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基于稳健设计的钛合金波纹管超塑成形工艺 总被引:3,自引:0,他引:3
根据稳健设计中的响应面法—复合设计法,用MARC有限元分析软件模拟了钛合金波纹管超塑成形过程的胀形、合模和充满3个阶段。根据模拟结果得到了钛合金波纹管质量评价指标波峰最小厚度及其影响因素筒坯高度和胀形阶段成形气压之间的二元一次和二元二次多项式回归公式,从而实现了钛合金波纹管超塑成形工艺参数的稳健设计。Ti-6Al-4V双波DN250波纹管超塑成形实验证明了回归公式的准确性和复合设计法用于钛合金波纹管超塑成形过程的可行性。 相似文献
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为研究细晶AZ31镁合金薄板超塑气胀成形的最佳工艺参数,利用有限元软件对超塑胀形过程进行了有限元数值模拟分析。通过选取不同的应变速率敏感性指数和成形压力,来分析应变速率敏感性指数和成形压力对厚度分布均匀性的影响,同时对成形过程中的应变速率变化进行了模拟分析。模拟结果表明.应变速率敏感性指数和成形压力对厚度分布均匀性影响很大;应变速率分布情况良好,在所要求的应变速率范围之内,说明应变速率敏感性指数,压力等参数的设计合理。 相似文献
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R. Verma P. A. Friedman A. K. Ghosh C. Kim S. Kim 《Journal of Materials Engineering and Performance》1995,4(5):543-550
Superplastic forming characteristics of a fine-grained 5083 aluminum sheet have been investigated by means of gas-pressure
forming of a rectangular pan. This part geometry lends itself to a simple representation in terms of nearly one-dimensional
sheet stretching and permits reasonably rigorous control of strain rate throughout the forming cycle. This study followed
a study of the uniaxial tensile properties carried out on this alloy. A two-stage forming cycle, which comprised a short,
rapid prestraining stage followed by a stage of slower rate of superplastic straining, was used because the uniaxial tensile
work showed enhancement of superplastic response of this alloy under this condition. The study examined the effect of process
parameters such as initial gas pressurization rate, level of hydrostatic pressure, and lubricants on the thinning characteristics
of the sheet, especially along the die entry radii. The gas pressure/time cycle was suitably modified to avoid premature sheet
failure due to excessive sheet thinning or cavitation. Cavitation under the biaxial forming condition and the effect of hydrostatic
pressure on cavitation suppression were evaluated. A defect-free pan with sharp corners was formed. 相似文献
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本文利用热拉伸实验、气胀成形实验、金相分析和扫描电镜观察,研究LZ91镁锂合金板材的超塑性、气胀成形性能及其组织结构。结果表明:在热拉伸变形温度为573 K、应变速率为0.001 s-1时,其伸长率可达343.7 %,应变速率敏感指数为0.697,轧制态的LZ91合金板材表现出优良的超塑性;在胀形温度573 K,胀形气压0.06 MPa条件下,板材成形高度为51.14 mm,高径比达1.279,说明该镁锂合金板材具有良好的超塑性成形潜力;在热拉伸变形和超塑性气胀成形过程中,均有动态再结晶现象产生,可有效提高该合金的塑性成形能力;在拉伸断口和胀形件破裂处断口均存在典型的超塑性空洞形貌特征,说明两者的主要变形机制均为晶界滑移,且合金超塑性失效的主要原因是空洞的长大和连接。 相似文献
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O. A. Kaibyshev R. V. Safiullin R. Y. Lutfullin V. V. Astanin 《Journal of Materials Engineering and Performance》1999,8(2):205-210
The peculiarities of solid state joint (SSJ) formation under conditions of superplastic forming (SPF) were investigated for
the titanium alloy VT6S (Ti-6Al-4V). The influence of annealing and SPF on the change of state of the alloy surface was considered.
