冷变形织构沿纯铜线材径向分布的研究

为了探讨显微组织与形变织构的相关性,对纯铜线材运用精确的线材织构测定方法进行织构测定,采用取向分布函数法（ODF）分析了织构沿纯铜线材径向的分布．研究表明：单晶铜线材表面织构组分由（100）,（112）与（110）组成．由表及里（100）呈现增加趋势,并在中心层成为主要织构组分;（112）先增加后减少;（110）呈现减少趋势．多晶铜线材表面织构组分有（100）,（111）,（112）．由表及里（100）呈现先增加后减少;（111）呈现增加趋势,并在中心层与（100）成为主要织构组分;（112）先减少后增加．     

塑性变形对单晶铜线材导电性影响的研究

为了研究塑性变形对单晶铜线材导电性的影响，以及电阻率与塑性变形量之间的定量关系，将Φ8mm的工业单晶铜线材冷拔后，得到塑性变形量不同的试样，用四端引线法精确测量其电阻率、结果表明，单晶铜线材的电阻率随塑性变形量的增加而上升，其原因是由于单晶铜线材的微观组织畸变程度随塑性变形量的增加而加剧。     

单晶铜线材在制备过程中的晶粒演化

采用了热型连续铸造方法,选用相同的工艺参数制备出不同直径的铜线材,用光学显微镜分析了线材晶粒形成及生长过程.结果表明:在一定的牵引速度下,纯铜线材晶粒生长的特征是从引晶开始阶段的等轴多晶体渐渐演化为柱状多晶体,最终形成单晶体;随着线材直径的增大,起始晶粒个数在增加;生长成单晶的时间也在增加,经X射线衍射和透射电镜分析能够确定,单晶铜线材晶体择优生长方向为<100>.     

线材冷轧织构演变的定量研究

为了探讨圆柱型线材压扁过程中晶粒取向的变化规律,借助于XRD织构衍射仪与三维取向分布函数(ODF)分析,研究了异步轧制的ECAP一道次处理后的实验样品的织构随着冷轧压下量的演变规律.实验结果表明:从快辊侧分析,织构取向密度沿着冷轧实验试样的厚度从表层到中心层随着形变量的增加,冷轧纯铁试样中主要织构组分逐渐形成了<110>//RD(轧向)的α-纤维织构和<111>//ND(轧面法向)的γ-纤维织构,且织构组分的取向密度级别逐渐增加.另外,通过反极图分析与定量计算可以知道:不同压下量下, <110>织构组分体积分数由表及里呈现增长趋势.<100>织构组分体积分数在压下量为0%,40%时由表及里先上升后下降.当压下量为80%时则出现相反变化趋势.当压下量为0%时,<111>织构组分体积分数先下降后升高.而压下量为40%,80%时<111>织构组分体积分数呈现上升趋势,沿着试样厚度存在一定差别.     

工业铜单晶线材浸蚀蚀坑的研究

对工业铜单晶线材用不同浸蚀剂,浸蚀时间,材料晶体取向等方面进行了浸蚀试验.结果表明,在氯化铁盐酸溶液中仅当配比为20 g(FeCl3)∶5 ml(HCl)∶100 ml(H2O)时会有蚀坑产生;蚀坑密度(EPD)随试样浸蚀时间和试样的变形量的增加而增大,当达到一定程度时会趋于饱和;铜单晶线材中(111)面EDP值高于(100)面;经过扫描电镜观察,判定该蚀坑为位错蚀坑.铜单晶线材中位错蚀坑密度与材料浸蚀时间,变形量以及晶体学取向有关.     

冷拔工艺对工业单晶铜线材组织和力学性能的影响

单晶铜线材常需经过冷拔变形才能使用,冷拔变形导致单晶铜线材的微观组织发生改变,影响其性能.文中在不同的冷拔工艺下,对热型连铸工业单晶铜线材进行了冷拔变形实验,分析了冷拔工艺对其组织和力学性能的影响.结果表明:当总体真应变一定时,较小的相邻模具真应变量和较低冷拔速度仅能使工业单晶铜线材内部晶粒拉长、变细.增加相邻模具真应变和冷拔速度均会导致线材内部局部区域出现形变位错界面和形变孪晶.随着冷拔速度和相邻模具真应变的增加,冷拔工业单晶铜线材的强度增加、延伸率下降.采用较低的冷拔速度,较小的相邻模具间真应变,工业单晶铜线材优异的塑性得以较好的延续,穿模成功率提升,冷拔过程中的断线率降低.     

