高碳钢方坯碳锰元素纵向分布及机理

Characteristics and mechanism of carbon element and manganese element distribution along casting direction in highcarbon billet

为降低高碳钢连铸方坯中偏析元素(碳、锰)沿拉坯方向分布的不均匀性,对70高碳钢(w([C])=0.7%)连铸方坯(170 mm×170 mm)拉坯方向碳、锰元素的分布特征及机理展开研究。在连铸坯中心纵断面的柱状晶区、混晶区与等轴晶区的代表位置,对碳、锰元素分布进行测量。研究结果表明,70高碳钢连铸方坯中心纵断面沿拉坯方向碳、锰元素的分布存在明显波动,且碳元素的波动程度大于锰元素;强冷工艺下,在不同位置碳、锰元素分布变得更为均匀的同时,其质量分数沿拉坯方向的波动程度也有所降低;在柱状晶区、混晶区和等轴晶区,碳元素质量分数沿拉坯方向的波动程度与二次枝晶间距之间均有一致的对应关系,即后者越小,前者也越小。

In order to reduce the unevenness of the segregated elements distribution（C and Mn）along the casting direction,the distribution characteristics and mechanism of C and Mn in continuous-casting 70 high-carbon-steel（w（[C]）=0.7%）billets（170 mm×170 mm）along the casting direction is studied. The distributions of C and Mn are measured at typical positions,which are located in columnar zone,mixed zone and equiaxed zone at both left and right sides of the central vertical section of the continuous-casting billet. Firstly,it is shown that there are significant fluctuations in C and Mn content at the central vertical section of the continuous- casting 70 high- carbon- steel billet along the casting direction,and C has greater fluctuation level than Mn. Moreover,both C and Mn contents not only become more even at different positions,but also fluctuate less obviously along the casting direction after adopting deep-cold process. Finally,in columnar zone,mixed zone and equiaxed zone,fluctuation level of C contents locating along the casting direction is in accordance with their second dendrite arm spacing（SDAS）,namely,the shorter the latter,the smaller the former.