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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Society for Nondestructive Testing
Journal Basic Information
Journal DOI :
The Korean Society for Nondestructive Testing
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Volume & Issues
Volume 22, Issue 6 - Dec 2002
Volume 22, Issue 5 - Oct 2002
Volume 22, Issue 4 - Aug 2002
Volume 22, Issue 3 - Jun 2002
Volume 22, Issue 2 - Apr 2002
Volume 22, Issue 1 - Feb 2002
Selecting the target year
The Signal Characteristics from Crack of Brittle Materials by Vickers Load
Nam, Ki-Woo ; Kim, Hyun-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 125~131
we analyzed acoustic emission signals obtained from three kinds of brittle materials under compression load by Vickers hardness tester. The results obtained can be summarized as follows; The signal in each material could be divided into three signal based on the properties of load. All specimens were not detected acoustic emission signals in stage II which was load constant region., and were detected in stage I and stage III. Glass was detected high amplitude signals in stage III.
were detected high amplitude signals in stage I.
Nondestructive Evaluation for Grain Refinement of Aluminum Alloy of Equal-Channel Angular Pressing
Ahn, Seok-Hwan ; Nam, Ki-Woo ; Kim, Jin-Hwan ; Kang, Suk-Bong ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 132~139
The grain size of aluminum alloy was refined to the submicrometer level by using equal-channel angular pressing(ECAP). The effect of grain size refinement was evaluated by the tensile test, micro-hardness test, microstructure observations, ultrasonic test and acoustic emission test. The strength and the Vickers hardness were increased significantly according to grain size refinement after equal-channel angular pressed. The ultrasonic velocity was faster after equal-channel angular pressed, and the high frequency range appeared. The results of the ultrasonic velocity and the frequency range are expected to be basic data that can prove the grain size refinement
Measurement of High Temperature Anisotropic Elastic Constants of Zr-2.5Nb Pressure Tube Materials by Resonant Ultrasound Spectroscopy
Cheong, Yong-Moo ; Kim, Sung-Soo ; Kim, Young-Suk ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 140~148
Anisotropic elastic constants of Zr-2.5Nb pressure tube materials were determined by a high temperature resonant ultrasound spectroscopy (RUS). The resonant frequencies were measured using alumina wave-guides and wide band ultrasonic transducers in a small furnace. The rectangular parallelepiped specimens were fabricated along with the axial, radial and circumferential direction of the pressure tube. A nine elastic stiffness tensor for orthotropic symmetry was determined in the range of room temperature
. As the temperature increases, the elastic constant tensor, cij gradually decreases. Higher elastic constants along the transverse direction compared to those along the axial or radial direction are similar to the case of Young's modulus or shear modulus. A crossing of shear elastic constants along axial direction and radial direction was observed near
. This fact corresponds to the crossing of c44 and c66 of single crystal zirconium
Aging Degradation Assessment of Materials by Ultrasonic Characterization
Park, Un-Su ; Park, Ik-Keun ; Kim, Duck-Hee ; Ahn, Hyung-Keun ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 149~154
An attempt was made to evaluate the changes of microstructures and mechanical properties with increasing aging time in 2.25Cr-1Mo steel. In this study, it was verified the feasibility of the evaluation for degraded 2.25Cr-1Mo steel by isothermal heat treatment at
up to 1,000 hours using surface SH wave and investigated the change of attenuation coefficient and propagation time. Attenuation coefficient had a tendency to increase according to degradation and propagation time drastically in the beginning of deterioration. A good correlation between ultrasonic attenuation coefficient and hardness was found, which made sure that attenuation coefficient is an potential parameter for evaluation of aging degradation. In addition, it has verified experimentally the frequency dependence of ultrasonic group velocity and attenuation coefficient using wavelet transform.
AE Characteristics of Fatigue Crack Opening and Closure in Structural Aluminum Alloy
Jeong, Jung-Chae ; Park, Phi-Lip ; Kim, Ki-Bok ; Lee, Seung-Seok ; Yoon, Dong-Jin ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 155~169
The objective of this study was to investigate the effect of crack opening and closure in the AE activities during fatigue test. Laboratory experiment using various materials and test conditions were carried out to identify AE characteristics of fatigue crack propagation. Compact tension specimens of 2024-T4 and 6061-T6 aluminum alloy were prepared for fatigue test. AE activities were analyzed based on the phase of the loading cycle. Generally, most of AE were generated when the crack begins' opening and the crack closes fully, whereas a few in the pull opening of the crack. Also AE activity in the peak loading of cycle was different with each specimen. However, in the same material, AE activity was not affected by the change of cyclic frequency (0.1, 0.2, 1.0Hz). It was found that AE activities during crack opening and closure depend on material properties such as micro-structure, tensile strength and yield strength.
