Measurements and modeling of air gap formation in iron-base alloys

Lagerstedt, Anders; Kron, J.; Yosef, Futsum Hailom; Fredriksson, Hasse

doi:10.1016/j.msea.2005.08.165

Cited by 23 publications

(16 citation statements)

References 12 publications

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“…The accurate modelling of the casting-mould interfacial heat transfer is seen as crucial but very difficult since it is connected with many key factors like superheat, latent heat, casting alloys and mould material. The researches on the heat transfer at the casting-mould interface including gas-gap formation during solidification of the casting have been done numerically and experimentally for different alloys (Kron et al, 2002(Kron et al, , 2004Harste and Schwerdtfeger, 2003;Lagerstedt et al, 2005). Lewis et al (Zhang et al, 1994) have employed a complex multi-constitutive thermo-mechanical model to predict the air widths.…”

Section: Introductionmentioning

confidence: 99%

Analysis of heat transfer through the casting‐mould interface including gas‐gap effect and application to TiAl castings

Wang

Djambazov²,

Pericleous³

2013

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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Purpose -The purpose of this paper is to describe how a 3D/1D transient heat transfer model has been developed for getting accurate thermal boundary conditions when investigating the heat transfer in the TiAl castings and also for reducing the computational cost and simplifying the mesh generation. Design/methodology/approach -Heat transfer in the mould is assumed to take place only in a direction perpendicular to the mould wall, called 1D heat transfer. The coordinates of cell centre and the temperature in the mould wall can be calculated by the model instead of meshing mould. Heat transfer in the mould is computed via the FD solution of a 1D heat transfer equation. Findings -For some types of geometry, the model works very well. However, for some, which contain the geometric feature called "dead corner", the model can't cover. There is some impact on the accuracy of the model. Practical implications -In the casting industry, the geometry of the casting is usually very complex and contains different features. This leads to difficult meshing when using numerical model to predict the casting process. Furthermore, an accurate calculation is very important on the thermal boundary during filling and solidification, to support practice, to improve the process and minimise the casting defects. Originality/value -In this paper, a novel method is developed to calculate the heat transfer through the casting-mould interface to the mould wall in a casting.

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Section: Introductionmentioning

confidence: 99%

Analysis of heat transfer through the casting‐mould interface including gas‐gap effect and application to TiAl castings

Wang

Djambazov²,

Pericleous³

2013

International Journal of Numerical Methods for Heat &Amp; Fluid Flow

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“…Then the volume fraction of gas is (1 À U). In order to accurately track the free surface during mould filling, the Counter Diffusion Method (CDM) [16,18] is used, which was developed initially as a corrective mechanism to counter interface smearing present when using conventional method Van Leer [19]. This method discretizes the free surface equation into a stable, fully implicit scheme which makes the computations an order of magnitude faster.…”

Section: Mathematical Modelmentioning

confidence: 99%

“…Later, Lewis et al proposed a correlation [10][11][12] to adjust the interfacial heat transfer coefficient with respect to casting interface temperature. Researchers have been numerically and experimentally studied the effect of gap on heat transfer for different alloys [13][14][15][16]. We calculated the heat transfer across the casting-mould interface by 3D/1D model including the effect of air gap [17].…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of heat transfer through casting–mould with 3D/1D patched transient heat transfer model

Wang

et al. 2015

International Journal of Heat and Mass Transfer

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“…In general, the IHTC shows a high value in the initial stage of solidification and then declines to a low steady value because the casting contracts from the mold surface, creating an interfacial gap. According to the truth that the reduction of the interfacial gap could increase the IHTC and the cooling rate, [6][7][8] we developed a new solidification process as NIGPMC to obtain a higher cooling rate. The key point of the new method is the introduction of a melt-mold, made of low-melting-point materials, which can be melted to eliminate the interfacial gap during solidification.…”

mentioning

confidence: 99%

“…Figure 4 depicts the heat transfer between the metal and the mold in CPMC and NIGPMC. The whole process of the interfacial heat transfer in CPMC can be divided into four stages [8] as schematized in Figures 4(a) through (d). For comparison, the process of the NIGPMC also contains four stages as indicated in Figures 4(e) through (h).…”

mentioning

confidence: 99%

Improving Cooling Rate During Solidification by Eliminating the Metal–Mold Interfacial Gap

Zeng

Zhang

et al. 2015

Metall Mater Trans A

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A new solidification process called non-interfacial-gap permanent-mold casting (NIGPMC) is proposed to improve the cooling rate by eliminating the metal-mold interfacial gap. High-Cr steel ingots were prepared by this process and conventional permanent-mold casing (CPMC) separately. Comparing with CPMC, the primary dendrite arm spacing obtained by NIGPMC is greatly refined. It is demonstrated that the NIGPMC is a promising pathway to refine the microstructure of the large ingot.A higher cooling rate is desired in the solidification processes because materials fabricated under this condition have several benefits, such as finer microstructure, extended solid solubility, improved strength, and better corrosion behavior. [1][2][3][4] It is known that the cooling rate is directly determined by the heat transfer which is regulated not only by the heat storage capacity of the mold material, but also by the heat transfer conditions within the metal itself and particularly at the metalmold interface. [1] To date, the investigations performed for improving cooling rate are mostly focused on the former using the water-cooled copper mold and the phasetransition-materials-cooled copper mold. [1,5] However, there are few studies on enhancing the heat transfer at the metal-mold interface.The heat extraction capacity of the metal-mold interface can be characterized by the metal-mold interfacial heat transfer coefficient (IHTC) that is a power function of time [6] :where h is the IHTC in units of W/m 2 K, t is time in seconds, and C i and n are constants depending on alloy composition, chill material, and superheat. In general, the IHTC shows a high value in the initial stage of solidification and then declines to a low steady value because the casting contracts from the mold surface, creating an interfacial gap. According to the truth that the reduction of the interfacial gap could increase the IHTC and the cooling rate, [6][7][8] we developed a new solidification process as NIGPMC to obtain a higher cooling rate. The key point of the new method is the introduction of a melt-mold, made of low-melting-point materials, which can be melted to eliminate the interfacial gap during solidification. For a better understanding of this process, we also studied the CPMC and quantificationally investigated the macro-and microstructure. Figure 1 presents the schematics of the conventional permanent-mold and the NIG permanent-mold. In these two processes, both of the permanent-molds are made of H13 steel with the chemical composition (wt pct) 0.4 C, 1.0 Si, 0.4 Mn, 5.1 Cr, 1.3 Mo, and 1.0 V. In the NIGPMC, the melt-mold is made of 6061 aluminum alloy with chemical composition (wt pct) 0.3 Cu, 1.0 Mg, 0.12 Mn, 0.25 Zn, 0.04 Cr, 0.6 Si, and 0.7 Fe. The sizes of these molds are also shown in Figure 1. In order to further clarify the mechanism of the NIGPMC, a K-type thermocouple was inserted into the melt-mold for recording the temperature profile.A high-Cr steel X12CrMoWVNbN10-1-1 (refer to X12 hereafter) with the chemical composition (wt pct)...

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Measurements and modeling of air gap formation in iron-base alloys

Cited by 23 publications

References 12 publications

Analysis of heat transfer through the casting‐mould interface including gas‐gap effect and application to TiAl castings

Analysis of heat transfer through the casting‐mould interface including gas‐gap effect and application to TiAl castings

Numerical modeling of heat transfer through casting–mould with 3D/1D patched transient heat transfer model

Improving Cooling Rate During Solidification by Eliminating the Metal–Mold Interfacial Gap

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