Nondestructive materials characterization and testing of casting materials
Casting materials are used whenever highest standards are requested regarding the mechanical properties of the component and the complexity of the component design. As the production of casting workpieces is relatively expensive, maximum utilization of the material is sought for. Nevertheless, the occurrence of defects and discontinuities inside the casting as well as the formation of dross or other defects at the casting surface cannot be completely excluded. These production-related defects lead to local degradation of material properties. A precise localization and characterization of the defects found is advantageous because it allows for either an efficient post-processing or at least an estimation of the fracture-mechanical consequences of defects that can make a post-processing expendable. In both cases, nondestructive testing (NDT) results in cost and material savings, sometimes even to a large extent. In addition, NDT can be used for quality control after post-processing or for the characterization of the raw material. For this purpose, Fraunhofer IZFP develops innovative nondestructive testing systems on the basis of ultrasound, X-ray, magnetic flux leakage and micromagnetic methods, which can be applied to components of different scales and different casting types (iron, steel, aluminium, etc.). The following paper exemplarily presents four current projects at IZFP dealing with aspects of the described issues.