**4. Conclusions**

In this study, the microstructural evaluation of A356 alloy using heat treatment and cooling slope followed by ECAP process was successfully carried out. The effect of grain refinement on the hardness and the corrosion resistance was investigated and the results obtained can be summarized as follows:


corrosion resistance was attributed to the refined Si particles that impeded the occurrences of microgalvanic cells on the protective layer of the alloy surface.

**Author Contributions:** M.A.G. carried out the experimental works, analysis and writing under the supervision of M.Z.O., I.F.M. and N.K.O.

**Funding:** This research was funded by Ministry of Education Malaysia and Universiti Kebangsaan Malaysia [DIP-2016-007].

**Acknowledgments:** The authors wish to express their gratitude to the Ministry of Education Malaysia and Universiti Kebangsaan Malaysia for the financial assistance and support.

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