THE USE OF SiC MATERIALS AS INOCULANTS IN GRAY CAST IRON AND THEIR EFFECTS ON MECHANICAL PROPERTIES

Abstract

Gray cast irons hold a significant place in the industry due to their excellent casting and engineering properties as well as their superior performance in various applications. Although the graphite flakes in the matrix structure result in lower hardness, strength, and impact resistance compared to steel and spheroidal graphite iron, gray cast iron is the most widely used material among iron-based groups in both the world and in Turkey due to its superior thermal conductivity and vibration damping capability. Various studies have been carried out to improve the weak properties caused by flake graphite through inoculation and other composition-based liquid metal treatments.The aim of this study is to investigate the effect of different inoculation processes on the microstructural and mechanical properties of gray cast iron materials. In the experimental studies, flow inoculation was applied during the pouring of the molten metal into the mold, and three different inoculants green SiC, metallurgical SiC, and a barium-containing additive were used. These samples, both uninoculated and inoculated with different materials, were evaluated through thermal analysis, microstructural examination, and mechanical tests. The results obtained from thermal analysis revealed that the eutectic temperature, recalescence, and graphite formation tendency changed depending on the inoculation process parameters. While D- and E-type graphite structures were predominantly observed in uninoculated samples, A-type graphite was formed in the inoculated samples, resulting in a more homogeneous structure. In the inoculated materials, due to the increased ferrite content, a decrease in hardness values and an increase in tensile and yield strength were observed. The findings of the study clearly demonstrate that inoculation is a significant factor that leads to improvements in not only graphite morphology but also in mechanical properties.

Keywords

• Gray cast iron
• thermal analysis
• casting simulation
• microstructure
• hardness

Supporting Institution

Erkunt Sanayi A.Ş.

Project Number

E24-019

Ethical Statement

This study has been prepared in accordance with the principles of scientific research and publication ethics. All sources used in the research process have been accurately and completely cited, and information taken from other studies has been used with appropriate references. No unethical practices such as plagiarism, data fabrication, falsification, duplicate publication or unjust authorship have been employed at any stage of the study. As the author, I declare that the study is original and has been completed in accordance with ethical rules.

Thanks

This study was supported by Erkunt Sanayi A.Ş. We would like to express our gratitude to the R&D Centre Directorate for their contributions.

SiC MALZEMELERİN GRİ DÖKME DEMİRDE AŞILAYICI OLARAK KULLANIMI VE MEKANİK ÖZELLİKLERE ETKİSİ

Abstract

Gri dökme demirler, üstün döküm ve mühendislik özellikleri ve kullanım alanlarında sergilediği üstün performans endüstride önemli bir yer tutmaktadır. Matris yapıda mevcut grafit lamelleri, çelik ve sfero malzemeye göre düşük sertlik, mukavemet, darbe direnci sergilemesine rağmen ısı iletkenliğinin ve titreşim söndürme kabiliyetinin yüksek olması gibi üstünlükleri sayesinde demir esaslı gurupta Dünyada ve ülkemizde en fazla kullanım alanı bulmuş malzemedir. Lamel grafitlerin neden olduğu zayıf özellikleri iyileştirmek için, aşılamaya ve diğer bileşime dayalı sıvı işlemelere yönelik çeşitli çalışmalar yürütülmüştür. Bu çalışmanın amacı, farklı aşılama işlemlerinin, gri dökme demir malzemelerin mikroyapısal ve mekanik özelliklere etkisini araştırmaktır. Deneysel çalışmalarda, sıvı metalin kalıba dökümü sırasında akışa aşılama yöntemi uygulanmış olup, çalışma kapsamında yeşil SiC, metalurjik SiC ve baryum içeren üç farklı aşılayıcı kullanılmıştır. Aşılanmamış ve farklı malzemeler ile aşılanmış olan bu numuneler; termal analiz, mikroyapı incelemesi ve mekanik testler gerçekleştirilerek değerlendirilmiştir. Uygulanan termal analiz verilerinden elde edilen sonuçlar, ötektik sıcaklık, geri ısınma miktarı ve grafitleşme eğiliminin, aşılama işlem parametreleri ile değişim gösterdiğini ortaya koymuştur. Aşılama işlemi uygulanmamış numunelerde D ve E tipi grafit yapıları yoğun olarak gözlenirken, aşılanmış olan numunelerde A tipi grafit oluşumunun gerçekleştiği ve daha homojen bir yapının elde edildiği belirlenmiştir. Aşılama işlemi uygulanan malzemelerde, artan ferrit oranına bağlı olarak, sertlik değerlerinde azalma, çekme ve akma mukavemetinde artış sağlanmıştır. Çalışma sonuçları, aşılama işleminin, grafit morfolojisinin yanında mekanik özelliklerde önemli gelişme sağlayan bir etken olduğunu açıkça ortaya koymaktadır.

Keywords

• Gri dökme demir
• termal analiz
• döküm simülasyonu
• mikroyapı
• sertlik.

Supporting Institution

Erkunt Sanayi A.Ş.

