共查询到19条相似文献,搜索用时 422 毫秒
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将UBET用于求解压缩圆环问题,可简便快速地取得上限解;进而采用该解绘制塑性加工中测量摩擦系数的理论校准曲线.对中性层的位置进行了精确求解;分析了绘制理论校准曲线时,总压缩量、压缩步长量等参数对其结果的影响. 相似文献
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采用最先进的热模拟机Gleeble-2000对Ti-6-2-4-2s钛合金在热镦粗时的流变应力进行了较为全面的研究.主要分析了在各变形温度、应变和应变速率下流变应力的变化情况,采用非线性数学回归的方法,回归出了Ti-6-2-4-2s钛合金在热镦粗变形时的流变应力数学模型. 相似文献
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目的研究TC4钛合金在多向锻造过程中的变形行为。方法基于Deform-3D模拟软件平台,对钛合金的多向锻造变形过程进行有限元模拟分析,研究不同工艺参数(锻造温度、锻造速度、锻造工步)下合金最大主应力、等效应变和载荷最大值的变化规律。结果多向锻造的每工步锻造为典型的镦粗过程,坯料中心部位一直受压应力作用,鼓肚处则出现最大拉应力。随着锻造温度的升高和锻造速度的减小,最大压应力和拉应力均减小,多工步锻造之后合金主应力场分布更加均匀。随着锻造工步的增加,坯料等效应变增大且中心大变形区域体积分数增加。最大载荷随锻造温度的升高和锻造速度的降低而减小,相同参数下不同锻造工步的载荷最大值变化不大。结论锻造温度、锻造速度、锻造工步对TC4钛合金多向锻造变形行为有显著的影响,适当选择多向锻造工艺参数,可以降低载荷并获得均匀性较好的坯料。 相似文献
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目的 针对铆接过程中铆钉钉杆发生镦粗变形,其变形的均匀性影响连接接头力学性能的问题,提出一种钉杆带有锥度的变径铆钉,以改善钉杆变形的均匀性.方法 基于三维有限元仿真方法,对准静态铆接过程进行仿真,获取锥形与常规半圆头铆钉在铆接后钉杆变形情况,同时对比分析板材残余应力变化情况.最后建立由钉杆变形均匀度与铆钉尺寸以及镦头高度组成的灰色系统,并通过对该系统进行关联度计算分析,确定铆钉尺寸及镦头高度对均匀度的影响.结果 锥形铆钉铆接后钉杆均匀性优于常规铆钉.使用不同铆钉进行铆接,板材残余应力有着相同变化趋势.铆钉尺寸、镦头高度对钉杆变形均匀度的关联度计算结果分别为0.608和0.596,铆钉尺寸变化对均匀度的影响大于镦头高度变化.结论 锥形铆钉对钉杆变形均匀性的改善有良好效果. 相似文献
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考虑相变的TC4钛合金流动应力研究 总被引:1,自引:0,他引:1
为完善TC4钛合金的塑性成形理论,必须建立准确的流动应力模型,而TC4钛合金的流动应力不仅与温度、应变速率和应变量相关,也受到βα+β相变的影响.本文通过等温实验和DSC实验研究了900℃时TC4钛合金的等温与连续冷却过程中的相变动力学,建立了相变动力学模型;通过Gleeble 3800热模拟机进行热压缩实验,根据实测的TC4钛合金在高温β区与低温α+β区的流动应力曲线,建立了流动应力模型;将相变动力学模型与流动应力模型结合,建立了考虑相变的流动应力模型;最后将TC4钛合金在900℃等温不同时间后进行压缩变形,对比实验得到的流动应力曲线与模型计算得到的流动应力曲线,验证了该模型的准确性. 相似文献
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R. E. Dutton V. Seetharaman R. L. Goetz S. L. Semiatin 《Materials Science and Engineering: A》1999,270(2):137
The application of the ring test to assess die–workpiece interface friction during forging of a flow softening material was investigated. Calibration curves were generated by conducting finite element method (FEM) simulations of ring forging with different friction factors. The method was validated by conducting isothermal, hot compression tests on rings of an α2 titanium aluminide alloy for both lubricated and unlubricated interface conditions. The FEM results for the flow softening material were compared to those generated assuming no flow softening. In all cases, the differences between the curves predicted for the flow softening and non-softening behaviors were quite small. Furthermore, for given values of the interface friction factor, the calibration curves were essentially independent of the strain rate sensitivity (m) and flow softening. 相似文献
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目的研究变形温度、应变速率等热力参数对TC21钛合金流动应力的影响规律,并构建出TC21钛合金本构方程。方法在热模拟试验机上对TC21钛合金进行了等温恒应变速率压缩实验,分析其真应力-真应变曲线。结果获得了该合金在变形温度范围为760~920℃、应变速率范围为0.001~10 s-1的流动应力数据,采用多元线性回归法建立了该合金的本构方程。结论误差分析表明,该本构方程具有较高精度,可为TC21钛合金锻造过程中的数值模拟和锻造热力参数的合理制定提供理论依据。 相似文献
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FE simulation for the forging process of TC6 alloy disc utilising a microstructural model 总被引:1,自引:0,他引:1
The interaction between the deformation behavior and microstructural evolution is the main characteristic in the forging process of a titanium alloy and the interaction can be researched using FE simulation. In this paper, a constitutive equation, considering the effects of grain size on the deformation behavior, is established for high temperature deformation of titanium alloys. Also, FE simulation of deformation behavior combined with heat transfer and grain size in the forging process of TC6 alloy disc is carried out. By FE simulation, the deformation distribution and grain size were illustrated for the forging of a TC6 alloy disc at 920 °C deformation temperature and 2.0 mm/s of hammer velocity. The calculated deformation load and grain size are in a good agreement with the experimental results. 相似文献
