半固态金属加工技术

半固态加工技术是一种新的材料成形技术。作者综述了半固态金属的成形工艺、坯料制备工艺、微观组织、国内外研究应用情况，展望了半固态金属加工技术的前景，并提出了应对措施。     

半固态加工技术的进展及我国应对措施

半固态金属成形技术具有高效、节能、近终形生产和成形件性能高等许多优点，被专家们称为21世纪最具前景的加工方法。本文介绍了半固态金属成形的成形工艺、坯料制备工艺、微观组织、数值模拟状况及国内外研究应用情况，展望了半固态金属 的前景，提出了我国的应对措施，     

半固态加工技术及其应用

半固态加工技术具有高效、节能、近净形生产以及制成品显微组织细化均匀、机械性能好等诸多优点，是一种很有发展前景的加工方法。介绍了半固态金属原料制备技术、重熔工艺和成形技术。综述了半固态加工技术的应用领域，并展望了其应用前景。     

半固态304型不锈钢凝固和重熔过程中的结构形态及形变特征

1前言 半固态金属成形主要用于对铝合金和镁合金等轻金属的加工。到目前为止，半固态金属成形一直被用来制造此类合金的各种金属部件，如汽车和移动电话的配件。对于轻金属半固态成形的绝大多数研究的目的是为了揭示轻金属合金半固态成形实用技术发展的基本特征。相比之下，对包括不锈钢在内的铁基合金半固态成形的研究还非常少，这可能是由于此类合金具有较高的熔点、较窄的半固态温度区间以及在凝固和重熔过程中发生复杂的γ←→δ相变。对铁基合金半固态成形工艺进行优化需要了解其在半固态时的材料特性。这些特性在半固态温度区间内受到材料显微结构变化的显著影响。对于铁基合金半固态成形的研究仍处于基础阶段。     

钢铁半固态成形技术的研究进展和展望

低熔点合金半固态成形技术被专家称为21世纪新兴的金属制造关键技术。该技术已经成功地在商业领域中运行，人们一直在探索将此技术应用于钢铁材料。本文综述了钢铁半固态成形技术的研究开发过程，介绍了钢铁半固态成形的工艺、浆料的制备方法、半固态金属的微观组织演变以及对这种成形工艺的展望。笔者认为电磁搅拌制备浆料方法中的搅拌是无接触搅拌，更适用于高熔点钢铁材料。由于触变成形工艺本身的特点，使其更适宜于钢铁等高熔点材料的半固态成形控制。     

半固态金属成形技术及应用

半固态金属加工是近年来金属加工技术研究的热点。本文论述了半固态金属坯料制备、成形方法、微观组织及其数值模拟，并阐述了其发展应用和前景。     

金属半固态铸造成形技术

金属的半固态铸造是近年来出现的一种新的铸造加工成形方法。该方法与传统的全液态铸造相比，具有节约能源、生产率高、产品质量好等优点。本文介绍了半固态金属浆料的制备方法，半固态压铸、半固态连铸等金属半固态铸造成形技术，并指出了存在的问题及进一步研究工作。     

钢铁材料半固态坯料制备与成形的研究现状与展望

半固态成形技术是冶金材料领域重要研究课题。本文总结了半固态钢铁等高熔点材料制备与成形技术中的组织演变、坯料制备和成形工艺等方面理论与应用研究成果，对其发展现状与趋势进行了分析与讨论，并指出钢铁等高熔点材料半固态成形技术广阔的应用前景。     

半固态金属的流变行为述评

叙述了半固态金属的流变学理论，常规铸造组织和半固态金属的流变行为，固相体积分数，剪切速率，冷却速度等因素对半固态金属表观粘度的影响，以及半固态成形技术的研究现状，以期推动半固态流变理论的研究和半固态加工技术的实际应用。     

国外半固态合金及复合材料成形技术发展概述

据美国国家研究委员会最近提出,半固态合金及复合材料成形技术,经过近20多年的研究和发展,到目前已逐步开始进入工业应用阶段,即将成为对21世纪的制造工业产生重要影响的新兴制造工艺。 半固态金属成形技术是随着搅动铸造     

半固态金属制备原理与应用

综述了半固态金属加工的特点以及主要制备方法。从金属凝固原理出发，结合实验结果论述了半固态金属组织的几种生成机制以及这些生成机制在工程实施中将遇到的困难。     

Microstructure and properties of semisolid hypereutectic high chromium cast iron prepared by slope cooling body method

Abstract

To improve the toughness of hypereutectic high chromium cast iron, the morphology of the primary carbides were improved by the slope cooling body method, a semisolid forming process. The semisolid specimens were prepared under different forming techniques, and the microstructure, impact toughness and wear resistance were studied. The results indicate that the morphology of primary carbide is improved, impact toughness initially increases then remains constant as the semisolid forming temperature increases, impact toughness was improved, but wear resistance was reduced.     

