同中包异钢种混浇模型在梅钢的应用

通过钢级、出钢记号、成分范围、产品最终用途制定了同中包异钢种混浇应用技术规范。在L4质量混浇坯出钢模型中,将现有的出钢记号通过混浇坯出钢记号表和混浇坯索引组关系表实现了出钢记号混浇管理。在炼钢L3中,根据精炼实际成分指导连铸混浇操作,并根据实际连铸混浇操作情况实现了混浇板坯的系统判定。     

冷轧多机组合同优化排产模型及算法(下)

3.2 单机组粗计划合同内调度 传递时间窗只是确定合同钢卷在各机组生产加工的合理时间范围,对于合同钢卷的具体加工顺序没有给出明确的规定.需要从企业生产工艺的约束和生产成本考虑优化合同钢卷加工次序,即完成单机组钢卷的生产调度.     

490MPa级汽车桥壳用热轧高强钢板研制

根据汽车桥壳用钢使用特点进行了成分设计;对铌、钛微合金钢在1450热轧机组进行了不同终轧温度和卷取温度热轧工艺的试验研究;结合桥壳钢技术要求,分析了化学成分、工艺参数、金相组织对桥壳钢性能的影响;确定了化学成分及符合攀钢生产条件的工艺制度;在此基础上研发了490MPa级热轧冲压桥壳专用钢板。     

Q345C钢的开发与工艺优化

天钢联合特钢炼钢厂为满足高级别角钢的市场需求,进行了Q345C钢的开发.该钢种要求钢中铝含量较高(A1≥0.020％),试生产时连铸塞棒水口结瘤严重,造成铸机连续2个浇次非计划停浇.对关键工序生产工艺进行优化后,再次生产时钢水浇铸性良好,铸坯性能完全满足C级钢的要求,成功开发了Q345C高级别角钢.     

开浇前中包充氩对圆坯钢水洁净度的影响

为研究开浇前中包充氩工艺对圆坯钢水洁净度的影响,设计了三种开浇前中包充氩工艺试验,量化分析了三种工艺条件下全氧及夹杂物的变化。结果表明,RH出站至CCM1期间,方案1~3钢中T.O分别增加16.3%、19.1%和77.6%,w(Al_2O_3)在10%以上的钙铝酸盐夹杂物数量密度分别增加26.8%、63.9%和345.1%,充氩炉次与不充氩炉次钢中夹杂物数量密度分别增加11.90%和211.78%,开浇前采用中包充氩有利于降低开浇阶段钢水的二次氧化,且充氩时间延长可进一步降低钢水的二次氧化,但考虑到中包充氩对中包温度的影响,建议开浇前中包充氩时间控制在3~5min。     

板坯连铸异钢种连浇混浇坯长度及成分变化模型的开发及应用

基于建立的连铸中间包及结晶器内钢液混合过程的物理模型,开发了板坯连铸异钢种连浇过程混浇坯长度及成分变化模型。以某钢厂单流板坯连铸机220 mm×1560 mm断面Q235与Q335Ti钢的混浇过程为研究对象,采用水模型试验结合数值模拟确定模型的关键参数,并通过开展现场试验对混浇坯取样验证模型的准确性。结果证明:混浇坯成分取样与模型预测的成分偏差小于5%,且模型预测的混浇坯长度与人工确定的一致。故采用该模型可跟踪不同混浇工况下中间包内及铸流上钢液的混合行为,准确预测混浇坯的长度以及成分变化规律。采用该模型研究了拉速及中间包内剩余钢液质量对混交坯长度及不同浇注长度铸坯C元素质量分数变化的影响规律。发现当拉速保持不变时,中间包内剩余钢液越多,混浇坯越长;当中间包内剩余钢液质量保持不变时,拉速越大混浇坯越短。相比而言,中间包内剩余钢液质量比拉速对混浇坯长度的影响更大。另外当拉速不变时,随着中间包内剩余钢液质量的增加,C元素质量分数由0.16%变化到0.18%的速率减慢;当中间包内剩余钢液质量不变时,随着拉速的增加,C元素质量分数由0.16%变化到0.18%的速率增加。因此异钢种连浇过程,适当提高拉速以及减少中间包内剩余钢液质量,可有效减少混浇坯长度,成分变化速率降低。      

CAS冶炼低碳低硅铝镇静钢的生产实践

新钢第二炼钢厂采用KR→BOF→CAS→CC工艺路线生产低碳低硅铝镇静钢,通过控制入炉铁水硫含量、转炉出钢挡渣及脱氧合金化、CAS精炼造渣及钙处理、连铸保护浇铸及稳定结晶器液面等措施,钢水可浇性增强,可实现一个浇次生产10炉及以上,钢水满足客户要求,w (Si)控制在0. 03%以下,低倍结果显示铸坯质量良好,C类中心偏析为1. 0级,中心疏松0. 5级。     

