Micromagnetic (3MA) and Multifrequency Eddy Current (MFEC) techniques were developed over the last years. These have been established to be most appropriate for the nondestructive evaluation of hardness. Combining complementary information of various physical material properties which can be measured by eddy current and micromagnetic techniques, a fast evaluation of hardness values can be achieved by using multiple regression or neural net analysis.

Hardness changes are due to microstructural changes introduced during processing. The fundamental understanding is outlined how physical properties measured by 3 MA and MFEC techniques is correlated to conventional hardness measurement, directly measuring the deformation resistance of a material when subjected to an indentor.

Future tasks for quality assessment will not only focus on further development of standard hardness checks but on Process Integrated Nondestructive Testing (PINT). These PINT-systems can be used for Process-FMEA and can be integrated in Quality Management Systems.

Multiparameter 3MA+MFEC- units and sensor systems are already in industrial use. They determine the quality characteristics after flame, inductive- and laser-hardening as well as after annealing processes. Results are obtained on as hardened surfaces without any additional surface preparation. The accuracy of the nondestructively evaluated hardness values is comparable to those values using established techniques.