• 비파괴검사학회지
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• 제10권1호
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• pp.91-95
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• 1990

Welding residual stress was measured by Barkhausen noise method. The calibration experiment was done for the quantitative analysis. The specimen for the calibration experiment must has the same thermo-mechanical history as the actual material to be tested. The Barkhausen noise were analysed by the pulse-height distribution. The results show that the distribution and magnitude of welding residual stress from Barkhausen noise method are in good agreement with those from blind hole method.

• 한국자기학회지
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• 제4권2호
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• pp.142-149
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• 1994

두께가 0.30 mm, 0.27 mm인 3% 방향성 규소강판에서 표면 선긋기의 간격(39~1.22 mm)과 집합조직(texture) 방향에 대한 선긋기 각도의 변화($90^{\circ}~50^{\circ}$)에 따라 Barkhausen Noise를 측정하였다. 두께 0.27 mm의 시편에서 선긋기를 하지 않았을 때와 선긋기의 간격이 39 mm인 경우 에 대체로 Barkhausen noise envelope은 두개의 peak 현상을 보였으며, 그 현상은 $180^{\circ}$ 자구벽(domain wall)이 생성과 소멸과정을 거듭할 때 많은 activation energy가 필요함에 따른 것으로 설명할 수 있었다. 선긋기 횟수를 늘려감에 따라 즉 선긋기의 간격이 줄어듦에 따라 Barkhausen noise envelope의 크기값이 감소하였지만, 선간격 9.75 mm부터는 감소현상이 둔화되는 것으로 나타났다. 이는 선긋기 획수가 늘어남에 따라 선긋기 근처에서 $180^{\circ}$ 자구의 생성과 소멸이 쉽게 일어나기 때문에 Barkhausen Noise의 크기가 감소하는 것으로 설명할 수 있다. 이러한 현상은 0.30 mm의 시편에서도 유사하게 설명될 수 있었다. Barkhausen noise power는 선긋기 간격이 줄어듦에 따라 감소하였으며, 각도변화에 따른 결과는 $50^{\circ}$ 근처에서 가장 적은 값을 보였다.

• 한국공작기계학회논문집
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• 제14권3호
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• pp.38-46
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• 2005

The destructive method is reliable and widely used for the estimation of material degradation but it have time-consuming and a great difficulty in preparing specimens from in-service industrial facilities. Therefore, the estimation of degraded structural materials used at high temperature by nondestructive evaluation such as electric resistance method, replica method, Barkhausen noise method, electro-chemical method and ultrasonic method are strongly desired. In this study, various nondestructive evaluation(NDE) parameters of the Barkhausen noise method, such as MPA(Maximum Peak Amplitude), RMS, IABNS(Internal Area of Barkhausen Noise on Signal) and average amplitude of frequency spectrum are investigated and correlated with thermal damage level of 2.25cr-1.0Mo steel using wavelet analysis. Those parameters tend to increase while thermal degradation proceeds. It also turns out that the wavelet technique can help to reduce experimental false call in data analysis.

• 대한기계학회논문집A
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• 제23권7호
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• pp.1215-1222
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• 1999

It is advantageous to use an NDE method to assess the mechanical properties of materials since the conventional method is time-consuming and sometimes requires cutting of sample from the material/component. This paper shows that the ultrasonic and the Barkhausen noise(BHN) methods can be used to accurately characterize forged reactor vessels. The attenuation coefficient of the ultrasonic wave was changed with heat treatment temperature and condition[as-quenched, tempered, PWHT]. The RMS[root mean square] voltage of Barkhausen noise depended on heat treatment temperature and conditions. The fracture appearance transition temperature(FATT) can be predicted using nondestructive evaluation methods.

• 한국음향학회:학술대회논문집
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• 한국음향학회 1999년도 학술발표대회 논문집 제18권 2호
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• pp.401-406
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• 1999

In relation to a non-destructive evaluation of irradiation damages of micro-structure interstitial, void and dislocation, the changes in the hysteresis loop, Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of $2.3\times10^{19}\;n/cm^2\;(E\geq1\;MeV)\;at\;288^{\circ}C$. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of $50\;{\mu}sec\;and\;20\;{\mu}sec$. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz; and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen.