A significant role of grain boundary sliding (GBS) in the formation of both surface microrelief and SSJ was established. It
was shown that SSJ formation under SPF conditions is primarily a deformation process. Corresponding schemes of the appearance
of surface microrelief and SSJ formation are proposed. 相似文献
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基于微细晶超塑性扩散连接方法,对TC4钛合金与1Cr18Ni9Ti不锈钢成功实现了直接扩散连接,系统分析了接头性能、界面微观结构及超塑性扩散连接机理。结果发现:TC4钛合金与1Cr18Ni9Ti奥氏体不锈钢直接超塑性扩散连接时,较佳连接工艺规范为:温度T=760~820 ℃,压力p=6~9 MPa,时间t=20~40 min;接头剪切强度τ=125.3~148.7 MPa。与一般直接扩散连接相比,连接温度降低了约100 ℃,接头的剪切强度提高了1倍以上,且连接试样无明显变形。细化热处理TC4钛合金与1Cr18Ni9Ti不锈钢超塑性扩散连接时,其接头的形成过程大致可分为3个阶段:形成紧密接触阶段、接触表面激活阶段及靠近活化中心的界面冶金结合区形成阶段。 相似文献
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大块非晶合金超塑性变形的研究现状与发展 总被引:1,自引:0,他引:1
文章对国内外非晶合金超塑性基本性能的研究工作进行了介绍和评述。根据材料成形工艺的要求,提出了非晶合金超塑性成形研究的内容。介绍了非晶合金超塑性拉伸实验和压缩实验的研究进展,分析了温度和成形速率对变形的影响,介绍了粘度的影响因素,对这些研究内容和热点问题进行了评述。展望了非晶合金超塑性研究的发展趋势,提出应加强非晶合金超塑性流动过程的理论研究。 相似文献
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钛合金激光焊缝是非理想的针状组织,对其超塑性变形机理的研究可进一步推进钛合金LBW/SPF技术的实际应用,也对材料成形机理的发展具有一定意义.研究结果表明,TC4钛合金激光焊接试样具有良好的超塑性变形能力,在变形过程中,焊缝发生两次重要的组织转变,即针状组织片层化和片层组织等轴化的组织转变.片层组织在应力作用下,通过断裂、解体和等轴化的过程而转变成等轴晶粒.片层断裂的主要机制是动态再结晶和应力挤压作用;片层解体的主要机制是晶界滑动和转动作用,接头组织的塑性流动机理为晶粒滚动和晶界滑动机理. 相似文献
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变形工艺对TC11钛合金超塑性的影响 总被引:1,自引:0,他引:1
为了研究TC11(Ti-6.5Al-3.5Mo-1.5Zr-0.3Si)钛合金的超塑性变形行为,采用两种改锻工艺细化坯料原始组织,然后在电子拉伸试验机上分别以恒速、恒应变速率和最大m值法进行拉伸实验.结果表明,TC11钛合金在α+β区通过三维镦拔改锻工艺,可以获得晶粒度为6μm的细晶等轴组织,而在β区拔长改锻的组织为粗大的魏氏组织.在变形温度为900℃的条件下,TC11钛合金通过最大m值超塑变形方式获得了异常高的超塑性,最大伸长率达到2300%;而采用常规的恒应变速率和恒速超塑变形,伸长率分别为1147%和1100%.说明TC11钛合金在α+β区通过三维镦拔改锻细化晶粒后,以最大m值超塑变形是获得较好超塑性的有效方法. 相似文献
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《稀有金属材料与工程》2004,21(6):10-13
简要介绍了超塑性在压力加工方面以及相变超塑性在焊接方面的应用。重点介绍了超塑性成形和超塑性成形/扩散焊接技术在钛合金上的应用、超塑成形模具材料选择的原则、以及提高SPF部件性能的措施。 相似文献
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Qizhen Li 《Journal of Materials Engineering and Performance》2008,17(3):363-368
Transformation superplastic forming is an attractive alternative forming technique to microstructural superplastic forming,
since it requires no special microstructures and, therefore, eliminates the limitation of superplastic forming capability
to only expensive materials with stable high-temperature fine grains. Transformation superplasticity occurs through biasing
the internal stress produced from an allotropic phase transformation by a small external stress. In this work, finite element
modeling was implemented to study the transformation superplastic forming of domes from flat circular thin plate samples.
