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Assessment of Quality of Power Beam Weld Joints

Objective


Despite significant improvements in power beam welding technology over recent years, it still remains impossible to characterise laser and EB welds in a unique fashion and to produce quantifiable mechanical properties. Guidance on design aspects of power beam welded joints is currently lacking for potential users so that they are often reluctant to opt for such a welding process despite the availability of the technology. The objective of this industrial project is to provide an improved understanding of the failure behaviour of similar and dissimilar laser and EB welds in order to be able to predict structural performance. The project programme extended current non-destructive (NDT) and destructive testing standards to power beam welded joints and provided recommendations for best practise and the changes necessary to current techniques to achieve this. In order to accomplish this, it is necessary to:

i) Identify major weldability and joint quality problems for various materials
ii) Develop techniques for the identification of defect types (NDT) and determination of mechanical and fracture behaviour of joints
iii) Develop and validate a methodology - European Quality Assessment Concept (EQAC) - for structural integrity assessment of power beam welded joints which takes into account the unique features of these joints
iv) Provide a first Weld-Defect-Catalogue for power beam weld joints using improved NDT methodology

The European Quality Assessment Concept (EQAC) for power beam welds developed in this project considers the unique features of power beam welds and their defects on various materials. Present mechanical and NDT standards do not take into account these features (strength mismatch, defect types, and weld shape etc) of power beam welds in a unified fashion. The structural reliability of these welds urgently needs a systematic effort to show their suitability for conventional as well as advanced structural components. Testing of structural components used in aerospace and civil engineering will be included to determine structural performance and validate the developed EQAC.

This project covers laser and electron beam weldability aspects of over twenty metallic structural materials. The consortium comprises a Research Centre (GKSS) specialised in testing and assessment of weld defects, a Nd:YAG laser source manufacturer (QUANTEL), a manufacturer of laser welded steel components (Thyssen Laser Technik), a company specialised in EB-welding of large structural components (CNIM), a company user of both power beam welding processes in repair of aerospace components and end user of the NDT for the inspection of the same components (INTERTURBINE), a steel manufacturer and large scale testing laboratory (BRITISH STEEL), a company experienced in CO2 laser welding of advanced materials (RTM), a company specialising in NDT (NU-TECH), a research centre (FORCE) with experience in laser welding of steels, a company (ANSALDO) manufacturing heavy industrial and power plant components.
Objectives and content

Despite significant improvements in power beam welding technology over recent years, it still remains impossible to characterise laser and EB welds in a unique fashion and to produce quantifiable mechanical properties. Guidance on design aspects of power beam welded joints is currently lacking for potential users so that they are often reluctant to opt for such a welding process despite the available technology to fabricate the joint. The objective of this proposal is to provide an improved understanding of the failure behaviour of similar and dissimilar laser and EB welds in order to be able to predict structural performance. The proposed programme will extend current nondestructive (NDT) and destructive testing standards to power beam welded joints and will result in recommendations for best practice and the changes necessary to current techniques to achieve this. In order to accomplish this, it is necessary to:

- Identify major weldability and joint quality problems for various materials.
- Develop techniques for the identification of defect types (NDT) and determination of mechanical and fracture behaviour of joints. - Develop and validate a methodology - European Quality Assessment Concept (EQAC)- for structural integrity assessment of power beam welded joints which takes into account the unique features of these joints
- Provide a first Weld-Defect-Catalogue for power beam weld joints using improved NDT methodology ( -focus X-ray radiography and radioscopy).
The European Quality Assessment Concept (EQAC) for power beam welds to be developed in this project will consider the unique features of power beam welds and their defects on various materials. Present mechanical and NDT standards do not take into account these features (strength mismatch, defect types and weld shape etc.) of power beam welds in a unified fashion. The structural reliability of these welds urgently needs a systematic effort to show their suitability for conventional as well as advanced structural components. Testing of structural components used in aerospace and civil engineering will be included to determine structural performance and validate the developed EQAC.

This project also covers laser and electron beam weldability aspects of various A1-alloys. It will establish welding conditions for optimum weld properties by developing new super pulsed 2kW Nd:YAG laser for this purpose.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

GKSS - FORSCHUNGSZENTRUM GEESTHACHT GMBH
Address
Max Planck-strasse 1
21502 Geesthacht
Germany

Participants (9)

Ansaldo Termosud SpA
Italy
Address
Via Milano 1600
70023 Gioia Del Colle Bari
CORUS U.K. LTD
United Kingdom
Address
Moorgate
S60 3AR Rotherham
Constructions Industrielles de la Méditerranée
France
Address
Z.i. De Brégaillon
83507 La Seyne-sur-mer
FORCE INSTITUTE
Denmark
Address
345,Park Allé 345
2605 Brondby
ISTITUTO PER LE RICERCHE DI TECNOLOGIA MECCANICA E PER L'AUTOMAZIONE S.P.A.
Italy
Address
Regione Lime
10080 Vico Canavese
Interturbine Germany GmbH
Germany
Address
36-38,Kisdorfer Weg
24568 Kaltenkirchen
Nutech GmbH
Germany
Address
5,Ilsahl
24536 Neumünster
Quantel SA
France
Address
Avenue De L'atlantique
91941 Les Ulis
THYSSENKRUPP LASER-TECHNIK GMBH
Germany
Address
15,Steinbachstrasse 15
52074 Aachen