轻合金管材热态内压成形性能测试及样件试制

介绍了轻合金热介质内压成形基本原理,研究了温度对镁合金和铝合金管材热态内压成形性能的影响,进行了镁合金变截面件和铝合金变径管成形试验.所建立的热介质内高压成形装置最高加热温度315℃,压力100MPa,可实现高压热介质的传输和密封、成形件温度和加载曲线控制等.对镁合金和铝合金管材在不同温度下成形性能的测试分析表明,轻合金热成形需综合考虑总延伸率、均匀延伸率和n值等参数随温度的变化,选取合适的成形温度.     

轻合金板材气压成形工艺的研究与应用

概述了轻合金板材气压成形工艺及其材料的研究与应用进展.探讨了爆炸成形、激光冲击成形、超塑性气胀成形、热态金属气压成形和快速塑性成形几种典型工艺的应用现状、工艺流程及关键技术.总结了铝、镁合金等工程材料超塑性研究所取得的重要成果.指出新型高应变速率工艺材料开发与应用和低成本、高性能产品的气压成形工艺研究将成为金属板材气压成形工艺的发展方向.     

有色金属板材若干温热加工成形技术的发展

介绍了有色金属材料加工先进新技术国内外发展和应用概况,包括近年来关于镁合金、钛合金、铝合金等典型有色金属材料领域出现的先进塑性成形技术,尤其温热加工成形技术。在镁合金板材冲压成形领域,介绍了镁合金板材温热冲压成形、差温冲压成形、温热液压成形和热冲锻成形以及镁合金型材温热拉弯成形等新工艺技术,为镁合金板材在汽车、电子、机车车辆等领域的应用奠定了技术基础。钛合金板材零件的热应力成形、热胀形成形、激光弯曲成形、高温蠕变成形技术都得到了发展和应用。随着铝合金的进一步应用和发展,一些低塑性难成形高强铝合金的用量在增加,应用领域在扩展。因此铝合金的温热液压成形、冲锻成形都有所发展。     

管材液压成形技术的发展——从前8届国际塑性加工会议看管材液压成形技术的发展

文章回顾了前8届国际塑性加工会议论文集中关于管材液压成形方面的文献,发现,早期的管材液压胀形技术内压较低,后来发展到可同时实现超高压和轴向补料;可成形零件的轴线由直线变为二维或三维空间曲线,种类大幅增加;适用于内高压成形的材料也由铝、铜、低碳钢等增加了不锈钢、铝合金、镁合金;同时热态内压成形技术也蓬勃发展起来。     

镁合金轮毂的塑性成形技术

利用镁合金在特定温度下具有较好塑性的特点,研究镁合金轮毂的塑性成形工艺。提出一种挤压与胀形的成形工艺,并设计加工出模具。通过试验成形出镁合金轮毂产品。通过检测轮毂不同部位的力学性能,结果表明:塑性变形对镁合金性能有较大的强化作用,最大抗拉强度、拉伸屈服强度及伸长率明显优于铸态试样,可满足汽车轮毂的使用要求。该技术为镁合金轮毂的成形开辟了新方向,促进了镁合金在汽车行业的应用。     

不同时效态7050铝合金时效成形中析出相对应力松弛行为的影响

铝合金时效成形方法结合了合金的蠕变松弛和析出强化作用,作为一种先进的整体壁板制造技术倍受航空制造业青睐。7xxx系铝合金在时效成形过程中的应力松弛行为受到合金内析出相与位错蠕变交互作用的影响从而制约着成形后零件质量与性能。本文采用设计的应力松弛试验研究了不同时效态(固溶态,欠时效态和峰时效态)7050铝合金内析出相对时效成形过程中应力松弛行为的影响,并通过位错热激活动力学参数计算和显微组织表征分析析出相与位错运动的交互作用。结果表明时效成形过程中析出相对位错热激活运动有明显地阻碍作用,因此含有不同尺度析出相铝合金的应力松弛行为表现不同,随着析出相尺度的增加合金应力松弛速率减缓,应力松弛极限增大。不同时效态7050铝合金位错激活体积计算和显微组织表征结果都证明了应力松弛过程中析出相增大对位错运动的阻碍作用也越显著。峰时效态7050铝合金的位错激活体积最大,时效成形后塑性应变的转化率最低。此外,时效成形过程中,7050铝合金内析出相对位错热激活的阻碍作用引起了槛应力现象,且随着析出相的增大槛应力也逐渐增大。     

轻合金电致塑性成形技术研究进展

轻合金室温难变形的特性在一定程度上限制了其广泛应用,而电致塑性成形技术在提高轻合金塑性、解决其成形性能差等方面具有较大优势。在传统金属材料电致塑性效应研究基础之上,综述了铝、镁、钛等典型轻合金电致塑性成形机理的研究进展,并对电致塑性成形工艺应用的研究情况进行了介绍。总结了轻合金电致塑性成形机理及应用研究的不足。     

振动塑性加工及其在轻合金成形中的应用

振动塑性加工是将超声波等形式的振动施加在塑性成形的模具或坯料上,以达到提高坯料变形能力和加工质量等目的的一种塑性成形技术.回顾了振动塑性加工技术及其在铝、镁等轻合金塑性成形领域的理论研究和应用情况,探讨了利用该技术提高镁合金塑性成形性能与质量的可能性.     

