连续退火机组塔式活套储存量及其高度的计算

<正>内容导读活套是连续生产机组不可缺少的重要设备,活套储存量的计算是否正确,影响到机组的长度及生产节奏,同时也影响到活套塔的有效高度,间接影响厂房高度。文章以某冷轧厂连续退火机组为例,分析了塔式活套储存量及活套塔高度的计算。某冷轧厂连续退火机组入、出口活套及检查活套均采用塔式活套,机组基本参数见表1,工艺布置简图如图1所示。     

湛江1 550 mm酸轧联合机组入口活套设计

结合湛江1 550 mm酸轧机组入口活套的设计分析结果及其控制方式,对常用的活套设计提出了有关的计算公式。具体阐述了该机组活套的工艺、设备选型、机组控制联锁和设备结构设计应考虑的技术要点,对常见活套的特点进行了分析比较,分析了活套基本原理和结构类别,结合具体的工程对活套进行了优化设计,阐述了活套设计计算过程。     

卧式活套结构分析与跑偏控制技术

在带钢连续化生产线中，活套作为机组的关键设备，用来储存带钢，实现机组工艺段连续运行，其设备可靠、运行稳定直接决定了机组产品的质量和产量。深入分析了一种支撑辊移动式卷扬驱动型卧式活套，详细剖析了其设备组成和结构特点。提出了从辊型设计、活套小车受力平衡、活套辊及其小车装配精度、活套轨道和活套小车安装精度、活套充套模式、活套张力控制等方面切实可行的防偏和控偏措施，从而控制住了带钢跑偏，为卧式活套设计提供了可靠的参考和借鉴。     

酸洗——轧机联合机组活套的设计

对我国引进的第１条酸洗－－思机联合机组的活套结构型式、活套贮量大小、活套运行方式及活套自动功能等方面进行了分析、计算。     

全连续冷连轧机组活套设计

随着我国轧钢技术的快速发展,全连续轧制在国内逐渐推广。在全连续轧制中,活套是保证全连续轧制顺利进行的重要设备,本文介绍了活套主要设备的组成,以及活套在全连续轧制中的工艺过程,活套量计算及活套速度控制的方法,实践证明该活套使用情况良好。     

全连续冷轧机组活套控制

全连续冷轧机组要求在轧机入口段换卷时,生产线主轧区不停车、不降速,为了保证主轧区的工作连续性,全连续冷轧机在轧机入口处都设有焊机和活套装置。本文阐述了全连续冷轧机组中活套的驱动控制、活套套量计算、活套张力控制、活套内焊缝跟踪等技术,并介绍了活套控制难点和注意事项。     

热连轧过程中活套辊与带钢"软接触"定位控制

针对热连轧过程中活套起套时可能产生的带钢“缩颈”现象，提出了“软接触”概念，将活套起套过程看作是活套电机加速度受限条件下时间最短时的角度最优控制问题，给出了活套初始高度的预报计算式，并用自适应方式来增加活套初始高度的预测精度。分析了起套过程中活套电机的加速度、速度、角位移之间的关系，并根据电机的运动特性和工艺要求，给出了各阶段最优的电机速度和电流设定曲线。     

冷轧连续机组活套设备的改进

针对冷轧连续机组中水平活套存在的带钢张力波动较大、带钢易跑偏、活套门摆臂易受损等问题,改进了活套充套和放套的驱动方式,以及活套的设备结构,由此提高了带钢运行的平稳性,对带钢跑偏的改善效果也很明显。     

连退机组入口立式活套带钢跑偏原因分析及治理

介绍了连退机组入口立式活套的结构和活套内带钢跑偏的现象, 根据活套小车转向辊上辊面两侧的标高数据和两头转向辊端面与垂直细钢丝的间距差异, 确定活套小车倾斜和偏转是造成带钢跑偏的主要原因, 通过调整使两根卷扬钢绳松紧一致, 并调节活套小车导向轮与垂直轨道的间隙, 有效治理了带钢的跑偏问题。     

卧式螺旋活套螺旋料道设计分析

活套是保证高频直缝焊管自动化生产不可缺少的重要设备,起到确保储料、供料以及主轧机连续工作的作用。以Φ219mm活套为例,介绍了卧式螺旋活套螺旋料道的主要结构设计原理,并阐明了卧式螺旋活套关键结构的理论设计依据。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。