Aeroengine turbine disks often consist of paramagnetic, that means non-ferromagnetic Nickel based alloys. Sometimes, parasitic small ferromagnetic particles can be included in these disks that may decrease the mechanical stability. For this reason, in case of a suspicion disks are to be analysed with respect to ferromagnetic inclusions. These inclusions generate a magnetic density which can be measured by a flux gate magnetometer using the magnetic remanence method [1]. The detection principle of ferromagnetic impurities in non-magnetic metallic materials is based on their remanence. Before such a measurement can be carried out, the aeroengine turbine disks are premagnetised in axial direction. As ferromagnetic materials show the well-known hysteresis behaviour, those materials can be magnetised by a strong magnetic field which drives the magnetic material into saturation. When removing the magnetic field, the remanence is left. This remaining flux density is used to detect them in non-magnetic materials.
