Industrial processing and chemical plants work at high temperatures and pressures, with often aggressive media and stainless steel is often the material of choice for these applications. If the ferrite content of the steel steel is too low, then welding of stainless material may crack at elevated temperature or with high stress or vibration. Alternatively, if the ferrite content is too high, the weld may be weaker and corrode.
To address the need to measure the amount of ferrite in a sample the Welding Research Council introduced the Ferrite Number (FN) as standardised value which related to the ferrite content of an equivalently magnetic weld metal.
The volume percentage of ferrite can be estimated as about 70% of the FN but the relationship depends upon the type and origin of the stainless steel used and the measurement technique. The latest MF300Fe+uses a transfer curve to convert measured FN to F%.
The instrument is calibrated using the secondary world standards validated by National Institute of Standards and Technology (NIST) in the USA. All 16 standards are used in the calibration giving an instrument with a measurement range from 0 to 115 FN. Transfer standards are supplied with the instrument allowing performance to be verified at any time.
A variety of measurement modes are supported to ensure that good repeatable measurements can be made.
- Non-destructive testing of the ferrite content in a range of 0.1 to 115 FN equivalent to 0.1 to 80.5% Fe in austenitic and duplex steel.
- Robust and portable.
- Standard or peak measurement of Ferrite Number.
- Estimate of ferrite percentage (using a FN to F% curve).
- Automatic zero on demand.
- Choice of probes: 10 mm diameter probe or 4 x 6 mm probe.
- Sprung loaded sleeve (4 mm x 6 mm probe).
- Supplied with 5 transfer standards allowing veracity of instrument to be checked.
- Storage of 1000 measurements including 4 character record ID, downloaded to PC with RS232/USB option.
- Use with high temperature samples (air-cooled probe option – 10 mm diameter probe).
- Simple measurement with small sample area.
- Units selectable between WRC-FN and %Fe.
- Calibration with standards traceable to World Secondary Standards.
- Supplied in carry case.