Relaxation of interphase stresses on the later stages of the heterogeneous decomposition of solid solutions. II. Variational problem

The study of relaxation processes upon the decomposition of solid solutions at the stage of coalescence in the regime of dislocation-matrix diffusion is performed using a “precipitated-phase-particle-feeding-dislocations” system as an example. Within the framework of the variational approach, the cases of the independent and interdependent variation of the fraction of the relaxed regions of the interphase surface and of the number of edge dislocations which supply the alloying component to the precipitated phase have been investigated. Under the assumption that implies the linearity of the possible connection between these parameters, the model approximation of the continuous nucleation of epitaxial defects, and the absence of free matrix dislocations near the particle in the initial state, it is shown that the decrease in the number of edge feeding dislocations in the process of relaxation of interphase stresses can occur only by means of “leakage” of dislocation segments localized in the precipitate outside the limits of the precipitate with the formation of structural dislocation loops on the interphase surface.     

Peculiarities of the macroscopic investigation of multicomponent electrochemichal deposits on the basis of the comparison of relative deviations

The paper presents an analysis of the available indicators of the correlation of the macroscopic distribution of the multicomponent electrochemical deposits and offers new indicators based on the principle of the comparison of the relative deviations from the average values of the sets of measurements of the dispersed parameters of electrochemical objects. The elaborated indicators reflect the correlation between the dispersed parameters with regard to the share in an aggregate (at the cathode macrolevel) of the compared feature of the relative deviations and allow for the objective checking of their estimation by other indicators. In addition, they enable a thorough investigation of the formation process of the multicomponent electrochemical deposits at the cathode macrolevel and application of their values for the purpose of the control and prediction of the functional structure of the deposits.     

Electroerosion treatment of dielectric materials

The authors worked out a new method of combined electric-erosion and electric-chemical processing of dielectrics in an electrolytic medium. This article is dedicated to the study of the process of passing an electric current through an aqueous solution of an electrolyte. With the help of measurements of the voltampere characteristics of the current passing through the electrolytes under study, the total character of the electrolytes’ dependence, which has 4 transition regimes, was determined. The characteristics of the transition regimes depend on both the electric regimes and the types of electrolytes and their concentration and don’t depend on the distance between the electrodes. It’s characteristic of characteristic third phase that a plasma envelope appears that is accompanied by distraction of the dielectric. It’s shown that the tension and corresponding current density at which the plasma envelope occurs exist for every type of electrolyte when the material of the cathode is not changed. The correlation between these parameters and the coefficient of the surface-tension of the studied electrolytes is determined. The results of the study include the dependence of the speed of the volumetric broaching upon such technological parameters as the electric power, the frequency of the revolution of the electrode device, the frequency of the relaxation of the generator, and the concentration of the electrolyte. The problem of the mechanisms of the influence of the electric discharge in the electrolyte upon dielectric is discussed.     

Asymmetry of the roll gap as a factor improving work of the hydraulic gauge control in the plate rolling mill

Plate mill in the Steel Plant Cz stochowa has been recently equipped with the hydraulic gauge control system. Analysis of the work of the mill after the modernisation has shown an increase of the loads by about 20%. Additionally, changes in the geometry of the stand resulted in about 35% increase of the stress in the upper traverse of the stand and about 20% increase of the stress in the lower traverse and in the poles. These additional loads are due to the work of the hydraulic gauge control system which, on the other hand, decreases the variations of the thickness along the plate and improves the flatness of the plate.

Investigation of the possibilities of the decrease of the rolling loads is the main objective of the present project. An assumption is made that an introduction of the asymmetrical rolling may be one of the ways of solving that task. Research on the practical aspects of the implementation of the asymmetrical rolling in the plate mill Cz stochowa were carried out. The asymmetry was introduced by varying the angular velocities of the upper and lower rolls. In the present work, the theoretical analysis of that problem has been performed using the finite-element code Elroll. The code uses rigid-plastic flow formulation coupled with the numerical solution of the general heat diffusion-convection equation. It has been earlier successively applied to the simulation of the metal flow and heat transfer during rolling of the bimetalic plates. In the present project program Elroll has been used for the calculation of the loads in the symmetrical and asymmetrical rolling of steel plates. Analysis of the results obtained for the rolling of eight different carbon-manganese steels has shown that asymmetrical rolling results in a decrease of the rolling loads in the last finishing passes ranging from few to more than 70%, depending on the process parameters. It is shown that an application of the asymmetrical rolling in the stands with the hydraulic gauge control leads to: i) an improvement of the flatness of the plate, ii) a decrease of the thickness variations along the plate, iii) an improvement of the transverse profile of the plate.     

