Measurements of magnetic minor hysteresis loops have been performed in martensitic stainless steel subjected to tensile creep test at 120 MPa and 873 K. The minor-loop coefficients as well as coercivity, which are indicators of internal stress, sharply increase at the primary creep and show a very s low increase at the secondary creep, followed by the steady increase at the ternary creep. A good correlation of the coefficients with creep strain cl early shows that magnetic method using minor hysteresis lo...
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Changes of Magnetic Hysteresis Properties due to Creep Damage in Martensitic Stainless Steel

Magnetic properties derived from major hysteresis loops are sensitive to the microstructures of iron-based steels and have therefore been used for nondestructive evaluation of degradation in ferromagnetic materials contained in structural components. A permeability obtained from ac small field excitation may be a more us eful parameter than one obtained from a major hysteresis loop from the viewpoints of electricity consumption and real-time measurement. In this paper, the relati on between the ac permeabi...
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Evaluation for Mechanical Properties of Ferromagnetic Steels by AC Permeability

This study demonstrates the possibility of applying magnetic methods to pressure vessel surveillanc e at nuclear power plants. Magnetic hesteresis-minor-loop measurement and TEM observation were pref ormed on thermally aged Fe-1.0wt%Cu model alloys. Minor loop parameters decreased with increasing a ging time. The mechanism is discussed in terms of Cu precipitation behaviors of cold-rolled alloys....
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Relation between Precipitation Behaviors and Magnetic Properties in Cold-rolled FeCu Model Alloys

This study demonstrates the possibility of applying magnetic methods to pressure vessel surveillance at nuclea r power plants. Charpy impact test and magnetic hysteresis-loop measurement were preformed on Fe-1.0wt%Cu model alloys. The ductile-brittle transition temperature and the coercivity increased by cold-rolling and thermal agi ng. This correlation originates from an increase in the dislocation density and a formation of Cu precipitates....
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Magnetic Properties of FeCu Model Alloys Embrittled by Cold-rolling and Thermal Aging

This study developed an apparatus for the measurement of magnetic properties of tensile test specimen. Experimental results show that the difference shape of BH curves of the steels cold-rolled with different rolling reduction. The coercive force has good correlation with Ductile-brittle transition temperature and Vickers hardness of the specimen. This result indicate s the possibility of nondestructive evaluation for the mechanical properties of tensile test pieces using magnetic methods....
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NDE for Mechanical Properties of Ferromagnetic Steels using Magnetic Measurement Apparatus

Magnetic NDE technique for an estimation of degradation distribution in tensile-tested structural steel has been developed. In order to scan magnetic properties of steel promptly , magnetic yoke-probe having primary and secondary coils wounded around the yoke was adopted. To simplify the detection procedure, the principle same as the transformer was emplo yed. The voltage induced at secondary coil decreases with the increase in the applied tensile stress. As for spatial distribution of output voltage, the ...
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NDE of degradation distribution in tensile-tested specimen using magnetic sensing

小林 悟 Satoru KOBAYASHI Magnetic NDE technique for installed structural steels using a magnetic single-yoke probe has been leveloped. In order to apply this technique to practical use, it is important to clear influence of a contact gap netween a single-yoke probe and specimens . Here, we investigated magnetic properties measured by a ingle-yoke probe, when an air gap length between the probe and specim ens changes. BH loops incline to he axis of magnetic field and magnetic field at B =0 decreases with inc...
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Influence of contact gap on NDE using magnetic single-yoke probe

Abstract Magnetic NDE of ferromagnetic steel using spectrum analysis of induced voltage at pick-up coil and magnetic induction has been studied. Magnetic yoke, having an excitation coil and a pick-up coil, was located on a specimen, and a sinusoidal current was applied to the excitation coil for magnetizing the specimen. A voltage induced at the pick-up coil was measured, and the corresponding magnetic in duction was calculated. Then, their frequency spectrums were obtained thorough Fourier analysis. For ...
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NDE of ferromagnetic steel using spectrum analysis of changes in inducedvoltage and magnetic flux density

Magnetic properties of heavy ion irradiated single crystalline Fe Cr films were investigated High quality Fe 20%Cr 001 films with a thickness of 30 nm were prepared by electron beam deposition and irradiated by 2 4MeV Cu2+ ions at various temperatures and magnetization curves were measured using a VSM Micro fabricated films and Fe Cr film with Cr concentration gradient 0% 13% were also prepared and magnetic domain struct ures were observed using a Kerr microscope The coercivity of Fe 20%Cr increased by ...
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The irradiation temperature and Chromium concentration dependence of the magnetic properties of heavy-ion irradiated Iron-Chromium alloys