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电磁搅拌是改善金属凝固组织,提高产品质量的有效手段,在水平连铸机上应用可改善铸坯质量。文章结合石横特钢厂水平连铸机生产实际,指出采用二级电磁搅拌装置的水平连铸电磁搅拌法可改善铸坯结晶状态,减少芯部缺陷。 相似文献
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末端电磁搅拌对弹簧钢连铸坯内部质量的影响 总被引:1,自引:1,他引:0
55SiCrA弹簧钢连铸坯容易出现内部质量问题,合理的末端电磁搅拌(F-EMS)能有效地改善连铸坯内部质量,但不合理的末端电磁搅拌会对连铸坯内部质量无改善作用甚至造成内部质量下降。为了提高连铸坯内部质量,得出最优末端电磁搅拌方案,研究了末端电磁搅拌参数对断面尺寸为150 mm×150 mm的55SiCrA弹簧钢连铸坯内部质量的影响。通过建立连铸过程凝固传热模型分析现行工艺下铸坯的凝固情况,确定末端电磁搅拌的位置为距弯月面8.45~8.73 m处。在测定末端电磁搅拌下连铸坯中心磁感应强度的基础上,对电流与频率进行匹配研究,并开展相应的工业试验。结果表明,在采用末端电磁搅拌参数为300 A/8 Hz时,55SiCrA弹簧钢的中心碳偏析平均值达到1.007,连铸坯中心缩孔改善,中心等轴晶率提高,连铸坯综合质量最好。 相似文献
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研究了过热度、拉速、二冷水量、电磁搅拌投用值以及轻压下量等主要连铸工艺参数改变对连铸坯中心偏析的影响。在不影响连铸坯表面质量的前提下,对铸坯凝固过程中影响铸坯内部偏析的拉速、二冷水量、电磁搅拌投用值和轻压下量等工艺参数进行优化,从而改善了连铸坯的中心缺陷,减少了铸坯中心偏析,提高了产品内部质量。 相似文献
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介绍了凝固末端电磁搅拌技术在酒钢宏兴炼轧厂3#方坯连铸机的应用实践,通过结合150 mm×150 mm小方坯连铸过程的工艺条件,对凝固末端电磁搅拌技术冶金原理的理论研究,验证了凝固末端电磁搅拌技术对连铸坯内部质量的影响。实践表明:凝固末端电磁搅拌技术能够有效改善中心偏析、V形偏析、中心疏松和缩孔缺陷,并且中心偏析的变化值和平均值都能显著减小,对高碳钢铸坯内部质量的改善效果明显。 相似文献
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在川崎钢铁公司水岛厂,连铸电磁搅拌始于1973年。它的应用结果表明,单点电磁搅拌能增加铸坯的等轴晶率,但不能显著降低铸坯的中心偏析。为了减少铸坯中心偏析,对单点电磁搅拌和多点电磁搅拌进行了广泛的工业性试验。本文根据铸坯凝固组织的形态,讨论了多点电磁搅拌对不同规格铸坯的影响。 相似文献
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铸坯高中心等轴晶率及小的二次枝晶臂间距有利于降低高碳钢M+E-EMS连铸坯中心偏析。通过建立GCr15钢220 mm×260 mm连铸坯耦合有限元-元胞自动机模型(CAFE)及二次枝晶臂间距(SDAS)模型,研究结晶器电磁搅拌、过热度和拉速对中心等轴晶率及二次枝晶臂间距的影响。结果表明,相比于拉速,过热度和结晶器电磁搅拌对其影响明显。随着过热度降低及结晶器电磁搅拌强度增加,铸坯中心等轴晶率增加而二次枝晶臂间距减小,而拉速对凝固终点和中心固相率影响大。工业试验结果表明,采用结晶器与凝固末端电磁搅拌,相比于过热度35℃和拉速0.75 m/min,控制过热度小于25℃且拉速调整为0.8 m/min时,轴承钢GCr15铸坯中心等轴晶率由原27%增加至38%且二次枝晶臂间距细化,中心碳偏析指数由原1.06~1.39降至0.93~1.13。 相似文献
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结晶器冷却强度与坯壳厚度的关系 总被引:3,自引:1,他引:3
根据斯蒂芬凝固定律直接导出了坯壳厚度与结晶器冷却强度及拉坯速度的关系。因此可根据坯壳厚度合理地确定冷却强度及拉坯速度或由冷却强度预测坯壳厚度。计算结果与传统的凝固平方根定律相吻合,从而可确定平方根定律的凝固系数。 相似文献
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Effects of continuous casting process parameters on carbon segregation degree of 38CrMoAl steel big round billet 总被引:2,自引:0,他引:2
The effects of continuous casting process parameters (superheat degree, casting speed and F- EMS) on the carbon segregation of round billet with diameter 600mm of 38CrMoAl steel were investigated by industrial experiments and numerical simulations. The results show that the equiaxed crystal rate and solidification structure both affect the carbon segregation. When the superheat is low, shrinkage tends to occur, and the shrinkage is often accompanied by severe segregation. When the superheat is high, the equiaxed grain ratio is lower, carbon segregation is also severer, so the superheat degree is controlled at 30??. With the increasing of casting speed?? it can obviously spur the growth of columnar crystals and formation of central pipe; both columnar crystals and central pipe are the major cause of segregation, so the suitable casting speed is 0. 19m/min. Final electromagnetic stirring has the effect of uniform liquid steel composition and temperature, which increases the density of solidification structure, and reduces the central shrinkage hole, thereby reducing carbon segregation, but the electromagnetic stirring effect is greatly affected by the installation position. Based on comprehensive consideration of the production and quality in practical production, the suitable process parameters are established: the optimal superheat is 30??, casting speed is 0. 