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S.M. Fatemi-Varzaneh A. Zarei-HanzakiJ.M. Cabrera 《Journal of Alloys and Compounds》2011,509(9):3806-3810
Severe plastic deformation was applied on a wrought AZ31 magnesium alloy by a new method called accumulative back extrusion (ABE). Instabilities of plastic flow in the form of localized shear bands were experimentally observed during ABE processing of the AZ31 alloy. The obtained microstructures show the appearance of shear bands in ABE processed specimens, the extent of which was observed to be decreased by increasing the temperature. The restricted flow (due to the deformation geometry) was discussed as the main cause of the latter behavior. A noticeable grain refinement was observed inside the shear bands which was attributed to the occurrence of continuous dynamic recrystallization inside the bands. To analyze the homogeneity of mechanical properties, the microhardness variations from the deformed bulk to the shear bands were measured and interpreted. The role of shear banding in grain refinement with no harmful effect on material soundness was explained. 相似文献
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AZ31镁合金散热器等温挤压成形金属流动规律研究 总被引:2,自引:0,他引:2
根据等温压缩实验所得AZ31变形镁合金应力-应变数据,通过回归法得出材料温成形数学模型,应用刚塑性有限元法模拟AZ31变形镁合金散热器等温挤压成形,着重探讨AZ31变形镁合金等温挤压成形过程中,变形力及金属流动规律.根据模拟得到的应力场、应变场、速度场及加载变化等,也可预测变形时产生的缺陷,为该类零件等温挤压成形工艺提供科学的依据. 相似文献
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挤压速度和电磁铸造锭坯对AZ31镁合金板材组织和性能影响 总被引:1,自引:0,他引:1
文章研究挤压条件下挤压速度和电磁铸造锭坯对挤压态AZ31镁合金板材组织和性能的影响。研究结果发现,挤压速度比较低时,板材晶粒尺寸小,板材的表面质量比较好;随着挤压速度的降低,抗拉强度、屈服强度和延伸率都有一定的提高。由于镁合金是HCP的晶体结构,同时对挤压速度非常敏感,对变形均匀性影响比较大,因此造成挤压板材的内外晶粒大小不均。在电磁场的作用下,溶质在晶内的固溶度增大,同时晶粒大小也比常规铸造的细小,因此电磁铸造的锭坯经挤压机挤压后,挤压板材的晶粒尺寸比较细小,且强度和塑性都有所提高。 相似文献
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AZ80镁合金变形特性及管材挤压数值模拟研究 总被引:1,自引:0,他引:1
利用Gleeble热模拟机研究了AZ80合金的高温变形特性。结果表明,流变应力取决于变形温度和变形速率。当应变速率一定时,流变应力随变形温度的升高而降低;当温度一定时,流变应力随着应变速率的升高而增大。根据AZ80镁合金真应力-真应变曲线,建立了其流变应力模型。采用刚塑性有限元法对AZ80镁合金管材挤压过程进行热力耦合数值模拟,并分析了高温挤压成形过程中变形力及金属流动规律,着重探讨了变形温度和挤压速度等挤压工艺参数对挤压力、应变场以及应力场的分布及变化情况的影响。模拟的结果为AZ80镁合金管材挤压工艺参数的制定、优化提供了科学依据。 相似文献
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《中国有色金属学会会刊》2022,32(8):2569-2577
A new severe plastic deformation method for manufacturing tubes made of AZ31 magnesium alloy with a large diameter was developed, which is called the TCESE (tube continuous extrusion?shear?expanding) process. The process combines direct extrusion with a two-step shear?expanding process. The influences of expanding ratios, extrusion temperatures on the deformation of finite element meshes, strain evolution and flow velocity of tube blanks during the TCESE process were researched based on numerical simulations by using DEFORM-3D software. Simulation results show that the maximum expanding ratio is 3.0 in the TCESE process. The deformation of finite element meshes of tube blanks is inhomogeneous in the shear?expanding zone, and the equivalent strains increase significantly during the TCESE process of the AZ31 magnesium alloy. A extrusion temperature of 380 °C and expanding ratio of 2.0 were selected as the optimized process parameters from the numerical simulation results. The average grain size of tubes fabricated by the TCESE process is approximately 10 µm. The TCESE process can refine grains of magnesium alloy tubes with the occurrence of dynamic recrystallization. The (0001) basal texture intensities of the magnesium alloy tube blanks decrease due to continuous plastic deformation during the TCESE process. The average hardness of the extruded tubes is approximately HV 75, which is obviously improved. 相似文献
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Wei Qiu Wen Xie Qi-Feng Li Wei-Ying Huang Li-Bo Zhou Wei Chen Jian Chen Yan-Jie Ren Mao-Hai Yao Ai-Hu Xiong Zhuo-Ran Zeng 《金属学报(英文版)》2023,36(2):237
