N. Buiron

Bio: N. Buiron is an academic researcher from University of Technology of Compiègne. The author has contributed to research in topics: Hysteresis & Deformation (engineering). The author has an hindex of 1, co-authored 1 publications receiving 62 citations.

Magnetic behaviour versus tensile deformation mechanisms in a non-oriented Fe–(3 wt.%)Si steel

Abstract: This study presents an extended in situ magnetic characterisation of a non-oriented (NO) Fe–(3 wt.%)Si steel. An appropriate experimental device was created and magnetic measurements were performed under uniaxial tensile stresses approaching and exceeding the macroscopic elastic limit σ e and in the corresponding unloaded states. Both Barkhausen noise and B–H hysteresis loops were measured. The sensitivity to stress was found to be qualitatively similar to that of polycrystalline iron. The different stages of the tensile deformation (perfectly elastic stage, microplastic yielding stage, the two strain-hardening stages) were clearly identified by the magnetic parameters. In the plastic strain domain, the coercive field H c and the inverse of the initial relative permeability 1/ μ r i linearly increase, while the maximal relative permeability μ r max and the Barkhausen noise peak height BN max linearly decrease with the applied stress σ . The remnant induction B r keeps a low and constant value. Furthermore, a linear dependence of 1/ μ r i , H c , μ r max and BN max on the kinematic hardening X was found. By using measurements on prestrained specimens under reloaded elastic stresses, an accurate identification of the effect of dislocations acting as pinning sites and of the magnetoelastic effect of long-range internal stresses was proposed.

Metal magnetic memory signal response to plastic deformation of low carbon steel

Abstract: Metal magnetic memory (MMM) technique can be potentially used to evaluate early damage of ferromagnetic materials nondestructively due to its high sensitivity to stress and stress–strain state. An experimental investigation of the effect of plastic deformation on magnetic behavior has been undertaken in low carbon steel specimens. The measurements were made under applied tension after unloading in the elastic–plastic region for different strain levels. Magnetic memory signals show apparently different variation characteristics in the elastic and plastic ranges, and the magnetic signals are sharply changed by a rather small plastic deformation, which is in agreement with the predictions of the modified magnetomechanical effect model correlating magnetic memory signal with plastic strain. The results of the present work indicate that the MMM method can detect macroyielding and early stage of plastic deformation effectively.

Experimental Research on Metal Magnetic Memory Method

Abstract: Metal magnetic memory (MMM) method is a novel, passive magnetic method for inspecting mechanical degradation of ferromagnetic components To promote a further understanding of the relation between the magnetic characteristics and mechanical deformation, the normal spontaneous stray field component and its gradient of Q235-steel specimens were measured during uniaxial tensile and compressive loading processes The results show that the normal spontaneous stray field component and its gradient are effective in capturing different deformation stages under tensions, but no detectable change can be found during the whole compressive loading processes Compared with the amplitude of the normal spontaneous stray field component, the gradient is a more sensitive parameter In addition, the result demonstrates that it is easy to differentiate macro-crack and plastic deformation because the differences among measured spontaneous stray field signals are obvious Moreover, various factors affecting test results were also considered

A novel approach of accurately evaluating residual stress and microstructure of welded electrical steels

Abstract: In the present research work the determination of residual stress distribution in welded non-oriented electrical steel samples is discussed. Tungsten inert gas was used for the welding method. Residual stress was directly determined through deformation measurements and appropriate math calculations. Two methods were used: the magnetic, non-destructive method of Barkhausen noise and the semi-destructive method of X-ray diffraction. In order to evaluate the accuracy and reliability of the magnetic method applied, the steel samples were subjected to both compressive and tensile stresses and the magnetic noise values were correlated to residual stress values through an appropriate calibration curve. The results were then verified by the XRD method and were further evaluated by examining the microstructure and the mechanical properties of the as received and welded samples through scanning electron microscopy and hardness measurements, respectively. It was found that the deviation between the two methods was within acceptable limits, thus implying potential applicability of the MBN method in non-destructive testing of materials.