16MnDR特厚钢板典型缺陷的形成原因分析

为了研究与探讨钢板典型缺陷的形成机理,并为钢板质量的稳定控制提供理论参考,采用金相显微镜与扫描电镜等仪器研究了特厚钢板表面裂纹、中心探伤不合格以及冲击性能不合格等典型缺陷的形成原因。结果表明,钢板表面裂纹的产生原因有两个,一是钢中有害元素偏高引起的热脆,二是夹杂物多造成的连铸坯裂纹并在轧制过程中扩展;钢板探伤不合格的原因是钢板芯部析出的粗大Nb、Ti、V类碳氮化物,并伴有MgO和Al₂O₃类大型夹杂物;钢板冲击性能不合的主要原因是芯部的带状组织和带状组织中含碳上贝氏体/马奥组织以及晶粒粗大和混晶。

Analysis of forming reasons of typical defects in 16MnDR extra-thick steel plate

In order to study and discuss the formation mechanism of typical defects of steel plate and provide theoretical reference for the stability control of steel plate quality, the causes of typical defects such as surface crack, unqualified center flaw detection and unqualified impact performance of extra thick steel plate were studied by means of metallographic microscope and scanning electron microscope. The results show that there are two causes for surface cracks of steel plate, one is the hot embrittlement caused by high harmful elements in steel, the other is the continuous casting billet crack caused by high inclusions and spread during rolling. The reason for the unqualified inspection of steel plate is the large Nb, Ti and V carbonitride precipitated from the steel plate core, accompanied by large MgO and Al₂O₃ inclusions. The main reasons for the poor impact performance are the banded structure of the rolled plate, the upper martensite/austenitic structure containing carbon in the banded structure, the coarse grain and mixed grain.