连铸坯轧制厚钢板极限规格缺陷分析与改进

Defect Analysis and Improvement of Continuous Casting Slab for Limit Thickness Steel Plate

针对连铸坯轧制特厚板超声波探伤不合格的问题,对连铸坯及钢板取样进行热酸浸低倍组织检验,并对钢板样进行金相分析。结果表明,连铸坯本身有较严重的中心疏松和中心偏析,钢板有疏松残留,偏析严重处伴生微裂纹。通过提高钢液纯净度,投用连铸电磁搅拌(S-EMS),优化轻压下工艺,增加单道次压下量等措施,保证了特厚板质量,探伤合格率达到98.97%。

Pointing at UT failure problem of ultra-thick steel plate rolling by continuous casting slab, the slab and the plate were sampled for macro-etch testing and the plate simples were made metallographic analysis. The results showed that the continuous casting billet itself had more severe central porosity and center segregation; The porosity was remained in the plate after rolling;Micro-crack was found around the position where severe segregation exists. Measurements were applied such as improvement of steel cleanness, application of S-EMS, optimization of soft reduction process, and increase of reduction amount of rolling pass, that guarantee the quality of ultra-thick plate. The UT pass rate reached 98.97% after improvement.