Advances in Duplex Stainless Steels

Duplex stainless steels (DSSs) are a group of stainless steels characterized by a biphasic microstructure consisting of ferrite and austenite. They are widely used in hostile environments, such as nuclear and petrochemical plants, oil and gas offshore applications, chemical plants, the paper and pulp industry, and the food and beverages industry as an alternative to the austenitic stainless steels. The optimization of the properties of duplex stainless steels can be achieved through a proper balance of ferrite and austenite. This balanced ratio between the two phases (50% of ferrite and 50% of austenite) is obtained with a suitable combination of chemical composition and solution heat treatment. However, due to the presence of the metastable austenitic phase and the instability of ferrite at high temperatures, these steels are sensitive to diffusive and diffusionless phase transformations, which may affect corrosion and mechanical properties, but there is a lack of research in the field of physical metallurgy regarding these transformations. Despite their diffusion as consolidated materials, many research fields are also focusing on the possibility of increasing duplex mechanical properties and corrosion resistance by composition and heat treatment optimization. Furthermore, special innovations are soon to be realized in the field of welding processes. This Special Issue presents a selection of interdisciplinary studies that cover physical metallurgy and processes and report on the experimental and theoretical progress concerning microstructural evolution during processing, microstructure–properties relations, and applications. Moreover, two papers regarding innovations in the welding of DSSs are also presented in the issue. In this editorial, the editors wish to briefly introduce the different articles published in the Special Issue