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Isothermal compression of the TC11 titanium alloy has been conducted on Gleebe-1500 hot-simulator at the deformation temperatures ranging from 1023 K to 1323 K, the strain rates ranging from 0.001 s−1 to 10.0 s−1, and the height reductions ranging from 50% to 70%. The effect of deformation temperature, strain rate and strain on the flow stress and the apparent activation energy for deformation is in depth analyzed. The experimental results show that the apparent activation energy for deformation in isothermal compression of the TC11 titanium alloy decreases with the increasing of strain. Moreover, the apparent activation energy for deformation in α + β two-phase region of the TC11 titanium alloy increases with the increasing of deformation temperature and decreases with the increasing of strain rate. A power dissipation efficiency map in isothermal compression of the TC11 titanium alloy is constructed at a strain of 0.6, in which three domains with higher power dissipation efficiency are observed, and deformation characteristics of the above-mentioned domains are analyzed. Finally, optical micrographs of the TC11 titanium alloy obtained on a Leica DMLP microscope showed the evidence of deformation in three domains. 相似文献
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采用分离式Hopkinson压杆装置对TC4钛合金和DT4电磁纯铁的帽形试样进行动态冲击实验,以研究两种材料高应变率下的绝热剪切行为,并分析材料热物理性能和力学性能对其绝热剪切敏感性的影响。实验所得流变应力-时间的关系曲线以及微观的金相分析都表明:尽管两种材料都发生了绝热剪切失效,但是TC4材料中的绝热剪切过程比较短暂,在失稳后的几个微秒之内材料就丧失了承载能力,并且带旁基体无明显塑性流变;而DT4材料中绝热剪切带的形成和扩展过程却要经历约60μs的时间,而带旁边的基体材料沿剪切方向发生了明显的塑性流变。通过对比两种材料绝热剪切带的扩展能,揭示了材料的比热、热导率和动态强度等参数对绝热剪切过程的影响。 相似文献
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《Materials Science & Technology》2013,29(2):197-203
AbstractThe interaction between the deformation behaviour and the microstructure evolution is the main characteristic in the forging process of titanium alloy and this interaction is researched using finite element (FE) simulation. Coupled simulation of deformation behaviour with microstructure evolution has been carried out by means of a new constitutive equation presented by Li et al. (Mater. Sci. Technol., 2004, 20, 1256–1260). The effect of deformation temperature, hammer velocity,height reduction and shear factor on the microstructure variables, including grain size and volume fraction, has been studied in the forging process of the TC6 titanium alloy disc with deformation temperatures of 880–940°C, hammer velocities of 1·2–12 000 mm min?1 and shear factor (m) of the friction of 0·1–0·4. The simulated results show that deformation temperature, hammer velocity and height reduction have a significant effect on themicrostructure evolution and this effect is more significant on the microstructure evolution in hot forging than that in isothermal forging. The simulated results are in good agreement with the experimental results. 相似文献
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采用等离子渗氮技术提升TC4钛合金的耐磨性并探究最优渗氮温度。利用LDM 1-100型等离子渗氮设备,在650,700,750,800,850℃和900℃温度下对TC4钛合金进行渗氮处理,保温时间均为10 h。利用光学显微镜、扫描电子显微镜、白光三维形貌仪、X射线衍射仪和显微硬度计分别对不同温度渗氮试样的微观组织结构、表面形貌、表面粗糙度、相结构和硬度进行表征。利用CETR UMT-3型多功能摩擦磨损试验机测试等离子渗氮后TC4钛合金的摩擦学性能。结果表明:TC4钛合金表面显微硬度和粗糙度随温度升高而增大,在900℃渗氮后TC4钛合金表面显微硬度达到了1318HV 0.05,约为基体(360HV 0.05)的4倍。硬度的升高是由于渗氮后试样表面形成了硬质氮化物相(TiN和Ti2N相),且随着渗氮温度升高氮化物的含量增加。相较于低温渗氮(低于750℃)的试样,850℃和900℃渗氮试样的承载能力显著提升。与原始TC4试样相比,渗氮处理后试样的磨损体积显著降低。当渗氮温度为850℃时,试样磨损体积为未处理试样磨损体积的1.2%(1 N),3.0%(3 N)和62.2%(5 N),试样的耐磨性提升更为显著。 相似文献
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通过摩擦氧浓度方法点燃涂覆NiCrAl/YSZ/NiCrAl-B.e复合涂层的TC11钛合金,采用XRD,SEM,EDS及EPMA等微观表征方法对其燃烧产物进行分析,进而探讨复合涂层对燃烧行为的影响机理。结果表明:燃烧试样的基体从中心孔沿径向往外呈分区组织演变特征,中心孔处的钛合金基体是着火源;当燃烧程度较低时,YSZ中间层对钛合金燃烧行为的影响较小;当剧烈燃烧时,YSZ中间层通过分解反应而在钛合金熔体中大量溶解,为钛合金熔体提供了O和Zr,加速了Ti与O的快速结合,同时ZrTiO_4燃烧产物的阻氧能力比TiO_2差,从而大大促进了钛合金的扩展燃烧。 相似文献