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ABSTRACTIn this paper, an electromagnetic torque device based on the theoretical model was established to determine the optimum frequency accurately and conveniently in billet and bloom continuous casting with in-mould electromagnetic stirring (M-EMS). Magnetic characteristics with M-EMS was investigated by numerical simulation and physical experiment with the application of electromagnetic torque device and gauss meter. In addition, the effects of stirring frequency with M-EMS on macro segregation and equiaxed crystal ratio were compared and analysed for 55SiCr with 150?mm?×?150?mm billet caster and BU with 310?×?360?mm bloom caster by a series of plant trials, respectively. The results showed that maximum magnetic flux density and maximum electromagnetic torque occurred with different frequency and same current in M-EMS, and central equiaxed crystal ratio and macro segregation has been significantly improved by optimum frequency with M-EMS. 相似文献
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The solidification structure of a continuous casting large round billet was analyzed by a cellular-automaton-finite-element coupling model using the ProCAST software.The actual and simulated solidification structures were compared under mold electromagnetic stirring (MEMS)conditions (current of 300 A and frequency of 3 Hz).There-after,the solidification structures of the large round billet were investigated under different superheats,casting speeds,and secondary cooling intensities.Finally,the effect of the MEMS current on the solidification structures was obtained under fixed superheat,casting speed,secondary cooling intensity,and MEMS frequency.The model accurately simulated the actual solidification structures of any steel,regardless of its size and the parameters used in the continuous casting process.The ratio of the central equiaxed grain zone was found to increase with decreasing su-perheat,increasing casting speed,decreasing secondary cooling intensity,and increasing MEMS current.The grain size obviously decreased with decreasing superheat and increasing MEMS current but was less sensitive to the casting speed and secondary cooling intensity. 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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通过对取向硅钢铸坯的低倍检验,研究了中间包钢水过热度、电磁搅拌电流、二冷水强度、拉速及断面尺寸对铸坯中心等轴晶率的影响。结果表明,试验条件下,中间包钢水过热度控制在14~18 ℃范围内时,因过热度不同引起的中心等轴晶率的变化较小,变化范围仅为0%~3%;电磁搅拌电流和铸坯断面尺寸对中心等轴晶率的影响较为明显,随搅拌电流的增大,中心等轴晶率呈增加的趋势,而当铸坯断面尺寸增加时其呈减小的趋势;二冷水强度和拉速对中心等轴晶率的影响相对较小,随着二冷水强度的增大,中心等轴晶率呈减小的趋势,而当拉速提高时其呈增加的趋势。 相似文献
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Based on Eulerian–Eulerian method, a 3D/2D multiphase solidification model, which takes into consideration the heat transfer and fluid flow with grains nucleation and crystal growth, is developed to predict the macrostructure evolution and macrosegregation in continuously cast round bloom. The results show that the mold electromagnetic stirring (M-EMS) can accelerate superheat dissipation and promote grain nucleation, but the horizontal swirl induced by M-EMS has a strong washing effect on the solidification front and leads to subsurface negative segregation. When the M-EMS current intensity increases from 200 to 300 A, the subsurface negative segregation ratio decreases from 0.935 to 0.875. The final electromagnetic stirring (F-EMS) not only improves the center segregation, but also leads to the formation of negative segregation zone near the round bloom center due to the enhancement of solute washing induced by F-EMS. As the F-EMS current intensity increases from 150 to 300 A, the center segregation ratio decreases from 1.148 to 1.075, and the negative segregation ratio near the strand center decreases from 0.985 to 0.977. Another phenomenon is found that the nucleation of equiaxed grain ahead of columnar tips restrains the solute diffusion and leads to a local macrosegregation in columnar-to-equiaxed transition zone. 相似文献
