Duplex Stainless Steel for Bridges Construction: Comparison between SAW and Laser-GMA Hybrid Welding

Abstract

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 we 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 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 subjected to be improved but acceptable figures were already achieved.