Microstructural Characterization of Additively Manufactured AISI 4140 Parts Using Magnetic Barkhausen Noise

This study investigates the application of magnetic Barkhausen noise (MBN) measurements for assessing the microstructural and residual stress characteristics of additively manufactured AISI 4140 steel. The research explores the influence of part geometry, residual stresses, and material hardness on the MBN signal, particularly in thin-walled structures produced using laser-based powder bed fusion (PBF-LB). Results indicate a strong correlation between wall thickness and MBN intensity, attributed to the penetration depth of the magnetic field and the resulting amplification in thinner sections. Furthermore, an anisotropic MBN response is observed due to residual stress distributions, with tensile stresses leading to a higher Barkhausen signal. These findings highlight the potential of MBN as a non-destructive evaluation method for quality assessment in additively manufactured components supporting future approaches for non-destructive assessment of material conditions in additively manufactured components.