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试验研究了结晶器电磁搅拌频率、拉速、过热度及二冷强度对SWRH82B连铸小方坯中心碳偏析的影响。研究结果表明,结晶器搅拌电流为300 A时,低电磁搅拌频率下铸坯中心碳偏析情况较好;拉速为1.8 m/min时,提高二冷比水量有利于改善中心碳偏析,但二冷比水量过高会加剧偏析;拉速为1.8 m/min时,二冷比水量为0.75 L/kg较为合适,拉速为1.9 m/min时,二冷比水量为0.8 L/kg是比较合适的;当过热度在20~30℃时,过热度对铸坯中心碳偏析的影响不大。 相似文献
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针对P110级石油管用圆坯27Mn2Cr钢连铸坯凝固组织差、中心缩孔严重等缺陷,结合实际生产工艺进行分析,发现不适宜的电磁搅拌工艺及与拉速匹配性差是引起上述问题的主要原因。因此,对结晶器和末端电搅强度进行测量及优化,同时建立?220 mm规格圆坯凝固传热模型,以确定合理的连铸机拉速。通过分析表明,拉速由1.30 m/min提高至1.70 m/min并搭配合理的电搅工艺,铸坯中心等轴晶所占比例由16%提高至25%,中心缩孔消失;同时铸坯内部碳偏析指数范围由0.938~1.062缩小至0.951~1.038,改善了石油套管用圆坯的内部质量。 相似文献
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通过对板坯逐层刨钢屑,采用化学分析和低倍组织检验的方法,研究了板坯连铸机二冷区电磁搅拌频率参数对1450mm×230mm板坯中心偏析和等轴晶率的影响.结果表明:单独采用二冷区电磁搅拌相比不采用电磁搅拌工艺的板坯中心偏析程度明显减轻,C、P、Mn的中心正偏析系数低于无电磁搅拌工艺的板坯;电磁搅拌频率为2Hz,5Hz和8Hz时板坯中心偏析都为B0.5级;电磁搅拌频率对中心等轴晶率略有影响,搅拌频率5Hz的情况下等轴晶率最大. 相似文献
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针对P110级石油管用圆坯27Mn2Cr钢连铸坯凝固组织差、中心缩孔严重等缺陷,结合实际生产工艺进行分析,发现不适宜的电磁搅拌工艺及与拉速匹配性差是引起上述问题的主要原因。因此,对结晶器和末端电搅强度进行测量及优化,同时建立?220 mm规格圆坯凝固传热模型,以确定合理的连铸机拉速。通过分析表明,拉速由1.30 m/min提高至1.70 m/min并搭配合理的电搅工艺,铸坯中心等轴晶所占比例由16%提高至25%,中心缩孔消失;同时铸坯内部碳偏析指数范围由0.938~1.062缩小至0.951~1.038,改善了石油套管用圆坯的内部质量。 相似文献
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Solidification structure of wheel steel round billet during the continuous casting process was simulated using FE (Finite Element)–CA (Cellular Automaton) coupling model. Variation of thermo‐physical parameters during solidification was considered based on a thermodynamic database. Meanwhile effect of electromagnetic stirring (EMS) was reflected by increasing both the thermal conductivity and crystal formation rate in liquid phase. It was found that the cooling curves and solidification structure calculated by this model agreed well with that in experiments. Optimum casting temperature range was discussed based on the simulation results and actual conditions in plant. An optimized casting superheat will be no more than 25 °C in order to obtain at least 50% equiaxed crystal ratio, while the degree of segregation in the billet is less than 1.05 correspondingly. 相似文献
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在多元合金CAFE模型的基础上,分析了微观组织参数(形核密度、高斯分解参数、Gibbs-Thomson系数等)与430不锈钢凝固过程中晶粒形貌的复杂关系,以及过热度与冷却强度等工艺参数对凝固组织的影响.研究发现,晶粒尺寸和柱状晶向等轴晶转变不仅与体最大形核过冷度有关,也受体形核密度的影响.高斯分解参数和Gibbs-Thomson系数增大时,一次枝晶间距减小,等轴晶范围增大;但当它们增加至一定范围后,其对显微结构的影响逐渐变得不明显.过热度或冷却强度增大时,等轴晶范围减小,但一次枝晶间距的变化不明显. 相似文献
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试验研究了结晶器电磁搅拌240 A/4 Hz时末端电磁搅拌(160 A/4 Hz~280 A/8 Hz),中间包钢水温度(1 500~1 542℃),拉速(1.7~1.9 m/min)和二冷区比水量(0.7~1.1 L/kg)对82B钢(/%:0.81C、0.76Mn、0.25Si、0.2Cr)150 mm×150 mm方坯中心碳偏析的影响。结果表明,在未采用末端电磁搅拌时,降低过热度和拉速、提高比水量有利于减少小方坯中心碳偏析。采用最佳的末端电磁搅拌参数160 A/6 Hz时,82B钢小方坯中心碳偏析指数最低,为1.02。 相似文献
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为改善20CrMnTi钢小方坯凝固组织,基于ProCAST软件中的CAFE模型,对其凝固组织进行数值模拟,研究了不同钢水过热度、铸坯拉速、二冷比水量对凝固组织的影响。模拟结果表明,降低钢水过热度、提高铸坯拉速、降低二冷比水量均可达到增大铸坯等轴晶率和细化晶粒的目的,其中过热度对其影响最大。过热度每降低10℃,等轴晶率平均增加3.7%;拉速每增加0.1 m/min,铸坯等轴晶率平均增加1.8%;比水量每降低0.1 L/kg,铸坯等轴晶率平均增加1.65%。生产应用表明,钢水过热度30℃时,当拉速由原2.2 m/min降低至2.1 m/min,二冷比水量由0.6 L/kg提高至0.7 L/kg,铸坯中心疏松明显减少。 相似文献
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ABSTRACTAn experimental apparatus for simulation of continuous casting process of GCr15 bearing steel billet is established. With the apparatus, the billets of diameter 140?mm are casted in various superheats and cooling conditions. The solidification macrostructure, dendrite morphology, segregation and carbide are investigated. It is shown that melting superheats and cooling conditions remarkably influence the microstructure and solute segregation. It is found that the secondary dendrite arm spacing of the steel increases with the increase of the superheat temperature, and with decrease of the cooling rate. Lower superheat with higher cooling rate promotes the refining of the microstructure. Refining equiaxed grains structure in the centre of the billet leads to lower segregation of carbon. Furthermore, with increasing cooling rates, the spacing of the pearlite laminar is refined and the precipitation of proeutectic carbides is suppressed. 相似文献