Optimization of spark plasma sintering temperature: Influence on microstructure and mechanical properties of SAF 2507 duplex stainless steel

Duplex stainless steels offer a wide range of application due to good mechanical properties and high corrosion resistance. Only duplex stainless steel with microstructure consisting of equal ferrite and austenite contents meets this requirement and other secondary phases deteriorate the properties. Microstructural and uniaxial tensile properties of the SAF 2507 duplex stainless steel (SDSS) prepared via spark plasma sintering are reported in this work. The SAF 2507 SDSS powder was consolidated via spark plasma sintering at 900 °C and 1100 °C. The microstructure of the samples sintered at the temperature of 900 °C contained numerous pores (volume porosity of 16 %), significant fraction of the σ-phase and the strength and plastic properties of this sample are low. The spark plasma sintering at 1100 °C produced a fully dense microstructure composed of ferrite and austenite with good mechanical properties. Post-manufacturing solution annealing resulted in a uniform austenite-ferrite microstructure for both spark plasma sintering temperatures. In the case of the sample sintered at 1100 °C, only minor changes occurred in microstructure and mechanical properties during post-manufacturing heat treatment. Properties of spark plasma sintered material were compared with the same alloy prepared by additive manufacturing. [Display omitted] •SAF 2507 super duplex stainless steel consolidated via spark plasma sintering.•Influence of sintering temperature on microstructure and mechanical properties.•Formation of σ-phase at the sintering temperature of 900 °C.•Duplex-phase microstructure and good mechanical properties after sintering at 1100 °C.•Balanced austenite-ferrite microstructure and good mechanical properties after solution annealing.