小方坯连铸过程实时温度场预报模型的开发

基于凝固传热学基本理论和对小方坯连铸工况的分析,采用二维有限差分法建立了小方坯连铸过程实时温度场预报模型,并自主开发了计算程序。通过调试,验证了该模型的实用性和准确性,实现了生产过程中小方坯温度场的实时预报,为动态配水及动态轻压下技术的开发打下了基础。     

利用NaOH水溶液-CO2系模型研究中间罐钢液的吸气速率

建立了盛钢桶到中间罐钢液吸气的物理模型，利用NaOH水溶液－CO2系模型来研究注流及中间罐液面的吸气（CO2）速率，从而考察操作参数对中间罐钢液吸气速率的影响。结果表明：氧分压、注流半径增加时，熔池内钢液的吸气速率提高；注流速度增加时，中间罐液面的吸气速率提高；另外，中间罐结构对中间罐液面吸气速率也有影响。     

高频电磁场对连铸初始凝固点的影响

连铸电磁搅拌过程中金属的初始凝固已被试验和数值模拟研究所证实，在金属内部的凝固温度曲线已被测量出，按照曲线就可以确定其初始凝固点的位置。研究发现，电磁场对凝固温度曲线的影响是很大的，且明显地降低了凝固初始点的位置。此外，根据测出的结晶器磁通量就可计算出电磁感应产生的热量。结晶器壁产生的感应热量用温度的形式在结晶器的内壁上被测量出来。为了弄清电磁场对注流金属和结晶器壁之间的内部热量转换行为的影响，进行了专门的试验测量内表面的热量转换系数。在上述测量的基础上，建立了一个描述金属注流传热和凝固的数学模型，从而计算出电磁场对金属注流凝固的影响。分析电磁场有三个主要作用：在金属内部产生热量、在结晶器壁产生热量、降低在金属注流和结晶器壁之间的传热速率。研究表明，结晶器壁产生的感应热量和结晶器和注流金属之间的传热速度的降低对凝固的影响。     

基于模糊聚类及神经网络的连铸漏钢预报

在模糊RBF神经网络的基础上,通过融合基于贴近度的改进FCM和Conditional FCM算法,建立了改进的模糊RBF网络模型;并结合某钢厂连铸现场采集的历史数据将该模型应用于连铸漏钢预报的过程中。结果表明,改进的网络模型能更准确地辨识连铸粘结漏钢过程中典型温度模式1和模式2,对二者的预报率分别达到949%和983%,报出率均达到100%,其预报性能更佳,能更有效地预报拉漏事故。     

连铸黏结漏钢发生机理及预报模型

连铸是炼钢过程非常重要的工序之一。连铸过程多发漏钢事故，其影响因素多且机理复杂，其中以黏结漏钢最为常见，约占总漏钢事故的70%。连铸漏钢事故造成钢液泄漏，容易发生灼烫、火灾甚至爆炸等安全事故，造成人员伤亡和巨大的财产损失。为解决上述问题，剖析了黏结裂口的扩展方式和黏结漏钢的形成机理；基于热电偶测温法预报黏结漏钢的原理，利用神经网络建立黏结漏钢预报模型，并运用遗传算法完成神经网络的优化，预报模型测试样本的正确报出率达到100%,预报率为97.56%;对空间网络模型进行了验证，A型空间网络模型的输出符合期望，可以实现黏结在空间裂口扩展的预报。模型具有很好的应用价值，可为连铸安全生产提供支撑。     

连铸坯温降数模的研究

对连铸坯堆放过程中温降规律的研究 ,有助于提高连铸坯装炉温度 ,降低加热炉燃耗 .文章建立的连铸坯温降数模 ,较好地模拟了保温坑中堆放连铸坯的温降过程 ,模型理论计算结果与实际相当吻合 ,两者误差小于 3% .     