• The Journal of the Acoustical Society of Korea
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• 제18권1E호
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• pp.7-12
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• 1999

In relation to a non-destructive evaluation of irradiation damages, the changes in the hysteresis loop and Barkhausen noise amplitude and the harmonics frequency due to a neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of RPV was irradiated to a neutron fluence of 2.3 ×10/sup 19/ n/㎠ (E ≥1 MeV) at 288℃. The saturation magnetization of neutron irradiated metal did not change. The neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by a neutron irradiation. The spectrum of Barkhausen noise is analysed with an applied frequency of 4 Hz and 8 Hz, sampling time of 50 μ sec and 20 μ sec. The harmonic frequency shows 4 Hz, 8 Hz, 12 Hz and 16 Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared on the irradiated specimen. In addition to the amplitude, the harmonic frequency of Barkhausen noise is taken into accounts as a promising tool for monitoring the irradiation induced degradation of the reactor materials such as a SA508 of PWR-RPV steel and a Zr₄ of HANARO-CNH.

• 한국음향학회:학술대회논문집
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• 한국음향학회 2000년도 학술발표대회 논문집 제19권 2호
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• pp.231-234
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• 2000

In relation to a non-destructive evaluation of irradiation damage of micro-structure of interstitial, void and dislocation, the changes in the hysteresis loop and Barkhausen noise amplitude and the harmonics frequency due to neutron irradiation were measured and evaluated. The Mn-Mo-Ni low alloy steel of reactor pressure vessel was irradiated to a neutron fluence of $2.3\times10^{19}n/cm^2$ $(E\ge1MeV)$ at $288^{\circ}C.$The saturation magnetization of neutron irradiated metal did not change. Neutron irradiation caused the coercivity to increase, whereas susceptibility to decrease. The amplitude of Barkhausen noise parameters associated with the domain wall motion were decreased by neutron irradiation. The spectrum of Barkhausen noise was analyzed with an applied frequency of 4Hz and 8Hz, and a sampling time of 50 $\mu$ sec and 20 $\mu$ sec. The harmonic frequency of Joule effect shows 4Hz, 8Hz, 12Hz and 16Hz reflected from an unirradiated specimen. On the contrary, the harmonic frequency disappeared for the irradiated specimen. Harmonic frequency of induced voltage of sinusoidal magnetic field And Spectrum of Barkhausen noise on material is determined.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 춘계학술발표회논문집(2)
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• pp.54-59
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• 1998

원자로 압력용기 용접열영향부의 세부영역별 열 cycle 재현(simulation) 시험편을 제작하여 기계적 특성시험, 미세조직시험 및 magnetic Barkhausen noise (BN) 측정을 수행하였다. 각 영역에서 보자력(coercivity)은 크게 변하지 않았으나, Barkhausen noise (BN) 는 현격한 차이를 볼 수 있었다. 용접열영향부 각 위치에 대한 BN 는 미세조직과 기계적특성의 변화와 어느정도 특징적 변화를 보였으나, 미세조직 인자별로 정량적인 관계를 찾기 위하여는 더욱 더 많은 연구가 필요한 것으로 보였다. 이는 BN 의 변화에 미치는 영향인자가 미세조직적으로 매우 복잡한 관계를 갖기 때문으로 생각되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 D
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• pp.1864-1866
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• 1999

The magnetic nondestructive test can be applied to evaluate the magnetic material characteristics and the fracture properties through the internal defects of SA-508 used in the pressure vessels of the nuclear power plants as the direct and accurate in-situ testing methods. The fracture toughness, yield strength and the stress distribution around the defects in the surface and sub-surface of magnetic materials can be directly estimated by Bark-hausen noise(BN) methods as NDT. The testing process of SA-508 by Barkhausen noise method was advanced by controlling the austenizing peak temperature and the time of maintenance at a constant austenizing peak temperature, therefore causing the variation of fracture toughness. Through above process. we can evaluate the variations of effective grain size and the correlation of effective grain size and FATT at each situation. And the stress distribution around the defects can be quantified nondestructively through Barkhausen method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집A
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• pp.210-215
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• 2001

The ferritic 2.25CrMo steel has been used for high temperature structure applications such as turbine rotors, boilers and pressure vessels in fossil plant and petroleum chemical facilities. However, this steel is known to result in aging degradation due to temper embrittlement, carbide induced brittleness and softening of matrix after long time exposure to high temperature. This research investigated the microstructural and mechanical changes after artificial degradation treatment and evaluated the degree of degradation by several nondestructive methods. The decrease of electrical resistivity and increase of magnetic Barkhausen noise(RMS voltage) with increasing aging time were observed. The change of electrical resistivity and Barkhausen noise showed a good correlation with the ductile-brittle transition temperature.