Ferrite content measurement, also known as a ferritescope test at Nusatek, is a non-destructive test and normally performed on site. The test uses a portable feritscope machine from Fischer. This handy equipment provides rapid and accurate data by using highly mobile digital technology. Ferrite content measurement is used to measure the ferrite value in stainless steel welds and duplex steel.
The measurement of ferrite content provides critical data to prevent any future failure or damage of the steel. Mechanical properties and corrosion resistance depend on the ferrite content in the steel especially at high temperatures. This ferritescope test is useful for industries such as oil and gas, power and process engineering plants that are exposed to high temperature, aggressive media and high pressure. In stainless steel, if the ferrite content is too low, the weldment is susceptible to hot-cracking or solidification cracks and if the ferrite content is too high, the toughness and ductility and corrosion resistance of the steel are reduced.
Duplex stainless steel and stainless steel welds have allowable ferrite content value which sometimes becomes more stringent for different application. In duplex stainless steel, a deficit of ferrite content can also reduce weld strength and contribute to the development of stress corrosion cracking.
Test results can be determined by ferrite number (FN) or by ferrite percentage (%) and reported in accordance with relevant technical specifications (AWS A4.2) and/or customer requirements. Reports issued are accompanied when necessary by drawings to identify the locations tested.
Experience client requirements spec:
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1) |
EN ISO 8249 |
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Determination of Ferrite Number (FN) in austenitic and duplex ferrite |
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Austenitic Cr-Ni Stainless steel weld metal. |
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2) |
SES 38.2 REV.07 |
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July 2013 |
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3) |
DEP 30.10.60.18 |
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Gen. February 2015 |
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4) |
DEP 31.38.01.31 |
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Gen. February 2014 |
Basic Principal
The Feritscope FMP30 measures according to the magnetic induction method. A magnetic field generated by a coil enters into interaction with the magnetic components of the specimen. The changes in the magnetic field induce a voltage proportional to the ferrite content in a second coil. This voltage is then evaluated. All magnetic components of the otherwise non-magnetic structure are recognized, that is, in addition to delta ferrite and other ferritic components transformation, martensite is also recognized.
