Microstructure and mechanical properties of pearlitic gray cast iron

Collini, Luca; Nicoletto, Gianni; Konečná, Radomila

doi:10.1016/j.msea.2007.11.070

Cited by 182 publications

(120 citation statements)

References 18 publications

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“…As shown in Fig. 4(b), the quenched matrix microstructure is changed from the bainite structure combined with lath-shaped martensite to pearlite (P) structure (α + Fe 3 C) across the interface [10]. Because the axial temperature gradient during directional solidification, the γ matrix was quenched from different temperatures, which leads to different quenched microstructures at different locations in the mushy zone, even within the same phase region of γ + G. This effect is likely the reason why the quenched matrix microstructures are different in Figs.…”

Section: Microstructure Evolution During Directional Solidificationmentioning

confidence: 99%

Microstructure evolution in grey cast iron during directional solidification

Ding

Feng

et al. 2017

Int J Miner Metall Mater

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Abstract:The solidification characteristics and microstructure evolution in grey cast iron were investigated through Jmat-Pro simulations and quenching performed during directional solidification. The phase transition sequence of grey cast iron was determined as L → L + γ → L + γ + G → γ + G → P (α + Fe 3 C) + α + G. The graphite can be formed in three ways: directly nucleated from liquid through the eutectic reaction (L → γ + G), independently precipitated from the oversaturated γ phase (γ → γ + G), and produced via the eutectoid transformation (γ → G + α). The area fraction and length of graphite as well as the primary dendrite spacing decrease with increasing cooling rate. Type-A graphite is formed at a low cooling rate, whereas a high cooling rate results in the precipitation of type-D graphite. After analyzing the graphite precipitation in the as-cast and transition regions separately solidified with and without inoculation, we concluded that, induced by the inoculant addition, the location of graphite precipitation changes from mainly the γ interdendritic region to the entire γ matrix. It suggests that inoculation mainly acts on graphite precipitation in the γ matrix, not in the liquid or at the solid-liquid front.

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Section: Microstructure Evolution During Directional Solidificationmentioning

confidence: 99%

Microstructure evolution in grey cast iron during directional solidification

Ding

Feng

et al. 2017

Int J Miner Metall Mater

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“…E-mail: kassiazzoug@gmail.com Overseas Foundry are in relation to the nucleation process and morphological transformations of graphite. The latter is dependent on the tensile strength of the cast iron (cracking sites) and the corrosion behavior in some corrosive environments [7,10,[19][20][21][22] .…”

Section: *M O Azzougmentioning

confidence: 99%

“…Kesseri et al [3] have also shown that the addition of niobium in chromium-rich cast irons improves the mechanical properties by the formation of MC-type niobium carbides. Similarly, the inoculation elements have a strong affinity to oxygen and sulfur [8][9][10][11] . Thus, oxides and sulphides of a homogeneous or heterogeneous nature formed in the melt give the graphite nucleation sites [12][13][14] .…”

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confidence: 99%

Niobium addition effect in molds at last cooling step on EN-GJL250 gray cast iron: Microstructural changes and electrochemical behavior

et al. 2018

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I t is well established that the variety of applications of cast iron is attributed to the presence of chemical elements in the solid solution as interstitial or substitutional form, such as so-called addition elements Ni, Cu, Ti, Cr, V and Nb [1][2][3][4] , and inoculation elements Al, Si, Ca, Sr, Mn, Zr, P, Sn and Ce [5][6][7] .In the foundry, additions are done by controlling the Abstract:The purpose of this study was to determine the impact of niobium addition as an inoculation element on the microstructure and electrochemical properties of EN-FGL250 gray cast iron. Niobium additions are in a powder form and have a 0.5 mm particle size at dfferent proportions of 1wt.% and 3wt.%. The addition was done during casting of the metal in the mold at the last cooling step of the melt cast iron. These additions have a significant impact on the phenomenon of solidification as the metal powder deposited in the sand molds creates new centers of germination and absorbs a lot of heat. The cooling rate directly affects the microstructure and electrochemical behavior. This is confirmed by SEM observations and electrochemical tests. Furthermore, the addition of niobium transforms the microstructure of gray cast iron from cellular structure into totally dendritic structure. As a consequence, the niobium addition affected the shape and size of graphite, thus considerably reducing the corrosion current density by increasing the polarization resistance R p . chemical composition of the melt rather than equivalent carbon, alloying elements and inoculation products. The minor additions of alloying elements for their affinities to carbon can be used to improve the mechanical properties of the cast iron mainly by the formation of M 7 C 3 , M 3 C and MC type carbides. Filipovic et al. [4] have shown that variable proportions of additions of niobium and vanadium to the hypoeutectic white cast iron containing 19% chromium modify its microstructure and affect its wear and hardness properties. Kesseri et al. [3] have also shown that the addition of niobium in chromium-rich cast irons improves the mechanical properties by the formation of MC-type niobium carbides. Similarly, the inoculation elements have a strong affinity to oxygen and sulfur [8][9][10][11] . Thus, oxides and sulphides of a homogeneous or heterogeneous nature formed in the melt give the graphite nucleation sites [12][13][14] . Some authors suggested that the Mn/S ratio affects the nucleation and morphology of graphite [15,16] . Other authors [17,18] indicated that the inoculations elements *M. O. Azzoug Male, born in 1979, Teacher (assistant master) at University of Sciences and Technology Houari Boumedienne Algiers, Algeria, also Ph.D student in Materials Science and Engineering. He is currently working on the development of a surface treatment process for gray cast irons directly in the manufacturing stage of parts without resorting to conventional (physical or chemical) surface treatments by metal deposition process or surface treatment. The influence of additions in ...

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“…The used material reveals the presence of a gray cast iron with lamellar graphite, graphite fine slides uniformly distributed in ferrite-pearlite mass base. A perlitic basic mass with fine graphite and homogeneous spread shows the 100 time higher wear resistance than a grey iron with ferrite based and graphite heterogeneous spread [18,19,20].…”

Section: Microstructural Analysismentioning

confidence: 99%