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Wave scattering and guided wave considerations in anisotropic media
tubing a matter of critical concern. Evaluating the integrity of CCSS tubing is, however, fraught with difficulties owing to the acoustically anisotropic nature of the material. This report investigates a novel and efficient method for enhancing the signal-to- clutter ratio through the application of the Wigner transform which is a two dimensional function showing the distribution of energy as a function of time and frequency. The specimen is inspected using the traditional pulse-echo method. The received signal is then effectively split into a number of decorrelated time signals which result directly from the application of Wigner transform. These signals are then averaged yielding the enhanced signal. Preliminary experimental results are given.
Rose, J.L.; Pilarski, A.; Tverdokhlebov, A.; Balasubramaniam, K.; Dale, J.; Diprimeo, D.
40018
Wave scattering and guided wave considerations in anisotropic media Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia ( U n i t e d States), 22-26 Jun. 1987. Vol. 7A, pp. 85-94. Edited by D . D . T h o m p s o n and D . E . Chimenti, P l e n u m Press, 1988. Of prime concern in this article is the anisotropic nature of centrifugally cast stainless steel used in the nuclear industry. There exists significant skew angle variations of 15 degrees or more at times that can cause serious problems in defect detection, location, classification, and sizing. With recent advances in the understanding of wave propagation in anisotropic media associated with critical angle reflectivity, surface waves, plate waves and longitudinal and shear wave scattering employing a newly developed point source Green's function numerical integration model, there exists an excellent chance that once the material characteristics are known with respect to its anisotropic character that a very accurate and a detailed defect classification analysis could be carried out. The purpose of this paper is to outline a numerical integration ultrasonic field analysis computation model and also to illustrate a variety of different experimental and analytical techniques that could be used to characterize the anisotropic nature and hence the corresponding grain structure associated with centrifugally cast stainless steel. 39900
Kopec, B.; Hanak, V.
Ultrasonic attenuation in quenched railway wheels N D T International, Voi. 22, No. 1, pp. 21-25 (Feb. 1989) Ultrasonic attenuation in the fine pearlitic steel used for railway wheels has been measured. Several structural factors that significantly affect ultrasonic wave attenuation in the frequency range 2-10 MHz have been found. These factors are: the grain and its distribution, the grain boundaries, the history of the grain and the content of the ferritic component. 39889 Bilgutay, N.M.; Li, X.; Saniie, J. Spectral analysis of randomly distributed scatterers for ultrasonic grain size estimation Ultrasonics, Vol. 27, No. 1, pp. 19-25 (Jan. 1989) Since the average grain size is an important parameter in material characterization, the non-destructive evaluation of the microstructure in polycrystaUine materials using ultrasonic backscattered echoes has significant practical implications. However, the complexity of the ultrasonic backscattered signal, which consists of interfering multiple echoes with random positions and amplitudes, makes accurate grain size evaluation difficult with conventional signal processing techniques. This paper introduces an alternative approach which examines the spectrum of an ensemble of randomly distributed scatterers with known distribution to establish a relationship between the spectral and temporal statistical properties of the scatterers. 39875
Sasahara, T.; Gothard, M.; Leonard, F.; Queen, H.
Tennessee valley authority experience with field application of advanced UT system I n t e r n a t i o n a l J o u r n a l of Pressure Vessels and Piping, Vol. 35, pp. 293306 (1988). (Proceedings of 5th I n t e r n a t i o n a l S e m i n a r on N o n d e s t r u c tive E x a m i n a t i o n in Relation to Structural Integrity, D a v o s , Switzerland, 26-27 A u g u s t 1987) An automated four-channel ultrasonic inspection system, the IntraSpect/98 has been developed. This paper describes the successful application of the IntraSpecV98 to the detection and sizing of IGSCC (intergranular stress corrosion cracking) in stainless piping, examination of weld overlay, field examination of creviced safe-ends of reactor pressure vessel and measurement of wall thinning of fossil plant steam piping. The system was also applied to technique development for generator retaining ring and cast stainless steel pipe examination. The application of IntraSpect will be expanded to heavy section examination. 39732
Kapitza, H.
Improvement of the defect detection capability of ultrasonic inspection of coarse.grained austenitic materials by means of a combination of signal enhancement methods. Final report (In German) F r a u h n e f e r - I n s t . fuer Z e r s t o e r u n g s f r e i e Pruefverfahren, Saarbr u e c k e n ( G e r m a n y ) . T I B / B 8 8 - 8 1 3 6 2 / G A R , 73 pp. (27 Sep. 1986) The decorrelation of ultrasonic, scattered signals by spatial or frequency variation is determined, together with the number of scattered signals with given flattening of the background. A prototype device is available that allows an examination of the geometry of electro-magnetic ultrasonic transducers (EMUS transducer) for the generation of shear horizontal waves. Ultrasonic propagation in textured materials (such as austenitic seam welds) is described analytically and numerically.
