Effect of Primary α-Al Morphology in Slurry on Segregation during 357 Semi-Solid Die Casting

Zhang, Hong; Li, Da Quan; Qu, Wen Ying; Zhang, Fan; Luo, Min; Midson, Stephen P.; Zhu, Qiang

doi:10.4028/www.scientific.net/ssp.285.398

Cited by 8 publications

(2 citation statements)

References 9 publications

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“…The SEED process is used to produce the initial semi-solid 357.0 aluminium slurries. To avoid the formation of dendritic structure and get a more spherical primary particle, the pouring temperature is set at 630 ℃, which is just above the liquidus (628 ℃, measured by the Differential Scanning Calorimetry (DSC)) [14]. After pouring, the crucible was swirled at 180 rpm for 120 s, and then quenched in water.…”

Section: Methodsmentioning

confidence: 99%

Preparation of Semi-Solid 357.0 Slurries with Different α-Al Phase Features by Solidification from Full Liquid State and Remelting

Chen

et al. 2022

SSP

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The characteristics of the solid phase, namely the volume fraction, particle size, and morphology, are dominant variables that can determine the viscosity of the semi-solid slurry. However, particle size and morphology were always being ignored and the solid fraction was simply determined using the temperature in the conventional power-law viscosity, resulting in a disagreement in the viscosity values in different researches. To make the power-law viscosity model more accurate for predicting the filling process of semi-solid die casting, it is essential to modify this viscosity model based on particle characteristics. Therefore, there is a fundamental demand to prepare semi-solid slurries with different α-Al phase features at first. This is achieved in this study by two kinds of heat history controlling methods: remelting and solidification, which can get slurries with spherical structure and dendric structure, respectively. The semi-solid 357.0 slurries with 0.11-0.43 solid fraction, 137-182μm particle size, and 0.81-0.90 shape factor were prepared in the remelting process, while dendritic structures (shape factor<0.5) with 0.1 and 0.3 solid fractions were obtained by solidification controlling from the full liquid state. Besides, the effect of parameters on the evolution of the α-Al phase has been discussed. These slurries with different solid features will be further used to quantify the influence of primary phase characteristics on rheological behavior and make the power-law viscosity model more accurate for simulation.

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Section: Methodsmentioning

confidence: 99%

Preparation of Semi-Solid 357.0 Slurries with Different α-Al Phase Features by Solidification from Full Liquid State and Remelting

Chen

et al. 2022

SSP

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“…The pouring temperature plays a crucial role in the size and morphology of α 1 -Al grains, which, in turn, affects their flow behavior and segregation during the die-casting process. Zhang [33] controlled the pouring temperature to obtain grains with different morphologies (dendrites and globular grains) and found that the dendritic structure led to severe segregation in the die-casting parts. Qi [34] investigated the segregation phenomenon of AC46000 castings at different wall thickness locations, where different wall thicknesses represented varying cooling rates.…”

Section: Segregation During Die-castingmentioning

confidence: 99%

A Comparative Study on Microstructure, Segregation, and Mechanical Properties of Al-Si-Mg Alloy Parts Processed by GISS-HPDC and SEED-HPDC

Gu,

Xiang,

et al. 2023

Materials

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There are multiple routes to prepare semi-solid slurries with a globular microstructure for semi-solid forming. The variations in the microstructure of semi-solid slurries prepared using different routes may lead to significant differences in the flow behavior and mechanical properties of rheo-diecasting parts. Therefore, it is crucial to have a comprehensive understanding of the microstructure evolution associated with different slurry preparation routes and their resulting effects. In this study, the gas-induced semi-solid process (GISS) and the swirl enthalpy equilibrium device (SEED) routes were employed to prepare semi-solid Al-Si-Mg slurries for their simplicity and productivity in potential industrial applications. The prepared slurries were then injected into the shoot sleeves of a high-pressure die casting (HPDC) machine to produce tensile test bars. Subsequently, the bars underwent T6 treatment to enhance their mechanical properties. The microstructure, segregation, and mechanical properties of the samples were investigated and compared with those of conventional HPDC. The results indicated that the GISS and SEED can produce semi-solid slurries containing a spherical α-Al primary phase, as opposed to the dendritic structure commonly found in conventional castings. The liquid fraction had a significant effect on the flow behavior, resulting in variations in liquid segregation and mechanical properties. It was observed that a higher solid fraction (>75%) had a suppressing effect on surface liquid segregation. In addition, the tendency for liquid segregation gradually increased along the filling direction due to the special flow behavior of the semi-solid slurry with a low solid fraction. Furthermore, under the same die-casting process parameters, the conventional HPDC samples exhibit higher yield stress (139 ± 3 MPa) compared to SEED-HPDC and GISS-HPDC samples, which may be attributed to the small grain size and the distribution of eutectic phases. After undergoing the T6 treatment, both SEED-HPDC and GISS-HPDC samples showed a significant improvement in yield and tensile strength. These improvements are a result of solution and precipitation strengthening effects as well as the spheroidization of the eutectic Si phase. Moreover, the heat-treated SEED-HPDC samples demonstrate higher ultimate strength (336 ± 5 MPa) and elongation (13.7 ± 0.3%) in comparison to the GISS-HPDC samples (307 ± 4 MPa, 8.8 ± 0.2%) after heat treatment, mainly due to their low porosity density. These findings suggest that both GISS-HPDC and SEED-HPDC processes can be utilized to produce parts with favorable mechanical properties by implementing appropriate heat treatments. However, further investigation is required to control the porosities of GISS-HPDC samples during heat treatment.

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Study on Semi-solid Slurry Preparation Process, Microstructure, and Mechanical Properties of Truck Bracket

Lang,

Wang,

Gao

et al. 2024

Inter Metalcast

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Effect of Primary α-Al Morphology in Slurry on Segregation during 357 Semi-Solid Die Casting

Cited by 8 publications

References 9 publications

Preparation of Semi-Solid 357.0 Slurries with Different α-Al Phase Features by Solidification from Full Liquid State and Remelting

Preparation of Semi-Solid 357.0 Slurries with Different α-Al Phase Features by Solidification from Full Liquid State and Remelting

A Comparative Study on Microstructure, Segregation, and Mechanical Properties of Al-Si-Mg Alloy Parts Processed by GISS-HPDC and SEED-HPDC

Study on Semi-solid Slurry Preparation Process, Microstructure, and Mechanical Properties of Truck Bracket

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