大学社会角色重构:一种对大学角色价值取向的社会学研究

大学学术性角色和非学术性角色之争,实质是对大学社会角色的批判和认识,大学社会角色的价值取向对大学的发展产生重要影响;从社会学角度研究大学的社会角色,有助于认识大学和社会发展的关系,有助于促进大学与社会融合,有助于实现大学的核心价值与达成大学的自我完善。     

高强度厚规格钢板板形控制研究

针对宝武鄂钢4 300 mm宽厚板轧机轧制高强度厚规格钢板出现的“搓衣板”和“蛇形弯”板形缺陷问题,对其产生原因进行了分析。结果表明: “搓衣板”板形缺陷的形成是由于轧机机架精度不够造成轧辊辊系不稳定,高强度钢板在轧制过程中上下表面金属变形不一致而导致的,同时由于钢板头部下扣,使钢板在轧制延伸时受阻,加剧了整板“搓衣板”板形缺陷的形成。轧机主电机负荷平衡功能的投入会干预到上下主电机速度的给定,造成钢板“蛇形弯”缺陷,同时由于轧机雪橇功能的过分使用会加剧该种板形缺陷的形成。为此,提出了加强轧机机架间隙精度的管理措施,有利于轧制过程中辊系的稳定;对钢板精轧阶段压下制度进行了优化,即末道次压下率为12%~17%时,可使钢板头部板形为单弧形上翘,不会产生“搓衣板”缺陷;对轧机主电机负荷平衡功能及雪橇功能进行了优化,减少了钢板咬入阶段上下主电机速度波动,有利于钢板头部“蛇形弯”的控制。上述措施实施后,厚规格高强度钢板板形明显改善,降低了生产成本,提升了宽厚板厂产品质量和市场竞争力。     

The electronic factor in the act of adsorption of ions on a metal surface

The physical mechanism of the electron contribution to the electrochemical potential (intrinsic energy) of ions adsorbed on a metal surface is studied. The problem is reduced to consideration of the single-electron binding state in the fields of two attractors. For the bond between the anion and metal, the attraction centers are the potential of the atomic core of the anion and the potential reflecting the effects of interaction of the excess quantum charge with plasma degrees of freedom of the metal and formation of a surface axial plasmaron. On the average, the above attractors are neutral and are characterized by a finite range of action. The intrinsic energy of the cation of the metal surface depends on the energy of the valence electron in Coulombic fields of the cation itself, on the potential of the surface axial plasmahole, and on the energy of the mutual Coulombic repulsion of the above electron-attraction centers. Expressions are proposed for electronbinding terms of ions with a metal point by analogy with the mechanisms of formation of chemical σ- and π-bonds with partial charge transfer in molecular compounds.     

高压隔膜泵单向阀阀隙流场的冲蚀磨损特性分析

目的 探究高压隔膜泵单向阀阀隙流场冲蚀磨损产生的原因及主要影响因素。方法 基于固液两相流基本理论和冲蚀模型,考虑颗粒保护效应及磨蚀效应,采用计算流体力学(CFD)方法模拟单向阀阀隙流场的冲蚀磨损行为,探究矿粉颗粒体积分数、颗粒粒径、单向阀半锥角、胶垫突出高度等参数对单向阀冲蚀磨损特性的影响。结果 矿粉颗粒紧贴阀芯壁面的剪切运动是造成阀芯发生冲蚀磨损失效的主要原因。当矿粉的体积分数由0.1增大到0.5时,由冲蚀造成的最大冲蚀磨损速率随之减小,由磨蚀造成的平均冲蚀磨损速率随之增大。当矿粉粒径为0.025~0.048 mm时,随着矿粉粒径的增大,平均冲蚀磨损速率随之增大。当矿粉粒径超过0.048 mm时,平均冲蚀磨损速率逐渐减小。当单向阀半锥角由30°增大到45°时,阀隙流场的最大流速由12.23 m/s减小至9.19 m/s,矿粉颗粒对阀芯壁面的最大冲蚀磨损速率减小了41.16%。阀隙流场的最大流速和冲蚀磨损速率随着胶垫突出高度h的增大而增大,同时位置也发生了相应变化。结论 矿粉颗粒体积分数的增加会加重粒子对阀芯壁面的损伤程度,随着粒径的增加,泵阀的最大冲蚀磨损速率先增大后减小,增大半锥角可以缓解颗粒对壁面的冲蚀磨损,增大胶垫突出高度会导致冲蚀磨损区域逐渐向胶垫突出位置集中。     

基于板料电磁翻边的电磁力分布及成形质量影响

本文针对铝合金板料电磁翻边工艺过程,采用数值模拟方法,研究板料上的电磁力分布特性以及几何参数对电磁力分布的影响规律,并揭示电磁力分布对翻边件成形质量的影响。结果表明,铝合金板料电磁翻边中,预制孔的存在使板料上形成电磁力边缘积聚效应,板料预制孔径和成形线圈内径参数通过改变线圈投影面积比影响电磁力分布;随着线圈投影面积比的减小,电磁力边缘积聚效应更加显著,边缘电磁力密度增大;电磁力分布较均匀时,圆角区材料塑性流动更显著,成形件能获得更高的成形高度与更小的边缘减薄率,变形区厚度分布较均匀,成形质量更好。     

