Ferrite Measurements in Duplex Stainless Steel Castings
The objective of the project is to develop secondary calibration standards that will permit the determination of ferrite percentage in duplex stainless steels using non-destructive magnetic measurements. The determination of ferrite percentage in duplex stainless steels has traditionally been accomplished by metallographic point counting. Metallographic procedures are laborious, the test is destructive of the sample, and the results can be subject to variation in etching technique. On the other hand, magnetic measurements are easier and are non-destructive, but depend on the distribution of ferrite composition from the bulk to the surface of the tested specimen. In this program, a correlation will be developed that will relate the magnetic measurements to the more fundamental metallographic measurements to determine ferrite composition in duplex stainless steels. The relationship will be validated in round-robin testing. Secondary test standards will then be prepared and recommendations for the continued production and distribution of these standards will be provided.