带液芯轻压下变形特征的视塑性研究

用视视塑性（网格）方法研究了铜复铅芯模拟样品轧制时的变形行为,与无铅芯的样品进行了比较,由此了解带液芯连铸坯轻压下时的变形特征。研究结果表明,坯壳的延伸与宽展均随轻压下量的增加而增中,但都较无液芯时小得多;液芯率大时,宽向变形以坯壳的“失稳外凸”为主,液芯率小时,则以坯壳侧壁的镦粗增厚”为主;铸坯的厚向变形基本上由液芯的减薄承担。     

连铸方坯带液芯轧制的模拟实验研究

连铸坯带液芯轧制是在金属动态凝固的过程中即进行压力加工,将冶金浇铸凝固与压力加工变形融合于一体的新工艺,本文采用常温下轧制填充塑性泥的空心方表铅件的方法,分别在菱方孔型和平辊上模拟忆制高温带液芯的连铸方坯,研究了连铸带液燕轧制时轧件的变形,液芯的流动,轧机的轧制负荷及孔型系统对变形的影响。     

薄板坯连铸液芯压下过程的数值仿真

基于修改的拉格朗日大变形热力耦合有限元模型,对薄板坯连铸的重要技术——液芯压下技术进行了仿真研究,并与实验结果进行了对比,两者基本吻合。研究结果显示,连铸坯经过压下辊的过程中,其应力状态发生较大的变化。研究表明,控制和优化连铸坯窄面附近区域的冷却条件是控制连铸坯窄面附近区域应力和变形的重要手段,采用提高连铸坯窄面附近区域的冷却模式,对防止连铸坯内裂纹的形成和液芯压下技术的顺利实施有重要意义     

连铸坯的下滑力的计算

本文针对连铸坯坯壳和液芯的比重不同这一事实,提出铸坯下滑力的计算方法,并附有计算程序。     

70钢小方坯凝固过程数值模拟研究

为控制线材轧制用连铸小方坯质量,应用数值模拟软件对鞍钢股份有限公司炼钢总厂120 mm×120 mm小方坯连铸凝固过程进行模拟。模拟结果表明,在合理的冷却制度下,过热度低于35℃,拉速约为3.0 m/min的条件下,可以将结晶器出口坯壳厚度、铸坯液芯长度和铸坯表面温度控制在合适的范围内,并防止铸坯表面及内部产生缺陷、保证浇铸安全。     

珠钢CSP薄板坯凝固层厚度研究

结合珠钢生产实际情况，采用射钉法来测定二冷区不同位置的凝固坯壳厚度，试验结果表明，4．8m／min拉速下铸坯液芯长度为4820mm，4．5m／min拉速下铸坯液芯为4490mm，两种拉速下连铸坯坯壳厚度的实际测量结果与凝固传热模型计算结果一致。整个凝固过程坯壳厚度生长符合平方根定律。     

薄板坯连铸连轧的液芯压下技术

介绍了国内外薄板坯连铸连轧流程中液芯压下技术的发展与应用情况,分析了液芯压下过程中铸坯的凝固机理以及变形的应变特点,并根据铸坯的凝固机理和坯壳凝固前沿的应变条件,提出了确定单辊压下量、压下量分配和总压下量的基本方法。     

大圆坯连铸带液芯矫直过程的应力、应变有限元模拟

应用Marc有限元软件对圆坯连铸的连续矫直变形过程进行模拟.以马鞍山钢铁公司大圆坯连铸机为原型,考虑铸坯与辊子的接触状态,建立了圆坯矫直变形模型;模拟分析了大圆坯连铸带液芯矫直过程中坯壳的应力、应变,得到了铸坯在矫直过程中的变形规律,可为铸机矫直工艺及设备设计提供参考依据,从而进一步优化铸坯的矫直变形,以提高圆坯的内部质量和表面质量.     

