Microstructural effects of preconditioning materials on gray iron and their impact on corrosion resistance
Keywords:
Corrosion resistance, Pearlitic microstructure, Gray iron, Preconditioning materials.Abstract
The corrosion of gray cast iron brake discs in aggressive environments is a growing concern for the automotive industry, particularly in hybrid and electric vehicles, where reduced brake usage promotes corrosion-related degradation. This phenomenon not only affects brake performance and service life but also contributes to particulate matter emissions with potential environmental and health impacts. The present study evaluated the influence of three preconditioning materials (metallurgical graphite, electrode graphite, and metallurgical coke) on the microstructure and corrosion resistance of gray cast iron. Three independent heats were produced under identical melting conditions at 1450 °C, using each preconditioning material separately. Three specimens were obtained from each heat for microstructural and electrochemical characterization. Quantitative image analysis was performed using ten measurements per experimental condition for the determination of the fine pearlite fraction, MnS inclusion density, and pearlite interlamellar spacing. Corrosion resistance was evaluated by potentiodynamic polarization in a 3.5 wt.% NaCl solution using a scan rate of 0.1667 mV/s over a potential range of ±0.5 V with respect to the corrosion potential. Five measurements were performed for each specimen, and the reported values represent mean values. Statistical differences among the evaluated conditions were assessed by one-way ANOVA (p < 0.05).
The gray cast iron preconditioned with metallurgical coke exhibited the highest MnS inclusion density (226 ± 5 MnS/mm²), the largest fraction of fine pearlite (55.35 ± 0.84%), and the smallest pearlite interlamellar spacing (170 ± 3.50 nm). Correspondingly, this alloy exhibited the lowest corrosion current density and corrosion rate (0.016 ± 0.002 mm/year), representing an approximately 65% reduction compared with the alloy preconditioned using electrode graphite. The results indicate that the improved corrosion resistance is associated with the combined influence of the selected preconditioning material and the resulting metallurgical conditions, including differences in sulfur content, Mn/S ratio, carbon equivalent, MnS inclusion density, and pearlite refinement. These findings demonstrate that appropriate selection of the preconditioning material can modify the solidification behavior and microstructural evolution of gray cast iron, thereby improving its corrosion performance in aggressive environments.
References
1. ACEA (2025) Economic and Market Report Global and EU auto industry: Full year 2024. Acea.
2. de Souza, A., de Oliveira-Júnior, J.F., Cardoso, K.R.A. and Gautam, S. (2025) Impact of vehicular emissions on ozone levels: A comprehensive study of nitric oxide and ozone interactions in urban areas. Geosystems and Geoenvironment, 4, 100348. https://doi.org/10.1016/j.geogeo.2024.100348
3. Al-Sabbagh, T.A. and Shreaz, S. (2025) Impact of Lead Pollution from Vehicular Traffic on Highway-Side Grazing Areas: Challenges and Mitigation Policies. Int. J. Environ. Res. Public Health, 22, 1–30. https://doi.org/10.3390/ijerph22020311 http://www.ncbi.nlm.nih.gov/pubmed/40003536
4. Selvi, M.S. and Önem, Ş. (2025) Impact of Variables in the UTAUT 2 Model on the Intention to Use a Fully Electric Car. Sustainability (Switzerland), 17, 1–24. https://doi.org/10.3390/su17073214
5. Alvarez-Diazcomas, A., Estévez-Bén, A.A., Rodríguez-Reséndiz,J., Carrillo-Serrano,R. V. and Álvarez-Alvarado,J.M. (2023) A High-Efficiency Capacitor-Based Battery Equalizer for Electric Vehicles. Sensors, 23, 1–16. https://doi.org/10.3390/s23115009 http://www.ncbi.nlm.nih.gov/pubmed/37299739
