What is Ferrite Testing?
Ferrite testing is a technique used to measure the delta ferrite content in austenitic stainless steel and duplex stainless steel. The delta ferrite content is measured to better understand an austenitic or duplex stainless steel’s susceptibility to corrosion, susceptibility to solidification cracking and other types of material failure. 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.
Ferrite testing is sometimes necessary to avoid material failure in duplex and austenitic stainless steels. A ferrite content that is too high or too low can be detrimental. 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. Also, the mechanical properties of the stainless steel could be negatively affected if the ferrite content is too high.