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金属流变成形机理探讨与实例分析 总被引:3,自引:0,他引:3
结合工程实际,对金属流变成形机理进行了初步探讨,从一维流变学模型理论出发,求出具有弹粘塑性性质的金属材料的本构方程,进而分析限三维复杂应力状态下,各向同性不可压粘塑性材料在轴对称流变成形过程中的应力场,速度场和流量计算公式,由此发现线性粘塑性介质只是非线性粘性介质的一种极限情况,文章详细讨论了该零件的试验条件和成形方法,最后进行了试验结果分析。 相似文献
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本文以Gleeble-1500为实验手段,研究了ZG15CrMoV和35钢在500—1400℃温度范围内的力学行为,结果表明,两种钢在高温下表现出越来越强的时变特征,应用系统辨识理论,以实验数据作为系统的输入—输出响应,确立了两种钢在高温下的力学行为可以较好地由一个五元件流变模型[M]=[H_1]—[H_2/N_2]-[N_3/S]予以描述,通过研制的流变模型和参数辨识软件,对ZG15CrMoV和35钢在上述温度范围内的流变参数进行了辨识,辨识结果与实验结果均能较好的吻合。 相似文献
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ZG15CrMoV和35钢在500—1400℃下的流变行为 总被引:1,自引:0,他引:1
本文以Gleeble-1500为实验手段,研究了ZG15CrMoV和35钢在500—1400℃温度范围内的力学行为,结果表明,两种钢在高温下表现出越来越强的时变特征,应用系统辨识理论,以实验数据作为系统的输入—输出响应,确立了两种钢在高温下的力学行为可以较好地由一个五元件流变模型[M]=[H_1]—[H_2/N_2]-[N_3/S]予以描述,通过研制的流变模型和参数辨识软件,对ZG15CrMoV和35钢在上述温度范围内的流变参数进行了辨识,辨识结果与实验结果均能较好的吻合。 相似文献
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使用Gleeble-3500热模拟试验机对TC21钛合金在温度为890~990℃、应变速率为0.01~10 s-1下进行了热模拟压缩实验,研究了该合金的高温流变行为。在变形条件下,该合金的流变应力随应变的增大逐渐增加,在达到峰值后又逐渐减小。基于实验数据,分别采用Arrhenius模型和修正Johnson-Cook模型构建了TC21钛合金本构模型,并对这两个模型的预测精度进行了分析对比。结果表明,修正Johnson-Cook本构模型预测值的平均绝对相对误差eAARE为7.2078%,相关系数r为0.96866;Arrhenius本构模型预测值的eAARE为12.6699%,r为0.95794,修正Johnson-Cook本构模型的精度高于Arrhenius本构模型,且在整个参数范围内具有一定的精度,可以较好地描述TC21钛合金的高温流变行为。 相似文献
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液固态合金流变性特点的研究 总被引:1,自引:1,他引:0
在对液固态铜合金、铸钢的流变性能测试的基础上,结合他人在铝合金流变性能方面的研究成果,通过对上述3种合金在液固态共存温度范围内的流变性能的综合分析,建立了液固态合金流变性能的统一机械模型和本构方程,分析了温度变化过程中合金的流变参数变化的规律。并从微观上对合金液固态的流变性能特点进行了分析。 相似文献
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半固态金属触变性质及应用新进展 总被引:11,自引:5,他引:6
简述了非枝晶结构半固态金属的触变行为并详细讲座了固相颗粒网状结构形成和破坏的原理,触变行为的流变学模型主要包括了依时行为模型和Kumar流变学模型。并给出了描述表象模型的状态方程和动力学方程,对网状组织的形成和破坏函数进行了说明,进而讲座了剪切力对固液两相的作用力,对非枝晶半因态金属为形成的应用现状和最新进展进行了综合评述。 相似文献
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为了研究退火态42CrMo钢的热变形行为,利用Gleeble3800热模拟试验机进行了单道次热压缩实验,获得了变形温度930~1230℃、应变速率0.001~1 s-1条件下的高温流变应力曲线。分别应用Arrhenius方程和Yada模型构建了42CrMo钢的高温本构模型和动态再结晶动力学模型,并基于动态材料模型应用不同变形条件下的峰值应力构建了其热加工图。结果表明,在大部分变形条件下,高温流变应力曲线呈典型动态再结晶特征,由于动态再结晶的作用,流变应力随变形温度的升高或应变速率的降低而减小。基于峰值应力构建的42CrMo钢高温本构模型和动态再结晶模型可以用于预测不同变形条件下的流变应力和微观组织演变。此外,根据42CrMo钢的热加工图,最佳热加工工艺参数范围为1100~1230℃、0.01~1 s-1。 相似文献
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指出对于水泵叶轮这种薄壁复杂铸件来说,消失模铸造能够充分发挥其许多独特的工艺优势.阐述了ZG20MnSi钢制水泵叶轮的消失模铸造生产技术及工艺控制要点:在模样制作时,确定泡沫密度非常关键,经过试验,确定轮毂与盖板的泡沫密度为0.020g/cm3,叶片的泡沫密度为0.025g/cm3;合理设计浇注系统;正确选用耐火涂料和型砂;充分提高型砂的填充密度.采取这些工艺措施后能够减轻或消除相关铸造缺陷,从而提高复杂近净形铸钢件的质量. 相似文献
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HAN Enhou HAN KYumei ZHENG Yuli KE Wei Corrosion Science Laboratory Institute of Corrosion Protection of Metals Academia Sinica Shenyang China postdoctoral Institute of Corrosion Protection of Metals Academia Sinica Shenyang China 《金属学报(英文版)》1993,6(6):373-378
Based on theoretical analysis about local strain,strain rate and dissolving rate at crack tip,the corrosion fatigue crack growth rate of steels ZG20SiMn and SM50B-Zc in fresh waterand 3.5% NaCl solution were measured experimentally,and the PH and electrode potentialwithin crack were also measured continuously along with crack propagating.It showed thatthe increase of crack growth rate,caused by both decreasing frequency and raising stressratio,was mainly accelerated by hydrogen embrittlement. 相似文献