连续铸轧结晶器内钢液在电磁力驱动下流动和传热的数学模型

本文阐述了连铸坯液芯轧制的优点和结晶器电磁搅拌对改善铸坯质量的重要意义。建立了描述连铸坯液芯轧制过程中结晶器内钢液在电磁力驱动下流动和传热的数学模型。     

板坯连铸带液芯轻压下过程的力学分析

利用热力学耦合模型对板坯连铸带液芯轻压下过程的铸坯变形抗力、拉坯阻力及其变化特性进行了理论计算.分析比较了不同轻压下和连铸过程工艺参数的影响.结果表明压下量、压下速率、拉坯速度及坯壳温度对铸坯变形抗力和拉坯阻力均有很大影响.计算结果为实际板坯连铸带液芯轻压下工艺设计提供了依据.     

Development of improved cube-on-edge texture from strand cast 3pct silicon-iron

The degree of cube-on-edge texture attainable by processing of coils hot rolled directly from strand cast slabs tends to be highly variable. Incomplete secondary recrystallization in the product results from excessive grain size in the reheated cast slabs. These large grains fail to recrystallize during subsequent rolling and annealing operations. Prerolling the cast slab about 25 pct produces a smaller grain size in the slab after reheating prior to hot rolling with the result of a uniform and improved texture in the product. The texture changes which take place with and without prerolling are described and analyzed.     

Development of improved cube-on-edge texture from strand cast 3pct silicon-iron

The degree of cube-on-edge texture attainable by processing of coils hot rolled directly from strand cast slabs tends to be highly variable. Incomplete secondary recrystallization in the product results from excessive grain size in the reheated cast slabs. These large grains fail to recrystallize during subsequent rolling and annealing operations. Prerolling the cast slab about 25 pct produces a smaller grain size in the slab after reheating prior to hot rolling with the result of a uniform and improved texture in the product. The texture changes which take place with and without prerolling are described and analyzed.     

高强度特厚板减量化轧制工艺

利用无微合金化Q345D连铸坯料,采用TMCP和RCR+ACC两工艺进行了厚80~85 mm高强度厚板工业试验,对比了两工艺厚板的组织和性能。试验结果表明,经两工艺轧制的钢板均实现了组织和性能的良好匹配。与TMCP工艺相比,采用RCR+ACC工艺的钢板厚度1/4位置和钢板心部组织均匀性、厚度方向上的性能均匀性较好;轧制过程在奥氏体高温区进行,变形抗力低,有利于降低轧机负荷或实现低速大压下轧制,且省去了TMCP工艺中间待温时间,减少了轧制道次,实现了厚板轧制过程的减量化。     

Microstructural evolution of austenite under conditions simulating thin slab casting and hot direct rolling

Abstract

The hot direct rolling (HDR) of thin slabs introduces some new microstructural phenomena with respect to conventional hot rolling of steels. This paper aims to investigate the microstructural changes of as cast austenite under these conditions. Current laboratory techniques for HDR simulation require a freshly cast slab for every experiment and a perfect link between casting and hot deformation. The present work adopted a new approach; the C–Mn steel is substituted by austenitic Fe–30Ni alloy, Conventional reheating before rolling replaces the direct link. The experimental ingot casting of Fe–30Ni alloy resulted in a solidification structure in good agreement with that of thin slabs of C–Mn steels. From metallographic observations, a mixed softening process and a strong grain refinement and homogenisation characterise the microstructural changes during HDR simulation. The microstructural behaviour and the grain refinement measured for the Fe–30Ni alloy is closely comparable with that predicted for C–Mn steels for the same conditions. The steel substitution appears to constitute a suitable and advantageous experimental approach for HDR simulation.     

Q345A 中板控轧控冷工艺试验

采用外购Q345A连铸板坯,在韶钢2500mm轧机上进行了以“再结晶区 未再结晶区”两阶段控轧及轧后空冷或水冷工艺为主体的中板控轧控冷试验,主要研究了轧制温度、终冷温度对钢板组织和性能的影响,为韶钢“大转炉一中板轧机”生产高强度低合金钢板进行了控轧控冷工艺的技术储备．     

