Quantitative Estimation of Formation of Shrinkage Porosity by the Niyama Criterion

Ivanina, E. S.; Monastyrskiy, V. P.; Ershov, M. Yu.

doi:10.1134/s2075113322010130

Cited by 4 publications

(3 citation statements)

References 7 publications

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“…Selain simulasi langsung, berbagai kriteria digunakan untuk memperkirakan pembentukan shrinkage berdasarkan parameter termofisika dari proses solidifikikasi [14]. Salah satu kriteria yang sering digunakan adalah Niyama kriteria [14]- [16]. Niyama kriteria adalah kriteria paling penting untuk prediksi porositas akibat shrinkage [15].…”

Section: Niyama Kriteriaunclassified

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Evaluasi Efisensi Riser Untuk Bentuk Riser Samping yang Berbeda Menggunakan Metode Simulasi Casting

Bahari,

Tulung Prayoga

2023

infotekmesin

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As the solidification reaches the hot spot area, no molten metal remains and shrinkage is formed. To anticipate the shrinkage, a riser is added to the casting system. An optimal riser design would produce free shrinkage components. One of the factors that affect riser efficiency is the riser shape. This study aims to find the most efficient side riser shape by using simulation software. The riser shape of tubes, tubes with a half sphere on top, hemispheres, conical tubes, tubes with an oval cross-section, and cubes are used in this experiment, with the volume of all risers kept constant. The most efficient shape of the riser is the tube. The tube riser produces a larger modulus. The tube riser generated directional solidification. The same pattern can be seen in the niyama criteria and solidification temperature, where the tube riser has a more continuous pattern compared to other riser shapes.

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Section: Niyama Kriteriaunclassified

“…Jika niyama kriteria lebih rendah dari nilai kritis, maka pembentukan shrinkage pasti terjadi. Namun, belum ada nilai kritis niyama kriteria yang pasti yang ditetapkan untuk macam material yang berbeda [14].…”

Section: Niyama Kriteriaunclassified

Evaluasi Efisensi Riser Untuk Bentuk Riser Samping yang Berbeda Menggunakan Metode Simulasi Casting

Bahari,

Tulung Prayoga

2023

infotekmesin

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“…Even above the critical number, a range of values reveals the existence of microporosity [9]. The criterion was built under the statement that links the Ny value and the pressure drop in the mushy zone [8,10]. Although the Ny critical value depends on the material, and, particularly, Niyama et al obtained values in the range 0.9-1.5 K 1/2 min 1/2 cm −1 , they stated for steel a value of 1 K 1/2 min 1/2 cm −1 as the critical one.…”

Section: Introductionmentioning

confidence: 99%

A Methodology to Define the Niyama Criterion Reinforced with the Solid Fraction Analysis: Application to Sand Casting of Steel Bars

Manjabacas,

Miguel

2023

Metals

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Niyama and solid fraction criteria are used to predict the solidification porosity and microporosity in computing simulation of casting processes. The solid fraction permits us to determine the areas that solidify last and that are a candidate for presenting porosity if a feeding system is not correctly designed. The Niyama criterion is locally obtained based on the thermal and cooling gradients at a point of the liquid casting. The Niyama value at a casting point varies rapidly from low rates to high ones during the last part of the metal solidification, which demands that the percentage of solidification of the metal is defined to determine the Niyama number. In addition, the Niyama threshold that establishes the soundness of the workpiece can vary according to the nature of the metal or the casting system. In this paper, a methodology to determine the solidification percentage is presented. The method is based on the Niyama number evolution during the solidification process at different key points. These points are validated by the solid fraction criterion as healthy or, on the contrary, as candidates for containing porosity. In addition, some considerations of the solid fraction criterion are visited since the threshold value for which the isolation of the last solidification areas can be defined is not clear. The research is validated by the empirical casting criteria existing in the literature for obtaining sound parts and applied to low-carbon steel bars produced by sand casting.

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Prediction of Porosity and Hot Tearing in Direct Chill Casting of AZ31 Magnesium Alloy

Divya

Penumakala

Nallathambi

2023

Trans Indian Inst Met

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Quantitative Estimation of Formation of Shrinkage Porosity by the Niyama Criterion

Cited by 4 publications

References 7 publications

Evaluasi Efisensi Riser Untuk Bentuk Riser Samping yang Berbeda Menggunakan Metode Simulasi Casting

Evaluasi Efisensi Riser Untuk Bentuk Riser Samping yang Berbeda Menggunakan Metode Simulasi Casting

A Methodology to Define the Niyama Criterion Reinforced with the Solid Fraction Analysis: Application to Sand Casting of Steel Bars

Prediction of Porosity and Hot Tearing in Direct Chill Casting of AZ31 Magnesium Alloy

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