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基于模拟及实验的Cu/NbTi异温包覆挤压界面结合研究

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稀有金属材料与工程 2023年第2期52卷 441-447页

作者：孙冬王哲江树勇张艳秋先进金属复合材料成形技术与装备教育部工程研究中心山西太原030024 太原理工大学机械与运载工程学院山西太原030024 哈尔滨工程大学机电工程学院山西太原150001 太原理工大学材料科学与工程学院山西太原030024

提出Cu/NbTi异温包覆挤压,即在塑性变形过程中Cu和NbTi具有不同的温度。Cu/NbTi异温包覆挤压可以有效降低包覆层Cu的变形温度,从而减小包覆层Cu和NbTi芯间的屈服应力差值,有助于二者的协调变形。采用刚粘塑性有限元法模拟凹模入口角分别... 详细信息

提出Cu/NbTi异温包覆挤压,即在塑性变形过程中Cu和NbTi具有不同的温度。Cu/NbTi异温包覆挤压可以有效降低包覆层Cu的变形温度,从而减小包覆层Cu和NbTi芯间的屈服应力差值,有助于二者的协调变形。采用刚粘塑性有限元法模拟凹模入口角分别为60°,120°和180°时Cu/NbTi异温包覆挤压过程,揭示其界面结合情况。模拟结果表明,增大凹模入口角有助于减小包覆层Cu和NbTi芯间的相对伸长量,有益于二者的界面结合。根据有限元模拟优化的工艺参数,进行了Cu/NbTi异温包覆挤压实验,凹模入口角为180°。实验结果表明,该条件下Cu/NbTi包覆挤压过程中金属稳定流动,包覆层Cu和NbTi芯协调变形,二者间相对伸长量较小。实验结果与模拟结果吻合较好。

关键词：塑性变形挤压 NbTi合金有限元法

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曲面扁壳类汽车覆盖件刚度的控制机制研究

材料科学与工艺 2012年第6期20卷 131-135,141页

作者：赵立红江树勇邢忠文张艳秋哈尔滨工程大学工程训练中心哈尔滨150001 哈尔滨工业大学机电工程学院哈尔滨150001

为有效控制和提高汽车覆盖件的刚度,以能够代表汽车覆盖件曲面特点的柱面扁壳件和双曲扁壳件为研究对象,采用数值模拟和试验相结合的方法,深入分析零件在成形过程中拉深筋、拉深深度及压边力对刚度的影响规律,并通过分析扁壳件成形后应... 详细信息

为有效控制和提高汽车覆盖件的刚度,以能够代表汽车覆盖件曲面特点的柱面扁壳件和双曲扁壳件为研究对象,采用数值模拟和试验相结合的方法,深入分析零件在成形过程中拉深筋、拉深深度及压边力对刚度的影响规律,并通过分析扁壳件成形后应力应变分布特点,揭示工艺条件对刚度的影响机制.研究表明:刚度随着压边力的增大而增大,增设拉深筋有助于提高曲面扁壳件的刚度;刚度随着拉深深度的增加而增大;工艺条件的改变可以增大塑性应变量,减少残余应力,并减少回弹,提高刚度.

关键词：汽车覆盖件刚度压边力拉深筋

Dynamic recovery and dynamic recrystallization of NiTi shape memory alloy under hot compression deformation

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Transactions of Nonferrous Metals Society of China 2013年第1期23卷 140-147页

作者：江树勇张艳秋赵亚楠哈尔滨工程大学工程训练中心哈尔滨150001

Mechanical behavior of nickel？titanium shape memory alloy（NiTi SMA） under hot deformation was investigated according to the true stress—strain curves of NiTi samples under compression at the strain rates of 0.001-1 s-1 and at the temperatures of 600？1000℃.Dynamic recovery and dynamic recrystallization of NiTi SMA were systematically investigated by microstructural *** influence of the strain rates,the deformation temperatures and the deformation degree on the dynamic recovery and dynamic recrystallization of NiTi SMA was obtained as *** SMA was characterized by the combination of dynamic recovery and dynamic recrystallization at 600℃ and 700℃,but the complete dynamic recrystallization occurred at other deformation *** the deformation temperatures or decreasing the stain rates leads to larger equiaxed *** deformation degree has an important influence on the dynamic recrystallization of NiTi *** exists the critical deformation degree during the dynamic recrystallization of NiTi SMA,beyond which the larger deformation degree contributes to obtaining the finer equiaxed grains.

