FW: [MW:18315] High Ferrite No.

Hello,

 

The results looks absurd.You never get ferrite to this high extent in 308L weld metal. To have the peace of mind and get the realistic results do the following:-

1. Using the Delong diagram, calculate the Cr & Ni Equivalent. Plot on X & Y axis and see the results (both in % Ferrite and in Ferrite No-FN). Refer the attached article for guidance. 
2. Check the calibration and accuracy of  Ferrite Meter. Try to take readings on known  test pads (usually one which comes with the equipment) and see the error. If required use these readings for "extrapolation"
3. Check the surface finish, if required power brush with brand new S.S brush. Many a time excessive grinding or brushing with previously used tools may produce erroneous results.
4. Check the electrode MTR  for ferrite readings.
5. If possible run another  test  coupon with the same electrode to extract specimens for ferrite measurements under microscope(see below)
6. Or if  permitted extract a test sample from the production welds (preferably from areas with high readings) and calculate ferrite by point count method (ASTM E-562

Let's know if it helps.

 

Thanks

 

Pradip Goswami, P.Eng,IWE

Welding & Metallurgical Specialist

Ontario, Canada

pgoswami@quickclic.net

pgoswami@sympatico.ca

 

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From: Harikrishnan N S <hari.qaqc@gmail.com>
To: materials-welding@Google groups.com
Sent: Tuesday, July 30, 2013 9:17 AM
Subject: [MW:18292] High Ferrite No.

Dear Experts

Recently I came across an issue of High Ferrite no. in the weld metal.

Parent Metal : A 304L

Weld Metal : 308L

Welding Process : GTAW

The affected area is only a quarter portion (3'o clock to 6'o clock position) of the 30" pipe where ferrite no has been observed as over 21 FN. and PMI has shown 1.57% of Mo. 

Please give your valuable comments and rectification measures for this. Refer the attached photos for clarity.

Thanks and Regards

Harikrishnan

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