Surface graphite degeneration in ductile iron castings for resin molds

Riposan, Iulian; Chişamera, Mihai; Stan, Stelian; Skaland, T.

doi:10.1016/s1007-0214(08)70028-2

Cited by 37 publications

(65 citation statements)

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“…Both Al and Zr support type A graphite formation with less undercooling and fewer free carbides, with zirconium having the highest effect. In order to minimize the pinholing, especially in green sand moulds and to obtain an efficient graphitization process, an Al content of 0.005-0.010 wt.% is recommended 17,47) ( Table 1). At this level (Fig.…”

Section: Recommendations For Foundry Applicationmentioning

confidence: 99%

Enhanced Quality in Electric Melt Grey Cast Irons

2013

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The paper reviews original data obtained by the authors, recently disconnected published, concerning the specific solidification pattern of low S (<0.05%) irons, with very low Al (<0.005%), melted and superheated in acid lined, coreless induction furnaces, and how superheating affects the iron quality with effective metallurgical treatments for use in these conditions. Solidification undercooling increased with increasing superheat, associated with significant changes in chemical composition, such as C, Si, Mn, Al and Zr, involved in the nucleation of graphite. The concept in the present paper sustains a three-stage model for nucleating flake graphite [(Mn,X)S type nuclei]. There are three important groups of elements [deoxidizer/ Mn, S/inoculating] and three technology stages in electric melt iron [superheat/pre-conditioning base iron/ final inoculation]. Different materials were used for pre-treatment of the iron melt, to control oxidization levels and/or to promote active graphite nucleation sites, including carbon materials and metallurgical silicon carbide. Special attention was paid to maintain Al and Zr recoveries in the melting furnace for their effects on the iron structure. A double treatment utilizing strong oxide forming elements, such as Al and Zr for preconditioning, followed by inoculation decreased eutectic undercooling parameters. This treatment improved graphite characteristics and avoided carbides. For foundry application, it is recommended to ensure (Mn,X)S compound formation, compatible for nucleating graphite with less eutectic undercooling. Attention is drawn to ensuring a control factor (%Mn) × (%S) equals 0.03 -0.06, accompanied by 0.005-0.010% Al and/or Zr content in inoculated grey irons.

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Section: Recommendations For Foundry Applicationmentioning

confidence: 99%

Enhanced Quality in Electric Melt Grey Cast Irons

2013

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“…This can be suppressed by adding rare earth elements (RE) with a proper stoichiometric ratio into molten metal containing an appropriate amount of S and Mn [9][10][11][12], as the resulting complex sulfide acts as a core for graphite [13,14]. Unfortunately, the cost of most RE elements makes them commercially unsuitable for cast iron products.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of High-Strength Gray Cast Iron Using Permanent Magnet Scrap

Park

Kim

Seo

et al. 2017

Archives of Metallurgy and Materials

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In this study, we have developed the manufacturing technology for high strength gray cast irons by using the spent permanent magnet scraps. The cast specimen inoculated by using a spent magnet scraps showed the excellent tensile strength up to 306MPa. This tensile strength value is 50MPa higher than that of the specimen cast without inoculation, and is similar to that of the specimen inoculated by using the expensive misch-metal. These superior mechanical properties are attributed to complex sulfides created during solidification that promote the formation and growth of Type-A graphite. It is therefore concluded that spent magnets scrap can provide an efficient and cost-effective inoculation agent for the fabrication of high-performance gray cast iron.

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“…Production of castings (especially thin-walled) of ductile iron, in loose self-hardening molding sands with furfuryl resin hardened by paratoluenesulfonic acid, brings a danger of forming defected casting microstructure, which the most often occurs in its surface layer (Ref [1][2][3][4][5][6][7][8][9][10]. This unfavorable effect is caused by sulfur contained in a hardener of resin binders, which enters the surface layer causing degradation of a nodular graphite into flake graphite.…”

Section: Introductionmentioning

confidence: 99%

Effect of Reclamation on the Skin Layer of Ductile Iron Cast in Furan Molds

Dańko

Holtzer

Górny

et al. 2013

J. of Materi Eng and Perform

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The paper presents the results of investigations of the influence of the quality of molding sand with furan resin hardened by paratoluenesulfonic acid, on the formation of microstructure and surface quality of ductile iron castings. Within the studies different molding sands were used: molding sand prepared with fresh sand and molding sands prepared with reclaimed sands of a different purification degree, determined by the ignition loss value. Various concentrations of sulfur and nitrogen in the sand molds as a function of the ignition loss were shown in the paper. A series of experimental melts of ductile iron in molds made of molding sand characterized by different levels of surface-active elements (e.g., sulfur) and different gas evolution rates were performed. It was shown that there exists a significant effect of the quality of the sand on the formation of the graphite degeneration layer.

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Surface graphite degeneration in ductile iron castings for resin molds

Cited by 37 publications

References 0 publications

Enhanced Quality in Electric Melt Grey Cast Irons

Enhanced Quality in Electric Melt Grey Cast Irons

Fabrication of High-Strength Gray Cast Iron Using Permanent Magnet Scrap

Effect of Reclamation on the Skin Layer of Ductile Iron Cast in Furan Molds

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