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Abstract
The aim of the project ‘Bridgeplex’, partly supported by the European Research Fund for Coal and Steel, was to explore the suitability of austenitic-ferritic (duplex) stainless steel for the construction of large welded bridges. Using duplex stainless steels for bridge decks would be a major step forward in providing durable, low maintenance structures, exploiting both their corrosion resistance and high mechanical properties, while fulfilling the required structural safety performances.
In this work, beyond the Bridgeplex planned activities, it was investigated the possibility to replace the longitudinal welded joint between the deck plate and the girder trapezoidal stiffeners, performed by SAW, with a comparable one fabricated by hybrid laser welding (LB-GMAW). Potential advantages that could be achieved are, among others, productivity improvement, better detail fatigue resistance and lower distortion of the welded structure.
The main differences obtained using SAW and LB-GMAW for the specific structural detail made in duplex stainless steel (UNS S32205) are presented. Technological, metallurgical features and weld integrity were mainly investigated. The utilization of the LB-GMAW technique resulted in the welded joint fully penetrated, differently from the case of SAW, a higher productivity and reduced distortions. From a metallurgical point of view (i.e. austenite-ferrite phase balancing), results are still to be improved but acceptable figures were already achieved.
Acknowledgements
We thank those cited for the information provided.
Notes
Paper presented at the 4th National Welding Day, Workshop: ‘welded austenitic–ferritic steel and aluminium alloy structures’ Genova, 25–26 October 2007.