热装和直轧是现代轧钢发展的方向

连铸坯的热送热装轧制和直轧,在工艺流程中取消了冷装时连铸坯表面清理和不同程度的取消了一些中间环节,从而缩短和简化了生产工艺流程,使生产线由传统的炼钢连铸与轧钢两个独立的生产工艺变革为炼钢与轧钢集约同步生产工艺。并且节省大量的能源消耗,提高生产率和成材率,降低了生产成本。本文的介绍旨在使钢铁企业在现有的条件下,通过适当的改造、研究和开发热送热装轧制和直接轧制所必须的支撑技术,有计划有步骤地实施这项工艺技术,从而使企业获得巨大的经济效益。     

Evolution of Surface Transversal Crack in Intermediate Slabs during Hot Rolling Deformation

In the continuous casting of steels,surface transversal cracks are often found.These defects may severely influence the final quality of the products.The evolution of transversal V-shaped cracks with different depth on the surface of a continuously cast steel slab during hot rolling was studied.The artificial V-shaped cracks were made on the surface.The rolling process parameters from an industrial rolling mill have been used as a reference.The specimens of rolled workpiece in intermediate slabs were obtained after different rolling passes.The morphology of surface crack and microstructure evolution in the rolling process were investigated by optical microscopy.The results show that the depth of surface transversal crack gradually decreased with the increase of rolling passes.The grain size of ferrite and pearlite on the sample surface also gradually reduced.The microstructures around cracks with the different depth are almost identical,without direct correlation with the initial crack depth.     

Cyclic-deformation system for the reduction of continuous-cast slabs

Introducing systems capable of profound reduction in a casting and rolling module improves the product quality, on account of the intense working of large continuous-cast slabs over the whole cross section and the production of uniform fine-grain structure of the metal, and also increases the cross section of continuous- cast billet. Analysis of the formation of nonmetallic inclusions and segregation in the axial zone of the thick rolled sheet is followed by analysis of the nonuniform deformation over the slag height in the reduction of large continuous-cast slabs at the 5000 mill at OAO Magnitogorskii Metallurgicheskii Kombinat. The structure of a cyclic-deformation system for preliminary deformation of large continuous-cast slabs is described, and its capabilities are explored. Hammers for preliminary deformation of large continuous-cast slabs are considered. Experimental data are presented for the deformation of continuous-cast steel 45 and 12Kh18N10T steel billet. The structure of the continuous-cast billet is assessed in the course of reduction on the cyclic-deformation system. The basic parameters of the system for preliminary deformation of large continuous- cast slabs are determined. The capabilities of the cyclic-deformation system are outlined in terms of increase in sheet quality. On that basis, the use of the cyclic-deformation system in the continuous-casting line for preliminary reduction of large continuous-cast slabs is recommended: it permits matching of the speed of continuous-casting and cyclic-deformation processes; and ensures 45–90% reduction in a single pass so as to obtain well-worked cast structure over the whole slab cross section. When using the cyclic-deformation system in the continuous-casting line, the continuous-cast slabs are reduced by means of the heat of the cast metal, thereby greatly reducing the energy consumption in billet production. The cyclic-deformation system may be used with thick-sheet and broad-strip mills for preliminary single-pass reduction of the hot slab, with improvement in sheet quality and reduction in the number of passes in the mills.     

钢坯切轧中旁弯的研究

简介采用以连铸板坯为原料的钢坯切轧工艺、孔型设计及切分机理;并全面阐述切分轧制中旁弯现象的形成、影响因素、对实现切分的作用和控制措施。     

Mechanism and Improvement of Straight Edge Seam Defect on Hot-rolled Plate Surfaces through Use of Chamfered Slabs

To improve the straight edge seam defect on hot-rolled steel plates,the deformation and temperature distribution of rectangular slabs and chamfered slabs during rolling in a pilot rolling experiment were analyzed in detail using the finite element method.The results showed that the crease formed on the lateral side near the edge of the plate as a result of uneven stress during broadside rolling.The creases rose to the surface with unrestricted spread and evolved into a straight edge seam during the subsequent straight rolling.To eliminate the straight edge seam defect,chamfered slabs were developed and investigated for rolling.The use of the chamfered slabs provided two advantages for rolling:the distribution of the temperature near the edge was ameliorated,and the deformation shape was improved by the chamfered shape.As a result,the risk of forming a straight edge seam defect was reduced by the use of a chamfered slab.