我国热连轧带钢生产技术进步20年

介绍了近 2 0年来我国热连轧带钢生产 3个发展阶段的概况 ;全面分析了我国 4类热轧带钢轧机所采用的先进和特色技术 ;同时综述了我国热轧带钢轧机的建设现状、存在问题及发展趋势 ,并对我国热轧带钢生产企业的进一步发展提出建议     

热轧带钢轧制的最新技术——无头轧制

介绍了热轧带钢轧机的无头轧制技术．在传统热带生产线上，采用成熟的热卷箱轧制技术，进而实现热轧带钢中间坯头尾对爆后的无头轧制，可提高傅带钢轧制的稳定性，提高带钢头尾部的尺寸精度．该技术是热带生产技术发展的新动向．     

薄规格热轧带钢板形影响因素及控制方法

随着钢铁行业持续低迷的市场形势和日趋激烈的行业竞争,节约成本、降低消耗、环境友好成为钢铁业的时代命题。薄规格热轧带钢在很多领域实现了"以热代冷"、"以薄代厚",不仅节约生产成本,也大大降低了资源能源消耗。文章通过对唐钢薄板坯连铸连轧生产线多年来薄规格热轧带钢生产经验的总结,分析了薄规格(≤2.0 mm)热轧带钢生产过程中的板形影响因素,着重阐述了轧辊凸度、轧辊氧化膜、层流冷却、卷取侧导板以及换辊周期的影响及应对措施,在薄规格热轧带钢的生产过程中具有一定的借鉴意义。     

1.2mm薄规格热轧带钢生产实践

作为资源节约、环境友好型材料的薄规格热轧带钢,不仅可以节约生产成本;也可以替代部分冷轧产品。文章通过对薄板坯连铸连轧生产线开发薄规格热轧带钢生产实践的分析,着重阐述了薄规格生产中加热制度、负荷分配、速度控制、活套技术、工艺润滑、板形控制以及表面检测等方面的实践经验,总结了1.2 mm薄规格热轧带钢生产过程的关键技术。指出1.2 mm薄规格热轧带钢的稳定批量生产是对蓄热式燃烧技术运用到辊底炉取得成功的有力证明,并且使薄规格以热代冷趋势向前迈进了一大步,满足了用户降低成本的实际需求。     

超快速冷却技术在热轧带钢生产中的应用

介绍了超快速冷却技术在热轧带钢生产中的应用,包括超快速冷却系统的布置,热轧生产线的改造,超快速冷却的过程控制和超快速冷却的数学模型等。热轧带钢采用超快速冷却代替层流冷却可提高其性能。     

热连轧卷取温度控制模型技术的发展

数学模型是热轧带钢温度控制的核心 ,对热轧带钢层流冷却卷取温度控制模型技术的发展状况进行了详细的综述 ,介绍了对换热机理的研究、过程数学模型开发方面的进展 ,分析了模型系统结构的特点及未来发展趋势     

低碳高锰热轧带钢带状组织控制实践

分析了热轧带钢内部带状组织产生的原因及其影响因素,并根据低碳高锰热轧带钢的实际生产研究了动态轻压下、低温终轧、低温卷取对改善热轧带钢带状组织的效果。     

热轧带钢刮伤缺陷的消除

针对某热轧带钢生产线带钢下表面存在刮伤缺陷的问题,对轧制线标高、后滑系数、导卫标高进行了优化计算,消除了热轧带钢下表面的刮伤缺陷,保证了带钢表面质量。     

热轧带钢颈缩补偿优化

针对首钢京唐钢铁有限公司2250mm热轧带钢生产线上存在部分带钢头部宽度出现颈缩的现象,通过优化热轧带钢颈缩控制的补偿参数,包括颈缩补偿开始位置、补偿长度和颈缩补偿量,消除了热轧带钢头部的颈缩现象。     

蒂森克虏伯集团欧洲钢铁分部完成对杜伊斯堡布鲁克豪森厂的现代化改造

蒂森克虏伯集团欧洲钢铁分部完成对德国杜伊斯堡（Duisburg）布鲁克毫森厂（Bruckhausen）1“热轧带钢生产线的现代化改造。10热轧带钢生产线经过两年多的改造,目前已恢复满负荷生产。蒂森克虏伯集团欧洲钢铁分部为提高杜伊斯堡厂的竞争力,确保自身在优质碳钢扁平材生产领域的技术领先优势,斥资2．4亿欧元进行了本轮改造。通过改造,该厂热轧带钢生产线生产工艺得到改进,产品质量显著提高,同时显著降低了能耗和二氧化碳排放量,使生产过程更为绿色环保。     

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).     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.