NDT International October 1989
39721
Bridge, B.; Bin Saffiey, H.J.
Monitoring of the annealing temperature and hardness of a l u m i n l u m alloys by ultrasonic back-scatter and critical an t~le reflectivity British J o u r n a l of Nondestructive Testing, Vol. 30, No. 6, pp. 392-399 (Nov. 1988) Two simple theories which relate shear wave attenuation coefficients to the amplitudes of critically reflected and back-scattered ultrasound, are presented. By combining back-scatter and reflectivity measurements, the models allow absolute attenuation coefficients due to scattering and absorption processes to be calculated. Quantities so calculated should be regarded as local values obtaining near the specimen surface only. In the case of the absorption coefficient, the near-surface values appears to be much larger than corresponding values within the bulk of the specimen. For the common aluminium alloy HE5TB 2000, the back-scattered and reflected signals, and therefore presumably the local shear wave attenuation coefficients, were found to be systematically related to annealing temperature and hardness. So these ultrasound techniques can be used to monitor the heat treatment of this particular alloy system. As the grain sizes and shapes varied in a complicated manner with the heat treatment parameters it is clear that grain size was not the main determinant of the scattering power. 39560
Dijkstra, F.H.; de Raad, J.A.; van Nisselroij, J.J.M.
Experience with the ultrasonic inspection of coarse.grained anisotropic alloyed steels Proceedings of the 4th E u r o p e a n C o n f e r e n c e o n N o n - D e s t r u c t i v e Testing, L o n d o n ( U n i t e d K i n g d o m ) , 13-17 Sep. 1987. Vol. 3, pp. 1617-1633. P e r g a m o n Press, 3173 pp. (1988) The present paper gives an overview of the practical experience gained with the use of refracted compressional waves for ultrasonic inspection. A better understanding of the interaction between grain structure and sound waves has led to the development of better probes, and to better flaw detectability. New probe concepts were developed, such as creeping wave probes and the round trip tandem technique. The use of a semi-mechanized inspection system further improved flaw detectability and inspection quality. Moreover, it was found to provide practical flexibility for use on a variety of pipe diameters and weld geometries in for instance a petrochemical or gas processing plant, both for stainless and for Duplex stainless steel welds. 39447
Vary, A.; Kautz, H.E.
Transfer function concept for ultrasonic characterization of material microstructures International A d v a n c e s in Nondestructive Testing, Vol. 13, pp. 193-250 (1987). Edited by W.J. M c G o n n a g l e . G o r d o n and Breach Science Publishers. Although expressions that relate ultrasonic attenuation to specific microstructural factors exist, they are fragmented and generally consists of ad hoc combinations of mechanisms for attenuation over particular frequency ranges. The approach given in this paper depends on treating material microstructures as elastomechanical filters that have analytically definable transfer functions. These transfer functions can be defined in terms of the frequency dependence of the ultrasonic attenuation coefficient. The transfer function concept provides a basis for synthesizing expressions that characterize polycrystalline materials relative to microstructural factors such as mean grains size, grain-size distribution functions, and grain boundary energy transmission. Although this approach is nonrigorous, it leads to a rational basis for combining the previously used diverse and fragmented equations for ultrasonic attenuation coefficients. 39420
Stringfellow, M.; Hawker, B.
New ultrasonic scanner for inspection of austeniti¢ steel Joining and Materials, Vol. 1, No. 4, pp. 170-173 (Oct. 1988) A new ultrasonic scanner and advanced inspection methods are described. Developed at UKAEA's Harwell Laboratory, the device compensates for changes in ultrasonic propagation caused by grain orientation in anstenitic welds. The new inspection methods after inspection of transition welds, spatial averaging, obtaining the best ultrasound spectrum and improved views of defects. Trials on full scale reactor nozzles, transition welds and pipework welds as well as fast reactor flat plate, T butt and cruciform austenitic welds are all planned for the future, and the new scanner will be tested to the full. 39390
Bernabei, P.; Borgna, R.; Callegari, L.
Performance and industrial implications of non-destructive testing on large forgings Proceedings of the 4th E u r o p e a n C o n f e r e n c e o n N o n - D e s t r u c t i v e Testing, L o n d o n ( U n i t e d K i n g d o m ) , 13-17 Sep. 1987. Vol. 2, pp. 971-991. P e r g a m o n Press, 3173 pp. (1988) The new role of non-destructive testing in the shrinking market of heavy forgings is discussed. A review of typical manufacturing cycles and highlights on non-destructive testing time is presented. This paper also considers the criteria, significance, reliability and actual data of non-destructive testing at different manufacturing stages (as forged, before and after quality heat treatments, etc.) The theory and industrial practice of the minimum detectable defect approach in the acceptance of heavy forgings. Possible evolution factors are suggested for flaws during heat treatments. The influence of the metallurgic parameters (steel making, forging techniques, heat treatments) on the detectability of flaws is considered.
