控制转炉炉壳蠕变变形

转炉采用镁碳砖炉衬后，炉壳温度急剧增加，炉壳的局部区域会发生永久变形。分析认为：炉壳的永久变形是由于蠕变变形引起，而不是塑性变形引起，给出了影响蠕变变形的因素，指出了控制炉壳蠕变变形的策略。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

中小型转炉炉壳变形的数值模拟

转炉炉壳温度升高是炉壳变形的主要原因,采用内衬石棉板隔热是降低中小型转炉炉壳温度、减轻炉壳蠕变变形的经济有效措施之一.模拟计算了某钢厂80t转炉炉壳温度场以及不同温度条件下炉壳热应力与石棉板厚度之间的关系,计算温度值与现场实测值基本吻合.当石棉板厚度为30mm左右时,炉壳温度可以控制在360℃以下;低于炉壳材质的蠕变温度,炉壳所受到的热膨胀应力仅为没加石棉板时的50%.     

转炉炉壳变形及处理措施的浅析

结合包钢CSP210 t转炉的托圈和炉壳修配改过程,借鉴国内外其它钢厂的宝贵经验,针对转炉炉壳蠕变变形问题,提出通过炉壳整形、改善炉壳材质及强化冷却炉壳来控制炉壳变形,保证炉壳与托圈的间隙,以提高炉壳使用寿命.     

转炉炉壳变形与对策

在分析转炉炉壳严重变形问题的基础上,提出了采用炉壳整形、改善炉壳材质以及强化炉壳冷却系统的措施来控制炉壳变形,并具体分析了这些措施的优缺点.     

宝钢300t转炉炉壳变形测试研究

针对宝钢炼钢厂三座转炉炉壳发生的严重变形问题,通过现场测试,分析了炉壳变形的状态及规律,指出转炉使用镁碳砖炉衬后炉壳温度升高是造成炉壳变形的主要原因,并提出了解决这一问题的措施和建议。     

转炉炉壳的变形分析及延长炉壳寿命的措施

分析了转炉炉壳变形的原因,提出了采用炉壳强化冷却的措施来控制炉壳变形,延长炉壳寿命,实现转炉炉壳的长寿化。     

转炉炉壳变形及其控制

大型转炉用镁碳砖炉衬后，炉壳温度可达４７０℃或更高，造成炉壳蠕变而变形。研究了转炉炉壳变形的状态及规律，分析了炉体机械应力、温度应力及膨胀应力。并通过蠕变实验预测炉壳的残余寿命。还介绍了改善及控制炉壳变形的整形技术和冷却技术。     

50吨转炉炉壳安装新工艺及应用

通过工艺方法的比较，可以看出“卷扬吊装”新工艺操作安全简便，缩短了炉壳安装时间，施工设施成本低。     

宝钢转炉炉壳长寿实践

为了提高炉龄,高导热镁碳砖在转炉上得到了普遍使用,钢水向炉壳的热传导由此也大幅提升,使炉壳表面温度维持在高温区域,从而引起了转炉炉壳变形加剧,导致转炉炉壳使用寿命缩短,影响正常安全生产.概述了宝钢在转炉炉壳长寿方面所做的一些工作,包括炉壳整形、耐蠕变的炉壳钢板研制及炉壳冷却技术的开发,并讨论了这些技术的效果和局限性.     

椭圆孔型中轧件变形的三维有限元分析

采用商用有限元软件ＭＡＲＣ／Ａｕｔｏｆｏｒｇｅ，用大变形弹塑性有限元力耦合的方法分析了不同形状的坯料在椭圆孔型中的变形情况，重点研究了轧件变形的不均匀性、孔形的变形能力、金属的流动规律的轧制力能参数的大小。     

宝钢300t转炉炉壳的整形效果及分析

在分析宝钢第一炼钢厂转炉炉壳整形必要性的基础上，对转炉炉壳整形的实际效果进行了分析，证明火工校正结合机械牵引的整形方法可以较好地增加炉壳与托圈之间的间隙。     

Continuum Microviscoelasticity Model for Aging Basic Creep of Early-Age Concrete

We propose a micromechanics model for aging basic creep of early-age concrete. Therefore, we formulate viscoelastic boundary value problems on two representative volume elements, one related to cement paste (composed of cement, water, hydrates, and air), and one related to concrete (composed of cement paste and aggregates). Homogenization of the “nonaging” elastic and viscoelastic properties of the material’s contituents involves the transformation of the aforementioned viscoelastic boundary value problems to the Laplace-Carson (LC) domain. There, formally elastic, classical self-consistent and Mori-Tanaka solutions are employed, leading to pointwisely defined LC-transformed tensorial creep and relaxation functions. Subsequently, the latter are back-transformed, by means of the Gaver-Wynn-Rho algorithm, into the time domain. Temporal derivatives of corresponding homogenized creep and relaxation tensors, evaluated for the current maturation state of the material (in terms of current volume fractions of cement, water, air, hydrates, and aggregates; being dependent on the hydration degree, as well as on the water-cement and aggregate-cement ratios) and for the current time period since loading of the hydrating composite material, allow for micromechanical prediction of the aging basic creep properties of early-age concrete.     

