ferrite measurement

By MBSims

Date 08-22-2004 16:55

Fisher FerriteScope, MagnaGage or Severn Gage.

By swnorris (****)

Date 08-23-2004 11:32

Hi jiweiming,

It is difficult to determine accurately how much ferrite is present in stainless steel weld metal. The ferrite content should be measured and specified as a ferrite number, which is not considered an absolute ferrite percentage. There is excellent agreement between laboratories when measuring ferrite using standard technique and ferrite numbers. A standard procedure for calibrating magnetic instruments to measure the delta ferrite content of austenitic stainless steel weld metal is available from the AWS.

By Mikeomni1 (*)

Date 08-23-2004 15:24

Also point counting in accordance with ASTM E562 on polished and etched specimens.

Regards,
Mike

By rmjiran Date 09-04-2005 05:22

hi
you can try this :
http://engm01.ms.ornl.gov/FNCoolingRate.html
good luck

By - Date 09-04-2005 13:33

For austenitic stainless steels, the Magna gage, Severn Gage, and the Ferrite Scope are all instruments used to measure ferrite content of SS filler metal deposits. All should be traceable to the latest revision of the AWS Standard ANSI/AWS A4.2. The Welding Research Council adopted the term Ferrite Number (FN) to be used in place of percentage ferrite to clearly indicate that the measuring instrument was calibrated to the WRC procedure. The Ferrite Number is to be used in the same way as was the previously used percentage-ferrite term.
In measuring ferrite in Duplex stainless steels, the FN can by calculated by using the Magna Gage with the counterweight (EFN). Since the original instrument only went to 28 FN, a counterweight is required to extend the measurement to a higher ferrite content.The relationship between percentage ferrite and FN can be determined as % ferrite = 0.55 EFN + 10.6.

Chuck