This work studied the relationship between biodegradation rate and grain size itself, excluding other structural factors such as segregations, impure inclusions, second phase particles, sub-structures, internal stresses and textures caused by alloying additions and deformation processing for pure Mg. A spectrum of grain size was obtained by annealing through changing the annealing temperature. Grain boundary influenced the hardness and the biodegradation behavior. The hardness was grain size-dependent, following a typical Hall-Petch relation: HV=18.45+92.31d-12. The biodegradation rate decreased with decreasing grain size, following a similar Hall-Petch relation: Pi=0.17-0.68d-12 or Pw=1.34-6.17d-12. This work should be helpful for better controlling biodegradation performance of biodegradable Mg alloys through varying their grain size.
Keywords: Hall–Petch relation; biodegradation; grain size; implant metals; pure Mg.