Inspection of stress corrosion cracking in welded stainless steel pipe using point-focusing electromagnetic-acoustic transducer

Abstract Point-focusing electromagnetic-acoustic transducers (PF-EMATs) for shear-vertical (SV) waves were developed for crack inspection of stainless-steel pipes. The transducer has improved defect detectability by accumulating SV waves generated by concentric line sources at a focal point in phase. An optimum frequency for defect detection was found to be 2 MHz, with which a crack of 0.5 mm depth near a weld was clearly detected. The EMAT exhibited defect detectability comparable to that of a conventional phased-array piezoelectric transducer, indicating that this new EMAT is highly practical for the non-contacting evaluation of stress-corrosion cracking in stainless steels.

[1]  H. Ogi,et al.  Line-focusing electromagnetic acoustic transducers for the detection of slit defects , 1999, IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control.

[2]  C. M. Fortunko,et al.  The design and use of electromagnetic acoustic wave transducers (EMATs) , 1983 .

[3]  Hirotsugu Ogi,et al.  Contactless measurement of bolt axial stress using a shear-wave electromagnetic acoustic transducer , 2001 .

[4]  Oliver B. Wright,et al.  Resonant electromagnetic excitation and detection of ultrasonic waves in thin sheets , 1992 .

[5]  R. M. Panos,et al.  Electromagnetic generation of electronically steered ultrasonic bulk waves , 1976 .

[6]  H. Pursey,et al.  The field and radiation impedance of mechanical radiators on the free surface of a semi-infinite isotropic solid , 1954, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[7]  G. A. Alers,et al.  High Frequency, Angle Beam EMATs for Weld Inspection , 1983 .

[8]  M. Dunn,et al.  Elastic constants and internal friction of an SiC-fiber-reinforced Ti-alloy-matrix crossply composite: Measurement and theory , 1999 .

[9]  R.B. Thompson,et al.  A model for the electromagnetic generation of ultrasonic guided waves in ferromagnetic metal polycrystals , 1978, IEEE Transactions on Sonics and Ultrasonics.

[10]  Hirotsugu Ogi,et al.  Line-focusing of ultrasonic SV wave by electromagnetic acoustic transducer , 1998 .

[11]  Hirotsugu Ogi,et al.  Mode Conversion and Total Reflection of Torsional Waves for Pipe Inspection , 2013 .

[12]  A. Overhauser,et al.  Electromagnetic generation of ultrasound in metals , 1977 .

[13]  Richard J. Dewhurst,et al.  Noncontact detection of surface‐breaking cracks using a laser acoustic source and an electromagnetic acoustic receiver , 1986 .

[14]  Hirotsugu Ogi,et al.  Development of shear-vertical-wave point-focusing electromagnetic acoustic transducer , 2015 .

[15]  J. Moulder,et al.  Residual stress determination in aluminium using electromagnetic acoustic transducers , 1985 .

[16]  H. Ogi,et al.  Resonance EMAT system for acoustoelastic stress measurement in sheet metals , 1993 .

[17]  Peter B. Nagy,et al.  Corrosion and erosion monitoring in plates and pipes using constant group velocity Lamb wave inspection. , 2014, Ultrasonics.

[18]  Steve Dixon,et al.  Localisation of defects with time and frequency measurements using pulsed arrays , 2014 .