离心电渣熔铸双基复合轧辊的研究与应用

采用电渣熔炼、卧式离心铸造和顶注填芯法相结合浇注离心复合铸铁轧辊的生产工艺,解决了产品在复合浇注过程中所产生的裂纹问题。通过改进离心电渣熔铸双基复合轧辊生产工艺参数,使离心电渣熔铸双基复合轧辊能批量生产。结果表明,产品的质量和性能满足轧辊的技术指标,比常规辊轧制能力提高30%~50%。     

电渣重熔在轧辊制造中的应用

现已表明,使用所谓电渣重熔钢来制造以前被认为必须采用锻钢制造的高硬度冷轧工作辊,是可能的。已经发现,在轧辊要经喷丸处理的薄板轧机和平整轧机中使用这种轧辊特别有利。本文介绍了这种轧辊的生产工艺和质量控制方法。本文认为可以进一步用电渣重熔法来制造复合轧辊的外壳和生产热轧辊,但是断定。在多数情况下,其经济性未必有利。     

铸造复合轧辊的几种新方法

高速钢用作轧辊材料使冷、热带钢工作辊寿命得到大幅度提高,但是用常规生产方法包括离心铸造法很难生产出高速钢复合轧辊。介绍了几种新的复合轧辊的生产方法,成功地生产出外层与心轴良好结合的高速钢复合轧辊,其中一些方法可方便地复合各种材料     

国内外铸造轧辊的制造水平简介

轧辊作为轧钢生产中的一种专用工模具,对企业提高质量、降低成本起着重要作用。轧辊制造方法由单体(整体)轧辊向复合轧辊改进;从早期的冲芯法生产复合辊工艺向离心铸造法生产复合辊工艺改进;并开发了热压配合装配轧辊、超硬环装配轧辊;或用各种补壳材料和芯材组装起来的复合轧辊等。     

专利

专利名称：轧机轧辊冷却装置;专利名称：一种轧钢用导辊装置;专利名称：一种轧钢用堆焊复合导卫板;专利名称：可轴向移动轧辊的六辊式轧机;专利名称：一种压延辊、轧辊牵引间隙调节装置.     

硬质合金复合轧辊的制造与应用

本文主要介绍了机械组合式、铸造式、冶金复合式、粘结式等复合轧辊的特点、国内外生产厂商、工艺流程等,并对几种复合方案进行了对比,其中机械组合式复合轧辊是目前国内外采用较多的一种复合轧辊的组合方式。重点分析了复合轧辊的轴向预应力、液压螺母组合方式、轴向顶紧力、辊环与芯轴的配合间隙等几个关键参数的计算与设计。轴向预应力在一定程度上可以阻碍裂纹的形成和发展,保护辊环端面;采用液压螺母组合方式压紧辊轴上的辊环;通过力矩平衡方程求出装配所需要轴向顶紧力,保证辊环的正常工作;复合轧辊辊环与芯轴的配合间隙应根据现场条件来确定。     

三辊行星轧机辊型的理论分析

本文通过对轧辊辊面上点的运动速度的分析,导出了三辊行星轧机的正常轧制条件及轧件不转条件,探讨了一种能保证轧件在变形区内不旋转的轧辊辊型的设计方法。     

离心复合铸造双金属轧辊的研究

使用立式离心机,研制了一种高铬铸铁灰铁双金属轧辊,确定了轧辊离心铸造的最佳工艺参数。研究结果表明:双金周复合轧辊具有辊颈强度高、辊面硬度高、耐磨性好等优点。与低镍铬铸铁轧辊相比,寿命提高一倍以上。     

复合轧辊用静置铸造法和离心铸造法的比较

<正> 五十多年前连续带材轧机的推广使用,给轧辊制造业带来了巨大的技术问题。在那以前,带材和板材在许多两辊式单机架轧机上生产,使用的是冷硬铸铁轧辊。连续轧机的出现标志着旧的两辊式单机架轧机的结束。然而,新的连续式轧机不能使用以前轧机上的轧辊,于是人们开发了一种全新型的轧辊,即双浇注(复合型)轧辊。复合轧辊的制造方法根据浇注方式的不同可分为静置铸造法和离心铸造法。本文就复合轧辊的制造法及其用各种方法生产的轧辊的组织结构差异作一简述。     

高碳高速钢复合轧辊

日本一家公司制成了一种高碳高速钢复合轧辊。该轧辊的辊芯是高强度锻钢,辊身的成分为：碳3．5％、铬2．7％、钨18％、钼8％、钒7％。辊身硬度为HS90。把这种复合轧辊装在热轧精整机组上使用,其耐磨性是一般无限冷硬轧辊的5倍;装在热轧精轧机组上使用,其耐磨性是一般高铬轧辊的3倍。使用这种复合轧辊,这可提高轧制生产力和钢板的表面质量。     

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。