The Effect of Increasing Silicon on Mechanical Properties of Ductile Iron

Arshad, Waseem; Mehmood, Amjad; Hashmi, M.F.; Rauf, Obaid ur

doi:10.1088/1742-6596/1082/1/012059

Cited by 5 publications

(1 citation statement)

References 7 publications

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“…For Arshad et al [10], the silicon content increased the elongation of graphite nodules to a certain extent and reduced the tensile strength. The increase in silicon content up to 2.8% generated a decrease in the ferrite content and reduced tensile strength.…”

Section: Machined Materialsmentioning

confidence: 93%

Influence of Si content on the machinability of ductile iron

Xavier¹,

Silva²,

Guesser³

et al. 2022

Tecnol. Metal. Mater. Min.

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The development of new chemical compositions of cast iron contributes to increasing the competitiveness of foundry and manufacturing companies that always seek to optimize the properties of these materials. Previous works detected machinability variation along the cross-section of nodular cast irons (DI) bars produced by continuous casting due to the variation of the microstructure and mechanical properties presented, with decreasing machinability from the periphery to the core. This variation imposes complications, as it implies different ideal (or optimal) cutting conditions along the crosssection of the round bars. Assays with ductile irons (DI) with varying silicon content showed that the reduction in silicon decreased the microhardness of ferrite and increased the percentage of pearlite in the matrix, thus generating a decrease in the ductility of the material. Thus, this work investigates the effect of silicon content on machinability variation along the cross-section of nodular cast iron bars in the turning process. Three different types of nodular cast iron alloys were used, differing by the amount of silicon in the composition. Material characterization and machining tests were carried out in three regions: the periphery, the intermediate region, and the core. The hardness, metallography, size of graphite nodules, and amount per region were analyzed in the characterization tests and compared to the evolution of wear and tool life machining force and surface roughness. The addition of different percentages of silicon did not avoid the differences in behavior between the three regions of the same material, but it changed the behavior of the three alloys studied. The silicon content affects the material's microstructure, which, together with the cooling rate, favors the differentiation of graphite nodules in different sizes, arrangements, and spacing. This differentiation contributes to the difference in the material's behavior in the machining between the regions along the cross-section. Strengthening in the core region was a trend in all three alloys. There was a statistical difference in roughness between the regions of the material. Cast iron with medium silicon content showed lower machining force and roughness values but close to those of high silicon. As with high-silicon cast iron, the forces remained at a more stabilized level, without significant variations between regions of the material.

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Section: Machined Materialsmentioning

confidence: 93%

Influence of Si content on the machinability of ductile iron

Xavier¹,

Silva²,

Guesser³

et al. 2022

Tecnol. Metal. Mater. Min.

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Effect of regular thicknesses on the microstructural and quantitative analysis for a hypo-eutectic ductile iron alloyed with Ni and V

Colin-García,

Sánchez-Alvarado,

Cruz-Ramírez

et al. 2024

J min metall B Metall

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Ductile iron contains free graphite nodules inside the metallic matrix, which generally consists of ferrite and pearlite in the as-cast condition. The casting thicknesses greatly influence on the size, shape, and quantity of the microconstituents of the metallic matrix and the graphite nodules and, therefore, on the mechanical properties. This investigation studied the cooling rate (imposed by the casting thicknesses) on the metallic matrix and the nodular characteristics of a ductile iron low alloyed with 0.8 %Ni and 0.15 %V. The ductile iron was manufactured by the sandwich technique with ladle inoculation. Six plates of different thicknesses, from 4.3 mm to 25.4 mm, were fabricated in a green sand mold. The microstructural characterization was performed by optical microscopy (OM), scanning electron microscopy (SEM), and the image J software by applying different quantification methods. The area method to obtain the average nodule size and nodularity provided more reliable results than the perimeter and total particle count methods. The hardness test on the Rockwell C scale carried out the mechanical characterization. The low content of vanadium added to the ductile cast iron had a negligible effect on the solidification pattern, mainly due to the graphitizing impact of the nickel and silicon addition. Thus, the microstructural features results are primarily due to the cooling rate imposed by the casting thickness. The thinnest casting section significantly improves the nodule count (414 Nod/mm2), sphericity (0.96), and nodularity (96.21 %). In contrast, the thickest casting plate obtained the highest volume fraction of graphite (10.85 %) and the lowest volume fraction of undesirable particles (0.36 %). The high cooling rate in the thinnest casting plate obtained the highest hardness of 31.56 HRC because of the higher contents of the volume fraction of pearlite (33.7 %) and carbides (4.5 %).

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Nodular Graphite Dissolution and Nucleus Observation: High-Temperature Dynamics of Ductile Iron Recycling

Adhiwiguna,

Nobakht,

Deike

2024

Metals

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This investigation examines the dynamic behavior of the nodular graphite structure in ductile cast iron at elevated temperatures during the recycling process. It comprises a systematic analysis of the impact of high temperature on the change in chemical composition, followed by a set of examinations of the nodular graphite structure dissolution mechanism at the early phase of the remelting process. The results indicate that prolonged holding at higher temperatures affects the carbon or silicon concentration due to oxidation, which correlates with the operating temperature and the dynamic concentration proportion of those two main alloying elements. It is also substantiated that the dissolution of nodular graphite, the only carbon source during the ductile cast iron remelting process, does not occur primarily in the liquid state but has already started during the solid phase because of austenitization. This dissolution is governed mainly by a surface reaction, as indicated by the residual graphite structure with preserved nonmetallic nuclei. Hence, this approach also provides an alternative method for observing the nodular graphite core by intentionally partially dissolving the graphite structure.

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The Effect of Increasing Silicon on Mechanical Properties of Ductile Iron

Cited by 5 publications

References 7 publications

Influence of Si content on the machinability of ductile iron

Influence of Si content on the machinability of ductile iron

Effect of regular thicknesses on the microstructural and quantitative analysis for a hypo-eutectic ductile iron alloyed with Ni and V

Nodular Graphite Dissolution and Nucleus Observation: High-Temperature Dynamics of Ductile Iron Recycling

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