Analysis of AISI-SAE 420 tempering steel by Magnetic Barkhausen Noise

In recent years Magnetic Barkhausen Noise (MBN) was potentiated as a Non Destructive Testing technique for microstructural characterization of ferromagnetic materials. The aim of this work is to use the Magnetic Barkhausen Noise to assess microstructural changes in a martensitic stainless steel AISI-SAE 420 subjected to hardening heat treatment at 1020°C with air cooling and subsequent tempering at temperatures of 100°C, 300°C, 500°C and 600°C. Microstructural characterization was performed using Scanning Electron Microscopy (SEM), Optical Microscopy (OM) and Vickers hardness tests (Hv). It was found a relation between the hardness after the different tempered and (RMS) values of the Barkhausen signals