Kinetic analysis of pore formation in die-cast metals and influence of absolute pressure on porosity

Cao, Hong‐Tao; Wang, Yuming; Shan, Qianyuan; Che, Junqi; Luo, Ziwei; Wang, Luhan; Huang, Mengtao

doi:10.1016/j.vacuum.2019.108828

Cited by 23 publications

(2 citation statements)

References 25 publications

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“…Cao et al discussed the effect of the absolute pressure in the cavity on the pore defects of die castings [28]. In the vacuum die-casting process, the formation of eddy currents during the filling of molten metal is the main cause of void defects.…”

Section: Calculation Of Density and Porositymentioning

confidence: 99%

The Stress Concentration Mechanism of Pores Affecting the Tensile Properties in Vacuum Die Casting Metals

et al. 2020

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The absolute pressure strongly affects the porosity and mechanical properties of castings produced by vacuum high-pressure die casting (V-HPDC) technology. The pore size, quantity and distribution of AlSi9Cu3 samples under three absolute pressures were evaluated by X-ray tomography and optical and electron microscopy. The paper presents an elaboration the stress concentration mechanism of pores affecting the tensile properties. According to a mathematical analysis of a sample under uniaxial stress, the greater the radius of the pore, the higher the stress value is at the pore perimeter. When the absolute pressure drops from 1013 mbar to 100 mbar, the porosity decreases from 6.8% to 2.8%, and the pore number and mean size decreases. In tensile tests, the pore sizes of the fracture surface decrease with decreasing absolute pressure, and the pore distribution becomes uniform. The tensile properties and extensibility of the sample are improved, and the microscopic fracture surface of the sample changes from cleavage fracture to quasi-cleavage fracture. The number, size and distribution of pores in die casting collectively affect the properties of the sample. Large-size or complex pores or pores with concentrated distributions produce large stress concentrations, decreasing the strength of the metal.

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Section: Calculation Of Density and Porositymentioning

confidence: 99%

The Stress Concentration Mechanism of Pores Affecting the Tensile Properties in Vacuum Die Casting Metals

et al. 2020

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“…Additionally, T6 heat treatment and welding are difficult in some cases. In particular, heat treatment by blistering on the surface of thin castings is very difficult [1][2][3]. Gas porosity occurs as a result of the lubricating oil (nitrogen formation), release agent (hydrogen formation), and air entrapment during the filling process.…”

Section: Introductionmentioning

confidence: 99%

Effect of Injected Oxygen Amount on the Gas Porosity and Mechanical Properties of a Pore-Free Die-Cast Al–Si–Cu Alloy

Kang

Jang

et al. 2021

Metals

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With the rise in the demand for eco-friendly and electric vehicles, welding and heat treatment are becoming very important to meet the necessary weight reduction, complexity, and high functionality of die castings. Pore-free (PF) die casting is an effective process that enables heat treatment and welding due to low gas porosities. Indeed, this process affords castings of low gas porosity, similar to those attained by high-vacuum die casting. In this study, we compared the gas porosities of different castings fabricated by PF die casting using varied injected oxygen amounts. The castings were all subjected to T6 heat treatment and analyzed by computed tomography (CT) to compare their microstructure and mechanical properties before and after T6 heat treatment. The results revealed that with the increasing injected oxygen amount, the gas porosity of the specimens decreased while their mechanical properties increased. In particular, the gas porosity was the lowest at 1.26 L. Moreover, the 1.26 L specimen displayed the best tensile strength, yield strength, and elongation results. Finally, Weibull distribution analysis revealed that the tensile strength and elongation repeatability and reproducibility increased with increasing injected oxygen amount.

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Elimination Mechanism of Shrinkage Porosity During Pressurized Solidification Process of 19Cr14Mn4Mo1N High-Nitrogen Steel Ingot

Zhu

et al. 2023

Metall Mater Trans B

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Kinetic analysis of pore formation in die-cast metals and influence of absolute pressure on porosity

Cited by 23 publications

References 25 publications

The Stress Concentration Mechanism of Pores Affecting the Tensile Properties in Vacuum Die Casting Metals

The Stress Concentration Mechanism of Pores Affecting the Tensile Properties in Vacuum Die Casting Metals

Effect of Injected Oxygen Amount on the Gas Porosity and Mechanical Properties of a Pore-Free Die-Cast Al–Si–Cu Alloy

Elimination Mechanism of Shrinkage Porosity During Pressurized Solidification Process of 19Cr14Mn4Mo1N High-Nitrogen Steel Ingot

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