Super duplex 2507 (2507 SDSS) is a two-phase austeno-ferritic stainless steel known for its good mechanical properties, especially for fatigue as well as corrosion resistance, due to its mixed microstructure. Metal additive manufacturing, and in particular the Directed Energy Deposition (DED) process, allows the construction or repair of structures for more complex geometries than conventional processes. DED process uses powder that is projected by an argon flow and melted by a laser in the printing area to form the material. This manufacturing protocol however results in different microstructures (grain sizes and orientation, phases repartition) from those observed in conventional processes and particularly forging. The objectives of the study are first to carefully analyse the microstructure of DED-manufactured 2507 SDSS and the effect of different heat treatments on it. Effects on the ratio between austenite and ferrite is particularly discussed. Then, the fatigue limit of this new "material-process" combination is investigated both with Staircase protocols and self-heating tests campaigns. A same grade forged steel is used as reference material. Fatigue limit modelling of DED-manufactured 2507 SDSS is finally performed on the basis of self-heating tests and a dedicated plastic constitutive model.