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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 147-153页

作者： Junjie Li Wenbo Yu Zhenyu Sun Weichen Zheng Liangwei Zhang Yanling Xue Wenning Liu shoumei xiong Center of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Traffic&Transportation Engineering Central South UniversityChangsha 410075China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

High pressure die casting(HPDC)AlSi10Mn Mg alloy castings are widely used in the automobile *** can optimize the mechanical properties of castings through heat treatment,while the release of thermal stress arouses the deformation of large integrated ***,the development of non-heat treatment Al alloys is becoming the hot *** addition,HPDC contains externally solidified crystals(ESCs),which are detrimental to the mechanical properties of *** achieve high strength and toughness of non-heat treatment die-casting Al-Si alloy,we used AlSi9Mn alloy as matrix with the introduction of Zr,Ti,Nb,and *** influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic *** results reveal that the addition of Ti increased ESCs'size and porosity,while the introduction of Nb refined ESCs and decreased ***,large-sized Al_3(Zr,Ti)phases formed and degraded the mechanical *** introduction of Ce resulted in the poisoning effect and reduced mechanical properties.

关键词： aluminium alloy high-pressure die-casting externally solidified crystals non-heat treatment

Microstructure Characteristics of the Eutectics of Die Cast AM60B Magnesium Alloy

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Journal of Materials Science & Technology 2011年第12期27卷 1150-1156页

作者： MengwuWu shoumei xiong Department of Mechanical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Automobile Safety and Energy Tsinghua University Beijing 100084 China

Under the cold-chamber high pressure die casting （HPDC） process, samples were produced with AM60B magnesium alloy to investigate the microstructure characteristics of the eutectics, especially focusing on the constitution, morphology and distribution of the eutectics over cross section of the castings. Attentions were also paid to study the effect of heat treatment on the eutectics in the die castings. Based on experimental analysis using optical microscopy （OM）, X-ray diffraction （XRD）, scanning electron microscopy （SEM） and energy-dispersive spectroscopy （EDS）, it was determined that fully divorced eutectics consisting of c^-Mg and l%MglzA112 appeared at the grain boundary of the primary c^-Mg in the as-cast microstructure. Islands and networks of β-Mg17Al12 phase were observed in the central region of the castings, while the β-Mg17Al12 phase revealed a more dispersed and granular morphology on the surface layer. The two phases ratio β/α in the central region of the castings was approximately 10%, which was higher than that on the surface layer. Besides, the defect bands contained a higher percentage of the eutectics than the adjacent regions. After aging treatment （T6）, only α-Mg phase was detected by XRD in the AM60B magnesium alloy, though a small amount of precipitated β-MgITAI12 phase was observed at the grain boundary. In contrast to the microstructure of die cast AZ91D magnesium alloy under the same T0 heat treatment, no discontinuous precipitation of the β-MgITAI12 phase was observed in AMO0B magnesium alloy die castings.

关键词： AM60B magnesium alloy High pressure die casting Fully divorced eutectic Heat treatment

A three-dimensional cellular automaton model for simulation of dendritic growth of magnesium alloy

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Acta Metallurgica Sinica(English Letters) 2012年第3期25卷 169-178页

作者： Mengwu WU shoumei xiong Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China State Key Laboratory of Automobile Safety and Energy Tsinghua UniversityBeijing 100084China

A numerical model based on the cellular automaton method for the three-dimensional simulation of dendritic growth of magnesium alloy was developed. The growth ki- netics was calculated from the complete solution of the transport equations. By con- structing a three-dimensional anisotropy model with the cubic CA cells, simulation of dendritic growth of magnesium alloy with six-fold symmetry in the basal plane was achieved. The model was applied to simulate the equiaxed dendritic growth and columnar dendritic growth under directional solidification, and its capability was addressed by comparing the simulated results to experimental results and those in the previously published works. Meanwhile, the three-dimensional simulated results were also compared with that of in two dimensions, offering a deep insight into the microstructure formation of magnesium alloy during solidification.

