, so the duplex SS test coupon will passes for pitting test?

(I made the weld test coupon for PQR to do the Pitting test, but the results have failed it.the electrode that we used for welding is
E-2209)

Kindly send ur reviews, so i can improve it the same.

Regards,

Ankit Khatri

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