NDTnet 1998 Aug, Vol.3 No.8

Full-Text - Abstract

We performed a complex Ultrasonic System for the Investigation of the material Structure (USIS). The authors present in this paper the results obtained with this system in investigation of the austenitic materials.
We have performed the measurements on the following types of steel: W16903; W14541; HP50. We have obtained a C-scan image on each probe in order to be sure that our samples are free flaws. The radio frequency signal was acquisited in ten points at two millimetres on each other. In every point the system has calculated the longitudinal wave velocity and It has performed the spectral analysis of the ultrasonic attenuation.
The same procedure was applied at the investigation the structure of the austenic weld. We measured the attenuation and the velocity in eight different points chosen after we obtained the time of flight and amplitude representation of the welded piece.

We have determined the grain size for all samples using the spectral dependence of the ultrasonic attenuation. This dependence could be described by the next relationship (1):

( f ) = (8 ³ / 375 ) ( V f⁴ A² ) / ( ₀²v_L⁸ ) [ 2 + 3 (v_L / V_T )5 ]     (1)

In this relation we used the next notations: V volume of scatterers; f - frequency; A anisotropy factor; v_L longitudinal wave velocity; V_T transversal wave velocity. The values obtained were compared with the results obtained by methalographical analysis. We present the results by the two methods in table 1

Table 1
The values of goon size determined by methalography (cf. ASTM E112) and
values obtained by spectral analysis on the same probes

Steel type	The grain size obtained by methalography	The grain size obtained by ultrasonic spectroscopy
W.1. 4541	5 - 6	31.20655
W.1.6903	6 - 7	27.50247
HP 50	-	-93.48207

Reference
1. Pappadalds E.P Journal of Acoustics Society of America 35, 1474 -1482

Abstract Source:
Book of Abstracts, 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN: 87-986898-0-00

Full-Text Source:
Proceedings of the 7th European Conference on Non-Destructive Testing, 26-29 May 1998, ISBN:

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