Improved degassing efficiency and mechanical properties of A356 aluminium alloy castings by high shear melt conditioning (HSMC) technology

Lazaro-Nebreda, Jaime; Patel, J. S.; Fan, Z.

doi:10.1016/j.jmatprotec.2021.117146

Cited by 27 publications

(42 citation statements)

References 32 publications

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“…The non-degassed melts showed a density index of 13.1%, which decreased to 6.4% after the degassing tablet treatment and to 2.6% after HSMC degassing. This higher performance of the HSMC technology for degassing agrees with previous findings [16]. During HSMC with argon injection, all bubbles were captured and finely dispersed through the liquid metal into a large number of gas bubbles with a size much lower than 1 mm in diameter.…”

Section: De-gassing By Hsmc Of the Zorba Cast Fraction Re-melted Ingotssupporting

confidence: 91%

“…For the first crucible, 0.2 wt.% of degassing tablet (FOSECO Nitral C19) was added with manual stirring. The HSMC device and Argon gas pipe were immersed in the second crucible and degassing applied at an Argon flow rate of 0.1 l/min at a rotation speed of 3000 rpm for 15 min [16]. The details of the HSMC device and assembly have been described in previous publication [12].…”

Section: Methodsmentioning

confidence: 99%

“…HSMC also affects the entrapped oxide bi-films in the melt and transforms them into small and well dispersed particles which are much easier to attach to the generated bubbles and removed from the melt by flotation. In addition, the melt surface remains stable, with minimal disturbance and no vortex, which minimizes the re-absorption of hydrogen and creation of new oxide bi-films [16]. The improved melt quality had a direct effect on the microstructure and integrity of the castings.…”

Section: De-gassing By Hsmc Of the Zorba Cast Fraction Re-melted Ingotsmentioning

confidence: 99%

“…It can be applied to casting processes, such as direct chill casting and twin roll casting [14]. It not only provides refinement and uniform distribution of the matrix and the Fe-rich phases [15], but also efficient degassing [16] and enhanced de-ironing [17], which has a significant effect on the reduction in microstructural defects and the improvement in tensile properties of the recycled aluminum alloy [15,18].…”

Section: Introductionmentioning

confidence: 99%

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High-Shear De-Gassing and De-Ironing of an Aluminum Casting Alloy Made Directly from Aluminum End-of-Life Vehicle Scrap

et al. 2021

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High-shear melt conditioning (HSMC) technology was used for degassing and de-ironing of an aluminum alloy recovered from the Zorba cast fraction of the non-ferrous scrap from shredded end-of-life vehicles. The results showed that the recovery of aluminum alloys from the Zorba cast fraction was more than 80%. High-shear melt conditioning improved the degassing process during melt treatment in comparison with the adding of degassing tablets. The efficiency of the de-ironing process using HSMC increased by up to 24% after, increasing the Mn content to 0.8% in the melt. Adding Mn to Zorba melt enhanced the de-ironing process and eliminated the formation of β-AlFeSi intermetallic particles, which have a detrimental effect on both the mechanical and corrosion properties of the alloy.

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Section: De-gassing By Hsmc Of the Zorba Cast Fraction Re-melted Ingotssupporting

confidence: 91%

Section: Methodsmentioning

confidence: 99%

Section: De-gassing By Hsmc Of the Zorba Cast Fraction Re-melted Ingotsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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High-Shear De-Gassing and De-Ironing of an Aluminum Casting Alloy Made Directly from Aluminum End-of-Life Vehicle Scrap

et al. 2021

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“…There has been considerable research focus on the impeller and flow optimization to remove challenges by a) reducing the inert gas consumption and processing time by reducing the average bubble size and increasing bubble rise time [17]; b) reducing the surface deformations and vortex generation that can accelerate the reabsorption of hydrogen and entrapment of oxide films [37]; and c) increasing impeller longevity, which is degraded by its direct contact with the melt [17]. Although these obstacles have been partly solved or limited, demand for better methods exists in the industry, and new studies [1,21,27,34] have been conducted to find more effective and sustainable aluminum degassing methods for large aluminum production lines.…”

Section: Introductionmentioning

confidence: 99%

Contactless Aluminum Degassing System—GaInSn Model Experiments and Numerical Study

Baranovskis

Berenis

Grants

et al. 2021

J. Sustain. Metall.

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Hydrogen dissolves in molten aluminum and it is essential to reduce hydrogen concentration before making aluminum product. We propose a novel contactless degassing method that uses electromagnetic forces to drive the melt flow and split the injected inert gas bubbles. A numerical and experimental model of the proposed system were studied with a focus on characterizing permanent magnet-driven flows. For solving the multiphysics problem numerically, we coupled OpenFoam for hydrodynamic calculations and Elmer for electromagnetic calculations. The velocity field and developed pressure in a laboratory-scale physical model built using GaInSn in different operating regimes were examined and compared with the numerical model predictions. To characterize the conditions for bubble collapse, velocity pulsations were measured, and turbulence generation rate was computed. The results verify the feasibility of scaling the proposed degassing system. By implementing this gas purging method, the need of a rotating impeller and its associated problems would be eliminated.

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The Effect of Rotary Degassing Treatments with Different Purging Gases on the Double Oxide- and Nitride Film Content of Liquid Aluminum Alloys

Gyarmati

Vincze

Fegyverneki

et al. 2022

Metall Mater Trans B

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Rotary degassing is one of the most frequently used melt treatment technologies used for processing liquid aluminum alloys. Despite this, the information available about the possible effects of this method on the double oxide- and nitride film (bifilm) content, especially when using different purging gases, is quite limited. For this reason, in this study, the effects of multiple rotary degassing treatments conducted with N2 and Ar purging gases on the bifilm quantity of a casting aluminum alloy were compared. The characterization of the melt quality was realized by the computed tomographic (CT) analysis of reduced pressure test (RPT) specimens, image analysis, and scanning electron microscopy (SEM) of the fracture surfaces of K-mold samples. Based on the results, by the application of Ar as a purging gas, relatively low bifilm content can be achieved. On the other hand, while the use of N2 leads to the formation of numerous small-sized nitride bifilms, which significantly increased the pore number density inside the RPT specimens. This can be associated with the nitride formation by the chemical reaction between the liquid aluminum alloy and the N2 purging gas bubbles during the degassing treatments. Graphical abstract

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Improved degassing efficiency and mechanical properties of A356 aluminium alloy castings by high shear melt conditioning (HSMC) technology

Cited by 27 publications

References 32 publications

High-Shear De-Gassing and De-Ironing of an Aluminum Casting Alloy Made Directly from Aluminum End-of-Life Vehicle Scrap

High-Shear De-Gassing and De-Ironing of an Aluminum Casting Alloy Made Directly from Aluminum End-of-Life Vehicle Scrap

Contactless Aluminum Degassing System—GaInSn Model Experiments and Numerical Study

The Effect of Rotary Degassing Treatments with Different Purging Gases on the Double Oxide- and Nitride Film Content of Liquid Aluminum Alloys

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