镁合金超塑性及其成形技术进展

阐述了金属超塑性的特点与分类,镁合金超塑性的研究方向及其变形机制.针对当前镁合金超塑性及其成形技术的研究现状,提出了新型镁合金超塑性成形技术的开发思路,为提高镁合金超塑性的工业应用及拓宽镁合金的应用范围提供参考.     

镁合金管件热态内压成形研究进展

首先简介了热态内压成形国内外研究现状,然后重点介绍了哈尔滨工业大学在热态内压成形装置和镁合金热态内压成形方面的研究进展。所研制的热态内压成形装置可在一定温度下实现镁舍金大膨胀率变径管、弯曲轴线变截面管的研制。采用AZ31B镁合金管材获得膨胀率30％,最大减薄率6．7％的变径管件;采用AZ61A镁合金管材试制了正方形截面件和某轿车样件,采用AZ31镁合金管材试制了截面带有小圆角的管件。介绍了上述样件的工艺过程,表明镁合金热态内压成形工艺具有广阔的应用前景。     

Overview of superplastic forming research at ford motor company

In an effort to reduce vehicle weight, the automotive industry has switched to aluminum sheet for many closure panels. Although the application of aluminum is compatible with existing manufacturing processes and has attractive qualities such as low density, good mechanical properties, and high corrosion resistance, it has less room-temperature formability than steel. The expanded forming limits that are possible with superplastic forming can significantly improve the ability to manufacture complex shapes from materials with limited formability. Aluminum closure panels produced by superplastic forming have been used by Ford Motor Company for over a decade. However, applications have been limited to low-volume, specialty vehicles due to the relatively slow cycle time and the cost penalty associated with the specially processed sheet alloys. While there has been substantial research on the superplastic characteristics of aluminum alloys, the bulk of this work has focused on the development of aerospace alloys, which are often too costly and perhaps inappropriate for automotive applications. Additionally, there has been a limited amount of work done to develop the technologies required to support the higher production volumes of the automotive industry. This work presents an automotive perspective on superplastic forming and an overview of the research being performed at Ford Motor Company to increase the production volume so superplastic forming can be cost competitive with more traditional forming technologies. This paper was presented at the International Symposium on Superplasticity and Superplastic Forming, sponsored by the Manufacturing Critical Sector at the ASM International AeroMat 2004 Conference and Exposition, June 8–9, 2004, in Seattle, WA. The symposium was organized by Daniel G. Sanders, The Boeing Company.     

喷射成形共晶铝硅合金的成形性研究

本文即针对喷射成形共晶铝硅合金成形性进行研究 ,采用Gleeble15 0 0实验机进行压缩比实验 ,并同时量测流动应力。本研究以涡卷式压缩机用之涡卷转子为载具 ,进行共晶铝硅合金锻件的开发分析。试锻结果确认喷射成形共晶铝硅合金具有近似于 60 61及 40 3 2的成形性 ,在相同锻造条件下 ,涡卷端面平面度与 60 61及 40 3 2并无显著差异     

开发中的冷弯成形新技术

冷弯成形具有成本低、可加工复杂截面的型材等优点,所成形的冷弯件在汽车、家具和建筑等领域的应用逐年增长。近年来,随着汽车行业对工件轻量化和安全性要求的不断提高,具有独特的高生产效率、高成材率优点的改进冷弯成形新工艺应运而生。本文主要介绍了最新研究的5种冷弯成形工艺,包括三维成形技术、非等厚辊弯成形技术、分枝辊弯成形技术、局部加热成形技术、热辊弯成形技术。前3种新冷弯成形工艺充分利用冷弯成形中逐道次成形的工艺特点,丰富了冷弯件的截面形状,打破了冷弯件的等截面、等厚度的固有概念。剩下两种新冷弯成形工艺直接改变了冷弯成形工艺在常温下成形的传统概念,使高强钢材料在冷弯成形工艺中应用范围扩大。     