The effect of vanadium nitride (VN) particles additives on microstructure and mechanical properties of the extruded AZ31 Mg alloy was systematically investigated. The experimental results revealed that the addition of 0.5 wt% VN decreased the average grain size of AZ31 Mg alloy from 6.4 to 4.9 µm. With the increase in VN content, the refining effect would weaken because excessive VN particles would negatively affect the dynamic recrystallization process of the alloys. The scanning electron microscopy and energy-dispersive spectroscopy indicated that AlN, VN and Al-V-N particles with different morphologies were distributed in the streamline along the extrusion direction during the extrusion process. The mechanical properties of AZ31 Mg alloy vary with the addition of VN. The extruded AZ31 + 0.5 wt% VN Mg alloy possesses an excellent combination of high strength and ductility. The yield strength and ultimate tensile strength of the extruded AZ31 + 0.5 wt% VN Mg alloy were increased without sacrificing ductility. This is mainly due to the grain refinement caused by double-heterogeneous nucleation particles. With a further increase in VN content, the presence of excessive VN particles increases the stress concentration, and the initiation source of microcracks in the alloy during alloy deformation makes the cracks more easily propagated and results in a decrease in the ductility of the extruded alloy. 相似文献
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光滑粒子流体动力学方法(Smooth Particle Hydrodynamics,SPH)在求解大变形问题方面具有优势。基于SPH法编写程序对AZ31镁合金的BP-ECAP过程进行三维数值模拟,并与相关研究文献进行对比,验证了编写的SPH法背压程序的正确性。对不同工艺参数下AZ31镁合金的背压-等通道挤压过程进行模拟,并从等效塑性应变及损伤值分布角度进行分析。模拟结果表明,选择恰当的背压值能有效地阻止镁合金变形过程中裂纹的萌生及扩展。 相似文献
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采用原位合成-半固态搅拌铸造法制备了TiB2/AZ31镁基复合材料,研究了热挤压对TiB2/AZ31镁基复合材料组织和力学性能的影响。结果表明:热挤压不仅能显著细化合金组织,而且能有效改善TiB2颗粒分布的均匀性。与铸态AZ31镁合金相比,铸态TiB2/AZ31镁基复合材料的硬度、抗拉强度都有一定程度的提高。经过热挤压后,TiB2/AZ31镁基复合材料的硬度和抗拉强度分别比基体合金提高了126.2%和98.8%,达到950 MPa和322 MPa。磨损表面形貌显示,TiB2颗粒的引入以及对TiB2/AZ31镁基复合材料进行热挤压,都可有效地提高材料的耐磨性。 相似文献
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AZ31镁合金的热挤压变形和力学性能分析 总被引:1,自引:0,他引:1
为了掌握高精度镁合金管材的生产工艺,通过对铸锭的均匀化处理,借助500 t挤压机、拉伸试验机、金相显微镜和透射电镜(TEM)对AZ31镁合金管材的等温挤压过程进行了研究,试制了AZ31镁合金挤压薄壁管材,获得了尺寸精度高、粗糙度小和壁厚差小的管材;分析了不同挤压条件下的AZ31镁合金管材的尺寸精度、组织、力学性能.研究结果表明:在挤压温度为623士20K挤出管材经523K×3h退火时其性能较好,抗拉强度、屈服强度和延伸率分别为270 MPa,175 MPa和23.1%. 相似文献
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AZ31 magnesium alloys were hot-extruded at 573 K and 623 K with extrusion ratio(λ) of 20,35 and 50.The corrosion and mechanical behavior of hot-extruded AZ31 were studied by galvanic tests and tensile tests.The microstructures of the studied AZ31 alloys were also investigated with optical microscope.The results show that,compared with the as-cast AZ31 alloy,the corrosion potentials of all hot-extruded AZ31 alloys are increased by 60 mV.Moreover,at the extrusion temperature of 623 K,the galvanic current o... 相似文献
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The effects of hot extrusion treatment on the microstructure and mechanical properties of AZ31-0.25%Sb Mg alloy were investigated by means of mechanical properties measurement and microstructure observation.The results show that the microstructure of AZ31-0.25%Sb Mg alloys consists ofα-Ms matrix,Mg_(17)Al_(12) and Mg_3Sb_2 phases.The ultimate tensile strength (UTS) and yield tensile strength(YTS) of the alloy are obviously enhanced by hot extrusion treatment,and the enhanced extent of UTS and YTS increas... 相似文献
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AZ31镁合金管材挤压成形数值模拟研究 总被引:3,自引:1,他引:2
根据等温压缩实验所得AZ31镁合金应力一应变数据,拟合出材料温成形应力一应变曲线,应用有限元法模拟AZ31镁合金管材的挤压成形,着重探讨了AZ31镁合金挤压成形过程中,温度、速度、润滑等因素对金属流动的影响,为管类零件挤压成形工艺提供了科学依据。 相似文献
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新型镁合金大变形技术的研究与验证 总被引:2,自引:0,他引:2
研究了一种正挤压与等通道挤压相结合的新的Extrusion-Shearing(ES)变形方法。应用有限元法对ES变形过程进行了计算机模拟,表明ES技术可以大大提高累积应变和动态再结晶晶粒的体积分数。在Gleeble1500热模拟机上安装ES成形模具,对ES成形挤出的棒料进行微观组织观察,并对热模拟的数据进行处理。结果表明,ES成形可以细化晶粒并提高成形的均匀性。计算机模拟和热模拟实验表明,ES成形是一种新型的镁合金大塑性变形方法,可以有效细化晶粒、提高组织的均匀性 相似文献