Use of electromagnetic acoustic resonance method to detect micro-voids viaevaluation of ultrasonic wave attenuation coefficient of SUS304 steel fabricated by hot isostatic press
H. Nishida et al., Use of electromagnetic acoustic resonance method to detect micro-voids viaevaluation of ultrasonic wave attenuation coefficient of SUS304 steel fabricated by hot isostatic press, JSME A, 44(1), 2001, pp. 8-16
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Mechanical Engineering
Journal title
JSME INTERNATIONAL JOURNAL SERIES A-SOLID MECHANICS AND MATERIAL ENGINEERING
Creep damage in SUS304 steel samples fabricated by a hot isostatic press (H
IP) at 1 050 degreesC was evaluated using the electromagnetic acoustic reso
nance (EMAR), noise energy and ultrasonic spectroscopy (first moment) metho
ds. The coefficients of attenuation of 1.1 to 5.4 MHz electromagnetically e
xcited acoustic waves in the samples were investigated. By reducing diffrac
tion loss and the loss to the electromagnetic acoustic transducer due to tr
ansmission of the ultrasonic waves via mechanical contacts, it was possible
to detect shear wave attenuation coefficients as low as 2.5 x 10(-4)/micro
second at 1.1 MHz. With specimens fabricated at pressure of 170 MPa, the at
tenuation coefficient increased in proportion to frequency up to 5.4 MHz, w
hereas with specimens fabricated at pressure lower than 80 MPa the attenuat
ion coefficient increased rapidly above 4 MHz. The void fraction was found
to be greater in specimens fabricated under lower pressure, which may be re
sponsible for the markedly higher ultrasonic attenuation in the specimens f
abricated at pressure lower than 80 MPa. It was apparent from the experimen
ts that the EMAR method detects creep voids with greater sensitivity than t
he other methods. Accordingly we hope it will be possible for the EMAR meth
od to be used on real facilities in the future.