Q345E卷轧薄板低温冲击性能不合原因分析与对策

通过对安钢3500mm炉卷轧机Q345E卷轧薄板低温冲击韧性的影响因素分析，指出主要影响因素为锰含量较高、二阶段累积压下量低和终轧温度偏高，这三者综合作用导致钢板晶粒粗大，板厚心部MnS夹杂物以及贝氏体增多。通过采用降低锰含量、降低初始卷轧温度并保证二阶段累积压下率在50％以上、降低终轧温度等措施，提高了Q345E卷轧薄板低温冲击韧性，冲击性能合格率达到98％以上。

CO AND CAUSE ANALYSIS OF UNQUALIFIED LOW TEMPERATURE IMPACT TOUGHNESS OF

In this study influence factors of low temperature impact toughness of the Q345E coil rolled sheet was analyzed, the result has shown that the main factors were the higher Mn content, two - stage cmnulative reduction and higher finish rolling temperature, these three combined effects lead to the coarse grain, MnS inclusions in the core section of thickness and the increased of bainite. Through lowering Mn content, reducing the initial coiling rolling temperature and keeping cumulative reduction ratio of the two stages above 50% , as well as lowering final rolling temperature and other measures, the lower tempera- ture impact toughness of Q345E coil roiled thin sheet is improved, the certified rate is greatly increased up to 98%