I want to know if there is a well-defined relationship between the size and morphology of the grains with the resistance to corrosion of metals
Dear Mr. Alcantara. I recently investigate the relationship between grain size and corrosion rate of low carbon steel. I hope it would be helpful.
Yes, there exist relationship on grain size and corrosion resistance. The fine grain structure is having better corrosion properties when compared with course grain structure. For example A333 pipe material is superior to A106 pipe material
The effect of grain size on the yield strength is well established using the Hall-Petch relation. However, no such unequivocal relation is available to describe the effect of grain size on the corrosion behavior. Several reports point out improvements in the corrosion resistance of the Mg alloys upon grain refinement. A decrease in the corrosion resistance has also been observed with the decrease in the grain size for different materials such as pure Mg, Al alloy and Ni- base alloy. In addition to the grain size, grain boundary character also influences the chemical reactivity of the material. It is well documented that low angle grain boundaries impart improved resistant to corrosion-creep interaction of the Alloy 600 in nuclear water reactors. It is demonstrated that low angle grain
boundaries (Σ3) showed better pitting resistance than that of high angle boundaries (Σ27) for a similar grain size.
For more details refer to this paper: N. Shrestha, V. Utgikar, K.S Raja, The Effect of Grain Size on the Corrosion Behavior of Mg-RE Alloy ZE10A, ECS Transactions, 85(13) (2018) 671-682
If the grain refinement is associated with increase in dislocation density, then the increased corrosion current density could be attributed to higher chemical potential of the defect sites (stored strain energy). Dislocation network could also act as short circuit paths for faster diffusion of atoms (increased flux) that increases the corrosion rate. On the other hand, if the faster diffusing atoms participate in the formation of an impervious passive layer (such as Cr2O3 type), then the icorr will decrease.
Decreasing the grain size means increasing the grain boundary area. If the metal is passivating type, a smaller grain decreases the corrosion current density. If it is not passive, a smaller grain increases the corrosion current density. K. D. Ralston, N. Birbilis, C. H. Davies, “Revealing the relationship between grain size and corrosion rate of metals”, Scripta Materialia 63 (2010) 1201-1204.
Dear Victor Alcántara
Grain refinement is a non linear (exponential) function of corrosion current density (icorr). Now, as the grain size decrease the total area of grain boundaries increase. This will increase the total surface energy of the metal since the energy and chemical reactivity of grain boundaries are higher than the grains . This trend makes the surface more reactive with its environment through increased surface electron activity.
I hope this answer be helpful.
https://iopscience.iop.org/article/10.1088/2053-1591/ab62fa/pdf
Best regards
Dear Mr. Alcantara. I recently investigate the relationship between grain size and corrosion rate of low carbon steel. I hope it would be helpful.
I support Maryam Soleimani Mohammed Hussein j. H. Al'Atia Balakrishna Palanki 's points.
Dear Maryam Soleimani and Hamed Mirzadeh
Yes, your work was clear and sober, and I personally benefited from its output and I referred to it in my answer through the link at the end of my answer. Thank you for these valuable details shown in fig3. I wish you continued success and progress.
Best regards
Mr. Alcantara. I recently investigate the relationship between grain size after hot working and corrosion resistance of a 316L austenitic stainless steel. I hope it would be helpful.
I think surface roughness is often induced during the grain refinement process, and this could influence the corrosion current density.
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