Project Number

E24-019

Ethical Statement

Bu çalışma, bilimsel araştırma ve yayın etiği ilkeleri gözetilerek hazırlanmıştır. Araştırma sürecinde kullanılan tüm kaynaklar doğru ve eksiksiz biçimde belirtilmiş, başka çalışmalardan alınan bilgiler ise uygun şekilde atıf yapılarak kullanılmıştır. Çalışmanın hiçbir aşamasında intihal, veri tahrifi, sahtecilik, tekrar yayın veya haksız yazarlık gibi etik dışı uygulamalara yer verilmemiştir. Yazar olarak, çalışmanın özgünlüğünü ve etik kurallara bağlı kalınarak tamamlandığını beyan ederim.

Thanks

Bu çalışma Erkunt Sanayi A.Ş. tarafından desteklenmiştir. Katkılarından dolayı Ar-Ge Merkezi Müdürlüğü’ne teşekkürlerimizi sunarız.

References

1. [1] Dryden, J. R., & Purdy, G. R. (1989). The effect of graphite on the mechanical properties of cast irons. Acta Metallurgica, 37(7), 1999-2006.
2. [2] Yakut, R. (2023). Investigation of mechanical properties of grey cast irons reinforced with carbon titanium nitride (TiNC). Lubricants, 11(10), 454.
3. [3] Ana-Marija, H., Zoran, G., & Anita, S. (2022). Effect of inoculation, cooling rate and charge composition on gray iron microstructure. Materials Science. Non-Equilibrium Phase Transformations., 8(1), 3-6.
4. [4] Sahu, S., Bhat, M. N., Kumar, A., Pratik, A., & Kumar, A. (2014). Effect of section thickness on the microstructure and hardness of gray cast iron (a simulation study). Int. J. Eng. Res. Technol, 3, 35-40.
5. [5] Metzger M., Seifert T., (2015) Computational assessment of the microstructure-dependent plasticity of lamellar gray cast iron – Part II: initial yield surfaces and directions, International Journal of Solids and Structures, 66, 194-206,
6. [6] Demin, D. (2017). Strength analysis of lamellar graphite cast iron in the" carbon (c)-carbon equivalent (Ceq)" factor space in the range of c=(3,425-3,563)% and Ceq=(4,214-4,372) %. Технологический аудит и резервы производства, 1(1 (33)), 24-32.
7. [7] Hecht, R. L., Dinwiddie, R. B. and Wang, H. (1999). Effect of graphite flake morphology on thermal diffusivity of gray cast iron used in automotive brake discs. Journal of Materials Science, 34, 4775-4781.
8. [8] Álvarez, L., Luis, C. J., & Puertas, I. (2004). Analysis of the influence of chemical composition on the mechanical and metallurgical properties of engine cylinder blocks in grey cast iron. Journal of materials processing technology, 153, 1039-1044.

