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Evaluation of the mold-filling ability of alloy melt in squeeze casting

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Journal of University of Science and Technology Beijing 2006年第1期13卷 60-66页

作者： Haiying Zhang shuming xing Qinghua Zhang Jianbo Tan Wen Liu Semisolid Forming Research Center Beijing Jiaotong University Beijing 100044 China Shijiazhuang Locomotive Depot Shijiazhuang 050000 China Department of Material and Engineering Hebei University of Science and Technology Shijiazhuang 050018 China

The mold-filling ability of alloy mclt in squceze casting process was evaluated by means of the maximum length of Archimedes spiral line. A theoretical evaluating model to predict the maximum filling length was built based on the flowing theory of the incompressible viscous fluid. It was proved by experiments and calculations that the mold-tilling pressure and velocity are prominent influencing factors on the mold-filling ability of alloy melt. The mold-filling ability increases with the increase of the mold-filling pressure and the decrease of the proper mold-filling velocity. Moreover, the pouring temperature relatively has less effect on the mold-filling ability under the experimental conditions. The maximum deviation of theoretical calculating values with experimental results is less than 15%. The model can quantitatively estimate the effect of every factor on the mold-filling ability.

关键词： squeeze casting process parameters mold-filling ability theoretical calculation experimental evaluation

Energy Dissipation and Apparent Viscosity of Semi-solid Metal during Rheological Processes PartⅠ: Energy Dissipation

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Journal of Materials Science & Technology 2007年第6期23卷 342-346页

作者： Wen LIU shuming xing Peiwei BAO Milan ZHANG Liming XIAO Beijing Jiaotong University Beijing 100044 China

The energy dissipation caused by the viscous force has great effects on the flow property of semi-solid metal during rheological processes such as slurry preparing, delivering and cavity filling. Experimental results in this paper indicate that the viscous friction between semi-solid metal and pipe wall, the collisions among the solid particles, and the liquid flow around particles are the three main types of energy dissipation. On the basis of the hydromechanics, the energy dissipation calculation model is built. It is demonstrated that the micro-structural parameters such as effective solid fraction, particle size and shape, and flow parameters such as the mean velocity, the fluctuant velocity of particles and the relative velocity between the fluid and solid phase, affect the energy dissipation of semi-solid metal.

关键词： Semi-solid metal Energy dissipation Rheology Apparent viscosity Model

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Particle motion behavior during gasiication of foam carrier in lost foam-squeeze casting of 20%TiC/ZG270-500 composites

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China Foundry 2013年第6期10卷 367-373页

作者： Bin Shibo xing shuming Guo Lijun Bao Peiwei School of Mechanical ElectronicControl Engineering Beijing Jiaotong University

The particle motion behavior affects the distribution of particles in the metal matrix and finally determines the mechanical properties of the particle reinforced metal-matrix composites. To obtain a uniform distribution of TiC particles and excellent strengthening effect in 20%TiC/ZG270-500 composites fabricated by lost foam-squeeze casting （LFSC）, the particle motion behavior in the gas gap and the conditions of the particles getting into the molten steel were investigated. The results show that the airflow velocity （vl） and TiC particle motion velocity （up） change little with the pouring temperature （Tp）, increase with an increase in metal filling velocity （Vp）, ratios of cross sections of in-gate/orifice （AAAo） and orifice/mould cavity （AolAI）, but the increase trend of up is more intense. The airflow pressure （P1） changes little with Tp and Ao/A1, but increases with the increasing of vp and AJAo. Besides, there is a critical velocity （v ＋｜3YLG cosθ/ppdp｜1/2）for the particles getting into the molten steel. The higher the particle motion velocity, the easier the particles get into the molten steel and the more uniform the distribution of the particles in the steel matrix. When Tp = 1,873 K, vp = 30 mm.s-1, AJAo =10 and Ao/AI = 0.02 in this study, the biggest TiC particle motion velocity （20.59 m.s-~） can be gained, and the steel matrix with the most uniformly distributed TiC particles and fine grains are obtained.

关键词： lost foam-squeeze casting (LFSC) particle motion velocity critical velocity particle distribution

Design of process parameters for direct squeeze casting

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Journal of University of Science and Technology Beijing 2008年第3期15卷 339-343页

作者： Milan Zhang shuming xing Liming Xiao Peiwei Bao Wen Liu Qiao Xin Semisolid Forming Research Center Beijing Jiaotong University Beijing 100044 China Department of Mathematics lli Normal University Yining 835000 China

On the basis of the analysis of solidification interval and temperature distribution of components manufactured by the squeeze casting method, formulas for calculating the solidification interval and compaction pressure were deduced according to the principal request that the compaction pressure should be equal to or greater than the plastic deformation resistance of the forming component when solidification ended. The solidification interval was proven to be associated with many factors, such as weight of the component, specific heat of the alloy, latent heat, pouring temperature, component temperature at the end of solidification and heat-transfer coefficients. The compaction pressure was related to the strain rate, deformation temperature, and dimension of the de- forming component. The solidification interval and compaction pressure calculated by the formulas deduced in this article were adopted in the production of 45 steel bidirectional chapiter valves, and components with excellent oerformance were manufactured.

