Ferrite testing commonly employs magnetic induction as a means to measure the ferrite content of a material, although there are other methods that are used.28 jun 2019
What is ferrite content?
Ferrite content is a measure of the amount of ferrite in a steel. Ferrite is one form of microstructure – the internal crystal structure – that can exist within steel. ... A ferritic microstructure in a stainless steel is usually associated with high strength and resistance to chloride stress corrosion cracking.
What is ferrite value?
A Ferrite Number is a description of the ferrite content of a weld metal determined using a standardized procedure. ... The Ferrite Number of a weld metal has been considered approximately equivalent to the percentage ferrite content, particularly at low FN values.
How is ferrite measured in stainless steel?
The FeritScope® measures the FN using the principle of magnetic induction. A magnetic field generated by the probe interacts with the magnetic phases present in the weld and induces a voltage in the secondary coil within the probe. The difference in the voltage can then be converted to a proportional FN scale.
Why is ferrite test required for stainless steel?
Ferrite testing is sometimes necessary to avoid material failure in duplex and austenitic stainless steels. ... If the ferrite content is too low, then the stainless steel may be susceptible to solidification cracking (hot cracking) upon welding. If the ferrite content is too high, then the risk of corrosion increases.28 jun 2019
What is ferrite content in stainless steel?
Duplex austenite-ferrite stainless steels should typically contain ferrite in the range 30-35 % to 60-65 % ferrite but not less than 20 or more than 70 % (approximately 30-110 FN).24 mar 2019
How is ferrite measured?
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. ... Ferrite content measurement is used to measure the ferrite value in stainless steel welds and duplex steel.
What is ferrite test in stainless steel?
Ferrite test is a fast, inexpensive, and accurate way to measure delta ferrite content in austenitic and duplex stainless steel. Ferrite testing can establish the ideal ferrite content balance between ductility, toughness, corrosion resistance, and crack prevention.
What is ferrite number in stainless steel welds?
Ferrite numbers between 0 and 7 correspond to the volume percentage of ferrite crystalline structure present in the weld metal; however, at higher percentages the ferrite number increases at a faster rate.19 nov 2018