Adição de Cr para endurecimento superficial do ferro fundido nodular na condição bruta de solidificação
Chromium addition in nodular cast iron for surface hardening in the as-cast condition
Robinson Tadeu Nadal Visar; Paula Fernanda da Silva Farina
Resumo
O ferro fundido nodular apresenta muitas vantagens frente aos demais ferros fundidos, porém, sua baixa resistência ao desgaste é uma desvantagem. Para aumentar a dureza superficial dos ferros fundidos nodulares, comumente são utilizados tratamentos termoquímicos. Com o objetivo de obter uma camada reforçada superficial no ferro fundido nodular, na condição bruta de solidificação, o presente trabalho propõe a adição de Cr na composição, a qual, aliada a um inserto metálico (de aço AISI 1020), produzirá uma camada superficial endurecida, rica em carbonetos. Para tanto, foram realizadas simulações computacionais e produzida a liga fundida para realização de ensaios de dureza, tração e caracterização metalográfica. A adição de 0,5% em peso de Cr no ferro fundido nodular, aliada ao resfriador de aço AISI 1020, mostrou-se eficaz para melhorar as propriedades de resistência mecânica superficial do ferro fundido nodular, mantendo as características do mesmo no núcleo da peça.
Palavras-chave
Abstract
Nodular cast iron has many advantages over other cast irons, but one disadvantage is its low wear resistance. Studies have been carried out to increase the surface hardness of nodular cast iron, the most common being thermochemical treatments. To obtain a reinforced surface layer on nodular cast iron in its as cast condition, this work proposes the addition of Cr to the composition, which, together with a metal insert (made from ISO 1020 steel), will produce a hardened layer, rich in carbides. To this end, computer simulations were carried out and the cast alloy was produced for hardness, tensile and metallographic characterization tests. The addition of 0.5 wt % of Cr to the nodular cast iron, combined with an ISO 1020 steel cooler, proved to be effective in improving the surface mechanical strength properties of the nodular cast iron, while maintaining its characteristics in the core of the part.
Keywords
Referências
1 Stefanescu DM. Modeling of cast iron solidification—the defining moments. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science. 2007;38(7):1433-1447. http://doi.org/10.1007/s11661- 007-9173-y.
2 Guesser WL. Propriedades mecânicas dos ferros fundidos. Joinville: Ed. Univille; 2012.
3 Skaland T. Nucleation mechanisms in ductile iron. In: Proceedings of the AFS Cast Iron Inoculation Conference; 2005; Schaumburg, IL. Schaumburg: American Foundry Society; 2005. p. 13-30.
4 Kopyciński D, Dorula J. The influence of iron powder and disintegrated steel scrap additives on the solidification of cast iron. Metallurgy and Foundry Engineering. 2010;36(2):97. http://doi.org/10.7494/mafe.2010.36.2.97.
5 Muhmond HM. On the inoculation and graphite morphologies of cast iron [thesis]. Stockholm: Royal Institute of Technology; 2014.
6 Santos ABS, Branco CHC. Metalurgia dos ferros fundidos cinzentos e nodulares. São Paulo: Instituto de Pesquisas Tecnológicas; 1991.
7 Basso A, Sikora J. Review on production processes and mechanical properties of dual phase austempered ductile iron. International Journal of Metalcasting. 2012;6(1):7-14. http://doi.org/10.1007/BF03355473.
8 Al-Ghonamy A, Ramadan M, Fathy N, Hafez KM, El-Wakil AA. Effect of graphite nodularity on mechanical properties of ductile iron for waterworks fittings and accessories. International Journal of Civil & Environmental Engineering. 2010;10:1-5.
9 Pearce J. Inoculation of cast irons: practices and developments. Foundry Trade Journal. 2008;181(3651):28-31.
10 Petrus Ł, Bulanowski A, Kołakowski J, Brzeżański M, Urbanowicz M, Sobieraj J, et al. The influence of selected melting parameters on the physical and chemical properties of cast iron. Archives of Foundry Engineering. 2020;20(1):105-110.
11 Vicente AA, Sartori Moreno JR, Santos TFA, Espinosa DCR, Tenório JAS. Nucleation and growth of graphite particles in ductile cast iron. Journal of Alloys and Compounds. 2019;775:1230-1234. http://doi.org/10.1016/j. jallcom.2018.10.136.
12 Campbell J. Complete casting handbook: metal casting processes, metallurgy, techniques and design. 1st ed. Waltham: Elsevier; 2011.
13 Kocatepe K, Cerah M, Erdogan M. Effect of martensite volume fraction and its morphology on the tensile properties of ferritic ductile iron with dual matrix structures. Journal of Materials Processing Technology. 2006;178(1-3):44-51. http://doi.org/10.1016/j.jmatprotec.2005.11.019.
14 Martinez Celis M, Valle N, Lacaze J, Thorbjornsson IÖ, Johannesson B, Thorgrimsson JT. Microstructure of as-cast reinforced ductile iron. International Journal of Cast Metals Research. 2011;24(2):76-82. http://doi.org/10.1179/1364 04610X12738456167384.
15 Shamanian M, Mousavi Abarghouie SMR, Mousavi Pour SR. Effects of surface alloying on microstructure and wear behavior of ductile iron. Surface and Coatings Technology. 2010;204(18-19):2910-2919.
16 Nascimento D, Santana PI. Ferros fundidos cinzento e branco. Joinville: Nova Letra; 2016.
17 Stefanescu DM. Science and engineering of casting solidification. 2nd ed. New York: Springer; 2009.
18 Tabrett CP, Sare IR, Ghomashchi MR. Microstructure-property relationships in high chromium white iron alloys. International Materials Reviews. 1996;41(2):59-82. http://doi.org/10.1179/imr.1996.41.2.59.
19 Oliveira LMO. Comportamento mecânico dos ferros fundidos avançados. Joinville: Ed. Univille; 2016.
20 Santos ABS. Efeitos da composição química na produção de ferros fundidos nodulares. In: Anais do 55º Congresso Anual da ABM; 2000; Rio de Janeiro, Brasil. São Paulo: ABM; 2000.
21 American Society for Testing and Materials. ASTM A536-84: standard specification for ductile iron castings. West Conshohocken: ASTM International; 2019.
Submetido em:
09/03/2025
Aceito em:
08/07/2025
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