亚包晶钢连铸坯角部横裂纹控制研究  

Control of transverse corner cracks on hypoperitectic steel slabs

作　　者：李树森[1,2] 张立峰[1] 杨小刚[1] 李明[1,2] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]首钢股份公司迁安钢铁公司,河北迁安064404

出　　处：《炼钢》2016年第3期67-72,共6页Steelmaking

基　　金：国家自然科学基金资助项目(51274034;51334002;51404019)

摘　　要：为了提高亚包晶钢连铸坯表面质量,运用低倍显微观察以及模拟等手段对亚包晶钢连铸坯角部横裂纹的形成机理进行了研究,研究结果表明:不同钢种角部横裂纹附近组织不一,碳质量分数为0.15%的钢种裂纹附近组织为均匀的铁素体+珠光体,而碳质量分数为0.093%的钢种的裂纹主要发生在厚度约50μm的沿晶先共析铁素体薄膜上,后者裂纹的发生率约为前者的3倍;碳含量对钢种塑性有根本性影响,从而影响角部横裂纹的发生,工业试验结果表明在碳质量分数低于0.1%范围内,将碳质量分数降低至0.07%,角部横裂纹的发生率可由原来的44%降低至约4%。二冷数值模拟优化结果表明,优化采用的弯曲段前弱冷模式及弯曲段之后内弧强冷模式的冷却方案可保证连铸坯内外弧角部温度均避开第Ⅲ脆性区,优化后裂纹数量及长度大幅度降低,角部横裂纹的发生可得到良好控制。In this article,various means such as microscopic observation and numerical simulation were carried out to study the influence factors and control of transverse corner cracks on hypoperitectic steel slabs for improving the slab surface quality.The results showed that the microstructures near transverse corner cracks changed with the steel carbon content.For example,the microstructures near the cracks were uniform ferrite and pearlite for the steel with carbon mass fraction at about 0.15 %.While the cracks were found at the intergranular ferrite film which thickness was about50μm for the steel carbon mass fraction was 0.093 %.The occurrence fraction for the latter steel was three times of the former one.The carbon content makes an essential influence on the hot ductility of steel.Controlling carbon mass fraction to 0.07% could sharp reduce the cracks occurrence fraction from 44 %to about 4 %in the carbon mass fraction range less than 0.1 %.According to the secondary cooling simulation results,a new secondary cooling scheme of weak cooling intensity before the bending segment and followed by strong cooling intensity at the straightening segments was suggested to ensure the slab corner temperatures avoiding brittle zone Ⅲ both at the bending and straightening segments,and it was proved to be effective in eliminating transverse corner cracks,both the cracks number and length were significantly reduced.

关 键 词：裂纹 先共析铁素体 降低碳含量 二冷优化 

分 类 号：TG777.1[金属学及工艺—刀具与模具]