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?
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