6. Szumska, E.M. (2025) Regenerative Braking Systems in Electric Vehicles: A Comprehensive Review of Design, Control Strategies, and Efficiency Challenges. Energies (Basel)., 18. https://doi.org/10.3390/en18102422
7. Jamadar, N.M. and Jadhav, H.T. (2021) Rule-based assistive hybrid electric brake system with energy generation for electric vehicle. Energy Sources, Part A: Recovery, Utilization and Environmental Effects, 43, 1–19. https://doi.org/10.1080/15567036.2021.2015485
8. Gweon, J., Shin, S., Jang, H., Lee, W., Kim, D. and Lee, K. (2018) The Factors Governing Corrosion Stiction of Brake Friction Materials to a Gray Cast Iron Disc. SAE Technical Papers, 2018-Octob, 5–12. https://doi.org/10.4271/2018-01-1899
9. Gweon, J., Park, J., Kyu, W., Yeon, D. and Jang, H. (2021) Root cause study of corrosion stiction by brake pads on the grey iron disc. Eng. Fail. Anal., 128, 1–13. https://doi.org/10.1016/j.engfailanal.2021.105583
10. Motta, M., Fedrizzi, L. and Andreatta, F. (2023) Corrosion Stiction in Automotive Braking Systems. Materials, 16. https://doi.org/10.3390/ma16103710
11. Mao, F., He, Y., Guo, A., Wang, X., Zhong, Y., Huang, Z., Chen, C. and Wei, S. (2025) Effect of vanadium and temperature on the tribological properties of gray cast iron. Journal of Materials Research and Technology, 38, 3578–3590. https://doi.org/10.1016/j.jmrt.2025.08.211
12. Kumar, A., Pandey, R., Kumar, R., Kumar, N. and Kiran, T.R. (2021) Materials Today: Proceedings Thermal analysis on car brake rotor using cast iron material with different geometries. Mater. Today Proc., 10.1016/j.matpr.2021.05.299. https://doi.org/10.1016/j.matpr.2021.05.299
13. Liu, Y., Lee, H., Hess, D. and Coryell, J. (2025) Thermomechanical Fatigue Behavior of Gray Cast Iron in Brake Rotors. In SAE Technical Papers. https://doi.org/10.4271/2025-01-8319
14. Wang, Y., Shuai, S. and Ge, Y. (2025) Controlling brake particle emissions: New brake disc needs more attention. Results in Engineering, 27, 107120. https://doi.org/10.1016/j.rineng.2025.107120
15. Catapano, F., Iorio, S. Di, Magno, A., Sequino, L. and Vaglieco, B.M. (2025) Brake particle emissions: Effect of temperature and modeling of temperature behavior. Results in Engineering, 26, 104872. https://doi.org/10.1016/j.rineng.2025.104872
16. Gonet, T. and Maher, B.A. (2019) Airborne, Vehicle-Derived Fe-Bearing Nanoparticles in the Urban Environment: A Review. Environ. Sci. Technol., 53, 9970–9991. https://doi.org/10.1021/acs.est.9b01505 http://www.ncbi.nlm.nih.gov/pubmed/31381310
17. Bruna, H., Allende-Seco, R., Artigas, A., Monsalve, A. and Sánchez, C. (2024) Effect of Copper and Nickel Content on the Corrosion Mechanisms in Ferritic Matrix Gray Cast Irons under Simulated Marine Environments. Metals (Basel)., 14. https://doi.org/10.3390/met14060696
18. Seikh, A.H., Sarkar, A., Singh, J.K., Mohammed, S.M.A.K., Alharthi, N. and Ghosh, M. (2019) Corrosion characteristics of copper-added austempered gray cast iron (AGCI). Materials, 12, 1–17. https://doi.org/10.3390/ma12030503
19. Godwin, I., Sunday, O., Fayomi, I. and Nwankwo, P. (2023) Investigation of the microstructure, corrosion resistance and hardness of bone particle reinforced cast iron for engine blocks application in automotive and marine industries. 2.
20. Dwulat, R., Janerka, K., Grzesiak, K. and Gałuszka, M. (2023) Influence of Charge Materials on the Metallurgical Quality of Gray Cast Iron. Archives of Foundry Engineering, 23, 66–71. https://doi.org/10.24425/afe.2023.144297
21. Futas, P., Pribulova, A., Petrik, J., Blasko, P., Junakova, A. and Sabik, V. (2023) Metallurgical Quality of Cast Iron Made from Steel Scrap and Possibilities of Its Improvement. Metals (Basel)., 13, 1–10. https://doi.org/10.3390/met13010027
22. Scherbring, S., Adams, B. and Mola, J. (2024) Impact of interlamellar spacing and non-pearlitic features on mechanical properties and cyclic damage initiation in near-eutectoid pearlitic steels. Materials Science and Engineering: A, 889. https://doi.org/10.1016/j.msea.2023.145846