Application of Non-linear Acoustic Effect for Evaluation of Degradation of 2.25Cr-1Mo Steel
Choi, Y.H. ; Jhang, K.Y. ; Park, I.K. ; Kim, H.M. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 170~176
Nonlinear acoustic effect has been considered as an effective tool for the evaluation of material degradation. In this paper, the applicability of nonlinear acoustic effect to the evaluation of degraded 2.25Cr-1Mo steel is investigated. Firstly, artificial aging was performed to simulate the microstructural degradation in 2.25Cr-1Mo steel arising from long time exposure at
. Secondly, ultrasonic nonlinear parameter was quantitatively measured by bi-spectrum and power spectrum. Nonlinear acoustic parameter from bi-spectrum was found to be clearly sensitive to the aging time.
Research on MFL PIG Design for the Inspection of Underground Gas Pipeline
Park, Sang-Ho ; Park, Gwan-Soo ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 177~186
This paper describes the magnetic flux leakage(MFL) type non-destructive testing(NDT) system to detect the 3D defects in underground gas pipe. Magnetic systems with permanent magnets and yokes are analyzed by 3D non-lineal finite element method(FEM) with optimum design. In case of under-saturation of gas pipe, sensing signals are too weak to detect. In case of over-saturation, the changes of the sensing signals are too low to detect the defects sensitively. So, the operating points of the magnetic system are optimized to increase the changes of the MFL signals. The effects of the depth and size of the defects on the sensing signals are analyzed to define the range and resolution of the MFL sensors. To increase the sensor's sensitivity, the back-yoke sensors are introduced and tested.
Development of Open-Connect Type Eddy Current Transducers for the Detection of Surface Flaws in Continuous Pipeline
Kim, Young-Joo ; Ahn, Bong-Young ; Lee, Seung-Seok ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 187~192
The open-connect type eddy current transducer for the flaw detection in continuously connected pipelines was developed. This eddy current transducer is for the on-line inspection of the tubes in industries, to which commercial encircling probes are not applicable. The excitation coil that consists of a ribbon type cable and a flat connector can be opened and closed on purpose. The sensing coils of this transducer are circumferentially arrayed near the outside of the tube wall but axially displaced from the exciter by about one and half tube diameter. In application to steel tubes, and the performance of this transducer was evaluated as a little behind those of magnetic saturation type in signal to noise ratio and flaw size decision, but usable to detect or to locate large size flaws in steel tubes. Surface cracks deeper than 19% of the tube thickness could be detected with good signal to noise ratio.
Evaluation of Abrasive Wear Face Using SAW
Kwon, Sung-D. ; Yoon, Seok-S. ; Song, Sung-J. ; Lee, Young-Z. ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 193~197
The frequency dependency of the Rayleigh surface wave was investigated indirectly by measuring the angular dependency of the backward radiation of the incident ultrasonic wave in the abrasion specimens, which was explained in view of the residual stress distribution. The peak intensity of the backward radiation profile decreased and the right half width of the profile increased with an increase of the variational rate of residual stress for the scuffing specimen. The peak intensity was also affected by the surface wave scattering during the propagation around the micro-damages. The peak angle might depend on not only the amount of residual stress but also the micro-structure. The result observed in this study demonstrates the high potential of the backward radiated ultrasound as a tool for the nondestructive evaluation of the subsurface gradients of materials.
Signal Characteristics of Eddy Current Test for Intergranular Attack of Steam Generator Tubes
Choi, Myung-Sik ; Lee, Deok-Hyun ; Cho, Se-Gon ; Yim, Chang-Jae ; Han, Jung-Ho ; Hur, Do-Haeng ;
Journal of the Korean Society for Nondestructive Testing, volume 22, issue 2, 2002, Pages 198~202
Beacuse intergranular attack (IGA), one of the locallized corrosion forms occurring on steam generator tubes, can not be fabricated by an electric discharge machining method, there are few data for the eddy current test (ECT) characteristics of IGA. In this paper, the characteristics of eddy current signals are evaluated using nonexpanded tubes with IGA defects formed in 0.1 M sodium tetrathionate solution at
. The detectability and sizing accuracy of IGA were discussed in terms of the coil type and frequency of the ECT probes.