关键词： squeeze casting solidification time temperature distribution compaction pressure

A New Analytical Model for the Flow Stress of Twin-roll Casting Magnesium Sheet at Elevated Temperatures

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Journal of Materials Science & Technology 2010年第5期26卷 461-466页

作者： Zhimin Liu,shuming xing ,Peiwei Bao,Nan Li,Shuqing Yao and Milan Zhang School of Mechanical,Electronic and Control Engineering,Beijing Jiaotong University,Beijing 100044,China [a] School of Mechanical Electronic and Control Engineering Beijing Jiaotong University Beijing 100044 China

To evaluate the flow stress of the twin-roll casting magnesium sheet in high temperature forming processes,a new analytical model was proposed by analyzing stress-strain curves measured under various temperatures and strain *** model can be parameterized to reflect the volume fraction of semi-sold grain and sold grains undergoing *** applying the new model,the result showed that the simulated stress-strain curves fit the experiment data very *** curve fitting can be employed for any magnesium sheet when the deformation conditions are *** evolution indicated that it affected the stress-strain curves *** mechanisms of dynamic recrystallization（DRX） depended on the operating deformation mechanisms,which changed with *** the volume fraction and grain size of DRX changed with the Zener-Hollomon parameter and temperatures.

关键词： Twin-roll casting Semi-sold grains Twinning

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Al-Si合金变质元素及其交互作用

材料导报 2018年第11期32卷 1870-1877页

作者：张佳虹邢书明北京交通大学机械与电子控制工程学院北京100044

铸造Al-Si合金具有轻量化、流动性好、气密性好、收缩率小和热膨胀系数低等优点,已成为铸造业中最受重视的结构材料之一。铸造Al-Si合金的力学性能主要取决于组织中的α-Al相、共晶硅、初生硅、金属间化合物、缺陷以及它们的形态、尺寸... 详细信息

铸造Al-Si合金具有轻量化、流动性好、气密性好、收缩率小和热膨胀系数低等优点,已成为铸造业中最受重视的结构材料之一。铸造Al-Si合金的力学性能主要取决于组织中的α-Al相、共晶硅、初生硅、金属间化合物、缺陷以及它们的形态、尺寸和分布,其中硅相和富Fe相的形貌、尺寸及分布对合金性能的影响尤为显著。未变质的Al-Si合金中针片状共晶硅和针状β-Fe相严重割裂基体,粗大块状初生硅和针片状共晶硅尖端和棱角部位产生应力集中,导致合金的性能尤其是塑性、强度和耐磨性显著降低。此外,硬脆的粗大初生硅还会加快机加工刀具的磨损,加工后零部件的表面光洁度也较差,无法满足实际生产的需要。快速凝固、电磁搅拌、超声处理、机械振动等特殊工艺技术虽然可以在一定程度上改善铸造铝硅合金的微观组织和性能,但是都需要专门的设备和特殊的条件,使其应用受到限制。变质处理不需要任何特殊设备,只需添加少量变质元素,就可以实现对其中α-Al相、共晶硅、富Fe相、细化初生硅等的有效调控,具有成本低、方法简单、效果显著等特点,已成为改善Al-Si合金组织、提高性能最有效的途径。然而,各变质元素的变质机理及它们之间的交互作用极其复杂,如何充分发挥各变质元素及它们之间积极的交互作用是当前的研究热点。近年来对单一变质元素的变质作用机理和效果的研究进展迅速,先后发现了Na、Sr、Sb、P、Ti、Mn和RE等都对铸造铝硅合金有一定的变质作用,并且对它们的变质时效性以及经济性都有了充分的认识。与此同时,也有许多研究者开始关注多元素的交互变质作用并在Sr-X、P-X、Mn-X、Ti-X等二元交互变质方面取得了重要的成果,使变质技术更加经济、有效和灵活。本文综述了铸造Al-Si合金常用单一变质元素的特点、变质作用机理和局限性,系统归纳了Sr、P、Ti、Mn和RE与其他元素间的交互作用规律,筛选出具有协同变质作用的二元/多元变质元素交互作用对,以期为深入探究二元/多元变质元素交互作用的机理,开发更高效、多样、绿色的复合变质剂及变质处理方法提供参考。

关键词： Al-Si合金变质元素交互作用

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Ca在铝合金中的作用

材料导报 2016年第19期30卷 26-31页

作者：张佳虹邢书明北京交通大学机械与电子控制工程学院北京100044

Ca在铝合金中的作用具有两面性,一方面表现出抑制P变质、降低流动性、增加氧化物夹杂等有害作用,另一方面体现出改善Al-Si合金中β-Fe相形态、细化初晶硅、变质共晶硅等有益影响。首先综述了Ca对铝合金显微组织、铸造性能、变质作用等... 详细信息

