电脉冲处理对纯铝形变织构及加工性能的影响

利用X-射线Schulz背反射法及拉伸试验等研究了电脉冲处理对纯铝冷轧带材的织构及加工性能的影响.结果表明:经电脉冲处理的纯铝冷轧带材织构与未经电脉冲处理有明显不同,这主要是因为经过电脉冲处理后,纯铝冷轧带材的晶粒得到细化,相对均匀的取向分布使各向同性程度提高,塑性变形相对均匀,各部位的塑性流动速度接近相同,其产生的剪...     

Effect of electric pulse treatment on solidification structure of an Al-15%Si alloy

1 IntroductionThe study of electric field (EF) modifying themetal microstructure has made some progress sinceAsoka applied electric current when a Pb-Sn alloysolidified [1-8]. Based on the different applying du-rations of EF to melt, there are two kinds o…     

The Effect of High Voltage Electric Pulse Treatment Process on the Concentration of <Emphasis Type="Italic">E. coli</Emphasis> Bacteria in Water

Disinfection of water and water resources from E. coli pathogenic bacteria using high voltage electric pulse treatment is studied. The methods of determination of concentration of microorganisms prior to and after the pulse treatment process are shown. The experimental results are presented on the effect of different modes of the treatment (crown, electric spark discharges), the period of the treatment (the number of discharges), the electric parameters of a high voltage generator (voltage, polarity, charging capacitance), and the initial concentration of microorganisms on changes in their quantity after the electric pulse impact. It was found that the degree of inactivation depends greatly on the mode and time of treatment (number of discharges), as well as the initial concentration of the microorganisms. The data on the most efficient modes of the electropulse treatment of a water medium are presented.     

电脉冲孕育处理对Al-5Cu合金热裂的影响

研究了不同电脉冲孕育处理参数对Al-5Cu合金热裂倾向的影响.结果表明,不同电脉冲孕育处理参数均可降低Al-5Cu合金的热裂倾向,处理后该合金热裂临界应力比未处理试样提高了约3倍.合金热裂倾向改善的原因是,电脉冲孕育处理细化了Al-5Cu合金组织,减少了共晶相的数量,缩短了合金凝固温度区间.     

电脉冲对HRB335螺纹钢凝固组织的影响

用不同的脉冲电流对HRB335螺纹钢进行孕育处理，研究了不同的电脉冲参数对其宏观组织和微观组织的影响。结果表明，将处理过的钢液在保温砖中冷却，晶粒明显得到了细化，枝晶大大减少，经过电脉冲处理后的HRB335螺纹钢的珠光体形态发生了显著的变化，片层间距明显缩短。     

脉冲电流对铸造ZA27合金中缩孔和疏松的影响

在砂型铸造ZA27合金的凝固过程中用脉冲电流进行处理。结果表明这种处理方法可以提高铸件的致密性,大大减少铸件中的缩孔和疏松。脉冲电流处理后铸件密度增加2．5％,电流对铸件中缩孔的分布也有影响。     

Effect of melt pulse electric current and thermal treatment on A356 alloy

Effects of the melt pulse electric current and thermal treatment on solidification structures of A356 alloy were investigated.In the experiments.the low temperature melt(953K and 903K)treated by pulse electric current was mixed with high temperature metl(1223K).By the control experiments,the results show that the solidification structure of A356 alloy is refined apparently by the pulse electric current together with melt thermal treatment process,and the mechanical properties.especially the elongation ratio of the specimen treated is improved greatly.The structure change of the melt by pulse electric current and melt thermal treatment is the main reason for the refinement of the solidification structure of A356 alloy.     

