<b>ABSTRACT</b></br>

There is still a considerable gap in the definition of the weldability of Duplex Stainless Steel (DSS). A lack of clarity that is explained by the standard specification of the maximum content of equivalent carbon that defines a “weldable” steel coupled with the fact that the alloying elements of DSS exceed this defined limit of weldability. In this paper, welding quality in an inert environment and in presence of chlorides is analyzed with the aim of defining optimum welding conditions of 2001, 2304, and 2205 DSS. The same procedure is followed for a hybrid weld between DSS 2205 and a low carbon mild steel, S275JR. As main output, this study defined the optimal welding conditions with tungsten inert gas without filler for each type of DSS weld that showed excellent anti-corrosion performance, with the exception of the DSS 2205-S275JR weld where widespread corrosion was observed. Additionally, this study established a relationship between the thermal input during welding and the content of alloying elements in defect-free joints. Furthermore, it demonstrated that an increase in ferrite content did not lead to a worse corrosion resistance, as expected after passivation.

</br>

<b>ACKNOWLEDGEMENTS</b></br>

This research was funded by ACERINOX EUROPA through Center for the Development of Industrial Technology (CDTI) within the frame of IISIS project, grant number IPT-20111023. </br>

The tests presented in this manuscript were performed as part of the IISIS: “Investigación Integrada en Islas Sostenibles” (Integrated research in Sustainable Islands) research project, in receipt of funding from the Center for the Development of Industrial Technology (CDTI) and the Technological Fund, part of the Spanish Ministry of Industry, through the INNPRONTA research program. The final goal of the project is to research different technologies for building offshore island-cities, involving construction, energy and smart technologies with leading companies and research centers focused on each field. In the field of construction, the challenge is to develop modular construction and special marine reinforced concrete for the construction of islands that are capable of withstanding corrosive marine environments. In this context, most pathologies linked to reinforced concrete in marine environments are caused by rebar deterioration within the concrete and especially by chloride attack. The use of stainless steels is a very promising way to solve this problem, as has been demonstrated in several tests, among which those presented in this paper. Besides, the authors want to acknowledge Mario Oyarbide and Adrián Gastesi in particular for their technical support during the experimental campaign performed on these steels. Authors would like to acknowledge UPV/EHU PPGA19/61 contract as well as to the IT1314-19 (Basque Government) and GIU19/029 (UPV/EHU) research groups and to Laboratoire des ciencies de l’ingenieur appliquées, Fédération IPRA-EA4581, from the Université de Pau et Pays de l’Adour, for their support setting a cooperation framework. Finally, we are also especially thankful to ACERINOX EUROPA (part of the ACERINOX Group) for funding the IISIS project, supplying the necessary rebar samples for testing, and particularly to Rafael Sanchez and Julia Contreras from Technical Dpt./Labs for their expertise and for their commitment that greatly assisted our research.