Microscaled Multi-frequency Eddy Current Analysis for High Throughput Characterization of Steel Micro-samples

In the present study microscaled samples were investigated using multi-frequency eddy current analysis with high spatial resolution. Multi-frequency eddy current analyses performed using different exciting frequencies have shown that the local signal distribution depends on the geometry of the samples. Due to this fact, the positioning of the sensor may influence the material state qualification. The investigation of several heat treatment conditions of steel 100Cr6 (AISI 52100) in spheroidized carbide, bainitic, martensitic quenched, and tempered states showed that the material states can be assessed and differentiated from each other. The recorded eddy current signals were analysed and discussed. It was shown that, with increased frequency, the differences of the values obtained for different material conditions increased, allowing a robust identifaction of the different states. The best differentiation was obtained for 10 MHz. The frequency-dependent position error was estimated. The position error decreased from 70% at10 kHz to 6% at 10 MHz. The study shows that this fast analysis method is qualified for fast screening of microscaled samples for high-throughput material development.