板坯连铸结晶器热态调宽过程的力学分析

根据板坯连铸结晶器热态调宽过程的特点建立了热态调宽过程的力学计算模型。将实际生产过程中的参数代入模型进行求解,并与实测的调宽液压缸推力进行比较,结果表明,计算模型可以较准确地描述板坯连铸结晶器热态调宽过程的力学特征。     

热送热装工艺中铸坯温度的在线预报模型

以连铸坯热送热装过程传热数学模型对热送热装工艺中铸坯温度变化模拟结果为基础，建立了传搁过程中铸坯温度变化在线实时预报的数学模型，在线模型能实时预报各种工况下铸坯的温度变化。     

连铸板坯的鼓肚应变速率

本文建立了新的连铸板坯鼓肚变形的计算模型，与原有的模型相比，该模型更接近于坯壳变形的实际情况，并且还可求出坯壳应变速率的值，结合钢的临界应变与应变速率的关系，可为确定连铸机的辊距提供更为科学的理论依据。     

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.     

连铸时超低碳钢结晶器内钢液增碳的研究

通过理论解析和实验测定,研究不同类型和配入量的碳质材料的连铸保护渣对0.003%C超低碳钢连铸结晶器(200 mm×100 mm)内钢液增碳的影响。结果表明,铸坯速度2.0 m/min在稳态浇注条件下,超低碳钢连铸结晶器内钢液增碳量仅为(1.2~2.4)×10^-6;在非稳态浇注时期,钢液最大增碳量达67.9×10^-6。保护渣的3种配加碳质材料中,石墨对结晶器内钢液增碳量影响最大,碳黑次之,活性碳最小。随着渣中碳质材料配入量的增加,钢液增碳量增大。     

Behaviour of Hydrogen in Industrial Scale Steel Melts

The behaviour of hydrogen during controlled industrial scale secondary steel making process has been examined in a variety of low alloy steels, sensitive to hydrogen flaking. The study examines the role played by the moisture in input raw materials such as the ferro-alloys, type of carbon additive and fluxes in enhancing the hydrogen content in the ladle furnace. Post alloying, the influence of vacuum degassing parameters such as the vacuum level, vacuum holding time, Ar flow rate, type of porous plug used, slag chemistry and the steel grade was examined. The vacuum degassing process was analysed using a kinetic model, which could justify the trends seen in the vacuum level, holding time and Ar gas flow rate. Finally, the hydrogen pick-up post vacuum degassing through slag cover and the casting tundish was found to be influenced by parameters such as the quality of the tundish spray mass, and casting sequence. The influence of steel grade in hydrogen removal was also examined.     

现代电弧炉流程钢液氮控制的试验研究

通过生产试验研究了电弧炉冶炼过程、LF精炼过程及连铸过程钢液氮的控制。研究表明，电弧炉冶炼过程主要是电弧区增氮，LF过程及连铸过程钢液增氮主要是钢液与大气接触，LF供电制度也对钢液吸氮有影响。     

Steel ladle exchange models during steelmaking and continuous casting process

The models and influencing factors of steel ladles exchange during the steelmaking and continuous casting process of H steel plant were investigated.Based on analysis of the operation process and turnover time of steel ladles, relationship models for the turnover number, turnover rate, continuous casting number, number of ladles with additional turnover, and number of ladles without additional turnover were built.The turnover rules of steel ladles for one basic oxygen furnace (BOF) matching one continuous caster (CC) and two BOFs matching two CCs modes were simulated by using a Gantt chart.The models of steel ladle exchange were proposed for casting of a single CC and overlapping casting of two CCs.By analyzing the influencing factors, the following conclusions were drawn.The exchange ladle should not have the task of transporting liquid steel in the CC that stops casting earli-er.The end time of the empty ladle in the CC that stops casting earlier should be earlier than the start time of the full ladle in the CC that stops casting later.After evaluating the factors influencing the start casting time, turnover cycle, casting time, continuous casting number, and overlapping time, a prioritization scheme of steel ladle exchange was proposed based on the steel grade.First, the turn-over cycle and single heat casting time were determined; based on these, a reasonable ladle turnover number was calculated.Second, the turnover number and continuous casting number were optimized for maximizing the number of ladles without additional turnover.Lastly, to reduce the casting number during the overlapping time to be lower than the turnover number, the overlapping time was shortened.     

