共查询到19条相似文献,搜索用时 78 毫秒
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采用多向镦粗对7075铝合金试样进行压缩,利用有限元软件对多向镦粗的组织晶粒度预报,探索模拟分析与实验分析相结合的方法,研究7075铝合金多向镦粗过程的组织晶粒变化规律,并对五道次镦粗试样与初始样进行室温拉伸力学性能测试和采用SEM断口形貌观察。模拟结果表明:经过5道次镦粗后试样中心区域的组织晶粒明显细化,晶粒尺寸从初始的40μm减小到17μm;随着道次的增加,组织晶粒细化效果逐渐减弱。对比模拟预报与实验分析结果表明:两者在晶粒细化程度上吻合良好;经过5道次镦粗之后,拉伸断裂强度从初始的547 MPa增加到665 MPa,断面收缩率从初始的7.1%增加到28.4%,断口韧窝深而大,强度塑性明显提高。 相似文献
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采用等通道转角挤压(ECAP)对MB15合金试样进行挤压,利用有限元软件DEFORM-3D进行ECAP晶粒组织模拟,探索采用有限元模拟与实验分析相结合的方法,研究镁合金ECAP成形过程的晶粒组织变化规律。模拟结果表明:数值模拟后试样从头部P1处、中部P2处到尾部P3处的晶粒组织细化程度明显减小,平均晶粒尺寸从初始的13.32μm减小到2.3~3.1μm;采用ECAP方法进行一道次挤压,试样的平均晶粒尺寸从13.32μm减小到2.2μm。对比数值模拟与实验分析结果表明:两者在晶粒细化程度上吻合良好。 相似文献
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等通道转角挤压对纯铜组织细化的作用 总被引:1,自引:0,他引:1
采用高速冲压,对纯铜进行等通道转角挤压(ECAE),利用透射电镜(TEM)观察和扫描电镜的背散射电子衍射(EBSD)分析,研究了应变速度对强烈塑性形变组织细化的作用,讨论了大角晶界超细晶粒的形成机理.结果表明,极快的应变速度可以显著增大大角晶界的百分数达76%,并使晶粒进一步细化,达到0.23 μm. 相似文献
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研究近α钛合金TA15经等通道转角挤压工艺(ECAP)加工后的维氏显微硬度及其变化规律。结果表明:TA15合金经ECAP挤压后,显微硬度显著提高,且合金试样外层硬度略高于芯部。合金的显微硬度与组织畸变程度、位错密度、晶粒尺寸以及相组成等密切相关。相变点以下挤压,挤压温度越低,硬度越高;相变点以上挤压,由于挤压后水冷过程中在β相内产生针状马氏体α′,硬度明显高于相变点以下挤压。模具转角越小,显微硬度越高。随挤压次数增加,硬度先增大后保持基本不变,而挤压路径对硬度的影响与挤压次数、挤压后细化效果密切相关。TA15合金经ECAP后退火,显微硬度明显降低。 相似文献
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镁合金等通道转角挤压过程中的晶粒细化机制 总被引:4,自引:0,他引:4
采用金相显微镜、背散射电子衍射(EBSD)和透射电子显微镜(TEM)分析ZK60镁合金在等通道转角挤压(ECAP)过程中不同部位的显微组织特征。结果表明:ZK60镁合金经240℃ECAP变形1道次后,合金的晶粒得到明显细化,但组织仍不均匀。剪切变形前,合金组织主要为粗大晶粒并伴有大量孪晶,剪切区的组织主要为剪切变形带和少量再结晶组织;剪切变形后,合金的晶粒组织主要为再结晶组织;合金ECAP过程的晶粒细化主要为机械剪切和动态再结晶的综合作用。 相似文献
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等径角挤压处理后的Mg-Gd-Y-Zr合金的微观组织和力学性能 总被引:1,自引:0,他引:1
研究等径角挤压过程中材料的微观组织和织构演变以及对其力学性能的影响。结果表明:挤压4道次后的微观组织是不均匀的,即在此过程中形成了粗晶区和细晶区2个区域。颗粒诱发的再结晶机制导致晶粒细化,在4道次后形成了更加随机的织构。与挤压前的原始材料相比较,经等径角挤压处理的材料虽然强度没有增加,但是塑性有了显著的提高。用织构改变和第二相颗粒解释了合金塑性的变化。 相似文献
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采用等通道转角挤压(ECAP)Bc路径对固溶态Mg-3.52Sn-3.32Al合金分别挤压1、4和8道次。利用光学显微镜、扫描电子显微镜、透射电子显微镜和X射线衍射仪分析合金的组织和相组成,并测试了其室温拉伸力学性能。结果表明,经ECAP挤压后,固溶态合金组织中析出大量细小的Mg2Sn相和极少量的Mg17Al12相。随挤压道次增加,合金的综合力学性能先提高后降低。经4道次挤压后,合金的综合拉伸力学性能相对较佳,抗拉强度、伸长率和硬度分别达到250 MPa、20.5%和61.3 HV9.8,较未ECAP时分别提高43.7%、105%和26.9%。经ECAP挤压的合金室温拉伸断口均呈韧性断裂。等通道转角挤压Mg-3.52Sn-3.32Al合金的力学性能受晶粒尺寸、析出相以及组织织构的共同影响。 相似文献
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Equal channel angular pressing(ECAP) was conducted at 250℃for 4 passes to the as-extruded Mg-3%Cu-1%Mn alloy with high strength and high damping capacity.After ECAP processing,the grain of as-extruded alloy is significantly refined to about 4μm,both yield strength and tensile strength of the as-extruded Mg-Cu-Mn alloy are decreased,but the ductility is improved.After the ECAP processing,the damping capacity of Mg-Cu-Mn alloy is decreased at room temperature,while is substantially increased at elevated te... 相似文献
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Grain boundary character distribution in equal-channel-angular pressed Zr was studied. Using a die design of 90°/20° and an
