Magneto-acoustic emission for the characterisation of ferritic stainless steel microstructural state

The role of residual stresses in the failure of metallic components and the need to determine such stresses is well recognised. Magneto-acoustic emission (MAE) is a relatively new non-destructive detection technique and its working principle is based on Barkhausen discontinuities or noise and magnetostriction when a ferromagnetic material is subjected to a varying magnetic field. MAE is being used to characterise the stress state of a ferritic stainless steel (AISI 430). Other stress measurement techniques; X-ray diffraction (XRD), magnetic Barkhausen noise (MBN) have also been used to support the results achieved using MAE. A new measurement parameter has been developed for microstructural characterisation called MAE absolute energy and has proved to be a useful quantitative method in MAE waveform measurement.