[MW:2733] RE: 2729] Ferrite Number (FN) for the deposited weld metal

 

 

Austenetic SS used in chemical /petrochemical plant require  good Corrosion resistance. For which delta ferrite plays the major role.

i)Increase in Delta Ferrite will reduce the corrosion resistance . Therefore in severe corrosion resistance requirement  , ferrite to be kept below 8% (Generally it is kept between  3-7 %)However  very low ferrite  causes defect like hot crack, fissures ,There is no code requirement but Ferrite requirement is decided by process licenser ,depending upon the service condition

ii)You can check ferrite No by Instrument called Ferrite Meter where you can get Ferrite No directly ,Some time You can check with respect to Delong Diagram ( Given in ASME Sec 2C ) by calculating /plotting the Cr , and Ni equivalent from actual chemical analysis of weld  

iii)My experience –some time Ferrite no increases due to work hardening of material If you measure by Ferrite meter

Regards

 

Hegde P.B.

09714714803

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of tong tong
Sent: Monday, July 20, 2009 9:31 AM
To: materials-welding@googlegroups.com
Subject: [MW:2729] Ferrite Number (FN) for the deposited weld metal

 

Dear All,

Regarding above mentioned subject, i would like to know in detail about ferrite number. I have a few questions to ask such as What is the ferrite number? Why it is so important? Materials subjected to ferrite number? Permissible limit of ferrite number? Code and standard that we refer to requirement of ferrite number? Procedure to perform ferrite number?..If anybody have experience or information regarding this subject hopefully you can share with me. Thank in advance for your kind cooperation


Regards
tong2

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