Different Analytical Methods to Determine the Influence of Pitting on the Residual Performance of Mg Alloys as Implant Materials

Mg alloys are prone to pitting due to their non-uniform protective corrosion layers, which can lead to an increase in stress intensity based on the notch effect, pit-to-crack transition, and thus premature failure. A small set of analytical methods to determine the extent of pitting and its effect on the resulting residual strength is presented. Micrographs, 3D microscopy, or 3D analysis using CT are used to determine the amount and geometry of pitting—each with advantages and disadvantages. The influence of the corrosion pits on the mechanical properties is tested by static, quasi-static, and cyclic test methods: by tensile, flexural, or fatigue testing—either after corrosion or overlapping. Knowledge about the critical pit is of general interest. Stress corrosion is discussed by applying static tests like C-ring testing, which also plays a role in slow strain rate tensile tests and stress corrosion cracking is more or less influenced by corrosion pits.