简述铝合金汽车轮毂发展现状

随着科技的进步,环保理念的深入人心,铝合金汽车轮毂因其质量轻、导热率高、成型性好以及产品外形美观等诸多优于钢质轮毂的特点被越来越广泛地应用.铝合金成型方式多种多样,从最早的重力铸造到低压铸造,而后为了进一步提升铝合金轮毂的性能,经过许多研究者的努力开发,又提出了铸造-热旋压以及半固态模锻工艺.同时,为了缩短铝合金轮毂更新的周期,学者们利用计算机对轮毂成型过程及成型过程中模具的状况进行模拟分析,预先找出实际生产中可能出现的问题及产生的缺陷,并进行调整改进,减少试生产所需时间.     

A CrNiCo Alloy as a Potential Tool Material in Semi‐solid Processing of Steels

Semisolid processing of aluminium and magnesium alloys has matured to become a well established manufacturing route for the production of intricate, thin‐walled parts with mechanical properties as good as forged grades. However, this innovative forming technology faces a major challenge in the case of steels. The tool materials must withstand the complex load profile and relatively higher forming temperatures which promote chemical interaction with steel slurries. Thixoforming tools ought to last thousands of forming cycles for industrial application to be attractive. Hot work tool steel dies proved to be entirely inadequate when thixoforming steels. In spite of extensive research on tool materials for the semisolid processing of steels, there is yet no material to fulfil this critical role. The present work was undertaken to explore the potential of a novel CrNiCo alloy as the tooling material in semisolid processing of steel.     

Yield behavior of commercial Al-Si alloys in the semisolid state

Systematic experimental work and modeling efforts have been conducted to characterize the yield behavior of commercial aluminum alloys in the semisolid state. In this study, extensive compression experiments were performed to measure the yield stress of semisolid aluminum slurries at high solid fractions (0.5 to 1.0), and a cone penetration method was employed to measure yield stress at low solid fractions (<0.5). A functional relationship between yield stress and temperature/solid fraction has been established for these alloys. The effect of the processing route on the resultant yield stress of the material in the semisolid state was studied by evaluating commercial A356 billets manufactured via magnetohydrodynamic stirring, grain refining, and UBE’s new rheocasting (NRC) processes, respectively. Detailed microstructure observations and image analyses reveal that the difference in yield-stress values among the alloys evaluated is intricately related to the semisolid structure. At a given solid fraction, the yield stress of semisolid slurries depends on microstructural indices (i.e., entrapped-liquid content, shape factor of the alpha phase, and the alpha particle size). In addition, numerical simulation results indicate that the finite yield stress of semisolid metals plays a significant role in determining the flow pattern during die filling. Depending on processing conditions, five distinct filling patterns (shell, disk, mound, bubble, and transition) have been identified and confirmed through experimental observations. Recent simulations demonstrate that the finite yield stress is also responsible for flow instabilities encountered in commercial forming operations, such as “toothpaste behavior.” Specifically, most flow instabilities can be avoided by properly controlling processing parameters and the initial semisolid microstructure. A stability map that provides a control guide for semisolid processing has been developed and is presented.     

喷射成型沉积坯组织及机械性能分析

喷射成型是近年来发展极其迅速的一种崭新的金属和合金成型技术，它不仅具有快速凝固的优点，可以生产低偏析、细晶粒、高致密度和近终形尺寸的坯料，而且简化了生产工序，从而比一般粉末冶金生产工艺降低了成本。用光学显微镜和扫描电子显微镜观察喷射成型制造的GCr15沉积坯，分析其组织结构和晶粒度的分布状况。同时，对沉积坯的密度、硬度进行测定分析。结果表明，沉积坯具有细小的等轴晶粒，化学成分比较均匀。在此基础上提出了一些改进微观组织和性能的措施。     

Material Flow Control and Optimization in High‐Pressure Sheet Metal Forming by Active‐Elastic Tools

High‐pressure forming of metal sheets is an innovative forming technology for the production of complex components and offers high potentials to improve the properties and qualities of sheet metal parts. This report describes investigations of a newly developed active‐elastic tool system referred to as ACTEC system. Unlike the use of a comparable semi‐rigid tool system, the ACTEC system shows improvements with respect to the material flow in the flange area and reduced sheet thinning in critical corner regions of the workpiece. In addition, the clamping forces respectively sealing forces necessary to avoid leakage in the tool system during the forming process can be reduced. Moreover, the specific design of the ACTEC‐system as well as current experimental examinations are presented and discussed.