Structural optimization, degradation behavior and mechanical properties of Mg-2Zn-1Mn alloy bone plates based on a stress corrosion prediction model

Degradable magnesium alloy bone plates possess excellent biocompatibility and mechanical compatibility, and thus have significant application potential in the field of fracture internal fixation. However, they are prone to corrosion in the physiological environment due to the combined action of corrosive media and service loads, resulting in local corrosion, stress corrosion cracking, and continuous degradation of mechanical properties, which affect the stability and safety of the implanted structure. Therefore, it is of great significance to reasonably control the degradation rate of the bone plate and improve its service reliability. This study focused on the Mg-2Zn-1Mn magnesium alloy bone plate and based on the previously established and calibrated point corrosion-stress corrosion coupling model, conducted optimization research on key structural parameters such as the bone plate geometry, hole spacing, hole diameter, and thickness. The results showed that the combination scheme of type (b) geometry, hole spacing of 9.0 mm, hole diameter of 3.4 mm, and thickness of 3.25 mm had superior comprehensive performance. Compared with the original structure, the quality loss rate of the optimized bone plate after 36 hours decreased to 29.41%, a reduction of 10.68%; the bending yield strength increased from 276 MPa to 305 MPa, and no fracture failure occurred during the degradation process. The study demonstrated that the optimization method of key structural parameters can effectively improve the service performance of degradable magnesium alloy bone plates.