连铸板坯表面纵裂纹的形成原因及控制

Cause analysis and improvement measures of longitudinal cracks on surface of continuous cast slab

连铸坯表面纵裂形成于结晶器内,由于凝固前沿树枝晶间富集液相导致的枝晶间脆性及结晶器中γ晶粒粗大导致的晶界脆性。在结晶器5种复杂应力的作用下,在结晶器内初生坯壳的薄弱处形成纵裂纹。坯壳出结晶器后,二冷段上部过强的冷却或对弧不良等各种应力都会促进纵裂纹的进一步扩展和延伸。为了防止纵裂纹萌生,首先要控制好结晶器保护渣及结晶器冷却工艺使结晶器传热均匀,防止坯壳凹陷变形;其次尽量降低钢中S、P等杂质元素含量,C含量避开包晶区。

Formation of longitudinal surface cracks of continuous casting slab in mold,due to enrichment by liquid phase between frontier dendrite solidification mold and interlanguage implementable caused by grain boundary implementable caused largeγgrain size in.Under the effect of five kinds of complex stress in mould,born in mold shell forming longitudinal crack at the weak.After the shell mold,upper secondary cooling too much cooling or bad,and other stress of arc will promote the further expansion and extension of longitudinal crack.In order to prevent longitudinal crack initiation,first control and mold cooling process of mold flux mould heat evenly,preventing deformation of shell SAG;secondly minimize the S,P,and other impurities in the steel elements,avoid peritectic C content area.