Eutectic Carbide Formation in High Mn Ductile Iron

Nili‐Ahmadabadi, Mahmoud; Niyama, Eisuke; Ohide, Taku

doi:10.1080/09534962.1994.11819148

Cited by 12 publications

(15 citation statements)

References 6 publications

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“…The function depends on two parameters, N s and b, whose physical meanings have been established in Eqs. [7], [11], and [14], respectively. In addition, notice that the qualitative properties of the function given by Eq.…”

Section: Theoretical Modelmentioning

confidence: 99%

“…(1) increasing strength and ductility in ADI iron, [5] (2) reducing microsegregation of alloying elements [6,7] and improving microstructural homogeneity (here, the type of eutectic transformation, stable or metastable, is also influenced due to the redistribution of alloying elements); (3) reducing the chilling tendency of cast iron; [8,9] (4) increasing preshrinkage expansion; [3] and (5) increasing the fraction of ferrite in the microstructure. [10] Accordingly, it can be stated that graphite eutectic cell and nodule count influenced some important factors for foundry practice.…”

Section: Introductionmentioning

confidence: 99%

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Graphite Nodule and Eutectic Cell Count in Cast Iron: Theoretical Model Based on Weibull Statistics and Experimental Verification

Fraś

Wiencek

Górny

et al. 2007

Metall Mater Trans A

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In this work, a model is proposed for heterogeneous nucleation on substrates whose size distribution can be described by the Weibull statistics. It is found that the nuclei density, N nuc can be given in terms of the maximum undercooling, DT m , by N nuc = N s exp (-b/DT m ), where N s is the density of nucleation sites in the melt and b is the nucleation coefficient (b > 0). When nucleation occurs on all possible substrates, the graphite nodule density, N V,n , or eutectic cell density, N V , after solidification equals N s . In this work, measurements of N V,n and N V values were carried out on experimental nodular and flake graphite iron castings processed under various inoculation conditions. The volumetric nodule N V,n or graphite eutectic cell N V count was estimated from the area nodule count, N A,n , or eutectic cell count, N A , on polished cast iron surface sections by stereological means. In addition, maximum undercoolings, DT m , were measured using thermal analysis. The experimental outcome indicates that the N V,n or N V count can be properly described by the proposed expression N V,n = N V = N s exp (-b/DT m ). Moreover, the N s and b values were experimentally determined. In particular, the proposed model suggests that the size distribution of nucleation sites is exponential in nature.

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Section: Theoretical Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Graphite Nodule and Eutectic Cell Count in Cast Iron: Theoretical Model Based on Weibull Statistics and Experimental Verification

Fraś

Wiencek

Górny

et al. 2007

Metall Mater Trans A

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“…In addition, the additions of Ni and Mo have been found to exhibit low strength and low hardness but high elongation and high impact energy, 28 but significant segregation of Mo during solidification occurs and forms Mo rich carbides in the cell boundaries, which causes iron embrittlement. [29][30][31] Therefore, in this study, Ni was added in some heats.…”

Section: Introductionmentioning

confidence: 99%

Assessments of relationship between microstructures and mechanical properties for heavy section ductile cast irons

Pan

Lin

Chang

2012

International Journal of Cast Metals Research

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The relationships between microstructures and mechanical properties of heavy section ductile cast irons used in large scale wind turbines have been assessed in this study. In addition, the required conditions for meeting either the tensile property requirements (z10%) or the impact toughness requirements (z10%) of specification EN-GJS-400-18U-LT for heavy section ductile cast irons have been obtained. Furthermore, the optimal conditions in terms of microstructure (nodule count and pearlite content) and tensile properties for fully complying with specification EN-GJS-400-18-U-LT have been established and are summarised as follows: 112 mm 22 (NC (Nodule Count)(173 mm 22 , 3%(P (Pearlite)(6%, 407 MPa(TS (Tensile Strength)(438 MPa, El (Elongation)>16?2%. Please define 'NC', 'P', 'TS' and 'El.' at the first mention. In addition, the change in I 220uC value as a function of casting section thickness or casting modulus Mc 2 had been drawn. Finally, late inoculation can be considered a crucial and necessary step in melt treatments to attain satisfactory microstructures and hence to conform to the target specification.

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“…6,[12][13][14] As mentioned before, in nodular cast iron each graphite nucleus gives rise to a single graphite nodule, consequently the nucleation stage establishes the final nodule count. Among the property improvements related to increasing nodule counts are, (a) an increase in the strength and ductility of ADI iron, 15) (b) improved microstructural homogeneity, 16,17) (c) reduction in the chilling tendency, 18,19) (d) increasing pre-shrinkage expansion 10) and (e) increasing fraction of ferrite in the microstructure. 20) Hence, it can be stated that graphite eutectic cells or graphite nodules play a significant role in the exhibited properties of cast iron and consequently they are key microstructural factors in the foundry practice.…”

Section: Introductionmentioning

confidence: 99%

Eutectic Cell and Nodule Count in Cast Iron: Part I. Theoretical Background

2007

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In this work, heat balance is incorporated in developing expressions of general validity for the solidification of hypo-eutectic flake graphite cast iron, as well as eutectic and slightly hyper-eutectic nodular iron. These expressions incorporate the active nucleation and growth processes that occur in flake and nodular graphite. The derived analytical equations describe the eutectic cell N and nodule count N n as a function of the solidification parameters and melt chemistry. From this analysis, eutectic cell or nodule counts can be predicted based on experimental data related to cooling rates and chemical composition. In particular, it has been found that the quality of the liquid cast iron is closely tied to its intrinsic nucleation properties (N s and b coefficients in the nucleation equation, N nuc ϭN s exp(Ϫb/DT m )), or directly to the graphite nuclei density, N nuc . Moreover, the outcome of the present work is used in providing a rational for the effect of technological factors such as the material mold ability to absorb heat, the casting modulus, pouring temperature, chemistry, inoculation practice, holding temperatures and times on the resultant cell count or nodule count in cast iron.KEY WORDS: gray cast iron; nodular cast iron; eutectic cell count; nodule count. 259

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Eutectic Carbide Formation in High Mn Ductile Iron

Cited by 12 publications

References 6 publications

Graphite Nodule and Eutectic Cell Count in Cast Iron: Theoretical Model Based on Weibull Statistics and Experimental Verification

Graphite Nodule and Eutectic Cell Count in Cast Iron: Theoretical Model Based on Weibull Statistics and Experimental Verification

Assessments of relationship between microstructures and mechanical properties for heavy section ductile cast irons

Eutectic Cell and Nodule Count in Cast Iron: Part I. Theoretical Background

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