电脉冲固溶对Al-22％Si-1．5％Cu合金组织的影响

利用光学显微镜观察及显微硬度测量等方法研究了在脉冲电流作用下，Al-22％Si-1．5％Cu合金经过固溶、时效后其显微组织及基体性能的变化。结果表明，采用短时间高密度脉冲电流作用于A1．22％Si-1．5％Cu合金固溶过程前期（作用时间为120S），可明显改善该合金初生硅相及Al2Cu相的形态和分布、显著提高基体的显微硬度。在固态相变经典形核理论的基础上，本文讨论了其作用机理。分析后认为脉冲电流影响了溶质原子的非平衡扩散过程，提高了固态相变的驱动力场从而降低扩散能垒，强化了溶质粒子扩散过程。     

高密度脉冲电流对纯铝凝固组织的影响及其内在机理研究

研究了高密度脉冲电流作用下纯铝凝固组织的变化,考察了不同放电电压和放电电容对纯铝晶粒尺寸的影响.从高能量密度脉冲电流对纯铝结晶的形核率、过冷度和热效应三个方面的影响.对高能量密度脉冲电流细化晶粒的机理做了深入分析.结果表明:高密度脉冲电流可以显著地细化纯铝的凝固组织.随着放电能量的提高,纯铝的晶粒尺寸有大幅度的减小,可以获得均匀细小的等轴晶;但是当放电能量达到270J后,晶粒随放电能量的升高反而变粗,生成大量的粗大的柱状晶.     

脉冲电场对Al-4%Cu合金固溶组织及固溶工艺的影响

采用电脉冲处理技术作用于Al-4%Cu合金的固溶过程中,能够明显改善Al-4%Cu合金的显微组织,使时效析出过程中相界和品界处的低熔点相含量明显减少,基体中的强化相(CuAl_2)含量明显增多,并且分布更加弥散均匀.同时还能够显著优化Al-4%Cu合金的热处理工艺.在固态相变经典形核理论的基础上,讨论了其作用机理.     

Effects of Ageing with Electric Pulse Treatment on Shape Memory Effect and Precipitation of Cr23C6 Carbide in a Pre-deformed Fe-Mn-Si-Cr-Ni-C Alloy

研究了电脉冲时效对预变形Fe-Mn-Si-Cr-Ni-C合金形状记忆效应及Cr23C6析出的影响.结果显示电脉冲处理能加速Cr和C原子的迁移及Cr23C6碳化物的析出,降低时效温度,缩短时效时间,能诱发Cr23C6碳化物的形核.在973K时效时具有电脉冲处理的预变形Fe-Mn-Si-Cr-Ni-C合金与没有电脉冲处理的合金相比,其形状回复率在30 min内从淬火合金的32％提高到最大值89.2％.     

非稳态脉冲电流对Q235钢组织细化的影响

研究了Q235钢在非稳态脉冲电流作用下正火后组织的变化。结果表明：脉冲电流可以细化Q235钢的正火组织。随着脉冲电压的升高、脉冲频率的增加，细化效果更加显著。并对脉冲电流能细化固态相变组织的机理进行了初步探讨。     

冷拔60Si2MnA钢丝的高强脉冲电流处理

由于加工硬化效应的影响,金属材料在发生塑性变形后其强度会增加.因此,冷拔钢丝的强度远高于拉拔前钢丝的强度,同时塑性变形能力远低于拉拔变形前.已发生较大拉拔变形的钢丝若需要进一步拉拔,常常需要采用高温退火方法来降低冷拔钢丝的强度和增加其塑性变形能力.本文将报道一种新的、可用于原位处理冷拔钢丝的高强脉冲电流处理方法.结果表明,在脉冲电流处理可使一种冷拔弹簧钢丝的强度显著降低,且塑性变形能力大幅增加.采用200 Hz的脉冲电流处理该冷拔弹簧钢丝1 min后,其力学性能与该钢丝在700℃条件下退火1 h后的力学性能相似.研究结果表明,高强脉冲电流处理方法是一种能使已发生加工硬化的金属材料有效软化的新方法.     

脉冲电流对Al-4%Cu合金铸造组织的细化作用

采用自行研制的XJDMG-1型脉冲电源,研究了不同参数下高频、大电流电脉冲对Al-4%Cu铸造组织的影响.分析了合金组织的晶粒尺寸和脉冲参数电流、电压、冲击频率以及电路自振荡频率之间的相关性.结果表明:电脉冲对Al-4%Cu合金有着明显的细化作用;电容的冲击频率和电路的自振荡频率对细化效果起着关键性的作用.     

