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Process monitoring and lifetime prediction

: Dobmann, G.

Czech Society for Nondestructive Testing; Deutsche Gesellschaft für Zerstörungsfreie Prüfung e.V. -DGZfP-, Berlin:
NDT in Progress : Meeting of NDT-Experts; June 20 - 22, 2001, Castle Trest', Czech Republic ; proceedings
Prag, 2001
ISBN: 80-238-7263-X
NDT in Progress, Meeting of NDT-Experts <2001, Prag>
Conference Paper
Fraunhofer IZFP ()
material characterization; process monitoring; process control; non-destructive characterization

Nondestructive characterization (NDC) of materials is a technology of increasing application by industrial users for process monitoring and control as well as in predictive maintenance procedures integrated in plant lifetime management systems. The main reason for this fact in materials processing is the need for a better process understanding and mastering in order to produce quality according to a zero-defect-principle and the objective to reduce non-conformities compared with a given quality specification. This means: Integration of NDC by use of intelligent sensors into monitoring and control systems to predict mechanic properties and to detect and document their discontinuities. For lifetime management of components in plants NDC is asked to support lifetime prediction procedures which have to be observed if lifetime extension is an objective to reduce costs.
NDC-technology, which in the last two decades was mainly pushed by research and development in different national and international programs now is matured for a wider range of applications. Micro-magnetic techniques have a special advantage to be applied for the mentioned objectives, because micro-magnetic intrinsic properties and mechanic properties are influenced by the same microstructure parameters and their changes as well as in volume fraction as well as in morphology and distribution during material processing and material degradation procedures. Furthermore they are sensitive for load-induced and residual stresses. However, their application is restricted to ferromagnetic materials and/or ferromagnetic material phases.
The contribution will introduce in the information content of the different techniques which contribute with redundancy and diversity to NDC of microstructures by discussing examples of process integration of NDE in steel industry, i.e. the online determination of yield strength and deep drawability parameters of cold rolled steel strips in a hot dip galvanizing line. The special emphasis of the contribution is to give characteristic examples which illuminate mainly the gain in economical benefit.
Due to the fact that in all European countries the construction of new nuclear power plants has been radically decreased since the 1970'ies, the nuclear power plants being currently in operation in European countries have reached at least the half of their design lifetime. The continuation of the operation of aging nuclear power plants in Europe is an economical solution for energy production but the safety aspects of aging structures are getting even more importance in the future. First NDC-approaches are discussed, documenting the micro-magnetic ability for fatigue (LCF and HCF) monitoring, detection and characterization of toughness reduction and embrittlement.