半固态加工技术的进展、前景及对策

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,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,国内外研究应用情况,展望了半固态金属的前景,并提出了应对措施。     

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。     

金属的半固态加工技术

半固态金属加工是近年来金属加工技术研究的热点，本文在总结半固态加工技术特点的基础上，对半固态合金坯(浆)料的制备方法、半固态合金的成形技术以及近几年出现的一些新工艺和新方法进行了详细的论述。     

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。     

半固态触变压射成形过程模拟及验证

根据触变铸造半固态合金的流变特性,将半固态触变成形过程的流动简化为均相等温层流流动,并对其进行了数值模拟和实验验证,数值模拟结果与实验充型结果基本相符.     

金属半固态加工技术的应用与进展

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、力学性能好等诸多优点，是一种很有前途的加工方法。介绍了半固态加工的原理、特点，以及用于制备合金和复合材料的研究情况及应用前景等。     

半固态铸造技术的进展

1前言采用与塑料注塑机相似的机器加工的金属近实形部件的半固态铸造技术就是触变成形技术,但所用的原料是镁粒而不是塑料,镁粒全部在机器里熔化和模压,不再需要外围的铸造设备,部件可以在20s生产周期里铸造成形,不需要热处理。在许多情况下,也不需要加工,因此如果订购1000个或更多的部件也可以在同一天里交货,如果已经有现成模具的话。触变成形技术的另外一些特点包括环境友好、防火安全、工人劳动条件舒适,实际情况是这一技术不需要SF6(一种使全球变暖的气体),不产生有害气体或渣,所生产部件一般为近实形(netshape),很少或甚至不需要进一…     

金属半固态加工技术及其在工业中的应用

半固态金属加工是近年来金属加工技术研究的热点，因为它具有一系列优点，最突出的是半固态材料的触变性，成形的零件精度高、质量好，能与净近成形或净终成形（Near-net-shape）接轨。本文详细阐述了半固态金属成形特点和半固态金属制品的力学特性，同时还介绍了半固态技术在工业中的应用。     

铝合金半固态挤压扩展成形过程三维数值模拟

以半固态挤压扩展成形A2017铝合金扁型材为研究对象,采用有限元方法对半固态挤压扩展成形过程热流耦合场进行三维数值模拟,建立了热流耦合数学模型,确定了计算模型的边界条件以及所研究合金的热物性参数,获得了不同工艺参数和模具设计参数下合金动态凝固过程的温度场和速度场,特别是模具设计参数对模腔内合金流动规律的影响,从而为合理设计成形模具,调整成形工艺,提高制品质量找到依据．     

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。     

板材成形中的技术革命

提出板材成型技术中存在技术革命。第一次技术革命以板材成形从工场走向工厂为标志;第二次技术革命以实验成形性评定和实验变形分析为标志;第三次技术革命以理论成型性评定及成型CAD/FMS的出现为标志,它是原材料工业迎接材料科学技术革命的一条有效途径。
板材成型成为一个科学领域必然要与板材生产密切结合,这就提出了发展板材系统工程的需要。板材系统工程的基本内容是:（a）板材生产,（b）板材成型,（c）板材冶金过程与板材成形过程的协同。
回顾计算机辅助成型性分析和工艺优化的发展,提出了计算机辅助战形性分析体系、计算机辅助成形工艺优化体系及板材成型学科体系并给出了这三种体系的框图。     

金属成型特殊非协调大变形有限元数值模拟

在金属成型领域,一种较新的特殊非协调大变形有限元法,即增强假设应变有限元法（简称EASM）已被研究用于进行数值模拟.为使该方法可适用于分析压缩大变形问题,对原由Simo提出的EASM列式进行了修正并编制了用于数值模拟变形过程的增强假设应变有限元程序EAS.FOR,通过2个标准算例来验证该方法的可行性和有效性.     

喷射成形过程雾化金属颗粒行为的数值模拟

采用CFD软件对喷射成形工艺过程雾化室内金属颗粒的行为进行了模拟,研究了不同雾化压力下、不同粒径的金属颗粒运动轨迹及温度变化情况。模拟结果表明,随着雾化压力的增大,金属颗粒的运动速度明显增加,金属颗粒到达沉积器上的温降更加显著,且颗粒运动轨迹的锥形区域扩散角减小;在相同的雾化压力下,粒径较大的金属颗粒在雾化室内的飞行速度和温降速率明显小于粒径较小的颗粒。     

Fast Algorithms for the Simulation of Electromagnetic Metal Forming

Despite the comprehensive understanding of the modelling and numerical simulation of electromagnetic metal forming that has recently been gained, the simulation of real forming situations is still a challenging task due to the large computational resources required. A bottleneck is the computation of the electromagnetic fields, since 100 000 up to several million unknowns are required to represent the geometry of a typical forming device. The purpose of this article is to present new techniques to speed up the simulation of electromagnetic metal forming with particular emphasis on the computation of the electromagnetic fields. An acceleration of the electromagnetic field computation is a significant step towards a virtual design of electromagnetic forming processes.     

