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Non-destructive determination of material properties and stresses

: Dobmann, G.; Höller, P.

Iida, K.; Whittle, J.M. ; American Society for Metals -ASM-, Metals Park/Ohio; British Institute of Nondestructive Testing:
10th International Conference on NDE in the Nuclear and Pressure Vessels Industries
Metals Park/Ohio, 1990
ISBN: 0-87170-506-0
International Conference on NDE in the Nuclear and Pressure Vessels Industries <10, 1990, Glasgow>
Fraunhofer IZFP ()
Characterization of property; micromagnetic technique; nondestructive testing; plastic deformation; shot-peening; Surfacestrengthening; ultrasonic absorption; ultrasonic technique; Eigenschaftscharakterisierung

The contribution reports to the state of the art in NDT for properties (NDTP) and NDT for stress (NDTS) with ultrasonic and micromagnetic techniques. The measurement of the time-of-flight of different ultrasonic wave modes and the measurement of back-scattered signals give information on the elastic properties and the density of the materials whereas absorption measurements are influenced by anelastic properties. The inspection data can be correlated with technical properties like yield strength, hardness, etc. Time-of-flight measurements furthermore yield direct access about the analysis of load induced and residual stress. The second tool for NDTP and NDTS are the micromagnetic techniques 3MA (micromagnetic-, multiparameter-, microstructure- and stressanalysis). Magnetic Barkhausen noise, incremental permeability, dynamic magnetostriction and the eddy current measurement of the electric conductivity and magnetic initial permeability in combination with the magnetic tangential field s trength are the techniques which give indirect access to independent information on the microstructure- and macro stress-states of the material. The information is received from irreversible and reversible dynamic magnetization processes, i.e. magnetic Bloch-wall (jumps and rotational processes) which are the result of interaction with desolcations, precipitations, dissolved atoms and stress fields. The multiparameter approach using a multiregression algorithm allows the separation of different influencing parameters and the correlation with mechanical or technical properties and the calibration in stress.