关键词： NiTi alloy shape memory alloy dynamic recovery dynamic recrystallization hot deformation

Fracture behavior and microstructure of as-cast NiTi shape memory alloy

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Transactions of Nonferrous Metals Society of China 2012年第6期22卷 1401-1406页

作者：江树勇张艳秋范红涛哈尔滨工程大学工程训练中心哈尔滨150001 哈尔滨工程大学材料科学与化学工程学院哈尔滨150001

The as-cast ingot of equiatomic nickel-titanium shape memory alloy （NiTi SMA） was prepared by vacuum consumable arc melting. The tensile tests and the compressive tests with respect to as-cast NiTi SMA were performed to study its mechanical properties of fracture. The microanalysis of as-cast NiTi SMA as well as its fractured samples was performed so as to better understand microstructure evolution and fracture behavior of NiTi SMA. Under tensile loading, the as-cast NiTi SMA shows higher plasticity and is characterized by ductile fracture at 750℃, but it demonstrates poorer plasticity and is characterized by cleavage fracture as well as transcrystalline fracture at room temperature and -100 ℃. Under compressive loading at -100 ~C, the as-cast NiTi SMA is characterized by shear fracture where the normal to the shearing fracture surface inclines about 45° to the compressive axis, and belongs to cleavage fracture where the cracks exoand via transcrvstalline fracture.

关键词： NiTi altoy shape memory alloy as-cast-NiTi microstructural evolution fracture behavior

Influence of cooling rate on phase transformation and microstructure of Ti-50.9%Ni shape memory alloy

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Transactions of Nonferrous Metals Society of China 2012年第11期22卷 2685-2690页

作者：张艳秋江树勇赵亚楠唐明哈尔滨工程大学工程训练中心哈尔滨150001

Heat treatment of Ti-50.9%Ni （mole fraction） alloy was studied by differential scanning calorimetry, X-ray diffraction, scanning electron microscopey and energy dispersive X-ray analysis to investigate the influence of cooling rate on transformation behavior and microstructures of NiTi shape memory alloy. The experimental results show that three-stage phase transformation can be induced at a very low cooling rate such as cooling in furnace. The cooling rate also has a great influence on the phase transformation temperatures. Both martensitic start transformation temperature （Ms） and martensitic finish transformation temperature （Mf） decrease with the decrease of the cooling rate, and decreasing the cooling rate contributes to enhancing the M→A austenite transformation temperature. The phase transformation hysteresis （Af-Mf） increases with the decrease of the cooling rate. Heat treatment is unable to eliminate the textures formed in hot working of NiTi sample, but can weaken the intensity of them. The cooling rate has little influence on the grain size.

关键词： NiTi alloy shape memory alloy phase transformation cooling rate martensitic transformation temperature austenite transformation temperature

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热变形钕铁硼永磁体晶界扩散技术研究进展

中国稀土学报 2023年

作者：郭贞山信华琤林鹏江树勇太原理工大学材料科学与工程学院

钕铁硼永磁体因其优异的性能得到了广泛应用，随着电动汽车、无人机、风力发电机等产业迅速发展，对钕铁硼永磁体的需求将会进一步增加。虽然钕铁硼永磁体的最大磁能积已接近理论极限，但作为永磁应用最重要性能之一的矫顽力仍远低于理... 详细信息

钕铁硼永磁体因其优异的性能得到了广泛应用，随着电动汽车、无人机、风力发电机等产业迅速发展，对钕铁硼永磁体的需求将会进一步增加。虽然钕铁硼永磁体的最大磁能积已接近理论极限，但作为永磁应用最重要性能之一的矫顽力仍远低于理论极限。热变形钕铁硼永磁体理论上可在不使用或少量使用重稀土的情况下获得高矫顽力，但实际生产中的矫顽力却比理论值低很多。近年来，晶界扩散技术成功应用到热变形钕铁硼永磁体上，有效提高了热变形钕铁硼永磁体的矫顽力，拓展了热变形钕铁硼永磁体的应用潜力，但鲜有人对其进行系统介绍。本文对热变形钕铁硼磁体晶界扩散技术从晶界扩散原理、起源与发展及研究进展三个方面进行了综述。

