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高碳钢82A断面180mm×240mm矩形坯轻压下试验中,铸坯心部碳元素产生了负偏析现象。将轻压下工艺与负偏析形成条件相结合,对中心负偏析形成机理进行了探讨。结果表明,轻压下消除了枝晶间富集溶质钢液向铸坯中心流动通道,铸坯中心受枝晶间富集溶质液体流动影响较小;凝固过程中心负偏析产生条件为vx/R<-0.042 2,即液相流动速度vx和凝固速度R方向相反为形成中心负偏析的必要而非充分条件;轻压下易满足该条件并在此基础上提出了2种形成机理,即轻压下挤压作用导致心部钢液流动速度方向的改变或者脱落枝晶在铸坯心部先形核凝固导致凝固速度方向的改变都可能导致中心负偏析的形成。
High-carbon steel 82A section 180mm × 240mm rectangular billet soft reduction test, the casting heart carbon element produced a negative segregation phenomenon. The formation process of negative segregation was combined with the soft reduction process to discuss the formation mechanism of center negative segregation. The results show that the flow path of enriched solute liquid between dendrites to the center of the slab is eliminated under the mild pressure, and the center of the slab is less affected by the flow of enriched solute liquid between the dendrites. The condition of the center negative segregation during the solidification is vx / R <-0.042 2, that is, the liquid phase flow velocity vx and solidification velocity R direction opposite to form a necessary but not sufficient conditions for the center negative segregation; easy to meet this condition under mild pressure and proposed two kinds of formation mechanism on the basis of that light Decreasing the squeezing action leads to the change of the direction of the velocity of the molten steel in the heart or the dendrite degeneration which may lead to the formation of center negative segregation.