连铸工艺生产34Mn2V非调质钢的质量控制

阐述了连铸工艺生产34Mn2V钢的质量水平.针对34Mn2V钢的性能及使用特点,通过采取钢包吹氩、LF和RH精炼、结晶器电磁搅拌、控制浇钢过热度及轻压下等技术措施,使大方坯连铸工艺生产的34Mn2V钢坯表面质量优良,纯净度高,其[H]≤1.8×10-6;T[O]≤12.0×10-6;A类夹杂≤2.0级,B、C类夹杂均≤1.0级,D类夹杂≤1.5级.冲制高压无缝气瓶的性能稳定,具有较高的强韧性水平,满足气瓶使用的安全性要求.     

通用车系变速箱支架用带钢材料的试验开发

采用已有汽车横梁钢坯料,试验不同轧制工艺,从而确定产品性能完全符合要求的工艺路线,研制出变速箱支架用窄带钢。试验结果表明,采用轧后控冷的工艺路线,得到的产品组织为铁素体+珠光体,晶粒度达到10级以上,带状组织1.0级,夹杂物均在1.0级以下,各项力学性能指标均符合用户的要求。     

大圆坯连铸机开浇漏钢的工艺改进

天钢大圆坯连铸机在首次热试时采用原设计的引锭头连接件和工艺参数后发生开浇漏钢.为了防止开浇漏钢的发生影响生产,天钢炼钢厂经过对引锭头连接件、冷料结构和工艺参数的改进后,有效地解决了开浇漏钢的问题,未再发生开浇漏钢事故.     

连铸混浇坯的过度时间及影响因素

为提高连铸比实现全连铸，鞍钢二炼钢在小方坯连浇不同钢种过渡段铸坯成分差异上做了试验研究，并指出小方坯连铸机增设钢水快速分析和快速节装置的必要性。     

Application of Mix Optimization Scheduling Approach for Steelmaking-Continuous Casting Process Based on Actual Steelmaking Industry

The models, algorithms and implementation results of a computerized scheduling system were introduced for the steelmaking-continuous casting process (SCCP) of a steel plant in China. The scheduling of SCCP in this plant required that each cast plan should be processed on time, the charges in the same cast should be processed continuously on the same caster, and the waiting time of the charges which are in front of each caster cannot exceed the given threshold. At the same time, the processing time of charges cannot be conflicted mutually in the same converters or refining furnaces. Based on the research background, a hybrid optimal scheduling approach and its application were discussed. Aiming at the main equipment scheduling, an optimal scheduling method was proposed which consisted of equipment assignment algorithm based on dynamic program (DP) technique and conflict elimination algorithm based on linear program (LP) technique. The approach guarantees that the charges are continuously processed on the same caster. Meanwhile, the requirement for high temperature ladle can also be satisfied due to the ladle matching function. Numerical results demonstrate solution quality, computational efficiency, and values of the models and algorithm.     

Methods of separating different grades of steel during continuous casting on section and slab casters

This article is devoted to the problem of separating different grades of steel cast in succession on section-and slab-type continuous casters, the goal being to reduce the incidence of rejection of steel for incorrect chemical composition. With this as their objective, researchers found that it is necessary to determine the optimum length of the specific semifinished products which serve to separate successive heats of dissimilar steels. A mathematical model was constructed to help determine the optimum lengths of the semifinished products. The model, based on material balance equations, makes it possible to determine the changes that take place in the constituent chemical elements when different grades of steel are cast back-to-back. Having been refined through the use of actual production data to describe those elements’ distributions in the continuous-cast semifinished product, the model was then used to develop an efficient method for extracting and pattern-shearing ingots that function as separators when different grades of steel are cast in a series. __________ Translated from Metallurg, No. 1, pp. 48–50, January, 2007.     

板坯连铸结晶器非稳态流场的模拟研究

本文运用数值模拟研究方法,研究高拉速厚板坯连铸非稳态结晶器流动特性,研究浸入式水口堵塞、水口不对中对结晶器流场、液面流速和对初生坯壳的影响。高拉速厚板坯连铸,铸坯质量下降,90%表面缺陷集中在铸坯边角区域,最严重的缺陷是铸坯中心和角部纵裂。非稳态工况对结晶器的流场影响因素更为显著,研究发现水口堵塞程度、水口出口流速、流量分配比是结晶器液面流速不对称、液面波动的主要影响因素,水口不对中是钢液流股对结晶器初生坯壳局部热冲击的主要因素,因此高拉速连铸应尽量避免非稳态工况操作,确保产品质量和效率的双赢。     

