**5. Conclusions**

In this paper, the reactive molecular dynamics simulation method studied the effect of different grain boundaries on the corrosion interface process of pure Fe-H2O. Our study shows that the stress release in the high-stress region of the grain boundary during the corrosion process promotes the rapid penetration of O ions into the grain boundary to form oxides, resulting in the occurrence of intergranular corrosion in pure iron. The effect of grain boundaries on intergranular corrosion is revealed from the point of view of simulation, which provides a theoretical explanation for the occurrence of intergranular corrosion in Fe-H2O corrosion in a realistic environment.

**Author Contributions:** Conceptualization, Z.L. and C.H.; methodology, Z.L. and C.H.; validation, Z.X. and Y.H.; formal analysis, Z.X.; investigation, Z.X.; data curation, Z.X.; writing—original draft preparation, Z.X.; writing—review and editing, Z.X., Y.H., W.H., C.H. and Q.W.; funding acquisition, Q.W. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported by the research project for Hua-long Pressurized Reactor (HPR1000) in China National Nuclear Corporation.

**Data Availability Statement:** Data sharing not applicable.

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

#### **References**

