Advances in early-stage NDT diagnostic methods with diffractometric examination of welded materials and components

Abstract

X-ray and neutron diffractometric methods are described for the early-stage diagnosis of materials. A comparison is made between traditional and innovative technologies, which aim at being included amongst the NDT methods usable on-site. Emphasis is also placed on the gradual removal from instruments of structural restraints, with a tendency towards anthropomorphic functionalities and flexibility. Prototype production and conceptual schemes are presented and discussed. Conceptual tests, applications and case studies are shown as per the state of the art. Particular reference is made to results obtained from data collected from materials containing welding (e.g. titanium alloys, P22, T92 and P92 steel) and micro- and nano-structural alterations (e.g. ceramics, glass and other materials). These results indicate the meaning and usefulness of the early observation of effects induced in the reticolum of metals by loads, residual stress and structural micro/nano variations. It follows that reticular measurements and the diffractometric methods related to them are onlythose currently available to obtain appropriate early-stage diagnosis. A discussion is provided of photonic (X-ray) and neutronic diffraction with corresponding limits and advantages. The hypothesis of creating a new mobile diagnostic device intended for the application of neutron diffraction is introduced.

Keywords::

• crystal structure
• development
• diffraction
• in service operation
• measuring instruments
• microstructure
• neutron radiation
• non-destructive testing
• prototypes
• radiography
• residual stress
• scope
• welded joints
• X-rays

Acknowledgements

This work was funded by the University of Pisa, by XRD Tools, S.r.l. and by the Region of Tuscany in accordance with regional operational plan POR CReO/FESR 2007–2013, Axis 1, Activity 1.1, area of intervention d.

The authors wish to express their esteem and gratitude to Ing. Donato Pinciroli of Ansaldo Caldaie, Dott. Roberto Crudeli of CND Service and the industrial engineer Maurizio Nerini for information on the materials mentioned in this work and Dott.ssa Maria Eva Del Seppia for her assistance in the processing of some of the data collected from the same. Our thanks are also extended to Prof. Giorgio Curzio, Dott. Valerio Giusti and Mr. Aldo Del Gratta of the University of Pisa for various aspects regarding neutrons.

Finally, we would like to mention Prof. Raffaello Carrara, Ing. Leonardo Leonardini, Ing. Silvano Aldrighetti, the industrial engineer Elio Tolle and Ing. Antonio Iannello for having quickly recognized the importance of the advances present in the temporal and logical sequence underlying early-stage, on-site diagnosis by means of the diffractometries referred to in this project.

Notes

This paper was presented at the National Welding Days 6 Workshop: ‘Diagnostics and non-destructive tests’, Genoa, 26–27 May 2011.

^1. The concept of non-destructive testing, in the strictest sense of the term, implies maintaining the component fixed at the place where it is operating.

^2. Masato Nagao. X-ray stress detection apparatus. JP-S51-16984A; 1976.

^3. Yasutsugu Kawabe. X-ray diffractometer. JP-S55-88148U.

^4. Berti G. Diffractometer and method for diffraction analysis. US7,260,178; 2007.

^5. Test conducted in collaboration with CND Service at Civitavecchia.

^6. Measurements and tests were conducted between 2009 and 2010 by XRD Tools, University of Pisa and CND Service (Internal XRD report).

^7. A version with reduced dimensions compared with those shown in Figure 2(b) is being developed within the framework of the TemArt project (“Diffrattomctro Portatile” nella sezione “Strumenti portatili per l'analisi materica” Coordinatore Salvatore Siano, POR CReO/FESR 2007–2013, Asse l Attività 1.1. Linee d'intervento d. 09/09/2009).

^8. Berti G. “Apparecchiatura mobile per irraggiamento e rilevazione di radiazioni”, N.0001362296.

^9. “Diffrattometria a raggi X e tecniche fotoniche di caratterizzazione e qualificazione dei materiali in loco”; Coordinatore Giovanni Berti (Università di Pisa) PRIN 2009 – 31/05/2010.

^10. Residual Stress by Neutron Diffraction © CEN – AFNOR Paris.

^11. NDVG – Neutron Diffractometer with Virtual Goniometer; coordinatore Giovanni Berti (Università di Pisa). NEST-2003-3 INSIGHT, 13/09/2004.

^12. Experiment conducted in 2004 by XRD-Tools and Pisa University (XRD-Tools internal report).

^18. XRD-tools s.r.l. internal reports.

Additional information

Notes on contributors

G. Berti

Giovanni Berti was awarded a degree in physics at the University of Pisa, where he still works as a researcher. He is a lecturer in diffractometric methods for surface diagnosis at the MFN Faculty of Science and in the diagnosis of biomaterials at the Faculty of Medicine and Surgery. He is the head of the Laboratory for Research and Development for X-Ray Diffractometry of the University of Pisa and Director of the Diffractometry Centre of the Pisa Research Consortium and XRD-Tools, an academic spin-off of the same university. He is the director of the CEN/TC138/WG10 group, the winner of the Amerigo Vespucci prize in 2008 (inventions section) and author of numerous works published in international journals. He has obtained three key patents and developed numerous international derivative patents. He is also a coordinator of national and international projects.

F. De Marco

Francesco De Marco has collaborated as a contractor for the Department of Earth Sciences at the University of Pisa since 1998 and during this period has carried out administrative duties for training courses and conventions held by the Department in collaboration with other national public bodies. He also provides consultancy for the development of both national and European projects and technical assistance regarding laboratory and field X-ray diffractometric instrumentation. A partner of XRD-Tools s.r.l. since 2004, he is currently also involved in measurement, functionality tests and concept verification for laboratory and on-site X-ray diffractometric-type instrumentation. He coordinates activities relating to production, sales and maintenance of X-ray diffractometers, manages the organizational administration section and is responsible for safety. He also supervises the technical office of the CEN/TC138WG10 ‘X-Ray Diffraction’ work group.