Evaluation of the of isothermal phases transformations and hardness measurements in SAF 2507 super duplex using Pulsed Eddy Currents

Abstract Super duplex stainless steel (SDSS) is utilized in various industries, including offshore, chemical, petrochemical, and pulp and paper. Exposure to certain temperatures can cause degradation of this material, reducing its mechanical and chemical properties, and potentially leading to equipment failure. In order to determine the residual lifespan of equipment made of SDSS, microstructural changes must be analyzed. Non-destructive techniques are favored over destructive methods, as they allow for the analysis without compromising the material. The Pulsed Eddy Current (PEC) technique, commonly used to detect corrosion under insulation, also has potential to determine mechanical properties of SDSS. The aim of this study was to investigate how the amount of ferrite in SAF 2507 steel samples, subjected to different heat treatments, affects the signal received by a PEC probe. Results showed that the signal amplitude is related to the amount of ferrite present. The findings were compared to those obtained through optical microscopy, hardness measurements and suggest the feasibility of using PEC for this purpose.