莱钢200mm厚Q235B特厚钢板的试制开发

Development of 200 mm Ultra-thick Plate Q235B in Laiwu Steel

利用300 mm厚连铸坯,采用TMCP工艺,通过合理分配轧制道次来保证单道次压下率和累计压下率,解决了压缩比低等问题,成功开发出200 mm厚Q235B特厚板。钢板厚度公差控制在±1.2 mm以内,板形良好,钢板1/4厚度0℃冲击功为86-91 J,1/2厚度0℃冲击功为55~77 J,厚度方向断面收缩率为27.0%-31.0%。钢板低温冲击韧性较差的主要原因是钢板组织中枝状晶破碎不彻底,在近表面形成了部分粗大魏氏体组织。

Using 300 mm thickness continuous casting slab, adopting TMCP process, ensuring single pass reduction ratio and cumulative reduction ratio by reasonable distribution of rolling passes, the problems of low compression ratio were solved and the Q235B ultra-thick plates with 200 mm thickness were developed. The thickness tolerance was controlled within ± 1.2 mm. The plate shape is better. The impact absorbed energy of the plate in 1/4 thickness and 1/2 thickness at 0 ℃ are 86-91 J and 55-77 J respectively. The area reduction in thickness direction is 27.0%-31.0%. Poor low-temperature impact toughness was caused by the dendritic crystal that was not completely broken and the part of the coarse Widmannstaetten structure was formed in the near surface.