Abstract:
The 17-4 precipitation hardenable (PH) stainless steel is a material of choice for various applications. Near-net-shape processes, such as the extrusion-based additive manufacturing (EAM), are attractive fabrication methods due to its simplicity, safety, and cost-effectiveness. The present study aimed to conduct a systematic comparative study into microstructural, mechanical, and electrochemical corrosion performance of EAM 17-4 PH stainless-steel samples across various states: as-printed, as-sintered, and post-processed. The as-sintered samples were further characterized, along and perpendicular to their build direction, including optical and scanning electron microscopy, tensile testing, and potentiodynamic polarization tests. The results demonstrated anisotropic behavior of as-sintered samples, dependent on build orientation. The samples printed perpendicular to the build direction demonstrated better mechanical performance, with higher ultimate tensile strength (28%) and elongation to failure (eightfold) compared to those printed along the build direction. In particular, the corrosion potential and pitting potential along the build direction (− 0.108 V, 0.059 V vs SCE, respectively) demonstrated better electrochemical corrosion properties, as compared to perpendicular to the build direction (− 0.181 V, − 0.015 V vs SCE, respectively). The effect of post-processing, encompassing machining and heat treatments (H900 and H1150), was investigated and compared with those of conventionally and additively manufactured 17-4 PH stainless-steel counterparts, offering a holistic understanding of the intricate interplay between processing parameters, microstructural evolution, and material properties, notably in the context of electrochemical corrosion resistance.