23. Genculu, S. (2024) Cast Irons -Properties and Applications. CAB worldwide.
24. Srivastava, R., Singh, B. and Saxena, K.K. (2019) Influence of S and Mn on mechanical properties and microstructure of grey cast iron: An overview. Mater. Today Proc., 26, 2770–2775. https://doi.org/10.1016/j.matpr.2020.02.577
25. De Santiago-Méndez, L.F., Castro-Román, M. de J., Herrera-Trejo, M., Mancha-Molinar, H. and Bravo, B. (2025) Influence of S and Mn Initial Concentrations on the Graphite Branching in Gray Cast Iron as Quantified by 2D Image Analysis. Materials, 18. https://doi.org/10.3390/ma18214837
26. Stefan, E., Chisamera, M., Riposan, I. and Stan, S. (2021) Graphite nucleation sites in commercial gray cast irons. Materials Today: Proceedings, 45, 4091-4095. https://doi.org/10.1016/j.matpr.2020.11.009
27. Lima, M.L., Albertin, E., Correa, E.R., Rabello, R.B. and Uehara, S. (2020) Pearlite Refining Strategies for Hypoeutectic Gray Cast Iron. International Journal of Metalcasting, 14, 766–773. https://doi.org/10.1007/s40962-020-00413-6
28. Roučka, J., Prochazka, J., Kana, V., Krutis, V. and Nedelova, K. (2019) The influence of lamellar graphite cast iron annealing on hardness and structure. Archives of Foundry Engineering, 19, 105–112. https://doi.org/10.24425/afe.2019.129639
29. Stefanescu, D.M., Alonso, G., Larrañaga, P. and Suarez, R. (2016) On the stable eutectic solidification of iron-carbon-silicon alloys. Acta Mater., 103, 103–114. https://doi.org/10.1016/j.actamat.2015.09.043
30. Alloys, I. (2020) Recent Developments in Understanding Nucleation and Crystallization of Spheroidal Graphite in.
31. Eiken, J. (2020) Calphad-based phase-field study of the interplay between spheroidal graphite growth and chemical segregation in ductile cast iron Calphad-based phase-field study of the interplay between spheroidal graphite growth and chemical segregation in ductile cast. Materials Science and Engineering, 861, 1–8. https://doi.org/10.1088/1757-899X/861/1/012055
32. Yin, R. yu (2021) Review on the study of metallurgical process engineering. International Journal of Minerals, Metallurgy and Materials, 28. https://doi.org/10.1007/s12613-020-2220-z
33. Ştefănescu, D.M., Alonso, G., Larrañaga, P., De La Fuente, E. and Suarez, R. (2018) Reassessment of crystal growth theory of graphite in cast iron. Materials Science Forum, 925 MSF, 36–44. https://doi.org/10.4028/www.scientific.net/MSF.925.36
34. Dwulat, R. and Janerka, K. (2023) Evaluation of the Metallurgical Quality of Nodular Cast Iron in the Production Conditions of a Foundry. Journal of Manufacturing and Materials Processing, 7. https://doi.org/10.3390/jmmp7010018
35. Wang, Z., Zhang, X., Yu, H., Liu, J., Cheng, L., Hu, S.E. and Wu, K. (2022) Effects of pearlite on corrosion initiation and propagation in weathering steels in marine environments. J. Mater. Sci., 57, 6039–6055. https://doi.org/10.1007/s10853-022-07001-5
36. Siswanto, A., Widodo, R. and Ardiansyah, E. (2020) Effect of interlamellar spacing on tensile strength gray cast iron with copper variations. J. Phys. Conf. Ser., 1450. https://doi.org/10.1088/1742-6596/1450/1/012127
37. Zhang, Y., Feng, X., Huang, Q., Li, Y., Hao, X. and Wang, C. (2023) The corrosion characteristics and mechanism of directionally solidified Mg-3Zn-xCa alloys. Journal of Magnesium and Alloys, 11, 3673–3687. https://doi.org/10.1016/j.jma.2022.02.010