叠轧法深度塑性变形铜组织的研究

用X-射线衍射分析法检测了异步叠轧和同步叠轧制备变形量不小于98.4%纯铜样品的变形织构、残余应力、位错密度、晶格点阵常数和晶粒大小,测试了加工态样品的维氏硬度.结果表明,异步叠轧铜变形织构是剪切织构{100}<011>,同步叠轧铜的变形织构是铜织构{112}<111>;异步叠轧和同步叠轧对晶粒大小、位错密度、微观应变、晶格点阵常数和硬度等没有显著影响;硬度、残余应力、位错密度、晶格点阵常数和晶粒大小随变形量的增大分别趋向一个常数.这暗示无限叠轧不能无限地细化晶粒.     

CSP薄板冷轧退火组织和织构的研究

采用EBSD分析方法,对CSP试验钢冷轧板退火过程中组织转变和再结晶织构的演变进行分析,结果表明,在退火过程中,α取向线上的{112}<110>和{110}<110>织构的取向密度基本上没有变化,{100}<110>织构的取向密度是逐渐降低的,而{111}<110>织构有所增强,γ取向线上{111}<011>和{111}<112>织构都是呈先降低后升高的趋势,而且最终{111}<011>和{111}<112>两种织构的取向密度趋于相等,分别为5.28和5.24.     

单晶连铸小直径铜线材的静拉伸力学性能研究

采用单晶连铸技术生产的单晶铜线材不仅具有优美的外观和内部质量，也具有非常优异的塑性加工性能．单晶铜线材在实际应用时，一般需要进行数次冷拔变形，因此，研究其力学性能，对单晶线材获得广泛应用具有实际意义．采用自制的单晶连铸设备，制备出直径为2．6mm的单晶铜线材和多晶铜线材．对两种线材的力学性能进行测试分析，并与普通铜线材进行对比．结果表明：采用单晶连铸技术生产的铜线材的抗拉强度和屈服强度均比普通铜线材低的多，而延伸率却有大幅度提升．同种技术生产的单晶和多晶两种线材相比，单晶铜线材的塑性更为优异．对拉伸断口进行扫描发现：单晶连铸多晶铜线材和普通铜线材的断裂为典型的微孔聚集型断裂，而单晶铜线材的断裂属于滑移延伸断裂．     

金属线材单晶化方法与设备

单晶线材是新一代的高保真、高清晰度的传输线材，也是高质量的网络传输用线，单晶制备技术是西安工业大学一个重要研究方向，近3年内获得国家自然科学基金、陕西省自然科学基金、国防“十五”项目等多项基金项目资助，解决了固液界面形状位置的控制等关键性问题，目前已经自行设计出年产量200吨的金属线材单晶化设备，解决了单晶连铸技术对所制备线材长度和直径的限制，已成功制备出直径为1mm、2mm、3mm、8mm的单晶铜、铝线材。通过工艺优化可以制备出直径小于1mm的单晶金属线材。     

Texture of deformed Cu-Cr-Zr alloys

The influences of plastic deformation, aging treatment, and alloying elements on the texture of Cu-Cr-Zr alloys were explored. The texture component and intensity of Cu-Cr-Zr alloys under various working conditions after aging treatment were characterized using the orientation distributing function (ODF). The influence of Zr content on the texture of Cu-Cr-Zr alloys was also analyzed. The reduction pass and deformation level were primary factors influencing the texture. Rolling texture appeared in a rolled plate and the fibrous textures of {111} and {001} were detected after 80% deformation. Fibrous texture with a main constituent of {111} improved the tensile strength of the alloy wire. The texture contents of {110}<331> and {110}<112> were predominated, whereas, those of {113}<332> and {112}<111> were in the minority in the Cu-Cr-Zr alloy with a higher Zr content (>0.5wt%). However, in the samples with a lower Zr content (<0.1wt%), the texture contents of {113}<332>, {112}<111>, and {111}<110> were in the majority.     

Microstructure evolution of single crystal copper wires in cold drawing

The deformation microstructure evolution of single crystal copper wires produced by OCC method has been studied with the help of TEM, EBSD and OM. The results show that there are a small number of dendrites and twins in the undeformed single crystal copper wires. However, it is difficult to observe these dendrites in deformed single crystal copper wires. The structure evolution of deformed single crystal copper wires during drawing process can be divided into three stages. When the true strain is lower than 0.94, macroscopic subdivision of grains is not evident, and the microscopic evolution of deformed structure is that the cells are formed and elongated in drawn direction. When the true strain is between 0.94 and 1.96, macroscopic subdivision of grains takes place, and the number of microbands located on {111} and cell blocks is much more than that with the true strain lower than 0.94. When the true strain is larger than 1.96, the macroscopic subdivision of grains becomes more evident than that with the true strain between 0.94 and 1.96, and S-bands structure and lamellar boundaries will be formed. From EBSD analysis, it is found that part of 〈100〉 texture resulting from solidifying is transformed into 〈111〉 and 〈112〉 due to shear deformation, but 〈100〉 texture component is still kept in majority. When the true strain is 0.94, the misorientation angle of dislocation boundaries resulting from deformation is lower than 14°. However, when the true strain arrives at 1.96, the misorientation angle of some boundaries will be greater than 50°, and the peak of misorientation angle distribution produced by texture evolution is located in the range between 25° and 30°. Supported by the National Natural Science Foundation of China (Grant Nos. 50471098 and 59971033), the Natural Science Foundation of Shaanxi Province, China (Grant No. 2003E101), and the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institution of MOE, China     

