| 摘要 |
Method for using the mechanical Barkhausen noise phenomenon, caused in ferromagnetic materials by the dislocation motion and the changing external mechanical loading, as a non-destructive measuring method, especially in determining the fatigue strength of the material. The method has two embodiments, the first of which has the following stages. The test piece (a) is loaded externally (stage 1), e.g., by a cyclic of other corresponding method, increases in its amplitude continuously (Fig. 2 a), and thus a dominating lattice defect arrangement from the point of view of the irreversible magnetization changes is created into the test piece. Simultaneously the changes in the effective value, the frequency, the size distribution or the mean value of the mechanical Barkhausen noise pulses induced during the fatigue of the ferromagnetic material are measured (b-f). Then (stage 2) the external loading is taken off. After this (stage 3), the test piece (a) is loaded externally, e.g., by a cyclic loading increasing in its amplitude continuously (Fig. 2 a), and simultaneously the maximum value appearing as the effective value, the frequency, the size distribution or the mean value of the mechanical Barkhausen noise pulses induced during the fatigue of the ferromagnetic material is measured. The loading amplitude corresponding to the measured maximum value also corresponds to the endurance limit (fatigue limit) of the test piece (Fig. 2 b). In the second embodiment, the test piece is magnetized with a stable magnetic field (g, h) in which case stages 1 and 2 of the first application mode are omitted and the measurement of the maximum point corresponding to the endurance limit (fatigue limit) of the test piece is done according to stage 3 of the first application mode. |