305
Rose, J.L.; Pilarski, A.; Tverdokhlebov, A.; Balasubramaniam, K.; Dale, J.; Diprimeo, D.
40018
Wave scattering and guided wave considerations in anisotropic media Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia ( U n i t e d States), 22-26 Jun. 1987. Vol. 7A, pp. 85-94. Edited by D . D . T h o m p s o n and D . E . Chimenti, P l e n u m Press, 1988. Of prime concern in this article is the anisotropic nature of centrifugally cast stainless steel used in the nuclear industry. There exists significant skew angle variations of 15 degrees or more at times that can cause serious problems in defect detection, location, classification, and sizing. With recent advances in the understanding of wave propagation in anisotropic media associated with critical angle reflectivity, surface waves, plate waves and longitudinal and shear wave scattering employing a newly developed point source Green's function numerical integration model, there exists an excellent chance that once the material characteristics are known with respect to its anisotropic character that a very accurate and a detailed defect classification analysis could be carried out. The purpose of this paper is to outline a numerical integration ultrasonic field analysis computation model and also to illustrate a variety of different experimental and analytical techniques that could be used to characterize the anisotropic nature and hence the corresponding grain structure associated with centrifugally cast stainless steel. 39900
Kopec, B.; Hanak, V.
Ultrasonic attenuation in quenched railway wheels N D T International, Voi. 22, No. 1, pp. 21-25 (Feb. 1989) Ultrasonic attenuation in the fine pearlitic steel used for railway wheels has been measured. Several structural factors that significantly affect ultrasonic wave attenuation in the frequency range 2-10 MHz have been found. These factors are: the grain and its distribution, the grain boundaries, the history of the grain and the content of the ferritic component. 39889 Bilgutay, N.M.; Li, X.; Saniie, J. Spectral analysis of randomly distributed scatterers for ultrasonic grain size estimation Ultrasonics, Vol. 27, No. 1, pp. 19-25 (Jan. 1989) Since the average grain size is an important parameter in material characterization, the non-destructive evaluation of the microstructure in polycrystaUine materials using ultrasonic backscattered echoes has significant practical implications. However, the complexity of the ultrasonic backscattered signal, which consists of interfering multiple echoes with random positions and amplitudes, makes accurate grain size evaluation difficult with conventional signal processing techniques. This paper introduces an alternative approach which examines the spectrum of an ensemble of randomly distributed scatterers with known distribution to establish a relationship between the spectral and temporal statistical properties of the scatterers. 39875
Sasahara, T.; Gothard, M.; Leonard, F.; Queen, H.
Tennessee valley authority experience with field application of advanced UT system I n t e r n a t i o n a l J o u r n a l of Pressure Vessels and Piping, Vol. 35, pp. 293306 (1988). (Proceedings of 5th I n t e r n a t i o n a l S e m i n a r on N o n d e s t r u c tive E x a m i n a t i o n in Relation to Structural Integrity, D a v o s , Switzerland, 26-27 A u g u s t 1987) An automated four-channel ultrasonic inspection system, the IntraSpect/98 has been developed. This paper describes the successful application of the IntraSpecV98 to the detection and sizing of IGSCC (intergranular stress corrosion cracking) in stainless piping, examination of weld overlay, field examination of creviced safe-ends of reactor pressure vessel and measurement of wall thinning of fossil plant steam piping. The system was also applied to technique development for generator retaining ring and cast stainless steel pipe examination. The application of IntraSpect will be expanded to heavy section examination. 39732
Kapitza, H.
Improvement of the defect detection capability of ultrasonic inspection of coarse.grained austenitic materials by means of a combination of signal enhancement methods. Final report (In German) F r a u h n e f e r - I n s t . fuer Z e r s t o e r u n g s f r e i e Pruefverfahren, Saarbr u e c k e n ( G e r m a n y ) . T I B / B 8 8 - 8 1 3 6 2 / G A R , 73 pp. (27 Sep. 1986) The decorrelation of ultrasonic, scattered signals by spatial or frequency variation is determined, together with the number of scattered signals with given flattening of the background. A prototype device is available that allows an examination of the geometry of electro-magnetic ultrasonic transducers (EMUS transducer) for the generation of shear horizontal waves. Ultrasonic propagation in textured materials (such as austenitic seam welds) is described analytically and numerically.
NDT International October 1989
39721
Bridge, B.; Bin Saffiey, H.J.
