The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Toivo Lepistö - One of the best experts on this subject based on the ideXlab platform.
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Barkhausen Noise evaluation of fatigue in high strength steel
International Journal of Materials & Product Technology, 2006Co-Authors: Mari Lindgren, Toivo LepistöAbstract:The rms value of Barkhausen Noise and residual stresses were followed as a function of the number of loading cycles in alternating bending fatigue of high strength steel. The measurements were carried out in several directions to ensure that changes in the angular anisotropy of Barkhausen Noise could be detected. The Barkhausen Noise amplitude in the loading direction changed only slightly due to cyclic deformation. On the other hand, in other directions, especially in the angle 60° with respect to the loading direction, significant alteration of Barkhausen Noise amplitude as a function of the number of loading cycles was observed. The angular anisotropy of Barkhausen Noise increased as a function of the number of loading cycles. The amount of increase depended on the strain amplitude. The changes in the Barkhausen Noise amplitude could not be explained solely on the basis of changes in residual stresses.
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On the stress vs. Barkhausen Noise relation in a duplex stainless steel
Ndt & E International, 2004Co-Authors: Mari Lindgren, Toivo LepistöAbstract:Abstract Various parameters of a Barkhausen Noise burst were measured under applied stress in prestrained duplex stainless steel specimens. After quenching, the root mean square value of the Barkhausen Noise amplitude was low because of the compressive macroscopic and interphase macrostresses in the ferrite phase. Prestraining increased the amplitude of the Barkhausen Noise in all measuring directions due to reduction of macroscopic compressive residual stress and introduction of tensile interphase microstresses in the ferrite phase. Under applied stress, Barkhausen Noise measured in the loading direction behaved similarly to ferritic steels: Barkhausen Noise increased under tensile stress and decreased under compressive stress. In the direction transverse to the loading axis, the Barkhausen Noise response was anomalous: Barkhausen Noise increased or remained unchanged under macroscopic compressive strain in the transverse direction and decreased under tensile strain in the transverse direction. In unstrained specimens in the loading direction, applied stress vs. Barkhausen Noise showed a linear relation under the applied stress range from −200 to 250 MPa. The stress sensitivity of the Barkhausen Noise was, however, low. In the prestrained specimens, the stress sensitivity was higher than in the unstrained specimens, especially under applied compressive stress.
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effect of cyclic deformation on Barkhausen Noise in a mild steel
Ndt & E International, 2003Co-Authors: Mari Lindgren, Toivo LepistöAbstract:The rms value of the Barkhausen Noise and residual stresses were followed as a function of loading cycles in alternating bending fatigue of mild steel specimens. The measurements were carried out in several directions so that the changes in the angular anisotropy of the Barkhausen Noise and reorientation of the macroscopic easy axis of magnetisation could be detected. In the loading direction the Barkhausen Noise amplitude decreased due to build-up of compressive residual stresses. This was followed by either an increase or a decrease in the Barkhausen Noise amplitude depending on the direction of the initial magnetic easy axis with respect to the loading direction. After the commencement of macroscopic plastic deformation the angular anisotropy of Barkhausen Noise augmented substantially. In the transverse direction to the loading axis Barkhausen Noise decreased in the beginning of loading, reached thereafter a minimum followed by an increase in Barkhausen Noise. When cycling under larger strain amplitudes the loading direction and the direction transverse to the loading axis exhibited least changes as a function of loading cycles compared to other directions. The results indicated that following Barkhausen Noise only in one direction, usually in the loading direction, as a function of loading cycles, may lead to misevaluation of the fatigue damage development. Monitoring of several directions gives much more reliable results and therefore it is highly recommended.
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Estimation of biaxial residual stress in welded steel tubes by Barkhausen Noise measurements
Advanced Engineering Materials, 2002Co-Authors: Mari Lindgren, Toivo LepistöAbstract:Relation between biaxial stress and Barkhausen Noise was evaluated in mild steel specimens by biaxial bending experiments. Residual stresses of welded steel tubes were evaluated by Barkhausen Noise and X-ray diffraction. Barkhausen Noise values were converted into residual stress values by interpolation from reference measurements made by X-ray diffraction and Barkhausen Noise. Residual stress values measured by both methods were consistent.
Pirfo S Barroso - One of the best experts on this subject based on the ideXlab platform.