电脉冲对取向硅钢凝固组织的影响

对熔融态钢液进行处理,研究了电脉冲对于取向硅钢凝固组织的影响作用,利用正交试验法研究了脉冲电容、频率、处理时间和电压等脉冲参数的作用效果.结果表明:电脉冲对钢锭晶粒组织具有明显的细化作用,凝固组织的等轴晶比例大幅上升,影响等轴晶比例的最显著性因素为脉冲频率,最优正交试验参数为电容1 200μF,脉冲频率1 Hz,处理时...     

Influences of electric pulse on solidification structure of LM-29 Al-Si alloy

The metallographic structure of LM-29 aluminum-silicon alloy modified by electric pulse treatment has been investigated and compared with those untreated. The solidification structure of LM-29 alloy has been analyzed by means of M1AP3 Quantimet image processing and analysis system, and then the solidification process has been analyzed by means of differential scanning calorimetry (DSC). The results indicate that the primary silicon phase was refined remarkably by electric pulse while the tensile strength and elongation properties increased accordingly. Electric pulse treatment can also increase the binding power between silicon clusters and alloy melt matrix, as a result, the precipitation of primary silicon phase is suppressed to meet the demand of supercooling degree for nucleating, correspondingly. The electric pulse modification has great influence on the size of silicon atomic cluster as well as its distribution in the melt, subsequently, leads to the refinement of solidification structure.     

高频脉冲电流对HT150灰铸铁凝固组织的影响

采用频率高于1000Hz的高频脉冲电流,在不同的电流参数下,对HT150灰铸铁进行脉冲电流处理.实验结果表明,在高频脉冲电流作用下铸铁石墨片细化,石墨片变得卷曲,共晶团尺寸减小.电流参数对电流的作用效果有显著影响.     

Numerical simulation of electromagnetic and flow fields of TiAI melt under electric field

This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAI melt under two electric fields. FEM (Finite Element Method) and APDL (ANSYS Parametric Design Language) were employed to perform the simulation, model setup, loading and problem solving. The melt in molds of same cross section area with different flakiness ratio (i.e. width/depth) under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field. The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1. The melt is driven bipolarly from the center in each electric field. It is also found that the pulse electric field actuates the TiAI melt to flow stronger than what the sinusoidal electric field does.     

Numerical simulation of electro-magnetic and flow fields of TiAl melt under electric field

This article aims at building an electromagnetic and fluid model, based on the Maxwell equations and Navier-Stokes equations, in TiAl melt under two electric fields.FEM (Finite Element Method) and APDL (ANSYS Parametric Design Language) were employed to perform the simulation, model setup, loading and problem solving.The melt in molds of same cross section area with different flakiness ratio (i.e.width/depth) under the load of sinusoidal current or pulse current was analyzed to obtain the distribution of electromagnetic field and flow field.The results show that the induced magnetic field occupies sufficiently the domain of the melt in the mold with a flakiness ratio of 5:1.The melt is driven bipolarly from the center in each electric field.It is also found that the pulse electric field actuates the TiAl melt to flow stronger than what the sinusoidal electric field does.     

脉冲电流对再制造毛坯裂纹尖端组织及性能的影响

以再制造为目标,利用高能脉冲电流冲击装置对含有单边裂纹的316奥氏体不锈钢进行脉冲电流处理。采用金相显微镜、X-射线衍射仪、电子背散射衍射(EBSD)、透射电子显微镜(TEM)等表征手段,研究高密度脉冲电流对裂纹尖端区域微观组织与结构的影响,分析裂纹尖端组织加热熔化及热处理时的组织演变过程。结果表明:脉冲电流处理后,裂纹尖端组织发生了明显细化并出现组织梯度,包括柱状晶区、再结晶区及基体区。脉冲电流的快速加热和快速冷却、高速电子风的产生、电致塑性等作用降低了再结晶或相变时的热力学屏障,提高了形核率,抑制了晶粒长大过程,获得了比原始晶粒尺寸小的再结晶晶粒,材料的力学性能得到提高。