On the porosity induced by externally solidified crystals in high-pressure die-cast of AM60B alloy and its effect on crack initiation and propagation

Li, X.; Xiong, Shoumei; Guo, Zhipeng

doi:10.1016/j.msea.2015.02.078

Cited by 71 publications

(15 citation statements)

References 22 publications

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“…1a. The observation of the microstructure and 3-D scanning of the X-ray tomography samples were the same as that reported by Li et al (2015). The axial fatigue tests were performed with a strain ratio of R = 0.1, a maximum cyclic stress of S max = 170 MPa, and a constant frequency of f = 10 Hz.…”

Section: Methodsmentioning

confidence: 97%

“…Niu et al (2000), Patel et al (2012), Wen et al (2012) and Wan et al (2013) studied the vacuum-assist HPDC process, and suggested that the improved mechanical properties could be attributed to the reduction of gas pores. Li et al (2015) reported that the shrinkage pores, induced by the ESCs, was shown to be one of the crack initiation sources in die castings, but there was little attention paid to the method of preventing ESCs from entering the die cavity to reduce the subsequently induced shrinkage pores.…”

Section: Introductionmentioning

confidence: 99%

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Improved mechanical properties in vacuum-assist high-pressure die casting of AZ91D alloy

Xiong

Zhang

2016

Journal of Materials Processing Technology

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Section: Methodsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Improved mechanical properties in vacuum-assist high-pressure die casting of AZ91D alloy

Xiong

Zhang

2016

Journal of Materials Processing Technology

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“…[9][10][11] Recently, three-dimensional (3D) porosity visualization studies have been extensively carried out through reconstruction from montage serial 2D sections 12,13) or high resolution X-ray computed tomography technology. [14][15][16][17] These quantitative analysis techniques make it possible to measure the porosity level with high accuracy, whereas their applications are limited to 2D metallographic sections or small-size specimens cut from HPDC castings. 15) To date the porosity levels in large-size HPDC castings are generally evaluated by measuring the density of the castings using Archimedes method.…”

Section: Introductionmentioning

confidence: 99%

Correlation between Density and Microstructural Features in Vacuum Die Cast AZ91D Magnesium Alloy

2017

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Vacuum die castings of AZ91D magnesium alloy were produced at different slow shot speeds and the correlation between density and microstructural features in the vacuum die castings were investigated. The density was measured by using Archimedes method. The microstructure was analyzed with optical microscope, scanning electron microscopy and image analysis software. It was found that the partially solidi ed gate can be early closed-off by large-size particles at low enough slow shot speeds, which causes high levels of porosity in the vacuum die castings and thus low densities of the castings. Archimedes method is not suitable for evaluating the porosity level in the vacuum die castings. Besides the porosity levels, the densities of the vacuum die castings are related to the ESCs contents in the castings and solidi cation conditions in the shot sleeve at the beginning of die lling.

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“…One of the key microstructure characteristics of die cast magnesium alloy is the appearance of relatively coarse dendrites which have been called "ESCs (Externally Solidified Crystals)" at the cross section of the castings. As for the microstructure characteristics and formation mechanism of the ESCs, systematic experimental studies have been carried out by the authors [5][6][7] and some metallurgists [8][9][10] . Especially combined with the research hotspot of microstructure simulation during various solidification processes [11][12][13] , a large amount of work has also been conducted regarding simulation of the dendritic growth of α-Mg with hcp (hexagonal close-packed) crystal structure [14,15] , and also microstructure simulation of die cast magnesium alloy considering the nucleation and growth of the ESCs [16] .…”

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confidence: 99%

Modeling studies on divorced eutectic formation of high pressure die cast magnesium alloy

Hua

Xiong

2018

China Foundry

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A s the lightest known structural metals, magnesium alloys have attracted much attention due to their superior properties such as low density, high specific strength, excellent castability, good machinability and recyclability [1,2] . Magnesium alloys have been widely used in automotive, aerospace and 3C (computer, communication and consumer electronics) industries to replace steel, cast iron and even aluminum alloy [3] . The high pressure die casting (HPDC) process is a netshape or near net-shape process with the advantages of high efficiency, considerable economic benefit and high precision of the product size. These remarkable advantages make the HPDC process particularly suitable for various complex productions with magnesium alloys, and generally, magnesium alloy parts are mainly formed by the HPDC process [4] .The performance of magnesium alloy die castings Abstract:The morphology and content of the divorced eutectic in the microstructure of high pressure die casting (HPDC) magnesium alloy have a great influence on the final performance of castings. Based on the previous work concerning simulation of the nucleation and dendritic growth of primary α-Mg during the solidification of magnesium alloy under HPDC process, an extension was made to the formerly established CA (Cellular Automaton) model with the purpose of modeling the nucleation and growth of Mg-Al eutectic. With a temperature field and solute field obtained during simulation of the primary α-Mg dendrites as the initial condition of the modified CA model, modeling of the Mg-Al eutectic with a divorced morphology was achieved. Moreover, the simulated results were in accordance with the experimental ones regarding the distribution and content of the divorced eutectic. Taking a "cover-plate" die casting with AM60 magnesium alloy as an example, the rapid solidification with a high cooling rate at the surface layer of the casting led to a fine and uniform grain size of primary α-Mg, while the divorced eutectic at the grain boundary revealed a more dispersed and granular morphology. Islands of divorced eutectic were observed at the central region of the casting, due to the existence of ESCs (Externally Solidified Crystals) which contributed to a coarse and non-uniform grain size of primary α-Mg. The volume percentage of the eutectic β-Mg 17 Al 12 phase is about 2%-6% in the die casting as a whole. The numerical model established in this study is of great significance to the study of the divorced eutectic in the microstructure of die cast magnesium alloy.

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On the porosity induced by externally solidified crystals in high-pressure die-cast of AM60B alloy and its effect on crack initiation and propagation

Cited by 71 publications

References 22 publications

Improved mechanical properties in vacuum-assist high-pressure die casting of AZ91D alloy

Improved mechanical properties in vacuum-assist high-pressure die casting of AZ91D alloy

Correlation between Density and Microstructural Features in Vacuum Die Cast AZ91D Magnesium Alloy

Modeling studies on divorced eutectic formation of high pressure die cast magnesium alloy

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