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XU Dong Shanghai Jiaotong University Shanghai ChinaAN Geying LI Qingchun Harbin Institute of Technology Harbin China 《金属学报(英文版)》1992,5(11):364-369
Mechanical properties of steels ZG15CrMoV and 35 in the temperature range of 500to 1400℃ have been experimently researched by means of Gleeble-1500.The experi-mental results is used as input-output responses,a rhelological model with five elementsof the mechanical behaviour of steels ZG15CrMoV and 35 at elevated temperatures,i.e[M]=[H_1]-[H_2/[N_2]-[S/N_3],is determined by a system identification method,andthe parameters of the model in the temperature range are also identified. 相似文献
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NaNO2对20SiMn低合金钢在3%NaCl溶液中空蚀损伤的缓蚀作用 总被引:2,自引:0,他引:2
利用磁致伸缩空蚀实验机研究了20SiMn低合金钢在3%NaCl和3%NaCl+NaNO2溶液中的空蚀行为.测量了静态和空蚀条件下的腐蚀电位变化、电化学阻抗谱和极化曲线.结果表明:NaNO2通过抑制腐蚀与空蚀间的交互作用,对20SiMn低合金钢在3%NaCl溶液中的空蚀损伤有良好的抑制作用,浓度为1%的NaNO2的缓蚀效率达到802%.添加NaNO2对20SiMn低合金钢在3%NaCl溶液中的电化学行为有显著影响.在3%NaCl溶液中,自腐蚀电位、线性极化电阻都随空蚀进行而逐渐负移和减小.与此相反,添加NaNO2后,20SiMn的自腐蚀电位、线性极化电阻都随空蚀的进行而逐渐正移和增大.3%NaCl+1%NaNO2溶液中的电化学阻抗谱特征与空蚀表面形貌的变化有较好的对应关系. 相似文献
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The experiments for rheologic behaviors of semisolid continuous casting billets of A356 alloy in semisolid state had been carried out with a multifunctional rheometer. The results show that the deformation rate increases with loading time, the maximum strain reaches to 120% (which is one time larger than that of traditional mold casting billet) and the strain can be rapidly eliminated to 10% after unloading. Moreover, there is a critic stress for billet deformation even in semisolid state, which is named as critic shear stress. This stress increases with the decreasing of heating time. The theologic behaviors can be expressed by five elements mechanical model (H_2- [N_1|H_2]-[N_2|S]) and can be modified with the increasing of heating time. 相似文献
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Binary phase diagrams are important tools for designing desired alloys. In the Sn-rich region of the Sn-In alloy phase diagram,
the solidus line appears as a dotted line in current literature plots to indicate uncertainty. The contour of the solidus
has now been clarified as a result of the present investigation. Four alloys, Sn70In30, Sn75In25, Sn80In20, and Sn85In15 were melted at 300 °C for 10 h and annealed between 120 and 200 °C in the (L + γ) two-phase region. The morphology and chemical
compositions of annealed specimens were analyzed using both field emission scanning electron spectroscopy and energy-dispersive
x-ray spectrometry. The results reveal that the liquid phase, initially appearing at the eutectic temperature, invades the
solid along grain boundaries with penetration gradually increasing with increasing annealing temperature and a granular structure
form. The average compositions in grains of Sn70In30, Sn75In25, Sn80In20, and Sn85In15 specimens correspond to the solidus concentrations, and the solidus line and (β + γ)/γ phase boundary can be determined as
a fit to these temperature-composition points. 相似文献