Monitoring of the annealing temperature and hardness of a l u m i n l u m alloys by ultrasonic back-scatter and critical an t~le reflectivity British J o u r n a l of Nondestructive Testing, Vol. 30, No. 6, pp. 392-399 (Nov. 1988) Two simple theories which relate shear wave attenuation coefficients to the amplitudes of critically reflected and back-scattered ultrasound, are presented. By combining back-scatter and reflectivity measurements, the models allow absolute attenuation coefficients due to scattering and absorption processes to be calculated. Quantities so calculated should be regarded as local values obtaining near the specimen surface only. In the case of the absorption coefficient, the near-surface values appears to be much larger than corresponding values within the bulk of the specimen. For the common aluminium alloy HE5TB 2000, the back-scattered and reflected signals, and therefore presumably the local shear wave attenuation coefficients, were found to be systematically related to annealing temperature and hardness. So these ultrasound techniques can be used to monitor the heat treatment of this particular alloy system. As the grain sizes and shapes varied in a complicated manner with the heat treatment parameters it is clear that grain size was not the main determinant of the scattering power. 39560
Dijkstra, F.H.; de Raad, J.A.; van Nisselroij, J.J.M.
Experience with the ultrasonic inspection of coarse.grained anisotropic alloyed steels Proceedings of the 4th E u r o p e a n C o n f e r e n c e o n N o n - D e s t r u c t i v e Testing, L o n d o n ( U n i t e d K i n g d o m ) , 13-17 Sep. 1987. Vol. 3, pp. 1617-1633. P e r g a m o n Press, 3173 pp. (1988) The present paper gives an overview of the practical experience gained with the use of refracted compressional waves for ultrasonic inspection. A better understanding of the interaction between grain structure and sound waves has led to the development of better probes, and to better flaw detectability. New probe concepts were developed, such as creeping wave probes and the round trip tandem technique. The use of a semi-mechanized inspection system further improved flaw detectability and inspection quality. Moreover, it was found to provide practical flexibility for use on a variety of pipe diameters and weld geometries in for instance a petrochemical or gas processing plant, both for stainless and for Duplex stainless steel welds. 39447
Vary, A.; Kautz, H.E.
Transfer function concept for ultrasonic characterization of material microstructures International A d v a n c e s in Nondestructive Testing, Vol. 13, pp. 193-250 (1987). Edited by W.J. M c G o n n a g l e . G o r d o n and Breach Science Publishers. Although expressions that relate ultrasonic attenuation to specific microstructural factors exist, they are fragmented and generally consists of ad hoc combinations of mechanisms for attenuation over particular frequency ranges. The approach given in this paper depends on treating material microstructures as elastomechanical filters that have analytically definable transfer functions. These transfer functions can be defined in terms of the frequency dependence of the ultrasonic attenuation coefficient. The transfer function concept provides a basis for synthesizing expressions that characterize polycrystalline materials relative to microstructural factors such as mean grains size, grain-size distribution functions, and grain boundary energy transmission. Although this approach is nonrigorous, it leads to a rational basis for combining the previously used diverse and fragmented equations for ultrasonic attenuation coefficients. 39420
Stringfellow, M.; Hawker, B.
New ultrasonic scanner for inspection of austeniti¢ steel Joining and Materials, Vol. 1, No. 4, pp. 170-173 (Oct. 1988) A new ultrasonic scanner and advanced inspection methods are described. Developed at UKAEA's Harwell Laboratory, the device compensates for changes in ultrasonic propagation caused by grain orientation in anstenitic welds. The new inspection methods after inspection of transition welds, spatial averaging, obtaining the best ultrasound spectrum and improved views of defects. Trials on full scale reactor nozzles, transition welds and pipework welds as well as fast reactor flat plate, T butt and cruciform austenitic welds are all planned for the future, and the new scanner will be tested to the full. 39390
Bernabei, P.; Borgna, R.; Callegari, L.
Performance and industrial implications of non-destructive testing on large forgings Proceedings of the 4th E u r o p e a n C o n f e r e n c e o n N o n - D e s t r u c t i v e Testing, L o n d o n ( U n i t e d K i n g d o m ) , 13-17 Sep. 1987. Vol. 2, pp. 971-991. P e r g a m o n Press, 3173 pp. (1988) The new role of non-destructive testing in the shrinking market of heavy forgings is discussed. A review of typical manufacturing cycles and highlights on non-destructive testing time is presented. This paper also considers the criteria, significance, reliability and actual data of non-destructive testing at different manufacturing stages (as forged, before and after quality heat treatments, etc.) The theory and industrial practice of the minimum detectable defect approach in the acceptance of heavy forgings. Possible evolution factors are suggested for flaws during heat treatments. The influence of the metallurgic parameters (steel making, forging techniques, heat treatments) on the detectability of flaws is considered.
305