关键词：永磁体钕铁硼热变形晶界扩散矫顽力

Deformation Mechanism of Hot Spinning of NiTi Shape Memory Alloy Tube Based on FEM

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Journal of Wuhan University of Technology(Materials Science) 2012年第5期27卷 811-814页

作者：江树勇 Industrial Training Centre Harbin Engineering University

As a successively and locally plastic deformation process, ball spinning is applied to manufacturing thin-walled Nickel-Titanium shape memory alloy （NiTi SMA） tube at high temperature. NiTi SMA tube blank belongs to the as-cast state which consists of a lot of dendritic grains and a few equiaxed grains. The compression tests of NiTi SMA were carried out at various strain rates at high temperature in order to obtain the constitutive model of NiTi SMA. Because NiTi SMA is sensitive to the strain rates at high temperature, rigid-viscoplastic finite element method （FEM） is used to simulate ball spinning of thin-walled NiTi SMA tube in order to analyze the deformation behavior of ball spinning of NiTi SMA tube. Stress fields, strain fields as well as velocity fields is obtained by means of rigid-viscoplastic FEM, which lays the profound foundations for studying the metal flow rule in ball spinning and forming perfect spun NiTi SMA tube.

关键词： shape memory alloy FEM ball spinning hot spinning NiTi tube

滚珠直径对薄壁筒形件反向滚珠旋压成形性影响研究

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材料科学与工艺 2011年第2期19卷 1-4,9页

作者：江树勇孙金凤赵立红张艳秋哈尔滨工程大学工程训练中心哈尔滨150001 哈尔滨工程大学材料科学与化学工程学院哈尔滨150001

以工艺实验和刚塑性有限元法为基础,研究了滚珠直径对薄壁筒形件反向滚珠旋压成形性的影响.有限元模拟结果表明,随着滚珠直径的增加,轴向旋压力的波动减小,滚珠前方金属堆积减小,金属稳定流动性增加.工艺实验结果表明,滚珠直径对薄壁筒... 详细信息

以工艺实验和刚塑性有限元法为基础,研究了滚珠直径对薄壁筒形件反向滚珠旋压成形性的影响.有限元模拟结果表明,随着滚珠直径的增加,轴向旋压力的波动减小,滚珠前方金属堆积减小,金属稳定流动性增加.工艺实验结果表明,滚珠直径对薄壁筒形件反向滚珠旋压成形性的影响存在两个临界值,而且随着滚珠直径的增加,滚珠旋压力增加,筒坯较易发生塑性变形,滚珠前方金属稳定流动性增加.有限元模拟结果与实验结果保持了良好的一致性.

关键词：强力旋压滚珠旋压滚珠直径有限元法

基于实验和元胞自动机模拟的TiNb合金非连续动态再结晶研究

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中南大学学报:英文版 2023年第9期30卷 2890-2905页

作者：孙冬江树勇张艳秋闫丙尧冯浩 Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment of Ministry of Education Taiyuan 030024China College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan 030024China College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China College of Mechanical and Electrical Engineering Harbin Engineering UniversityHarbin 150001China

TiNb合金因其良好的塑性、机械加工性能和超导电性而被广泛应用于低温超导领域。动态再结晶作为材料加工过程中常见的软化行为,对材料的组织和性能有重要的影响。将实验与元胞自动机模拟相结合,研究了TiNb合金在热压缩过程中的非连续动... 详细信息

TiNb合金因其良好的塑性、机械加工性能和超导电性而被广泛应用于低温超导领域。动态再结晶作为材料加工过程中常见的软化行为,对材料的组织和性能有重要的影响。将实验与元胞自动机模拟相结合,研究了TiNb合金在热压缩过程中的非连续动态再结晶行为。元胞自动机模拟可以较为准确地预测TiNb合金的非连续动态再结晶行为。再结晶晶粒的平均尺寸和体积分数随着变形温度的升高而增大,随着应变速率的升高而减小。TiNb合金变形试样中的锯齿状晶界和再结晶晶粒形核位置符合晶界弓出机制特征。此外,非连续动态再结晶晶粒的随机取向效应有助于减弱TiNb合金中变形织构的强度。

关键词： TiNb合金塑性变形动态再结晶元胞自动机织构