The evolution and distribution of stress, strain, and dome thickness was analyzed in detail. The thickness distributions in
the formed domes were compared with the theoretical predictions of two models, which assume different stress states in the
domes. The appropriate stress state was identified through this comparison. Different gas pressure amplitudes were applied
during forming to investigate the effect on the formed-dome apex height, when the forming time was fixed.
This article was presented at Materials Science & Technology 2007, Automotive and Ground Vehicles symposium held September
16-20, 2007, in Detroit, MI. 相似文献
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George Luckey Jr. Peter Friedman Klaus Weinmann 《Journal of Materials Processing Technology》2009,209(4):2152-2160
The conventional superplastic forming (SPF) of complex and deep geometries can result in excessive thinning and necking. To address these issues, a two-stage SPF process has been developed and demonstrated in forming trials using a superplastic aluminum sheet alloy. Within a single die, gas pressure is used to form the blank into a preform die cavity prior to the pressure being reversed to form the sheet into the final component cavity. The preforming of the blank creates length of line, while preserving metal thickness in certain regions to improve the thickness profile of the final part. In this work, a preform has been designed to improve the forming of a complex component by providing a superior thickness profile as compared to a conventional single stage forming cycle. Finite element analysis was used to guide the design of the preform cavity since the preforming surface was not intuitive and could cause wrinkling in the final part. 相似文献
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An innovative method has been developed that replaces argon as the pressure source for superplastic forming. In this new process,
several solid materials are placed in a closed system to generate pressure and are capable of forming superplastic alloy plates
at specific temperatures. In the present study, the total pressures for the decomposition of ( CaCO3+ C) and MgCO3 have been theoretically calculated from thermodynamics. The results show that a pressure range of 40 to 396 psi can be obtained
for the ( CaCO3 + C) system between 850 and 1000 °, which is suitable for the superplastic forming of Ti-6Al-4V and Superdux 64 ( Nippon
Yakin Kogy Co., Ltd., Sanei Bridge, Kyobasi 1-5-8, Chyuoku, Tokyo 104, Japan) stainless steel. The pressure for MgCO3 system between 480 and 515 ° ranges from 78 to 160 psi, which is suitable for the superplastic forming of 8090 Al-Li and
7475 Al-Zn-Mg alloys. The calculated temperature dependence of pressure is consistent with the experimentally measured results.
Furthermore, the forming rates, wall thickness distributions, tensile properties, and microstructures of the four alloys after
forming have been shown to be very similar to those of conventional superplastic forming by argon pressurization. 相似文献
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综述了高应变速率超塑材料种类、变形机理和应用技术的最新进展。高应变速率超塑材料主要是铝基复合材料及铝合金,最近,对镁合金、纳米材料、钛合金高应变速率超塑性能的研究也已开始。高应变速率超塑性在工业中的应用已经起步,例如快速超塑成形技术、一模多件技术等,可以实现中等批量、甚至大批量生产,但是主要集中在铝合金上。未来激光辅助超塑成形技术、电塑性辅助超塑成形技术值得期待。 相似文献
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X. D. Ding H. M. Zbib C. H. Hamilton A. E. Bayoumi 《Journal of Materials Engineering and Performance》1995,4(4):474-485
The superplastic blow-forming process of thin sheets is analyzed, and an optimal stable deformation path that reduces production
time is obtained. The analysis is based on an analytical model for the superplastic forming (SPF) of a long rectangular box
made of Ti-6Al-4V alloy at 900 °C use of a microstructure-based constitutive equation for the strain rate and grain growth,
a stability criterion, and a variable strain rate control. It is shown that by imposing a variable strain rate control scheme
derived from the stability analysis, an optimal forming time can be developed while maintaining a stable deformation path.
Some other control schemes also show effectiveness in either reducing the localized thinning in the formed sheet or reducing
the required forming time. Effects of friction and initial grain sizes on the forming pressure profile and the thickness distribution
of the formed sheet are also investigated. 相似文献