operation temperature of 350°C. The initial grain size of 20 μm was reduced to about 270 nm with 4 passes via route Bc. The grain growth kinetics of the recrystallized state was obtained by experiment and Monte-Carlo computer simulation, respectively,
which showed good agreement. Based on kinetics and morphological characteristics, it was concluded that the grain coarsening
mechanism was governed by normal grain growth. No sign of abnormal grain growth was detected either in the experiment or in
simulation despite taking into consideration anisotropy in grain boundary energy as well as its mobility. This indicates that
grain boundaries produced by severely deformed Zr are stable against explosive coarsening. The evolution characteristics of
the microstructure in the present ECA pressed and recrystallized Zr differed from those of cold rolled Ti in that the grain
boundary misorientation distribution and texture were rather stable during grain growth.
Jointly Appointed by the Center for Advanced Aerospace Materials
This article is based on a presentation made in the 2002 Korea-US symposium on the “Phase Transformations of Nano-Materials,”
organized as a special program of the 2002 Annual Meeting of the Korean Institute of Metals and Materials, held at Yonsei
University, Seoul, Korea on October 25–26, 2002. 相似文献
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研究通过铸造法制备的含Al3(Sc,Zr)相的7075铝合金静态再结晶行为和再结晶行为与力学性能的关系.Sc和Zr复合添加使Sc?Zr?7075铝合金保留挤压变形过程中形成的大部分纤维组织及高密度位错,导致合金的再结晶转变量由35%降低至22%,相应的亚结构保持量由59%升高至67%.Sc和Zr有效抑制7075铝合金再... 相似文献
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等通道转角挤压(Equal channel angular pressing,ECAP)方法是制备性能优异超细晶材料最常见的大塑性变形方法之一。模角、挤压路径、挤压道次、挤压温度和挤压速度等因素都会影响等通道转角挤压制备超细晶材料的性能;等通道转角挤压的模具也在不断地优化,如背压-等通道转角挤压(Back pressure ECAP,BP-ECAP)模具、可加热的模具以及在等通道转角挤压基础上形成的板材连续剪切技术等,这些新的模具可以改变ECAP变形过程中的组织均匀性。本文综述了等通道转角挤压制备超细晶材料的最新研究进展,并指出了几个需要深入研究的问题及方向。 相似文献
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C.M. Cepeda-Jiménez J.M. García-Infanta O.A. RuanoF. Carreño 《Journal of Alloys and Compounds》2011,509(40):9589-9597
The mechanical properties of an overaged Al 7075-O alloy processed by ECAP were examined by tensile tests at intermediate-high temperatures ranging from 250 to 400 °C and strain rates from 10−5 to 10−1 s−1. The influence of the number of ECAP passes on the ductility enhancement was evaluated. Elongation to failure, eF, significantly increased with increasing the number of ECAP passes up to 8 at 130 °C. The alloy processed under these conditions exhibited a maximum value of 322% at 300 °C and an initial strain rate of 10−3 s−1. High strain rate, eF = 210%, at a strain rate as high as 10−2 s−1. The large elongations together with lower stresses and lower stress exponents than those for the start material confirm that grain boundary sliding (GBS) is the operative deformation mechanism. A loss of superplastic behaviour at temperatures above 350 °C is related to abnormal grain growth and a change of deformation mechanism. 相似文献