28m/min, the combination of electromagnetic stirring is M- EMS+S- EMS+F- EMS, and the corresponding electromagnetic stirring parameters are M- EMS of 101A/2Hz??S- EMS of 200A/8Hz??F- ME of 900A/8Hz. Under the above process conditions, it will be more reasonable for the F- EMS installation position to move 0. 4-0. 5m toward the meniscus. 相似文献
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矩形坯连铸凝固传热的数学模型 总被引:5,自引:0,他引:5
根据连铸矩形坯凝固传热特点,在上海浦东钢铁有限公司1号连铸机二冷系统改造中,动用直接差分法建立了二维非稳态矩形坯凝固传热数学模型,已应用于连铸凝固过程的模拟计算,在分析拉速、浇注温度等在数对钢水凝固过程的影响后,为提高拉速找到了理论依据。 相似文献
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The processes of solidification and heat extraction are important for the continuous casting of steel. In this work, investigations on the influence of support roller contact on solidification in a strand of a slab caster, such as surface temperature and strand shell growth, and on thermal strain and stress in the slab have been carried out. The results show that roller contact has an influence on the solidification of steel and on the thermo‐mechanical behaviour of the strand. 相似文献
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铁素体不锈钢凝固过程中形成的柱状晶会影响钢的成形性,减少甚至避免铸坯柱状晶的形成,促进等轴晶的形成,对铁素体不锈钢来说尤为重要。采用连铸和模铸的试验方法浇铸了铁素体不锈钢430,以分析影响其凝固结构的因素。结果表明,电磁搅拌对430不锈钢连铸坯等轴晶的形成作用显著。无论模铸试验还是连铸试验,冷却强度对430铸坯柱状晶的形成都有明显的影响。在模铸试验条件下,碳、氮含量越高,越有利于其凝固时等轴晶的形成;在连铸试验条件下,由于温度梯度大,碳、氮含量对凝固组织的影响被削弱,但如果对钢液进行搅拌,碳、氮含量的变化对凝固组织仍然有明显的影响。 相似文献
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Wilhelm Schneider 《国际钢铁研究》1983,54(12):487-490
Quasi-steady solidification near origin of strand. Analytical solution of heat diffusion equation in solid subject to boundary conditions at solidification front and at mould. Stability of solutions. Two-phase region (mushy-zone) in alloy casting. 相似文献
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Centreline macrosegregation is often observed in continuous slab casting of steel. Two of the main macrosegregation formation mechanisms are bulging and feeding. Both were studied and compared in the current work by using a two‐phase volume averaging model considering only columnar solidification. The casting of the strand itself is modelled by applying a predefined velocity following the casting speed and solid shell deformation (e.g. bulging). Three different cases are simulated and discussed. (i) The first case considers the influence of the feeding flow during solidification without taking bulging into account. Negative macrosegregation is observed in the centre of the casting in this case. (ii) The second case takes the flow caused by series of bulging along the solidifying strand shell into account, and is, therefore, representative for an ideal situation where bulging takes place without solidification shrinkage. In this case positive centreline segregation is found. (iii) The last case shows the results of a simulation which combines both shrinkage‐ and bulging‐induced flows. It is found that under the current casting conditions the bulging effect dominates over the shrinkage effect, and so positive centreline segregation is predicted. 相似文献