To evaluate the efficiency of metal components, ductile damage caused by the metal forming process needs to be considered. In case hardening steel, ductile damage is represented by voids in the microstructure caused mostly by delamination and cracking of manganese sulfide inclusions. Automated EDX particle analysis in scanning electron microscopy has proven to be a useful damage quantification method, delivering large area information in mm²-range at high resolution (µm-range). Elemental information gathered by EDX spectra combined with the image-information obtained by either secondary or backscattered electrons allow a reliable differentiation between steel matrix, varying inclusion types and ductile damage in form of voids.
At low electron excitation energies, the size of the electron interaction volume is reduced, leading to an increased spatial resolution of back scattered electron images and EDX measurements. A more accurate result would therefore be expected. However, the energy range of the EDX spectra on which the classification of ductile damage and inclusions rely, is also reduced when working at low excitation energies. An investigation of the influence of the excitation energy is therefore performed to improve the method and determine optimal working conditions for the automated EDX particle analysis.
Cross sections of differently formed 16MnCrS5 components are metallographically prepared and investigated using the automated EDX particle analysis in an SEM. The measurements are repeated on identical measurement fields using varying electron excitation energies. The gathered results are compared with focus on void area and classification of particles to evaluate at which operating energies the most reliable results are obtained.