运用凝固传热模型，计算出了连铸坯在不同凝固阶段的冷却速率，对经典的BF微观偏析模型进行了修正，并以此为基础建立了由化学成分的不均匀性导致的Mn-Cr系齿轮钢淬透性带宽预测模型，分析了不同二次冷却强度对淬透性带宽的影响。由淬透性带宽预测模型得知，20CrMnTi连铸坯试样淬透性带宽呈抛物线状分布，淬透性带宽曲线在端淬距离0～15 mm范围内呈上升趋势，距离端淬距离超过15 mm时呈下降趋势，距离端淬约15 mm处试样的淬透性带宽取得最大值；适当提高二冷区冷却强度可以缩小连铸坯试样的最大淬透性带宽。
The heat transfer model of the solidification process of billet in CCM was used to calculate the cooling rates in different stages of solidification,the classical BF micro-segregation model was modified,based on which a predic-tion model of hardenability bandwidth induced by the inhomogeneity of chemical compositions for Mn-Cr gear steel was established. The effect of secondary cooling intensity on the distribution of hardenability bandwidth of 20CrMnTi steel was also investigated. The calculated results shows that the hardenability bandwidth of 20CrMNTi continuous casting bil-let along jominy distance was parabolic. The hardenability bandwidth-Jominy distance curve firstly appeared up-trend within 15 mm and then down-trend,and the hardenability bandwidth reached maximal value at the point of Jominy dis-tance of 15 mm. It indicated that Appropriate improvement of secondary cooling intensity can narrow the biggest harden-ability bandwidth of casting billets.
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