**4. Conclusions**

Anodization displayed a profound effect on the fatigue strength of the AZ31B alloy. S-*N* curves obtained in the tension-tension mode, in air and PBS solution, indicated that the fatigue limit was reduced by the corrosive electrolyte when the magnesium alloy was tested in the polished condition. Conversely, it increased for the anodized alloy tested in PBS in comparison to the tests conducted in air. However, a reduction of approximately 60% of the fatigue strength was observed for the anodized samples with respect to the polished ones, either in air or PBS solution. The presence of the anodized layer entails remarkable surface changes that affect the fatigue behavior of the AZ31 alloy, mostly related to surface porosity and roughness heterogeneities at the anodized layer/substrate interface. The fracture surface displayed a more brittle character for the anodized alloy fractured in PBS solution when compared to air. Oxide particles are likely to act as stress risers, increasing the crack propagation rate in PBS solution.

**Author Contributions:** Conceptualization, R.A.A. and L.A.d.O.; Methodlogy, R.A.A. and L.A.d.O.; investigation, L.A.d.O., S.L.d.S. and V.A.d.O.; Writing—original draft preparation, L.A.d.O. and R.A.A.; Supervision, R.A.A.; funding acquisition, R.A.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the São Paulo Research Foundation (FAPESP), process number 2015/22921-6 and CAPES (Finance Code 001).

**Data Availability Statement:** The data obtained in this study are available from the corresponding author on reasonable request.

**Acknowledgments:** FATEC-SP, DEMa-UFSCar and the Multiuser Experimental Facilities (CEM-UFABC) are acknowledged for the experimental support.

**Conflicts of Interest:** The authors declare no conflict of interest.
