Rapid high resolution micromagnetic material property imaging and defect detection via magneto-optical sensing

Micromagnetic inspection methods are key tools in non-destructive testing (NDT) for industrial quality assurance over the entire product life cycle. The 3MA method developed at Fraunhofer IZFP exploits correlations between ferromagnetic microstructure and (micro-) magnetic material behavior, enhanced by machine learning, to determine mechanical and technological properties [1]. Increasing demands on highly loaded steels require spatially resolved testing. This is because mechanical loads, damage, and property-defining processes (e.g. case hardening or laser hardening) are often locally inhomogeneous. Current techniques face a trade-off between high spatial resolution at low inspection speed and faster array-based scanning with limited resolution. Magnetooptical sensors based on the Faraday effect enable high throughput micromagnetic inspection and thus overcome the previously mentioned limitations. Within the VIP+ project VISiMOS, a 3MA-inspired methodology was developed. In addition, a laboratory demonstrator with a high-speed camera and integrated magnetization yoke were built. Furthermore, a data-efficient signal-processing approach for feature extraction was developed. The demonstrator and methodology have been validated.