In this paper an extension of the sintering method at atmospheric pressure, already used for tool steels, is proposed for prealloyed duplex stainless steel powders. A wide temperature range is tested and the effectiveness of boron as activator of the process is investigated. In all the samples no evidence of liquid phase is observed ; the sintering process allows full density in case of no boron addition and it occurs by solid phase diffusion, enhanced by the presence of two phases, austenite and ferrite : this makes needless to add boron as activator. We obtain density and hardness values comparable with the “as-cast” ones, isotropic phases structure and γ/δ ratio of about 50/50 for the best sintering temperature (1150 °C).