Current tasks and problems of welding production in Russia

Results of the investigations of the effect of changes in the composition of the shielding gas on the energy parameters and the cross section of the arc column in the shielding gas are presented. It is shown that the periodic variation of the composition of the shielding gas from helium to argon is accompanied by a cyclic short-term increase in the pressure of the welding arc and also by a surge of welding current. The periodic variation of the composition of the shielding gas in the arc refines the structure of the weld metal and increases the solidification cracking resistance of aluminium alloys.     

气固两相流饲料输送管道结构优化研究

目的 针对饲料输送管道气固两相流对弯管壁面冲蚀磨损严重的问题,提出一种在弯管外侧加设辅助气流的新型结构.方法 运用计算流体力学方法,采用离散相模型(Discrete Phase Model,DPM)研究普通和新型弯管的冲蚀磨损情况,模型的有效性通过普通弯管压降梯度实验加以验证.通过分析两种弯管的流场分布情况,进一步研究空气进口速度、颗粒质量流量和颗粒粒径等因素对弯管冲蚀磨损的影响.结果 随着空气进口速度的增加,弯管的平均冲蚀磨损速率先减小、后增大,但新型弯管的平均冲蚀磨损速率降低了7.1％～8.5％,且当空气进口速度为35 m/s时,平均冲蚀磨损速率最小.当颗粒质量流量增加时,弯管平均冲蚀磨损速率基本呈线性增长,但新型弯管平均冲蚀磨损速率的增长速率略小于普通弯管,且平均冲蚀磨损速率降低了8.2％～9.7％.当颗粒粒径增加时,弯管的平均冲蚀磨损速率先急剧增大、后平缓变化,但新型弯管平均冲蚀磨损速率降低了8.2％～17％.结论 通过研究发现,弯管外侧均存在冲蚀磨损,但新型结构均能有效减小弯管的冲蚀磨损.颗粒质量流量对弯管冲蚀磨损的影响最大,且颗粒质量流量越大,平均冲蚀磨损速率越大.颗粒粒径对降低弯管冲蚀磨损的效果最好,且颗粒粒径越小,效果越佳.     

Asymmetry of the yield strength in single crystals of titanium nickelide

Based on the results of the experimental studies of the temperature dependence of the yield stress of single crystals of TiNi alloys and of the mechanism of the mechanical twinning of the B2 phase as a martensite-type local reversible phase transformation, the asymmetry of the mechanical behavior of these materials during tension and compression in the [001] direction has been investigated. It is shown that a specific feature of this mechanism is the fact that the critical mode of distortion which determines stresses during mechanical twinning is a homogeneous deformation of transformation of the Bain-deformation type. To analyze the asymmetry of these stresses during tension and compression, a concept of the factor of normal stresses reduced to the principal axes of the tensor of the homogeneous deformation of transformation is introduced. It is shown that this factor can be used for analyzing the asymmetry of the mechanical behavior of single crystals of TiNi alloys.     

低锡量镀锡板点锈原因分析和预防

针对低锡量镀锡板点锈问题,测试了锡层孔隙率、锡层在基板上的截面分布、基板表面轮廓形貌以及Tafel曲线,从电化学腐蚀角度分析了点锈的原因。结果表明：点锈产生的原因与镀锡板表面漏铁有关,Fe²⁺的溢出与锡层产生电势差,为原电池的形成创造了条件。助熔剂对镀锡板的腐蚀性和溜平作用使锡层聚集在基板表面的凹坑处,加剧了镀锡板表面漏铁的概率。基板的表面轮廓越复杂,凸点数越多,越易导致锡层分布越不均匀,镀锡板耐蚀性越差。为此,对助熔剂进行了管控,高锡量镀锡板仍用助熔剂助熔,低锡量镀锡板改为水助熔,且当助熔剂槽切换为水助熔的时候,需要确保槽内无助熔剂残留。对平整工艺段的基板表面轮廓进行管控,通过改变工作辊的毛化参数,降低连退基板的凸点数,同时限定凸点数低于80个/8 mm的基板可用于低锡量镀锡板的生产,如凸点数高于80个/8 mm,则用于高锡量镀锡板的生产实践。     