Creep Deformation of Fiber Reinforced Plastics-Plated Reinforced Concrete Tensile Members

The problem of long-term creep deformation of reinforced concrete tensile elements strengthened by external fiber reinforced plastic (FRP) plates is studied. Formation of discrete cracks in concrete under tension is taken into account. A kinematic model is used, where relative slips between concrete, steel bars, and FRP plates are considered, governed by viscous interface shear stress–slip laws. Bazant’ solidification theory and exponential algorithm are used to obtain incremental constitutive equations for concrete as well as for steel-concrete and FRP-concrete interface laws. Moreover, cohesive normal stresses across transverse cracks in concrete are considered. The incremental differential system of equations is transformed into a nonlinear algebraic system by a finite difference discretization with respect to axial coordinate. Several numerical examples are presented, concerning both short-term and long-term loadings. It is shown that reinforcing by means of FRP plates or sheets has significant beneficial effects on the behavior of reinforced concrete elements under service loadings because (1) it increases concrete tension stiffening effect and (2) it strongly reduces crack width. The present study shows that these beneficial effects are preserved also in the case of long-term loadings.     

Determination of Shear and Bulk Moduli of Viscoelastic Solids from the Indirect Tension Creep Test

Because of its efficiency in analyzing complex viscoelastic problems, the finite-element (FE) analysis has been widely used to identify the time- and rate-dependent effects of viscoelastic materials on various structural conditions. When performing the FE analysis on a viscoelastic structure, most FE programs require fundamental material properties, shear and bulk moduli, of the given viscoelastic material as their input. However, the shear and bulk modulus tests are difficult to perform, so they have been commonly estimated from a single material test on the basis of the assumption that the Poisson’s ratio of viscoelastic materials is a time-independent constant. Such an assumption, however, might not be suitable because the Poisson’s ratio of the viscoelastic materials is also a function of time. Therefore, this study developed computation algorithms for determining the time-dependent Poisson’s ratio and shear and bulk moduli of asphalt mixtures, which have been well recognized as a viscoelastic material, by employing the indirect tension testing system. The shear and bulk moduli determined by the developed approach appear to be reasonable and realistic. Their applicability and reliability were also verified by comparing experimental data to the results of the FE analysis performed on the same circular specimen as that used in the indirect tension creep test.     

A Novel Process Control Model for Extracting Vanadium Semi‐Steel in Basic Oxygen Furnace Based on Steelmaking Mechanism

A novel process control model for basic oxygen furnace (BOF) steelmaking is proposed based on metallurgy mechanism, with lower contents of carbon, manganese, silicon, and lower temperature in semi‐steel after extracting vanadium. According to mass balance and heat balance, a static control model is built up, with slagging model, temperature model, and oxygen supply model. When actual amount of oxygen supply reaches 85% of theoretical value calculated by static model, quasi‐dynamic control model is activated to predict carbon and temperature in later period of steelmaking. A steelmaking process control system for semi‐steel smelting on 120 tonne BOF is developed in a steelmaking plant in China. Based on test of three steel grades, this model acts a guide for BOF steelmaking with semi‐steel, not only providing tactic, but also pointing out a feasible method for BOF process control without sub‐lance or off‐gas analyzer.     

Application of Differential Operator with Servo-Order Function in Model of Viscoelastic Deformation Process

The aim of the present paper is the application of a differential operator of variable order in constitutive relations for viscoelastic material. The dependence of the order function on the strain and strain rate is evaluated on the basis of known experimental results on deformation of polymeric materials. Established dependences are used for studying the vibrations of a 1-degree-of-freedom oscillator, in which the viscoelastic deformation is governed by a servo order function.     

轧制变形对重轨脱碳深度的影响

钢厂轧制U75V钢(%:0.71～0.80C、0.50～0.80Si、0.70～1.05Mn、0.04～0.12V、0.23Cu)60 kg/m重轨的铸坯尺寸为380 mm×280 mm,经第2架粗轧后坯料的断面面积为18 015 mm²。通过轧制变形试验和显微镜观察测试,结合生产现场技术参数建立了有限元模型,以研究分析轧制变形对脱碳层影响。得出经第1粗轧机架和第2粗轧机架孔型轧制后,轨头脱碳层从1.2mm降至0.53 mm,轨腰脱碳层从1.5 mm降至0.54 mm,轨底脱碳层从1.5 mm降至0.83 mm。实测成品轨头的脱碳层为0.2 mm。     

钢的化学成分对变形抗力基值和数学模型系数的影响

介绍了钢的化学成分对变形抗力数学模型σ＝ｓσｏε＾ａ（１０ε）＾ｂ（ｔ／１０００）＾ｃ的系数及变形抗力基值的影响，利用影响函数方程确定某一个具体钢号的变形抗力数学模型。