9. [9] Thilak, G., Chandramohan, P., Saravanan, V. S., & Nandakumar, B. (2025). Austempering of Directional Control Valves made using Flake Graphite Iron and Compacted Graphite Iron—A Performance Study. International Journal of Metalcasting, 1-20.
10. [10] Kutelu, B. J., Adubi, E. G., & Seidu, S. O. (2021). Chilling Effect of Inoculation on the Microstructure and Hardness Property of Hypo-Eutectic Grey Cast Iron. FUOYE Journal of Engineering and Technology, 6(2), 72-77.
11. [11] Martin, D. R., Moreno, J. R. S., & de Albuquerque Vicente, A. (2015). Effects of different inoculants on the microstructural characteristics of gray cast iron gg-25, hardness and useful life of tools. Acta Scientiarum. Technology, 37(4), 355-360.
12. [12] Wang, G., Chen, X., Li, Y., & Liu, Z. (2018). Effects of inoculation on the pearlitic gray cast iron with high thermal conductivity and tensile strength. Materials, 11(10), 1876.
13. [13] Fay, A. (2020). Influence of inoculation on cast iron machinability: Case studies. China Foundry, 17(2), 150-157.
14. [14] Chisamera, M., Stelian, S. T. A. N., Riposan, I., Stefan, E., Costache, G. (2008). Thermal analysis of inoculated grey cast irons. The Annals of “Dunarea de Jos” University of Galati. Fascicle IX, Metallurgy and Materials Science, 31(2), 11-16.
15. [15] Riposan, I., Chisamera, M., Stan, S., Skaland, T. (2003). Graphite nucleant (microinclusion) characterization in Ca/Sr inoculated grey irons. International Journal of Cast Metals Research, 16(1-3), 105-111.
16. [16] Riposan, I., Stan, S., Uta, V., Stefan, I. (2017). Cast iron inoculation enhanced by supplementary oxy-sulfides forming elements. Journal of Materials Engineering and Performance, 26(9), 4217-4226.
17. [17] Stefan, E., Chisamera, M., Riposan, I., Stan, S. (2021). Graphite nucleation sites in commercial grey cast irons. Materials Today: Proceedings, 45, 4091-4095.
18. [18] Riposan, I., Chisamera, M., Stan, S., White, D. (2009). Complex (Mn, X) S compounds-major sites for graphite nucleation in grey cast iron. China Foundry, 6(4), 352-358.
19. [19] Stefan, E., Riposan, I., Chisamera, M., Stan, S. (2020). Lanthanum role in the graphite formation in gray cast irons. Minerals, 10(12), 1146.
20. [20] Patel, D., Nanavati, P., Chug, C. (2013). Effect of Ca and Ba Containing Ferrosilicon Inoculants on Microstructure and Tensile Properties of IS-210, and IS-1862 Cast Irons. In Proceedings of the National Conference on Emerging Trends in Engineering Technology & Management, Ahmedabad, Gujarat, India, 1-8.
21. [21] González H.C, Espitia P.P, Sierra R.A., (2017) Fading and graphite nucleation sites in grey iron inoculated using silicon carbide, R. revista Matéria, 22 (2).
22. [22] Edalati K., Akhlaghi F., Nili-Ahmadabadi M. (2005). Influence of SiC and FeSi addition on the characteristics of gray cast iron melts poured at different temperatures. Journal of Materials Processing Technology, 160(2), 183-187.
23. [23] Aydoğuş A., Acarer M. (2019). Küresel Grafitli Dökme Demirlerde Aşılayıcıların Mikroyapı Ve Mekanik Özelliklere Etkisi. Selcuk University Journal of Engineering Sciences, 18(3), 199-208.
24. [24] Stefanescu D. M., Suarez R., Kim S. B. (2020). 90 years of thermal analysis as a control tool in the melting of cast iron. China Foundry, 17(2), 69-84.
25. [25] Muhmond H. M. (2014). On the inoculation and graphite morphologies of cast iron (Doctoral dissertation, KTH Royal Institute of Technology).
26. [26] Metal Casting Institute. (n.d.). Iron types. Retrieved April 20, 2025. https://metalcastinginstitute.com/iron-types/
27. [27] Stefanescu Doru. (2015). Science and Engineering of Casting Solidification Third Edition. 10.1007/978-3-319-15693-4.
28. [28] Riposan I., Lefter C. – Inoculation of Cast Iron: Principles and Practices, AFS Casting Conference 2012
29. [29] Koch M., Soulas, K. (2014). Inoculation of grey and ductile iron. 7th International Foundry Congress, Ankiros Fairs, 11–13 Eylül 2014, İstanbul,Türkiye. https://akademi.tudoksad.org.tr/site/file?u=20181123070549_congress_file_143.pdf&t=Inoculation+of+Grey+and+Ductile+Iron
30. [30] Dorula, J., Kopyciński, D., Guzik, E., & Szczęsny, A. (2022). Procedure of Eliminating Porosity in Grey Cast Iron with Low Sulphur Content. Materials, 15(18), 6273.
31. [31] Janerka, K., Kostrzewski, Ł., Stawarz, M., Jezierski, J., & Szajnar, J. (2022). Various aspects of application of silicon carbide in the process of cast iron Melting. Archives of Metallurgy and Materials, 67.
32. [32] Xue, W., & Li, Y. (2016). Pretreatments of gray cast iron with different inoculants. Journal of Alloys and Compounds, 689, 408-415.
33. [33] Omranian, P., Shakeri, N., Mohamemadpour, A., Khailpour, M., & Alavi, N. (2013). Use of silicon carbide as an inoculant in ductile iron casting to reduce the cost with keeping the properties. Metal Journal, 15(5), 1-5.
34. [34] Persson, P. E., Udroiu, A., Vomacka, P., Xiaojing, W., & Sjögren, T. (2010). ATAS® as a tool for analyzing, stabilizing and optimizing the graphite precipitation in grey cast iron. In Proceedings of the 69th World Foundry Congress, Hangzhou, China 1-16.
35. [35] V. Fourlakidis, J. Ekengård and A. Diószegi (2010) Non-metallic inclusions in lamellar graphite iron 10th International Symposium on the Science and Processing of Cast Iron. https://www.researchgate.net/publication/281406663_Nonmetallic_Inclusions_in_Lamellar_Graphite_Iron
36. [36] Stefanescu, D. M. (2002). Science and Engineering of Casting Solidification. Springer.
37. [37] Loper, C. R., & Gundlach, R. B. (1991). Inoculation of Cast Irons. AFS Transactions, 99, 407–416.
38. [38] Lacaze, J., & Sertucha, J. (2015). On the fading of inoculation effect in cast irons, Materials Science and Engineering: A, 645, 212–219.
39. [39] Elliott, R. (1988). Cast Iron Technology. Butterworth-Heinemann.
40. [40] Tim Semleit, Ida Adhiwiguna, Jasen Wijaya, Rüdiger Deike, Duisburg (2021) Investigation of silicon carbide dissolution behavior in molten cast iron under specific consideration of the formation of reaction layers, Gıessereı Special, 1, 46 – 53.