1、B. Chassignole et al. / NDT&E International 43 (2010) 273-2829Contents lists available at ScienceDirectELSEVIERNDT&E Internationaljournal homepage: Ultrasonic and structural characterization of anisotropic austenitic stainless steel welds: Towards a higher reliability in ultrasonic non-destructive t
2、estingB. Chassignolea, R. El Guerjoumab,*, M.-A. Ploixc, T. Fouquetda EDF R&D, Materials and Component Mechanics Department, Moret sur Loing 77818, France b Universite du Maine and CNRS, LAUM UMR CNRS 6613, Le Mans 72000, France c INSA de Lyon and CNRS, MATEIS UMR CNRS 5510, Villeurbanne 69621, Fran
3、ce d EDF R&D, Sinetics Department, Clamart 92141, Franceabstractarticle infoArticle history:Received 22 September 2006 Received in revised form 28 November 2009 Accepted 7 December 2009 Available online 29 December 2009Keywords:WeldUltrasonicNon-destructive testing Nuclear engineering Anisotropy Mod
4、eling AttenuationThe non-destructive testing of austenitic stainless steel welds of the primary coolant piping system is a significant problem for the nuclear industry. Ultrasonic techniques would be very helpful to detect, locate and size potential defects. Unfortunately, austenitic welds are coars
5、e-grained, heterogeneous and anisotropic. This leads to aberration and scattering of the ultrasonic waves. In this paper, we present several experimental results of ultrasonic testing of two austenitic welds exhibiting high anisotropy. In order to explain the observed display of wave propagation phe
6、nomena such as beam deviation, we use finite element modeling. The modeling is associated with a complete characterization of the inspected welds. Two essential characteristics of the welds are determined: the average elastic constants of the weld and the grain orientations. The capability of the mo
7、del is illustrated in different testing configurations. This work associating structural characterization and modeling shows that a better understanding of the phenomena of ultrasonic propagation should allow the interpretation and reliability of the industrial inspections of heterogeneous anisotrop
8、ic welds to be improved. 2009 Elsevier Ltd. All rights reserved.0963-8695/$-see front matter & 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.ndteint.2009.12.0051. IntroductionTo assure the structural integrity of nuclear pressurized water reactors, the non-destructive testing (NDT) technique
9、s must allow the detection of potential defects in the austenitic stainless steel pipes and welds of the primary coolant piping system. In particular, manufacturing flaws (inclusions, voids or lacks of fusion) or in-service flaws (cracks) could be present in the welded joints.In French nuclear power
10、 plants, the in-service inspections of austenitic welds are carried out mainly on the basis of radiographic techniques. Ultrasonic inspections are rarely used because they are confronted with all the problems of testing coarsegrained, heterogeneous, anisotropic material 1-3. However, ultrasonic tech
11、niques would help to complement the information provided by radiography which efficiently detects defects but has some limitations as to their location and size.A weld made of austenitic stainless steel in some cases presents strong anisotropy varying continuously from one area to another all over t
12、he weld giving rise to heterogeneous anisotropy 1-3. The effect of anisotropy on the propagation ofn Corresponding author.E-mail address: rachid.elguerjoumauniv-lemans.fr (R. El Guerjouma).ultrasound makes the velocity direction-dependent and makes the group velocity different from phase velocity in
13、 both amplitude and direction 4.Furthermore, deviation of the ultrasonic beam within the weld material may cause difficulties in locating defects. Scattering of the ultrasonic energy results in some directions of propagation having a poor signal-to-noise ratio. To understand the anisotropy of the wa
14、ve amplitudes recorded in ultrasonic inspection experiments, the complexity of wave propagation in these media has to be considered.To study these phenomena, modeling is very helpful. Indeed, modeling can reveal the quantitative features and thus help in the optimization of conventional ultrasonic N
15、DT techniques and in the development of new ones. The simulation of ultrasonic testing using appropriate models allows us to perform, for example, parametric studies and obtain quantitative simulated results. The theory of wave propagation into anisotropic and homogeneous media already allows the pr
16、ediction of beam skewing and divergence effects 4-7. When considering the more complicated case of heterogeneous anisotropic structures, modeling studies require realistic descriptions from the mechanical and metallurgical point of view of the various kinds of weld structures, especially the ones where anisotropy is strong.Over the last few years many studies have be