管件电磁胀形极限的实验研究

电磁成形可明显提高铝合金的的成形性，因此在汽车工业中有广泛的应用前景。本文根据电磁胀形特点对管件电磁胀形的成形极限进行实验研究，建立了1060纯铝和3A21铝合金的电磁成形极限线，并且研究了尺寸对3A21铝环的极限成形性能的影响。     

Manufacturing of Long Products Made of Innovative Lightweight Materials

The processing of innovative lightweight materials to sheet metal components and assemblies with globally or locally defined properties is the object of this work. It takes a load-dependent design of components and assemblies, for example, based on the composition of different construction materials or a targeted setting of component areas with specified characteristics to fully exploit the lightweight potential when substituting conventionally used materials. Different process chains for the manufacturing of roll-formed long products made of magnesium alloys and high-strength steels with locally defined properties will be presented in this paper. Depending on the kind of material to be formed and the desired product characteristics, different temperature managements are needed for capable processes. Due to limited formability at room temperature, magnesium alloys require a heating of the forming zones above 200–225 °C throughout the bending process in order to activate additional gliding planes and to avoid any failures in the radii. The realization of local hardening effects requires at least one process-integrated heat treatment when roll forming manganese–boron steels. For both processes, it is imperative to realize a heating and cooling down or quenching appropriate for the manufacturing of long products with the required quality. Additionally, proper line speeds that allow a continuously operated economical production have to be considered. Research results including design, FEA, realization and experimentation of the mentioned process chains and strategies will be described in detail.     

高性能镁合金的特种制备技术

镁合金管、棒、板及异型材料在汽车、电子、航空、航天等领域具有重要的应用价值和广阔的应用前景，但其加工成形性能差。采用快速凝固、喷射沉积技术制备镁合金，可细化合金的晶粒，改善其变形能力，是获得高性能镁合金材料的最佳选择。本文系统介绍了快速凝固、喷射沉积技术制备高性能镁合金材料的方法。     

航空铝锂合金热成形研究进展

与传统铝合金相比,铝锂合金拥有更低的密度、更高的比强度、更好的耐腐蚀性,在航空、航天和航海领域得到了广泛应用。铝锂合金的优异性能归因于在铝基体中添加元素锂。但铝锂合金存在常温延伸率低、回弹大和各向异性强等问题,这些问题严重限制了铝锂合金的应用。为解决铝锂合金常温成形性差的问题,国内外学者针对铝锂合金热成形工艺开展了大量研究。本文首先介绍铝锂合金的发展,随后基于基础实验、失稳理论以及损伤理论三个方面介绍铝锂合金热成形研究进展,了解铝锂合金高温宏微观变形机理以及损伤演化规律,从而实现铝锂合金零件在高温条件下成形成性一体化控制;最后对航空铝锂合金热成形的发展趋势进行了展望。本文可为航空铝锂合金材料热成形生产工艺的制定提供一定的理论参考。     

Superplastic Response of Continuously Cast AZ31B Magnesium Sheet Alloys

Magnesium sheet is typically produced for commercial applications with the traditional DC-ingot casting method. As a result of the hexagonal close-packed crystallographic structure in magnesium, multiple rolling passes and annealing steps are required to reduce the thickness of the ingots. Thus, high fabrication costs characterize the creation of magnesium sheet suitable for common forming operations. Recently, continuous casting (CC) technology, where molten metal is solidified directly into sheet form, has been applied to magnesium alloys; this method has shown the potential to significantly reduce the cost of fabricating magnesium sheet alloys. In order to understand the viability of the CC process, a study was conducted to investigate the superplastic potential of alloys produced by this method. This study focused on AZ31B Mg that was continuously-cast on twin-roll casters from three different suppliers. These three materials were compared with a production DC-cast AZ31B alloy in terms of microstructure, elevated-temperature tensile properties, and superplastic forming response. The data from this study found that microstructural features such as grain size and segregation can significantly affect the forming response. Additionally, the CC alloys can have equivalent or superior SPF response compared to DC-cast alloys, as demonstrated in both elevated temperature tensile tests and superplastic forming trials using a rectangular pan die.     

Characterization of yielding behavior of sheet metal under biaxial stress condition at elevated temperatures

The enhancement of material modeling in fields of sheet metal forming is essential for finite element-based designing of processes and dimensioning of parts. Since new lightweight materials, e.g. aluminum and magnesium wrought alloys show anisotropic and temperature-dependent forming behavior adequate testing methods and evaluation strategies have to be developed to obtain the reliable material data. For that purpose an experimental setup has been designed at the Chair of Manufacturing Technology which enables biaxial tensile testing of sheet metal at elevated temperatures. In this paper, the setup is introduced and the obtained results, i.e. experimentally determined yield loci and subsequent yield loci as a function of temperature are given for the well-known aluminum alloy AA6016 as well as the magnesium alloy AZ31.