连铸二冷参数的优化和控制研究

近些年连铸过程模拟成为研究的重点,模拟的根本目的在于优化连铸过程.为在保证连铸坯质量的前提下进一步提高连铸生产率,基于数学上的子问题接近优化技术建立了连铸过程二冷参数优化系统,可对不同钢种、不同拉速、不同冶金限制准则下的二冷各段配水进行最优化.运用优化后的这些过程参数,将使铸机以最大生产率、最小消耗运行,同时又保证了生产无缺陷铸坯.整个优化系统包括两个模块,一个是热过程模拟模块,另一个是设计优化模块,系统靠在两个模块之间反复自动循环调用而使参数得到优化.     

坯壳鼓肚对铸机矫直区内铸坯变形的影响

 在连铸机辊列矫直段,带液芯铸坯的坯壳同时受钢水静压力与矫直力的作用,坯壳固液交界面处的矫直应变与鼓肚应变发生叠加。如果总应变超过临界值,就会发生内裂。确定矫直区坯壳固液交界面处的应变与应变速率,对铸机辊列设计与工艺参数的设定有重要的意义。基于高温坯壳力学特性,建立了连续矫直理论中铸坯坯壳变形的数学模型。利用该模型计算坯壳鼓肚变形,并与实测数据进行对比,验证了模型的有效性。根据某厂由奥钢联设计的工业板坯连铸机的辊列参数,利用该模型计算铸坯横截面的应变与应变速率。最后分析了不同辊间距与不同拉坯速度情况下矫直区内铸坯坯壳固液交界面处的应变速率变化规律,结合不同钢种的临界应变速率得到铸机矫直段辊间距的取值范围。     

连铸板坯凝固过程应变及内裂纹研究

通过建立连铸板坯凝固过程的传热模型,获得板坯冷却传热过程的主要凝固参数,在此基础上建立了凝固前沿坯壳所承受的应变模型,定量计算了凝固过程的主要应变,讨论了其主要影响因素,并针对实际铸机的设备和工艺状况,计算了其生产过程的应变,讨论了具体钢种产生裂纹的可能性。     

连轧中型生产线矫直机改造

介绍了宣钢连轧中型生产线矫直机改造情况.因800矫直机矫直能力不足,限制了更大规格、更高强度钢种产品及矿用U型钢的开发生产,技术人员根据连轧中型生产线工艺布置及设计品种的工艺要求,对矫直机改造提出技术要求.根据现场使用经验,自主设计了各规格矫直辊;在矫直机初步设计审查中,对矫直机部分结构提出改进方案,使矫直机更适用于现场工艺.通过矫直机改造,提高了矫直能力,增加了矫直产品规格,提高了产品产量和质量,满足了市场需求.     

Two-Stage Mathematical Programming Approach for Steelmaking Process Scheduling Under Variable Electricity Price

 The steelmaking process scheduling problem by considering variable electricity price (SMSPVEP) was investigated. A decomposition approach was proposed for the SMSPVEP. At the first stage, mathematical programming was utilized to minimize the maximum completion time for each cast without considering variable electricity price. At the second stage, based on obtained relative schedules of all casts, a mathematical model was formulated with an objective of minimizing the energy cost for all casts scheduling problem. The two-stage models were tested on randomly generated instances based on the practical process in a Chinese steelmaking plant. Computational results demonstrate the effectiveness of the proposed approach.     

The Effect of Graphite Fraction and Morphology on the Plastic Deformation Behavior of Cast Irons

The plastic deformation behavior of cast irons, covering the majority of graphite morphologies, has not been comprehensively studied previously. In this investigation, the effect of graphite morphology and graphite fraction on the plastic deformation behavior of pearlitic cast irons has been evaluated. The investigation is based on tensile tests performed on various different cast iron grades, where the graphite morphology and volume fraction have been varied. Pearlitic steel with alloying levels corresponding to the cast irons were also studied to evaluate how the cast iron matrix behaves in tension without the effects of the graphite phase. It is concluded that as the roundness of the graphite phase increases, the strain hardening exponent decreases. This demonstrates that the amount of plastic deformation is higher in the matrix of lamellar cast iron grades compared to compacted and nodular cast iron grades. Furthermore, this study shows that the strength coefficient in flake graphite cast irons increases as the graphite fraction decreases due to the weakening effect of the graphite phase. This study presents relationships between the strain hardening exponent and the strength coefficient and the roundness and fraction of the graphite phase. Using these correlations to model the plastic part of the stress-strain curves of pearlitic cast irons, we were able to calculate curves in good agreement with experimentally determined curves, especially for gray cast irons and ductile iron.