西德贝勒(Bhler)公司优质钢水平连铸机的展发

与普通连铸机相比,水平连铸机具有产品质量好,投资费用低的优点。可用于生产小规格铸坯及高合金钢铸坯。它还适用于浇注程序频繁改变的小批量生产及小钢厂的生产。目前,在连铸设备上可浇注低合金钢和高合金钢的扁坯、大小方坯。这些连铸坯用于生产冷轧板、变压器用硅钢片、无缝钢管、棒材、线材及汽车工业所用的钢材。这里主要采用弧形连铸设备。在大多数情况下,连铸坯的质量同普通铸坯的质量是一样好的。在世界上,不少国家的冶炼厂正在研究用     

小型棒线材生产连铸－轧钢工艺衔接优化

通过对国内多个小型棒线材企业连铸－轧钢工艺衔接实际生产情况的调研及分析,剖析了小型棒线材连铸－轧钢工艺衔接现状及普遍存在的问题,提出了通过改进生产组织模式、在连铸和轧线加热炉之间增设保温缓冲台架、热坯收集台架、低温坯剔除台架及保温坑等设施的优化方案,可使热送热装比提高到90％以上,加热炉实行冷热坯分装,经济效益明显。     

鞍钢大型钢坯连轧作业线的设计特点

介绍了鞍钢大型厂连铸连轧生产线连轧作业区生产工艺特点,设备性能及主要技术参数,该生产线实现了连铸坯热送热装,平均热装温度为800℃,连轧作业区集重轨坯,线材坯和圆管坯生产于一体,是一条短流程的连铸连轧生产线。     

水岛厂增大连铸异形坯断面扩大H型钢产品范围

日本川崎钢铁公司水岛厂通过增大连铸异形坯的断面尺寸,实现用一种连铸异形坯生产H300×300～H900×300的H型钢。该厂原来用连铸异形坯生产H型钢的最大规格为H800×300mm。大于此规格的H型钢,需用连铸板坯作为原料,经两火轧制而得到成品。最近,该厂增大了连铸异形坯的断面尺寸,即异形坯的腹板高度增大100mm,腹板厚度增大20mm,连铸异形坯尺寸为560×400×140×75mm。使用这种大断面连铸异     

钢连铸连轧的发展现状

一、连铸连轧的条件目前,铸坯和结晶器之间的摩擦力限制了方坯垂直或水平连铸时的拉坯速度,使铸速小于4米/分,(多数为2米/分)。就不同钢种和规格来说,为了降低能耗和设备投资,都希望提高拉坯速度,实现连铸连轧。目前一台线材轧机生产能力已超过50吨/时。130毫米方坯,连铸连轧要求的拉坯速度至少为6米/分,才能充分利用余热而不要中间加热。     

高温合金线材真空水平连铸过程的数值模拟

采用基于连续介质的耦合求解模型研究了镍基合金线材K418和GH4169在真空水平连铸过程中的流动、传热和凝固过程。模型考虑了流体流动过程对凝固过程的影响,以及间隙性的水平连铸周期性拉坯曲线(拉-停-拉)对水平连铸过程中的流动和温度场分布的影响。利用校正后的模型分析了水平连铸过程中拉-停-拉过程中的瞬态流动和凝固过程,研究了不同合金种类、拉速、冷却强度对线材水平连铸过程中的凝固行为的影响。结果表明:在水平连铸周期性拉坯过程中,结晶器内的熔体流动模式和温度模式是周期性变化的,其影响着线材初始坯壳的生长。与K418相比,在相同的计算条件下,GH4169有较低的表面温度而显示了更快的坯壳增长。高拉速和低冷却强度将增加线材表面温度,并增加液芯长度。目前模型再现了水平连铸过程中特定拉坯曲线引起的凝固的本质特征,可为水平连铸过程中改进生产工艺、优化拉坯曲线、减少合金线材缺陷提供指导和参考。     

45号圆钢纵裂分析

针对进口45号钢连铸坯轧制生产大规格圆钢(≥φ160mm)时产生的纵向裂纹，借助扫描电镜，结合生产记录，从生产工艺、裂纹形态等方面进行了分析。结果表明：生产工艺符合操作规程，但裂纹内部有夹杂物，两侧有脱碳现象，裂纹末端沿铁素体偏析带延伸，偏析带内部也存在夹杂物。因此，连铸坯上存在的成分偏析带及偏析带内的夹杂物才是造成钢材纵向裂纹的根本原因。     

水平连铸102钢圆管坯工艺参数研究

研究了水平连铸生产φ130mm规格102钢圆管坯的主要工艺参数，分析了连铸拉坯阻力大、起铸难等现象的产生原因．提出了化学成分(特别是V、Ti、B)及B与N的反应产物BN在分离环上的析出、起铸工艺、钢液过热度、结晶器锥度、反推量等是该钢生产成功与否的关键因素．并给出了其适当的控制范围。     

厚板连铸坯清理后断面尺寸修正方法

为完善连铸板坯清理后尺寸修正的经验方法，通过对铸坯清理后的几何解析，结合宝钢5m厚板生产实际情况与断面规格尺寸，建立了一种稳定、准确的连铸坯清理后的尺寸修正方法。     

张家港高速线材车间设计介绍

介绍了具有当前世界线材轧机最高水平的张家港高速线材轧机的工艺、设备情况及主要技术参数；重点介绍了其工艺和设备特点，即在国内线材生产中领先采用了连铸坯直接热装技术，并采用了步过梁式加热炉、摩根第六代V型超重级轧机、控制冷却及在线恻径技术等。     

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.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

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).     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

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.