冷却比表面积对高炉炉缸铸铁冷却壁传热的影响研究

基于ANSYS软件,建立炉缸铸铁冷却壁三维传热模型,分析了冷却比表面积对冷却壁传热的影响。结果表明:冷却壁比表面积在0.5增加至1.1时对冷却壁传热影响较大,比表面积在1.1以上时对冷却壁传热影响较小;通过减小水管间距来增大冷却比表面积时,冷却比表面积对冷却壁宽度方向温度分布的均匀性影响较大,而对冷却壁高度方向温度分布的均匀性影响较小;通过改变水管直径来改变比表面积时,冷却比表面积对冷却壁温度分布的均匀性影响较小;炉缸冷却壁冷却比表面积即冷却结构对温度梯度的影响较大,冷却水量对温度梯度的影响较小。最后对几座典型高炉炉缸冷却壁的冷却比表面积进行对比分析,结合数值计算结果,建议将炉缸冷却壁冷却比表面积控制在1.1以上。     

济钢近几年铁前系统技术进步

为了实现炼铁系统的高效、低成本生产，济钢近几年通过实施烧结机头机尾磁力密封新技术、球团竖炉烘床改造、炉顶布料技术、活跃炉缸技术、炉型维护技术以及新型复合式冷却壁的技术开发，高炉技术经济指标明显改善，为降低生铁成本，提高市场竞争力创造了条件。     

本钢6#高炉炉役后期低强度冶炼低耗生产实践

本钢板材有限公司6#高炉炉役后期炉缸冷却壁热流强度上升,在保障炉缸安全的前提下,对6#高炉操作制度进行不断摸索和优化,探寻在低冶炼强度下合理的操作制度,以降低燃料消耗。文章介绍了对6#高炉采取钒钛矿入炉和降低冶炼强度等措施护炉,在低强度冶炼条件下采取降低富氧、缩小风口面积、缩小矿批重等措施,在保证炉况顺行的基础上实现了低强度冶炼低耗生产。     

高炉新型冷却壁制造技术

本文论述了高炉炉体冷却设备采用新型冷却壁，提高高炉一代炉役寿命，给炼铁生产带来的巨大经济效益，着重介绍了高炉新型冷却壁的结构特点及其制造技术。     

唐钢2000m~3高炉强化冶炼实践

唐钢1号高炉炉容2000m3,采用了陶瓷杯炉缸、砖壁合一的薄内衬结构、铜冷却壁、软水密闭串联循环冷却等一系列先进技术。通过高炉操作技术进步和精料、富氧、喷煤、高风温等一系列强化冶炼技术的应用,使高炉在保证稳定、顺行的基础上,高炉利用系数逐渐提高到2.6t/(m3·d),各项技术经济指标也不断优化,取得了较好的经济效益。     

5#高炉炉役后期维护实践

高炉的寿命主要取决于炉缸的工作寿命。5#高炉自2001年10月扩容性改造大修开炉至今,已生产十几年,累计生铁产量已达到25284439 t,单位炉容产铁量达到9725 t/m~3,高炉进入炉役后期生产。由于炉缸电偶温度点损坏,为了安全生产起见,新增加炉缸及炉身冷却壁水温差监测系统。稳定生产的同时严密监测炉缸水温差和热量强度的变化,以及炉缸钢甲电偶温度的变化;通过控制炉内冶炼强度,积极调整送风和装料制度,加强炉内及炉前操作管理,针对原燃料的变化及时调整操作思路,积极对炉缸进行维护。目前5#高炉炉役后期生产稳定,在保障安全生产的前提下使各项指标得到进一步的优化。     

高炉炉喉冷却壁保护板的新型更换方法

为保证大型高炉的稳定、长寿,高炉炉喉水冷冷却壁逐渐取代传统高炉的炉喉钢砖,并在冷却壁内部增设了一层保护板,使得高炉布料操作时料流不会直接冲刷冷却壁,从而延长冷却壁使用寿命。但是,一旦冷却壁保护板脱落就会使遭受料流冲刷的炉喉冷却壁加速磨损,对高炉稳定运行造成极大隐患。文章介绍了在高炉不用降料面、不用炉内进入的前提下利用定修相对短的时间在外部操作实现更换炉喉保护板的方法。该方法利用齿轮箱布料溜槽的旋转和摆动功能,巧妙地将生产设备作为检修辅助工具,把握高炉定修机会成功完成炉喉保护板的更换,有利于改善施工环境、降低劳动强度和施工成本,使高炉停机率大幅降低。     

创新技术在本钢5号高炉中修中的应用

本钢炼铁厂5号高炉1972年建成,2001年扩容大修,高炉在炉腹、炉腰以及炉身下部的B2和S1两段铜冷却壁是引进PW公司设计国内首次采用超长壁体。B2和S1两段铜冷却壁每段46块,每段冷却壁共有184根水管。由于冷却壁过长,受热应力作用容易变形,B2和S1两段铜冷却壁水管出现漏水。通过本次改造将二段冷却壁改为四段铸铜冷却壁,为尽早恢复炉况,利用中修进行改造,为保证工期,在中修过程中采用了科学管理和多项创新技术,使5号高炉提前投产,并短期内达产,创造了可观的经济效益。     

唐钢1号高炉炉缸维护实践

针对唐钢1号高炉年修以来炉缸炉底温度迅速升高及炉缸水温差异常升高的情况,文章通过从开炉达产到具体操作过程分析并列出了几个可能导致前者的主要因素,然后根据主要成因通过采取配加钒钛矿、增加炉缸冷却强度、堵炉缸侧壁温度高的上方风口、加强炉前出铁组织、增加炉底测温点、调整操作制度、加强原燃料管理、炉缸定期灌浆等措施和手段,炉缸炉底温度得到有效控制,同时炉况稳定顺行,并在炉缸维护的过程中亦实现了较好的经济技术条件,对高炉的护炉与生产有一定的指导作用。     

高炉铜冷却壁破损分析与处理

本钢新1号高炉有效容积4747 m3,炉腹至炉身下部采用铜冷却壁冷却,炉腰部位铜冷却壁在生产中渣皮稳定性差,脱落频繁,在生产不到6年后出现大面积破损,被迫多次休风,威胁到高炉安全生产。通过分析发现,炉腰铜冷却壁受到高温炉料、煤气流冲击造成磨损;操作制度造成软熔带根部过低;铜冷却壁应力影响渣皮等原因是冷却壁破损的主要原因。经过研究,提出了改用雾化冷却、插入微型铜冷却棒、炉皮强制打水等解决方案。改造后,保证了安全生产,取得了良好的效果,但如果从根本上解决破损问题,应空料线停炉更换冷却壁。     

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.     

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.     

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.