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Improved Welding Procedures for Dissimilar Joints

Project Code: 0902-03


Identify welding and heat treatment procedures giving improved resistance of dissimilar metal interfaces to in-service failures.

Project Outline

Welding will be undertaken to provide a series of dissimilar welds for characterisation and validation testing purposes, including welds made using a range of heat inputs to produce a range of interface chemistries. Chemistry and microstructure assessment of the partially mixed zone, as-welded, will be undertaken to provide understanding of the complex microstructure and chemistry of the partially mixed zone, and the effect of welding parameters on the microstructure and chemistry of this particular region.

In addition, PWHT trials will be performed to provide understanding of the effect of PWHT on microstructure and chemistry, particularly carbon diffusion, via electron microprobe analysis and scanning electron microscopy, including EBSD.

A series of environmental tests will be performed to produce data on relative susceptibilities of different joints. Data from current weld practice and the derived optimised weld processes will be generated, to establish the degree of control of performance that can be achieved.

Relevant Industry Sectors

Oil and Gas, Power

Technical and Economic Benefits

Through the development of physically based models capable of predicting the microstructures developed after welding and heat treatment of dissimilar metal joints, considerable savings are possible by minimizing the need for physical testing of new metal combinations and reducing the risk of in-service failure by avoiding microstructures susceptible to cracking in the environments of interest.

The output of the research will provide welding industries with an integrated tool to guide the discovery of new materials and/or process routes to manufacture weld components with improved interface properties which improve their performance, through the choice of appropriate components and an improved tuning of the welding process.

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