数值模拟在汽车板成形中的应用

在汽车和冶金工业中,板成形数值模拟广泛地应用于零件的选材和模具的设计.文章论述了板成形数值模拟的基本方法及其发挥的重要作用,并采用动力显式有限元软件DYNA3D对轿车顶板的冲压成形过程进行仿真计算,分析了成形安全裕度.     

Development of a Robot‐Based Sheet Metal Forming Process

This paper describes a new sheet metal forming process for the production of sheet components for prototypes and small lot sizes. The generation of the shape is based on kinematics and is implemented by means of a new forming machine consisting of two industrial robots. Compared to conventional sheet metal forming machines, this newly developed forming process offers a high geometrical form flexibility, and comparatively small deformation forces enable high deformation degrees. The principle of the procedure is based on flexible shaping by means of a freely programmable path‐synchronous movement of the two robots. The final shape is produced by the incremental infeed of the forming tool in depth direction and its movement along the contour in lateral direction at each level of the depth direction. The supporting tool with its simple geometry is used to support the sheet metal and follows the forming tool at the rear side of the sheet metal. The sheet metal components manufactured in first attempts are of simple geometry like frustum and frustum of pyramids as well as spherical cups. Among other things the forming results are improved by an adjustment of the movement strategy, a variation of individual process parameters and geometric modifications of the tools. In addition to a measurement of the form deviations of the sheet with a Coordinate Measurement Machine, screened and deformed sheets are used for deformation analyses. Furthermore, the incremental forming process is analysed with assistance of the finite element method. In total the results show that a robot‐based sheet metal forming with kinematic shape generation is possible and leads to acceptable forming results. In order to be able to use the potential of this process, a goal‐oriented process design is as necessary as specific process knowledge. In order to achieve process stability and safety, the essential process parameters and the process boundaries have to be determined.     

Experimental and Numerical Failure Criteria for Sheet Metal Forming

For sheet metal forming, often the forming limit diagram (FLD) is used as failure criterion as it can be derived easily in experiments. It is based on the assumption that localization of strain in the sheet plane is responsible for crack initiation, but application of FLD is limited to linear strain paths. Hence, only forming processes with approximately the same deformation history as the experiments carried out for FLD determination should be evaluated by this criterion. Forming limit stress diagrams (FLSD) do not exhibit such strict limitations. They are based on the assumption that principal stresses in the sheet plane are responsible for crack initiation. As these stresses are usually calculated by FE analysis using elastic plastic material laws, strain hardening is considered. Two‐step forming tests as application examples prove the FLSD to be adequate for evaluation of non‐linear forming processes with alternating forming directions. Nevertheless, FLSD are derived in extensive investigations which makes them unattractive for most industrial applications. Furthermore, both FLD and FLSD do not consider the physical background of ductile crack initiation which is provoked by an interaction of local stress triaxiality and equivalent plastic strain. Hence, a reliable failure criterion should concentrate on these two parameters. The Gurson‐Tvergaard‐Needleman‐ (GTN‐) damage model can predict crack initiation during sheet metal forming. Application of the GTN model to 2 step forming tests with the bake hardening steel H220BD+Z showed good agreement to experimental results although a sensitivity of the model to mesh size and stress triaxiality is observed.     

Transformation Induced Martensite Evolution in Metal Forming Processes of Stainless Steels

Because of their high corrosion resistance and deformation characteristics, the industrial application of stainless steels is of high importance. During deep drawing processes, phase transformation of austenite to martensite occurs, which leads to an increased strain hardening of the material. The phase transformation depends on alloying constituents, transformation temperatures, stresses and strains. Consequently, in the design of deep drawing processes of stainless steels the phase transformation has to be considered. This paper presents a mathematical model for the calculation of the martensite evolution depending on temperatures, stresses and strains. The precise simulation of deep drawing processes of stainless steels can be enabled by the implementation of this model into commercial FE‐programs.