关键词： Magnesium alloy Dendritic growth Cellular automaton method: Three-dimensional

Characterization of the Protective Surface Films Formed on Molten AZ91D Magnesium Alloy in SO_2/Air Atmospheres in a Sealed Furnace

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Journal of Materials Science & Technology 2014年第4期30卷 353-358页

作者： Xianfei Wang shoumei xiong Department of Mechanical Engineering Tsinghua University State Key Laboratory of Automotive Safety and Energy Tsinghua University

Surface films that formed on molten AZ91D magnesium alloy in S02/air cover gases at 680 ℃ in a sealed furnace were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Auger electron spectroscopy. It is revealed that the film formed on molten AZ91D alloy surface in cover gas with high air content can prevent the molten AZ91D alloy from oxidation and ignition. The surface film contained three elements, namely magnesium, oxygen and sulfur, and was mainly composed of MgO and MgS. The properties of the film depended on air content in the cover gas and holding time. Thermodynamic calculation showed that MgSO4 was the stable phase, and it was concluded that the formation of MgS04 was important for the formation of the protective surface film in S02/air atmospheres.

关键词： Magnesium alloy S02 Sealed furnace Gas protection Surface film

STUDY ON NUMERICAL SIMULATION OF MOLD-FILLING AND SOLIDIFICATION PROCESSES OF SHAPED CASTING

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Chinese Journal of Mechanical Engineering 1999年第1期12卷 5-11页

作者： shoumei, xiong Baicheng, Liu Qinghua Univ Beijing China

The latest progress on the study of numerical simulation of mold filling and solidification process of shaped casting is reviewed. In mold filling process simulation of castings, the SOLA VOF algorithmis is improved in efficient free surface treatment and turbulence consideration, and parallel computational techniques are implemented to accelerate the fluid flow calculation time as well. Methods for predication of shrinkage defects of steel castings and S G. iron castings are developed based on the solidification simulation. In order to reduce the residual stress and deformation of castings, a combined FDM/FEM method is implemented for the modelling of stresses. Numerical models for the simulation of micro structure and prediction of mechanical properties of S G. iron are developed. The verifications and applications of the simulation software show that the models and techniques adopted in current research work are efficient and appropriate for the numerical simulation of shaped castings.

关键词： Casting Mold filling Solidification Numerical simulation

Effects of runner design and pressurization on the microstructure of a high-pressure die cast Mg-3.0Nd-0.3Zn-0.6Zr alloy

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1310-1316页

作者： Tongtong Zhang Wenbo Yu Chaosheng Ma Yuqi Zhou shoumei xiong Center of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

To clarify the relationship between externally solidified crystals(ESCs)and other defects,e.g.,defect bands and pores,two dimensional(2D)and three dimensional(3D)characterization methods were adopted to analyze castings produced using a modified ingate system equipped with and without an ESC *** reduction of ESCs strongly reduced defect band width and shrinkage pore *** reducing the quantity and size of ESCs,net-shrinkage pores were transformed into isolated island-shrinkage *** determined via statistical analysis that the mechanical properties of high pressure die castings were strongly related to the size and fraction of the ESCs rather than porosity *** reduction of ESCs also caused tensile transgranular fracture modes to transform into intergranular fracture ***,casting pressurization strongly reduced pore morphology,volume,and size.

关键词： high-pressure die casting externally solidified crystals porosity 3D reconstruction runner design

Determination of interfacial heat transfer coefficient and its application in high pressure die casting process

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China Foundry 2014年第4期11卷 314-321页

作者： Cao Yongyou Guo Zhipeng xiong shoumei School of Materials Science and Engineering Tsinghua University State Key Laboratory of Automobile Safety and Energy Tsinghua University

In this paper,the research progress of the interfacial heat transfer in high pressure die casting(HPDC)is *** including determination of the interfacial heat transfer coefficient(IHTC),influence of casting thickness,process parameters and casting alloys on the IHTC are summarized and discussed.A thermal boundary condition model was developed based on the two correlations:(a)IHTC and casting solid fraction and(b)IHTC peak value and initial die surface *** boundary model was then applied during the determination of the temperature field in HPDC and excellent agreement was found.

