Development of a room-temperature microforming process applied to pure magnesium treated by annealing in bioabsorbable miniplate implant applications

• Room-temperature microforming for magnesium miniplate implants. • Annealing treatment to enable room-temperature microforming. • Improved mechanical properties and corrosion resistance by annealing. • Optimal condition at c/d approximately 1 with a ∼24 μm grain size. The trend in the selection of materials for temporary implants has shifted from inert to bioabsorbable metals to minimize the need for implant removal surgeries. Among bioabsorbable metals, magnesium has emerged as a promising option due to its remarkable biocompatibility, closely matching bone elastic modulus and density. However, microforming magnesium at room temperature presents challenges due to the size effect and the low formability of magnesium. This research focuses on developing a room-temperature microforming process for bioabsorbable maxillofacial miniplate implants using magnesium treated by an annealing process to address these challenges. The investigation explores the role of the grain size effect through annealing and examines the impact of parameters such as punch velocity and clearance on the performance of the miniplate implant. The quality of the miniplate implant is determined by the ratio of the sheared surface to the sheet thickness. The highest-quality sheared edge of pure magnesium sheets with a thickness of 0.5 mm was achieved with a grain size of ∼24 μm, obtained after annealing at 250 °C for 30 min, with a punch velocity of 4 mm/s and a clearance of 25 μm. The study found that this most favorable condition was achieved when the clearance-to-grain size ratio (c/d) is approximately 1. Furthermore, corrosion testing of the miniplate with a grain size of ∼24 μm revealed reduced corrosion, indicating that annealing notably improves corrosion resistance, despite this specimen having the largest grain size.