Re: [MW:8624] Re: Ferrite No and percentage

Hi, Please find below. 01. What is the difference between ferrite number and ferrite percentage? Ferrite percentage no longer used,it has been replaced by Ferrite Number Ferrite Number is an arbitrary standardized value designating the ferrite content of an austenitic stainless steel weld metal. It should be used in place of percent ferrite or volume percent ferrite on a direct replacement basis. FN has been adopted as a relative measure for quantifying ferritic content using standardized magnetic techniques. The FN approach was developed in order to reduce the large variation in ferrite levels determined on a given specimen when measured using different techniques in different laboratories. FN approximates the "volume percent ferrite" at levels below 8 FN; above this level, deviation occurs. A number of instruments are commercially available for determining the ferrite content of welds, including the Magne gage, Severn gage, and ferrite scope. 02. its required for which materials? Ferrite number is a measure of = Chromium & Nickel equivalent in an Austenitic stainless steel material. It should be between 3-7% max. Very low ferrite can lead to cracks. It is a measure of denoting the ferrite content in an stainless steel. Ferrite Number has been adopted as a relative measure for quantifying ferritic content using standardized magnetic techniques. The Ferrite Number approach was developed in order to reduce the large variation in ferrite levels determined on a given specimen when measured using different techniques in different labratories. The ferrite level is only important to assure minimum exposure to solidification cracking when depositing austenitic stainless steel weld metal. The lower ferrite number is better for corrosion resistance, while balancing higher ferrite content to avoid solidification cracking in the weld deposit. I would not worry about lower ferrite numbers for clad overlay welding, if no cracking is observed (Liquid Penetrant verification). Thanks & Regards, (Karthik) Karthikeyan.S QA/QC Manager Getabec Energy Co.,Ltd. 379,Moo6,Soi8,Nikhomphatana, Rayong-21180, Thailand. Phone: 0066 38 897035-8 (Off) Fax: 0066 38 897034 Hand Phone: 0066 892512282 --- On Thu, 12/9/10, Suresh Babu <suresh75.babu@gmail.com> wrote: From: Suresh Babu <suresh75.babu@gmail.com> Subject: [MW:8612] Re: Ferrite No and percentage To: "Materials & Welding" <materials-welding@googlegroups.com> Date: Thursday, December 9, 2010, 12:46 AM Ferrite Number is an arbitrary standardized value designating the ferrite content of an austenitic stainless steel weld metal. It should be used in place of percent ferrite or volume percent ferrite on a direct replacement basis. FN has been adopted as a relative measure for quantifying ferritic content using standardized magnetic techniques. The FN approach was developed in order to reduce the large variation in ferrite levels determined on a given specimen when measured using different techniques in different laboratories. FN approximates the "volume percent ferrite" at levels below 8 FN; above this level, deviation occurs. A number of instruments are commercially available for determining the ferrite content of welds, including the Magne gage, Severn gage, and ferrite scope. For more clarity have glance to the following: Ferrite number is a means of measuring the proportion of Delta-Ferrite present A magnetically determined unit for ferrite determination. Delta-Ferrite is the Solid solution of Carbon in  Delta -iron. Found only in high temperature region (>1410ºC) BCC structure Max. solid solubility of carbon is 0.1% at 1495ºC Minimum FN is required to decrease hot cracking tendency of the weld. Higher values of FN reduces the Corrosion resistance property of the weld FN can be : Predicted using Constitution Diagrams Measured using instruments like Feritscope An instrument which directly gives the value of Ferrite Number present in a weld. Works on Magnetic Induction principle On Dec 8, 7:29 pm, Manav Malhotra <manav6...@yahoo.com> wrote: > Can anyone tell me whats the difference between ferrite no and percentage and > its required for which materials? -- To post to this group, send email to materials-welding@googlegroups.com To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com For more options, visit this group's bolg at http://materials-welding.blogspot.com/ The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.

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The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.