Digital Image Analysis Technique for Characterization of Shrinkage and Gas (Air) Porosity in Cast Magnesium Alloys

Balasundaram, A.; Gokhale, A.M.

doi:10.1002/9781118805497.ch28

Cited by 5 publications

(5 citation statements)

References 11 publications

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“…These effects severely limit the elongation of the alloy [4][5][6][7][8][9]. Generally, the pores are formed by residual gas in the castings and the gas involved in the filling process of a metallic liquid [10,11]. Vacuum die casting has attracted extensive attention as an advanced die casting technology that uses vacuum technology to remove air in the mold cavity for the purpose of reducing the casting porosity and enhancing the mechanical properties [12][13][14][15][16].…”

Section: Introductionmentioning

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: Introductionmentioning

confidence: 99%

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

et al. 2020

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“…Currently, AZ91D alloy is used mainly in the high pressure die casting for structural components. However, HPDC components contain a substantial amount of defects due to gas entrapment and solidification shrinkage [3]. The defects not only affect mechanical properties, but also deny the opportunity for property enhancement by heat treatment.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and Property of Rheo-Diecasting Magnesium-Alloy with Forced Convection Mixing Process

Zhou

Kang

et al. 2014

SSP

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Taking AZ91D magnesium alloy as experimental material, the rheo-diecasting process was implemented by combining the self-developed forced convection rheomoulding device with high pressure die casting machine. Microstructural characteristics of the RDC tensile samples were discussed. Microstructure of semisolid slurry at different rotational speed prepared by FCR device was investigated. Tensile properties and fracture morphology of rheo-diecasting process in different conditions were studied as well. The results indicate that the excellent semisolid microstructure of AZ91D tensile samples can be obtained by forced convection rheo-diecasting process. With the increase of rotational speed, the mean size of the primary particles diminishes and the shape factor increases. The tensile properties of as-cast RDC samples are obviously better than conventional diecasting samples. T6 heat treatment can increase tensile strength and elongation of RDC tensile samples to 286MPa and 6.1%, respectively. The yield strength and elongation of T4 heat treated RDC samples are 100MPa and 12.6%.

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“…Mg-Al based alloys offer a good combination of castability, mechanical properties and corrosion resistance [1][2][3], are the most widely used commercial magnesium among aerospace, automotive and 3C industry. Currently, the applications of the Mg alloys are mainly achieved by high pressure die-cast in automotive industry, due to high efficiency, low cost and produce complex parts [3,4]. While, Service temperature of Mg-Al alloys cannot exceed 120 ℃, because of β-Mg 17 Al 12 phase is easy to soften [5,6].…”

Section: Introductionmentioning

confidence: 99%

Influence of Heat Treatment on Microstructure and Mechanical Properties of Die-Cast AZ91D Alloy with RE Elements

Yuan

Zhang

et al. 2014

AMM

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The effect of online solution and subsequent age heat treatment on microstructure and mechanical properties of die-cast AZ91D +1wt. %RE alloy were researched. The results indicated that online solution heat treatment led to inhibit some β-Mg17Al12 phase precipitation, and remained the Al element in matrix plays a role of solid solution strengthening. The online solution samples were aged at 160°C, 180°Cand 200°C. Microstructure results suggested that age treatment caused some lamellar β-Mg17Al12 phases precipitated near grain boundaries. The tensile properties of samples under air cool, online solution and subsequent age heat treatment were tested, which UTS were 194 MPa, 243 MPa and 244 MPa, and the elongation were 3.67%, 3.97% and 1.6%, respectively. The results indicated that the online solution could enhance the mechanical properties significantly, which the subsequent age heat treatment could not improve.

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Digital Image Analysis Technique for Characterization of Shrinkage and Gas (Air) Porosity in Cast Magnesium Alloys

Cited by 5 publications

References 11 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

Microstructure and Property of Rheo-Diecasting Magnesium-Alloy with Forced Convection Mixing Process

Influence of Heat Treatment on Microstructure and Mechanical Properties of Die-Cast AZ91D Alloy with RE Elements

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