Modeling texture development during cold rolling of IF steel by crystal plasticity finite element method

With the consideration of slip deformation mechanism and various slip systems of body centered cubic (BCC) metals,Taylor-type and finite element polycrystai models were embedded into the commercial finite element code ABAQUS to realize crystal plasticity finte element modeling,based on the rate dependent crystal constitutive equations.Initial orientations measured by electron backscatter diffraction (EBSD) were directly input into the crystal plasticity finite element model to simulate the development of rolling texture of interstitial-flee steel (IF steel) at various reductions.The modeled results show a good agreement with the experimental results.With increasing reduction,the predicted and experimental rolling textures tend to sharper,and the results simulated by the Taylor-type model are stronger than those simulated by finite element model.Conclusions are obtained that rolling textures calculated with 48 {110}<111>+{ 112}<111>+{123}<111> slip systems are more approximate to EBSD results.     

多晶铜轴对称变形织构的纵向塑性各向异性

应用Taylor类多晶体塑性模型对轴对称变形下多晶铜的变形织构进行了数值模拟,分析了变形过程中多晶铜屈服应力的各向异性演化情况;计算分2步:先对随机分布多晶集合体进行轴对称拉伸,然后分别沿已变形的多晶集合体的各方向再进行拉伸变形,得到了屈服应力的取向分布及纵向塑性各向异性的直观图像,为变形织构塑性各向异性力学行为的宏观模型描述提供了一个数值实验。     

Fabrication of pure copper rods containing continuous columnar crystals by continuous unidirectional solidification technology

Pure copper rods containing continuous colunmar crystals were fabricated using the downward CUS (Continuous Unidirectional Solidification) equipment. When the technological parameters were set as the ranges of mould temperature 1100-1300℃, cooling distance (the distance from the exit of the cast mould to the start point of cooling) 10-20 nun, casting speed 0.2-2.5 mm/s, cooling water (20-25℃) volume 1000-1320 L/h, and when these parameters matched reasonably, the CUS process was performed stably, and pure copper rods containing continuous columnar crystals with bright and smooth surface were produced. The dendritic arm spacing of the crystals in copper rods decreased with increasing the casting speed. The results of the texture by X-ray diffraction analysis showed that the rods has strong (100) fiber texture.     

电子显微取向成像及其在单晶铜线材研究中的应用

本文从基本原理、设备构造、角度和空间分辩率、试样制备方法以及数据处理等方面,系统地介绍了一种新的材料研究方法——电子显微取向成像.同时,结合在研课题的一些研究进展,针对变形前后单晶铜线材的组织演化,探讨了电子显微取向成像技术在微观组织、织构和晶体转动以及位错界面分析等中的应用,以展现电子显微取向成像的功能和应用.     

Processing limit maps for the stable deformation of dieless drawing

Tin bronze wires were produced by dieless drawing. The effects of heating power, the distance between cooler and heater as well as feeding speed on the diameter, the temperature field, and the deformation region profile of the wires were investigated. The results indi-cated that each processing parameter exhibited both lower and upper limits of stable deformation based on the criterion of stable deformation with the diameter fluctuation of ±0.05 mm. Both the temperature and its gradient of the deformation r...     

COMPUTER SIMULATION OF DISLOCATION CORES IN B2 NIAL INTERMETALLICS *

ＴｈｅｄｅｆｏｒｍａｔｉｏｎｍｅｃｈａｎｉｓｍｓａｎｄｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓｏｆＮｉＡｌｈａｖｅｂｅｎｓｔｕｄｉｅｄｅｘｔｅｎｓｉｖｅｌｙｄｕｅｔｏｉｔｓｐｏｔｅｎｔｉａｌｆｏｒｈｉｇｈｔｅｍｐｅｒａｔｕｒｅａｐｐｌｉｃａｔｉｏ...     

Influences of microstructure and texture on crack propagation path of X70 acicular ferrite pipeline steel

The aspects of two pipeline steels with different technologies were investigated by using transmission electron microscopy (TEM) and electron back-scattered diffraction (EBSD).The microstructure presents a typical acicular ferrite characteristic with free particles of martensite/austenite (M/A) constituent,which distributes in grains and at grain boundaries.The bulk textures of the pipeline steel plate are {112}<110> and <111> fibers,respectively,and the {112} <110> component is the favorable texture benefiting for drop weight tear test.Moreover,low angle boundaries and low coincidence site lattice boundaries are inactive and more resistant to fracture than high energy random boundaries.