This study is an initial attempt to investigate the possibility of substituting conventional laboratory destructive testing techniques at Sandvik's strip steel production facilities with the 3MA (Micro-magnetic Multi-parameter Microstructure and Stress Analysis) NDT (nondestructive testing) technique. The interest for the research comes from various problems with the actual destructive testing method. Sandvik manufactures thin strip steel (among other products) and controls the quality of its product by taking samples from the ends of the strip and measuring the sample's material properties in a separate laboratory. Hence, the sample preparation process is time and material consuming, and the results obtained from the laboratory measurements are not always representative of the real values along the whole length of the strip (usually several kilometers). Therefore, the present project involves the correlation between three material properties (Vickers hardness, tensile strength and carbide density) and a selection of micro-magnetic parameters measured with the 3MA-II equipment manufactured by the Fraunhofer IZFP institute. The 3MA-II system is based on four measuring techniques (harmonic analysis, magnetic Barkhausen noise, incremental permeability and Eddy current testing) and is capable of recording up to 41 micro-magnetic parameters. Samples of two different steel grades (composition) were used in the study. The results for hardness and tensile strength (average relative errors of 1.04% and 0.78%, respectively) corroborated the applicability of the 3MA technique to steel strip inspection. Thus, the implementation of this technique would lead to an improvement in the company's energy efficiency and sustainability. However, finding a good correlation between micromagnetic parameters and material properties is not always possible and, in the case of carbide density, no reliable correlation was achieved. So, further experiments are proposed for future studies regarding carbide density and other material properties.

Temperature drifts, tool deterioration, unknown vibrations as well as spindle play are major effects which decrease the achievable precision of computerized numerically controlled (CNC) lathes and lead to shape deviations between the processed work pieces. Since currently no measurement system exist for fast, precise and insitu 3d shape monitoring with keyhole access, much effort has to be made to simulate and compensate these effects. Therefore we introduce an optical interferometric sensor for absolute 3d shape measurements, which was integrated into a working lathe. According to the spindle rotational speed, a measurement rate of 2,500 Hz was achieved. In-situ absolute shape, surface profile and vibration measurements are presented. While thermal drifts of the sensor led to errors of several µm for the absolute shape, reference measurements with a coordinate machine show, that the surface profile could be measured with an uncertainty below one micron. Additionally, the spindle play of 0.8 µm was measured with the sensor.