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investigation of shot peened austenitic stainless steel 304l by means of magnetic Barkhausen Noise
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Xavier Kleber, Pirfo S BarrosoAbstract:Different shot peening conditions were applied to an austenitic stainless steel AISI 304L in order to transform austenite to martensite α′ at different depths. Magnetic Barkhausen Noise measurements performed on this steel reveal a correlation between the strength of the signal and the depth of the treatment. The combined effect of the volume fraction of martensite and the residual stress in martensite determined using X-ray diffraction analysis were found to be responsible for the evolution of the Barkhausen Noise response. Using tensile plastic deformation, the residual stress in martensite was changed, giving rise to a strong increase of the Barkhausen Noise activity. This variation was correlated to a modification of the sign and amplitude of the residual stress in the martensite phase. Directional measurements of the Barkhausen Noise revealed the anisotropy of the residual stresses induced by the tensile plastic deformation. It is concluded that the Barkhausen Noise activity recording could lead to the determination of the residual stresses in martensite induced by shot peening processes.
Mari Lindgren - One of the best experts on this subject based on the ideXlab platform.
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Barkhausen Noise evaluation of fatigue in high strength steel
International Journal of Materials & Product Technology, 2006Co-Authors: Mari Lindgren, Toivo LepistöAbstract:The rms value of Barkhausen Noise and residual stresses were followed as a function of the number of loading cycles in alternating bending fatigue of high strength steel. The measurements were carried out in several directions to ensure that changes in the angular anisotropy of Barkhausen Noise could be detected. The Barkhausen Noise amplitude in the loading direction changed only slightly due to cyclic deformation. On the other hand, in other directions, especially in the angle 60° with respect to the loading direction, significant alteration of Barkhausen Noise amplitude as a function of the number of loading cycles was observed. The angular anisotropy of Barkhausen Noise increased as a function of the number of loading cycles. The amount of increase depended on the strain amplitude. The changes in the Barkhausen Noise amplitude could not be explained solely on the basis of changes in residual stresses.
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On the stress vs. Barkhausen Noise relation in a duplex stainless steel
Ndt & E International, 2004Co-Authors: Mari Lindgren, Toivo LepistöAbstract:Abstract Various parameters of a Barkhausen Noise burst were measured under applied stress in prestrained duplex stainless steel specimens. After quenching, the root mean square value of the Barkhausen Noise amplitude was low because of the compressive macroscopic and interphase macrostresses in the ferrite phase. Prestraining increased the amplitude of the Barkhausen Noise in all measuring directions due to reduction of macroscopic compressive residual stress and introduction of tensile interphase microstresses in the ferrite phase. Under applied stress, Barkhausen Noise measured in the loading direction behaved similarly to ferritic steels: Barkhausen Noise increased under tensile stress and decreased under compressive stress. In the direction transverse to the loading axis, the Barkhausen Noise response was anomalous: Barkhausen Noise increased or remained unchanged under macroscopic compressive strain in the transverse direction and decreased under tensile strain in the transverse direction. In unstrained specimens in the loading direction, applied stress vs. Barkhausen Noise showed a linear relation under the applied stress range from −200 to 250 MPa. The stress sensitivity of the Barkhausen Noise was, however, low. In the prestrained specimens, the stress sensitivity was higher than in the unstrained specimens, especially under applied compressive stress.
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effect of cyclic deformation on Barkhausen Noise in a mild steel
Ndt & E International, 2003Co-Authors: Mari Lindgren, Toivo LepistöAbstract:The rms value of the Barkhausen Noise and residual stresses were followed as a function of loading cycles in alternating bending fatigue of mild steel specimens. The measurements were carried out in several directions so that the changes in the angular anisotropy of the Barkhausen Noise and reorientation of the macroscopic easy axis of magnetisation could be detected. In the loading direction the Barkhausen Noise amplitude decreased due to build-up of compressive residual stresses. This was followed by either an increase or a decrease in the Barkhausen Noise amplitude depending on the direction of the initial magnetic easy axis with respect to the loading direction. After the commencement of macroscopic plastic deformation the angular anisotropy of Barkhausen Noise augmented substantially. In the transverse direction to the loading axis Barkhausen Noise decreased in the beginning of loading, reached thereafter a minimum followed by an increase in Barkhausen Noise. When cycling under larger strain amplitudes the loading direction and the direction transverse to the loading axis exhibited least changes as a function of loading cycles compared to other directions. The results indicated that following Barkhausen Noise only in one direction, usually in the loading direction, as a function of loading cycles, may lead to misevaluation of the fatigue damage development. Monitoring of several directions gives much more reliable results and therefore it is highly recommended.
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Estimation of biaxial residual stress in welded steel tubes by Barkhausen Noise measurements
Advanced Engineering Materials, 2002Co-Authors: Mari Lindgren, Toivo LepistöAbstract:Relation between biaxial stress and Barkhausen Noise was evaluated in mild steel specimens by biaxial bending experiments. Residual stresses of welded steel tubes were evaluated by Barkhausen Noise and X-ray diffraction. Barkhausen Noise values were converted into residual stress values by interpolation from reference measurements made by X-ray diffraction and Barkhausen Noise. Residual stress values measured by both methods were consistent.