EAF 留碳操作生产中、高碳钢的工艺实践

在70tEAF-LF-CCM 流程生产50CrVA、60Si2Mn、77Mn 等中、高碳钢时,EAF 炼钢过程采用 20%～30%热装铁水,控制供氧强度,二元渣碱度1.8~2.8可有效进行留碳操作。生产统计表明,EAF 留碳 操作终点C 为0.25%～0.53%,P为0.006%~0.015%,钢水温度1593～1625℃。 EAF 留碳操作虽使冶炼 周期延长5～10 min,但LF 喂丝量降低1/2以上,显著降低冶炼成本和提高钢水质量。     

Spectral factors in the perception of vowel quantity in Icelandic

The aim of this study was to clarify the effect of heating rate on the development of both transient and residual stresses in investment molds. Solid, cylindrical, gypsum-based molds were modeled and theoretical calculations made of temperature distributions with a constant heating rate. These calculations used experimental thermal diffusivity data obtained with a laser flash method. The simulations calculated transient thermal stresses during heating and at the end of heating for two surface conditions: an unrestricted surface, and a surface restricted by a casting ring. The simulation model developed nonuniform strains and stresses at casting temperature; tangential stress was compressive at the surface and tensile at the mid-point for the unrestricted surface model. The surface restricted model developed compressive tangential stresses throughout the mold at the casting temperature. This resulted in significant thermal strain differences compared to the magnitudes of expansion of the mold due to heating.     

Source and Control of Nitrogen for X70 Pipeline Steel

The effects of some key factors on nitrogen absorption during the smelting process of X70 pipeline steel were studied,and the source of nitrogen pick-up was analyzed to find the bottleneck for nitrogen control.A series of measures were put forward to decrease the nitrogen pick-up.The results indicated that an exponential relationship existed between the nitrogen absorption index and the free oxygen in molten steel.Nitrogen absorption index could decrease below 0.3when free oxygen in molten steel was above 100×10~(-6) after tapping.For low sulfur killed steel,the nitrogen absorption ratio and sulfur content satisfied a linear relationship with a slope of-0.007.Low free-oxygen and sulfur were beneficial to the deep desulfurization during vacuum treatment.The contradiction of high desulfurization ratio and low nitrogen pick-up during LF process could be resolved by skimming oxidizing slag after tapping and making new high basicity top slag.After optimization,the average content of nitrogen in final product decreased from 46×10(-6)to 35×10(-6).     

Microstructure and Mechanical Properties of Laser Welded Titanium 6Al-4V

Laser butt welds were fabricated in a titanium alloy (Ti-6A1-4V, AMS 4911-Tal0 BSS, annealed) using a Control Laser 2 kW CW CO₂ laser. The relationships between the weld microstructure and mechanical properties are described and compared to the theoretical thermal history of the weld zone as calculated from a three-dimensional heat transfer model of the process. The structure of the weld zone was examined by radiography to detect any gross porosity as well as by both optical and electron microscopy in order to identify the microstructure. The oxygen pick-up during gas shielded laser welding was analyzed to correlate further with the observed mechanical properties. It was found that optimally fabricated laser welds have a very good combination of weld microstructure and mechanical properties, ranking this process as one which can produce high quality welds.     

薄带连铸304不锈钢高温热变形时真应力真应变计算模型的研究

提出了薄带连铸304不锈钢在高温热变形过程中,当出现颈缩时以四棱台进行变形的模型.根据拉伸过程中采集的瞬时载荷、瞬时位移数据,应用matlab软件建立了其在热变形过程中的真应力真应变计算模型,并把实际测量的截面面积与模型计算值进行了比较.结果表明:模型的计算值与实测值吻合得较好.因此,根据建立的计算模型得到了薄带连铸304不锈钢的变形抗力数学表达式.     

马钢CSP流程钢水增碳现象的分析

针对马钢LD＋LF＋CSP流程生产低碳钢的生产过程，对转炉出钢后至连铸期间钢水的增碳现象进行计算和分析，找出增碳的主要原因，并提出改进的建议。