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Barkhausen noise measurements and related mesurements in ferromagnetic materials


Birnbaum, G.; Auld, B.A. ; American Society for Nondestructive Testing -ASNT-, Columbus/Ohio:
Sensing for materials characterization, processing and manufacturing
Columbus: American Society for Nondestructive Testing (ASNT), 1998 (Topics on Nondestructive Evaluation Series 1)
ISBN: 1-57117-067-7
Book Article
Fraunhofer IZFP ()
Barkhausen noise; ferromagnetic material

In 1979, Matzkanin, Beissner and Teller published the NTIAC-79-2 report: the Barkhausen effect and its applications to non-destructive testing [1]. In the following years - and stimulated by the published work - R&D projects for NDT-techniques were started under the sponsorship of the Ministry of Research and Development in the Reactor Safety Research Programme in Germany, in the field of materials characterization in order to provide techniques for pre-service and in-service inspection as a part of quality management. Such techniques are sensitive and reliable, particularly for the prediction of strength and thoughness. As ferritic steels (pressure vessels and pipelines in the primary circuit) are of special interest, R&D was concentrated on micromagnetic techniques, i.e., Barkhausen noise and related measurement. These techniques are sensitive to the microstructure and its changes under service and/or repair conditions. In order to characterize, in an unambiguous way, microstructural as well as residual stress states, numerical modelling was applied using advanced tools of mathematical statistics and approximation theory, i.e., multiparameter regression algorithms and neutral networks. The basics for transducer and sensor development were found as a result of this work. The research has two basis themes: the first is the underlying science and validation of the measurement methods; the second is their applications to quality control and processing. We present here results of R&D projects sponsored by the European Community for Coal and Steel in its basic research programme, mainly to the deep drawability characterization of steel sheets and characterization of hardness of heavy steel plates. On example is to the monitoring of laser hardering where surface hardness, hardness depth and induced residual stresses are of interest. A last example is of materials characterization in the casting industry.