O. Stupakov - One of the best experts on this subject based on the ideXlab platform.
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stabilization of Barkhausen Noise readings by controlling a surface field waveform
Measurement Science and Technology, 2014Co-Authors: O. StupakovAbstract:Insufficient reproducibility and measured results that are difficult to interpret are the main obstacles to widespread practical implementation of the magnetic Barkhausen Noise technique as a useful non-destructive tool. This work gives a clear experimental proof that precise control of the surface magnetic field stabilizes the subsurface Barkhausen Noise readout with respect to the magnetizing yoke lift-off. The surface magnetic fields above the sample were measured at two different distances by Hall sensors; the real sample field was obtained by linear extrapolation of these surface field waveforms to the sample face. This extrapolated field waveform was then adjusted to the standard triangular/sinusoidal shapes with a multi-parameter digital feedback procedure. The Barkhausen Noise signal was measured locally with a bobbin coil placed on the same surface area where the magnetic field was measured.
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evaluation of surface decarburization depth by magnetic Barkhausen Noise technique
Journal of Magnetism and Magnetic Materials, 2011Co-Authors: O. Stupakov, I. Tomáš, O Perevertov, B SkrbekAbstract:Industrially unfavorable process of steel surface decarburization was induced by annealing in air. Two methods of after-anneal surface treatment were used: an acid pickling and a sand blasting. The obtained decarburized layers were examined by optical microscope, wave dispersive spectrometer, and surface X-ray diffraction method. Magnetic Barkhausen Noise technique was tested for applicability of non-destructive characterization of the decarburized layer depth. A newly introduced parameter, Barkhausen Noise coercivity, was proposed for practical use due to its sensitivity to decarburization and stability to measurement conditions. Other magnetic parameters, e.g. number of Barkhausen Noise counts, were found to be sensitive to the compressive residual stress caused by the sand blasting.
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Measurement of Barkhausen Noise and its correlation with magnetic permeability
Journal of Magnetism and Magnetic Materials, 2008Co-Authors: O. Stupakov, Jozef Pal’a, V. V. Yurchenko, I. Tomáš, Jan BydzovskyAbstract:The paper investigates applicability of the Barkhausen Noise technique as a non-destructive testing method and its correlation with the magnetic hysteresis measurement. The hysteresis and the Barkhausen Noise experiments were performed at laboratory and industrial configurations on a model series of open flat samples plastically deformed by mechanical tension. The sample magnetic field was measured with the help of a near-surface Hall sensor. The results proved interrelation between the magnetic differential permeability and the Barkhausen Noise envelope. However, significant quantitative discrepancies between them were also obtained. The reasons of these deviations as well as the main measurement problems were discussed in order to help to standardize the Barkhausen Noise technique and to extend a number of the used parameters for the non-destructive testing.
Xavier Kleber - One of the best experts on this subject based on the ideXlab platform.
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investigation of shot peened austenitic stainless steel 304l by means of magnetic Barkhausen Noise
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Xavier Kleber, Pirfo S BarrosoAbstract:Different shot peening conditions were applied to an austenitic stainless steel AISI 304L in order to transform austenite to martensite α′ at different depths. Magnetic Barkhausen Noise measurements performed on this steel reveal a correlation between the strength of the signal and the depth of the treatment. The combined effect of the volume fraction of martensite and the residual stress in martensite determined using X-ray diffraction analysis were found to be responsible for the evolution of the Barkhausen Noise response. Using tensile plastic deformation, the residual stress in martensite was changed, giving rise to a strong increase of the Barkhausen Noise activity. This variation was correlated to a modification of the sign and amplitude of the residual stress in the martensite phase. Directional measurements of the Barkhausen Noise revealed the anisotropy of the residual stresses induced by the tensile plastic deformation. It is concluded that the Barkhausen Noise activity recording could lead to the determination of the residual stresses in martensite induced by shot peening processes.
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Dual-phase steels characterization using Magnetic Barkhausen Noise measurements
Materials Science Forum, 2005Co-Authors: Xavier Kleber, J. Merlin, H. PetitgandAbstract:Magnetic Barkhausen Noise measurements have been carried out to characterize ferrite-martensite duplex microstructures and industrial Dual-Phase steels. We have first studied ferrite-martensite duplex steels, for which the volume fraction and the carbon content of martensite were higher than for industrial Dual-Phase steels. We found linear evolutions between ferrite peak parameters and its proportion. We applied these results to industrial Dual-Phase steels and show that Barkhausen Noise measurement can be successfully used for Dual-Phase steels characterization, and in particular for assessment of ferrite proportion.