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Purpose As additive manufacturing techniques, such as selective laser melting, allow for straightforward production of parts on basis of simple computer-aided design files only, unauthorized replication can be facilitated. Thus, identification and tracking of individual parts are increasingly vital in light of globalized competition. This paper aims to overcome the susceptibility of additive manufacturing techniques for product piracy by establishing a method for introducing and reading out product identification markers not visible by naked-eye inspection. Design/methodology/approach Lasers of different nominal power were used for altering the solidification mechanisms during processing in distinct areas of the samples. The resulting local microstructural characteristics and mechanical properties, respectively, were determined by scanning electron microscopy and hardness measurements. The applicability of an advanced eddy current technique for reading out local differences in electro-magnetic properties was examined. Findings The findings show that distinct microstructural features are obtained in dependence of the locally applied laser power. These features manifest themselves not only in terms of grain morphology, texture and hardness but also induce changes in the local electro-magnetic properties. The inscribed pattern can be non-destructively visualized by using an advanced eddy current technique. Originality/value Conventional copy protection basically consists in supplementary labelling or surface modification. In the present study, a new method is proposed for additively manufactured parts, overcoming the drawbacks of the former methods through process-induced microstructure manipulation. Slight alterations in the electro-magnetic material properties can be detected by advanced eddy current method allowing for identification of arbitrary and inimitable component information in additively manufactured parts.

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In this study, magnesium is alloyed with varying amounts of the ferromagnetic alloying element cobalt in order to obtain lightweight load-sensitive materials with sensory properties which allow an online-monitoring of mechanical forces applied to components made from Mg-Co alloys. An optimized casting process with the use of extruded Mg-Co powder rods is utilized which enables the production of magnetic magnesium alloys with a reproducible Co concentration. The efficiency of the casting process is confirmed by SEM analyses. Microstructures and Co-rich precipitations of various Mg-Co alloys are investigated by means of EDS and XRD analyses. The Mg-Co alloys' mechanical strengths are determined by tensile tests. Magnetic properties of the Mg-Co sensor alloys depending on the cobalt content and the acting mechanical load are measured utilizing the harmonic analysis of eddy-current signals. Within the scope of this work, the influence of the element cobalt on magnesium is investigated in detail and an optimal cobalt concentration is defined based on the performed examinations.