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基于热-黏弹塑性本构方程建立了大钢锭凝固时热-流-力耦合的3D有限元模型,并对8.5t钢锭浇注过程中不同位置处热流密度、气隙宽度和界面换热系数的变化规律进行了模拟分析。结果表明,钢水与钢锭模刚刚接触时的热流密度和换热系数最大,二者随后迅速下降,且角部区域的下降趋势略大于面部。凝固初期时热流密度和换热系数的最大值位置并非位于面部中心,而是在1/4宽度处;由于宽面对钢水静压力的抵抗作用小于窄面,其界面热流密度和换热系数也略大于窄面。凝固中后期时,换热系数的区域差异逐渐趋于不明显。同时,建立了基于凝固时间和界面温度的平均换热系数的反算模型。应用2个模型所求结果计算的钢锭和钢锭模温度变化与实测值及热-流-力耦合模型结果基本一致。进一步研究发现,界面换热系数随温度的变化规律可推广应用到3~30t钢锭的模拟研究中,计算结果与实际更为符合。
Based on the thermo - viscoelastic - plastic constitutive equation, a 3D finite element model of the thermo - hydro - mechanical coupling during the solidification of a large ingot was established. The heat flux, air gap width and interfacial heat transfer coefficient The change rule carries on the simulation analysis. The results show that the heat flux density and heat transfer coefficient of the molten steel and the steel ingot mold are the maximum when they are in contact with each other. Both of them then drop rapidly, and the downward trend in the corner area is slightly larger than that of the face. At the initial stage of solidification, the maximum value of heat flux and heat transfer coefficient is not located at the center of the face, but at ¼ width. Because the resistance of wide face to molten steel is smaller than that of narrow face, the heat flux and heat transfer coefficient Slightly larger than narrow. In the middle and late stage of solidification, the regional differences of heat transfer coefficient tended to be insignificant. At the same time, an inverse model of the average heat transfer coefficient based on the setting time and interface temperature was established. The temperature changes of ingot and ingot mold calculated by the results of two models are basically consistent with the measured value and the thermo-hydro-mechanical coupling model. Further study found that the law of interface heat transfer coefficient with temperature can be extended to 3 ~ 30t steel ingot simulation study, the calculated results more in line with the actual.