AH32船板内部裂纹成因分析

Analysis of inner cracks of AH32 steel continuous casting slab

以鞍钢股份有限公司AH32船板钢为研究对象,利用Thermo-Calc热力学软件对钢中MnS的析出行为进行了模拟计算;研究了平衡状态下元素含量的变化对MnS析出规律的影响以及AH32船板钢凝固过程特点;利用Quanta-400型扫描电镜对AH32船板内部裂纹进行了微观观察及能谱分析,最终认为共晶反应形成的片状MnS析出物为裂纹产生的主要原因。生产中采取了降低硫含量、二冷弱冷、低拉速、优化电磁搅拌工艺及钙处理等多项措施,取得了明显效果。

Taking ship steel plate AH32 as the object of study the precipitation behaviour of MnS in the steel is analog computed with thermodynamics software TheroCalc and in the meanwhile the effects of change of element content on the law of MnS precipitation as well as characteristics of solidification process of ship steel plate AH32 are studied and micro observation and energy spectrum analysis on the inner cracks of the steel plate are conducted using SEM Quanta-400. It’s concluded that the primary cause to the inner crack is schistose MnS precipitant arising from eutectic reaction. A series of counter measures such as reduction of sulfur content, low drawing speed and weak cooling in the secondary cooling zone, optimization of electromagnetic stirring process and calcium treatment have been implemented and very sound results have been achieved.