试棒结构及钎料包扎工艺对烧结质量的影响

针对"烧结+钎焊"的电机转子真空钎焊方式,通过肉眼观察试棒烧结钎料后的钎料附着率及表面质量对试棒的结构及钎料包扎工艺分别进行实验研究。在试棒烧结阶段,设计适合于烧结的试棒结构,通过实验进行如下的设计及工艺方案改进:试棒设计顶针结构,钎缝部位与装夹部位一次加工成形,确保了钎缝部位与装夹部位的同轴度,为后续试棒的钎料包扎工艺设计及改进提供基础保障。设计6种钎料的绑扎方式,并实验优化对两种方式进行进一步的改进设计;比较两种钎料绑扎方式的优缺点,确定"不锈钢皮+不锈钢丝"的绑扎方式;最后对这种绑扎方式做进一步的改进设计,获得质量优良的烧结钎缝。本研究设计的试棒结构及钎料包扎工艺为后续电机转子的真空钎焊打下了坚实的基础。     

面齿轮高速铣削表面粗糙度建模与实验分析

根据对面齿轮高速铣削齿面表面粗糙度的形成机理,分析了面齿轮高速铣削加工中的面齿轮齿面方程,建立了面齿轮高速铣削加工中的铣刀运动轨迹方程。根据高速铣削加工过程中球头铣刀刀刃实际扫成面的交点方程的坐标系,求出高速铣削残留高度。根据球头铣刀受力偏心和弯曲变形,求出面齿轮高速铣削瞬态铣削高度,进而编写M文件计算不同参数变化时对表面粗糙度的影响,通过计算值与实测值的对比,其最大误差在12.8%,结果表明,粗糙度数学模型计算值和实测值基本一致。     

卡箍对L形航空液压管道振动影响研究

利用ANSYS对L形航空液压管道进行仿真分析,研究装配不同数量卡箍及卡箍约束不同位置对L形管道固有频率的影响.分析添加不同数量卡箍后管道在脉动流体作用下最大范式应力的变化.结果表明:在管道长度一定的情况下,适当增加卡箍数量以及改变卡箍的约束位置对于管道频率有明显的提高效果;随卡箍数量的增加,管道在脉动流体作用下的最大范式应力逐渐减小,但卡箍约束对管道流体脉动最大应力的影响幅值降低.     

车削和铣削加工表面塑性变形对TC4试件疲劳性能的影响

目的 探究车削和铣削加工表面塑性变形层中纤维组织方向对钛合金TC4试件抗疲劳性能的影响规律和机理,完善表面完整性研究体系,为实际航空结构件的抗疲劳制造提供参考。方法 基于钛合金TC4进行车削和铣削加工的表面完整性试验和试件疲劳性能测试试验,通过合理地选用加工参数以控制试件的表面完整性指标,从而更加直观地分析塑性变形层中纤维组织方向与试件疲劳寿命之间的关系。结果 实验中车削疲劳试件的表面粗糙度、表面显微硬度和表面残余应力3个指标均优于铣削试件,两者的表面形貌也十分类似,但后者的抗疲劳性能达到前者的12~48倍,塑性变形层中纤维组织方向的不同是铣削试件抗疲劳性能远大于车削试件的主要因素。结论 不同加工方式形成的加工表面机制不同,表层纤维组织的塑性变形方向和变形程度也存在较大差异。车削疲劳试件的纤维组织沿试件的周向,铣削疲劳试件的纤维组织沿试件的轴向,在承受轴向的交变载荷时,沿着轴向的纤维组织可以抑制疲劳裂纹的萌生和扩展,大幅提升钛合金TC4试件的抗疲劳性能。     

振动电解加工脉冲参数对TC17钛合金成形质量的影响研究

通过振动电解加工TC17钛合金浅孔,研究了振动电解加工脉冲参数对浅孔中心凸台成形精度及凸台顶部非加工面杂散腐蚀的影响,并利用ANSYS软件进行加工区域电场分析。结果表明:TC17钛合金非加工表面易受杂散腐蚀,在电流密度约10 A/cm2时会发生点蚀;脉冲宽度是影响TC17钛合金电解加工精度和质量的主要参数,随着脉宽减小,凸台底部直径更接近电极内孔直径,凸台锥度显著降低,同时非加工面杂散腐蚀明显减弱,而单纯增大脉间宽度效果并不明显。     

UOE钝边铣削单元与钢板综合作用对铣削的影响

针对UOE生产线铣边机铣削过程中钢板钝边高度超差问题,从钝边铣削单元在钢板宽度方向的偏移运动分别与钢板的偏移、偏转运动综合作用着手,系统地分析了钝边高度的变化规律,建立了钝边高度与钢板偏移量的函数关系式,并绘制出两种综合作用下钢板钝边高度的变化曲线.明确了钝边高度变化趋势与钝边铣削单元和钢板运动之间的关系,为快速确定钝边高度超差原因及解决措施提供理论依据,对设备的改进具有一定的参考价值.     

带传动式仿人机械手抓取规划及稳定性分析

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