UNS S32205 for bridge construction: an experience of application

In the field of the civil engineering, duplex stainless steels represent a technical and economical attractive alternative to the coated carbon steels, thanks to their high mechanical and good corrosion resistance properties. For the construction of bridges in aggressive environment as seaside, the atmospheric conditions require the use of an appropriate duplex grade. One of the aims of the European Bridgeplex project (RFCS-CR-04040) was to evaluate the ability of UR45NMo (UNS S32205 / EN 1.4462) to be used in an economic way for this application. After selection of critical components of an orthotropic bridge, numerous welding trials have been performed by OMBA I&E, a company specialized in bridge construction. In a first part, this paper presents a welding and forming comparison of duplex stainless to carbon steel. A preliminary technical and financial evaluation comparing the shop and yard performance and costs for duplex stainless steel (D.S.S.) and carbon steel is performed. In the second part, the behaviour of the duplex grade is studied by the mean of mechanical and fracture mechanics tests, and microstructure observations, on the duplex base metal and on its welded joints.