Bio-Tribocorrosion Analysis of Additive Manufactured and Wrought 316L Stainless Steel for Biomedical Applications
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Medical implants manufactured using traditional methods are not satisfying the needs of today s patients. Additive manufacturing (AM) may be the enabling technology which can provide implants with the needed service life, mechanical properties and degree of mobility. When implanted in the human body, orthopedic implants are exposed to corrosive body fluids and complex loading and wear, affecting the service life. In addition, metal products released by the corrosion and tribocorrosion (the combination of wear and corrosion) processes can have an adverse effect on patient health and well-being. In this investigation, the main goal is to explore the potential replacement of conventionally manufactured medical implants with additive manufactured ones. Porosities, defects and residual stresses are inherent to AM components, and could affect the corrosion and tribocorrosion behavior of the material. There is a lack of understanding of the corrosion and tribocorrosion behavior of additive manufactured materials, inhibiting the progress of 3D-printed implant technology. Therefore, it is important to develop knowledge on this topic to help close this research gap. In this work, the corrosion and tribocorrosion behaviors of additive 316L stainless steel and its wrought counterpart are studied experimentally in two electrolytes; a 0.9 wt\% NaCl solution and a simulated body fluid with the protein albumin. The experimental results show that the additive 316L samples have the stronger passive film, and undergo less material loss during tribocorrosion conditions. The wrought 316L samples undergo less corrosion rate in both the corrosion and tribocorrosion experiments, and they show the better ability to repassivate during tribocorrosion conditions. Both material versions undergo less corrosion rate, less material loss and show higher corrosion resistance in the simulated body fluid due to the effects of the albumin proteins. The main conclusion drawn from this investigation is that although additive 316L show better performance in terms of the strength of the passive film and material loss, wrought 316L show better overall performance in both corrosion and tribocorrosion behavior. This suggests that additive manufactured 316L is not a suitable replacement for wrought 316L for biomedical applications, and further research into this topic is required.