关键词： high pressure die casting interfacial heat transfer coefficient inverse method

Determination of Interfacial Heat Transfer Behavior at the Metal/Shot Sleeve of High Pressure Die Casting Process of AZ91D Alloy

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Journal of Materials Science & Technology 2017年第1期33卷 52-58页

作者： Wenbo Yu Yongyou Cao Xiaobo Li Zhipeng Guo shoumei xiong School of Materials Science and Engineering Tsinghua University Beijing 100084 China Laboratory for Advanced Materials Processing Technology Ministry of Education. Tsinghua University Beijing 100084 China

The interfacial heat transfer behavior at the metalJshot sleeve interface in the high pressure die casting （HPDC） process of AZ91D alloy is carefully investigated. Based on the temperature measurements along the shot sleeve, inverse method has been developed to determine the interfacial heat transfer coefficient in the shot sleeve. Under static condition, Interracial heat transfer coefficient （IHTC） peak values are 11.9, 7,3, 8.33kWm-2K-1 at pouring zone （S2）, middle zone （S5）, and end zone （510）, respectively. During the casting process, the IHTC curve displays a second peak of 6.1 kWm-2 K-1 at middle zone during the casting process at a slow speed of 0.3 ms 1 Subsequently, when the high speed started, the IHTC curve reached a second peal〈 of 12.9 kW m-2K-1 at end zone. Furthermore, under different slow casting speeds, both the calculated initial temperature （TIDs） and the maximum temperature （Tsimax） of shot sleeve surface first decrease from 0.1 ms-1 to 0.3 ms-1, but increase again from 0.3 ms-1 to 0.6 ms-1. This result agrees with the experimental results obtained in a series of ＂plate-shape＂ casting experiments under different slow speeds, which reveals that the amount of ESCs decreases to the minimum values at 0.3 m s-1 and increase again with the increasing casting slow speed.

关键词： High pressure die casting (HPDC) Interracial heat transfer behavior Inverse method Slow casting speed

Heat Transfer between Casting and Die during High Pressure Die Casting Process of AM50 Alloy-Modeling and Experimental Results

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Journal of Materials Science & Technology 2008年第1期24卷 131-135页

作者： Zhipeng GUO shoumei xiong Sang-Hyun Cho Jeong-Kil Choi Key Laboratory for Advanced Manufacturing by Materials Processing Technology Department of Mechanical Engineering Tsinghua University Beijing 100084 China Advanced Material R＆D Center Korean Institute of Industrial Technology 994-32 Dongchun-Dong Yonsu-Ku Inchon Korea

A method based on die casting experiments and mathematic modeling is presented for the determination of the heat flow density （HFD） and interfacial heat transfer coefficient （IHTC） during the high pressure die casting （HPDC） *** were carried out using step shape casting and a commercial magnesium alloy,*** profiles were measured and recorded using thermocouples embedded inside the die. Based on these temperature readings,the HFD and IHTC were successfully determined and the calculation results show that the HFD and IHTC at the metal-die interface increases sharply right after the fast phase injection process until approaching their maximum values,after which their values decrease to a much lower level until the dies are *** patterns of heat transfer behavior were found between the die and the casting at different *** thinner the casting was,the more quickly the HFD and IHTC reached their steady ***,the values for both the HFD and IHTC values were different between die and casting at different thicknesses.

关键词： : Interfacial heat transfer coefficient High pressure die casting process AM50 Magnesium alloy

The effect of slow shot speed and casting pressure on the 3D microstructure of high pressure die casting AE44 magnesium alloy

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Journal of Magnesium and Alloys 2023年第2期11卷 753-761页

作者： Chaosheng Ma Wenbo YU Tongtong Zhang Zihua Zhang Yihu Ma shoumei xiong Center of Materials Science and Engineering School of Mechanical and Electronic Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Research Center of Rail Vehicles Safety Monitoring and Health Management Beijing Jiaotong UniversityBeijing 100044China School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

3D reconstruction and 2D observation were conducted to characterize the microstructure of the castings produced through high pressure die casting with different *** results indicate that shrinkage pores generally co-existed with externally solidiﬁed crystals(ESCs).In specimen produced without fast slow shot speed,big net-shrinkage pores accompanied with ESCs were found in the center of the *** the casting pressurization was introduced,the shrinkage pores gathered to the specimen center and became much less due to the optimization of melt *** more porosity was found near the gate rather than in the middle of the rod bar,especially gas ***ﬁlling process simulation reveals that the middle position of the bars wasﬁrstlyﬁlled and followed by the near gate position accompanied with one intense turbulentﬂow.

关键词： HPDC parameters Externally solidiﬁed crystals(ESCs) Porosity 3D reconstruction.