Ca在铝合金中的作用具有两面性,一方面表现出抑制P变质、降低流动性、增加氧化物夹杂等有害作用,另一方面体现出改善Al-Si合金中β-Fe相形态、细化初晶硅、变质共晶硅等有益影响。首先综述了Ca对铝合金显微组织、铸造性能、变质作用等的影响;其次系统归纳了Ca与Si、Fe、P、Sr、Cu等元素的二元交互作用规律,其中Ca-Si、Ca-Fe、Ca-Sr、Ca-Cu等元素二元交互均表现出协同作用,而Ca-P的抑制作用可以通过添加B或C2Cl6来消除;最后,开发含Ca的二元、多元联合变质剂,深化Ca对铝合金微合金化作用机理以及再生循环过程中Ca对其他元素的影响等都是今后重点研究的思路与方向。

关键词： Ca铝合金显微组织微合金化性能

Effect of Process Factors on Microstructure of Semisolid Continuous Casting Billets

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 242-245页

作者： shuming xing, Qijie Zhai, Hanqi Hu ( Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China School of Material Science and Engineering, Shanghai University, Shanghai 200072, China Material Science and Engineering School, Univer Department of Mechanical Engineering Tsinghua University Beijing 100084 China School of Material Science and Engineering Shanghai University Shanghai 200072 China Material Science and Engineering School University of Science and Technology Beijing Beijing 100083 China

Semisolid continuous casting (SSCC) is a new technology to produce billets for semisolid metal forming (SSMF). The effect of process factors, such as pouring temperature, stirring rate, preheating temperature and thermal conductivity of stirring chamber, on the microstructure of SSCC billets was studied by means of the factorial experimental method. The results show that the microstructure of SSCC billets can be controlled by the above-mentioned four process factors. In order to obtain fine and rounded granular grains in an SSCC billet, the pouring temperature, preheating temperature and stirring rate should be kept in a moderate range, and the thermal conductivity of stirring chamber should be high. The regression equations with the process factors connecting the microstructure was also set up based on experimental data.

关键词： semisolid metal continuous casting process factors microstructure Metallurgy

颗粒增强金属基复合材料界面结合强度的表征：理论模型、有限元模拟和实验测试

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材料导报 2019年第5期33卷 862-870页

作者：邱博邢书明董琦北京交通大学机械与电子控制工程学院北京100044

金属基复合材料的综合性能优异,应用领域广泛,在这类材料中,增强相与基体之间的界面结合情况是影响材料性能的关键因素之一,而界面结合强度是衡量界面结合情况最重要的定量化指标。到目前为止,研究者们已经提出了许多测量复合材料界面... 详细信息

金属基复合材料的综合性能优异,应用领域广泛,在这类材料中,增强相与基体之间的界面结合情况是影响材料性能的关键因素之一,而界面结合强度是衡量界面结合情况最重要的定量化指标。到目前为止,研究者们已经提出了许多测量复合材料界面强度的方法,包括早期就已经提出并一直沿用的微观力学测试方法,如单纤维拉出法、单纤维断裂法和微粘结测试法等,以及以材料宏观性能来评价界面应力状态的宏观实验方法,如横向弯曲实验、横向拉伸实验以及导槽剪切实验等。根据测量过程是否需要对界面进行破坏又可以分为声发射技术、声显微技术、拉曼光谱等技术的非破坏性方法以及一些需要破坏界面从而达到测量目的的破坏性方法。虽然诸多学者对复合材料界面结合强度的测量与表征做了大量的研究工作并取得了重大进展,但这些测试方法基本上都是基于纤维增强金属复合材料的成果,对于颇有前景的颗粒增强金属复合材料而言,这些测试手段却因颗粒增强相在形状和尺度上的特殊性而难以奏效,从而造成定量表征颗粒增强金属基复合材料界面结合强度相关研究的发展较为缓慢。为了解决颗粒增强相与金属基体界面强度难以测量的问题,许多研究者在建立理论模型的基础上通过有限元模拟的方法来表征界面的结合强度。这种方法可以用来预测颗粒增强金属基复合材料的界面结合强度,具有一定的指导意义,但是计算机模拟的方法在建模及计算过程中很大程度上对颗粒增强相的形状、分布状态以及界面的形变方式进行了简化处理,导致其结果与实际情况往往存在一定的误差。在这种情况下,研究者们开始寻求通过实验测试的方法来定量表征颗粒与金属基体之间的界面结合强度,也就是通过测量界面处的剪切强度或拉伸强度来表征界面的结合强度。本文针对颗粒增强金属基复合材料,归纳了国内外研究者们基于不同原理对界面结合强度进行研究和预测的理论模型,论述了对界面结合强度进行定量表征的有限元模拟测试法以及实验测试法,以期在一定程度上为界面设计与结合强度控制提供参考。

关键词：金属基复合材料颗粒增强界面结合强度