Q345B钢直装轧制厚板冷弯裂纹分析  

Analysis of cold bending crack on Q345B direct rolling thick plate

作　　者：康伟[1] 方恩俊[2] 李超[2] 于赋志[1] 张宁[1] 廖相巍[1] 

机构地区：[1]鞍钢股份有限公司技术中心冶金工艺所,辽宁鞍山114009 [2]鞍钢股份有限公司鲅鱼圈分公司炼钢部,辽宁营口115007

出　　处：《炼钢》2014年第3期16-19,23,共5页Steelmaking

摘　　要：某钢厂Q345B钢供厚板轧制铸坯改直装轧制工艺后,轧制后钢板出现冷弯裂纹。通过对热装、直装轧制工艺的钢板金相组织、夹杂物、析出物进行研究,发现直装轧制工艺的钢板内的带状组织、MnS夹杂是冷弯裂纹产生的主要原因。另外直装轧制工艺钢板内析出物较少,不能充分发挥微合金元素的强化作用。带状组织产生的根本原因是连铸坯在凝固过程中碳和其他元素一起产生枝晶偏析,轧制过程中枝晶偏析逐渐转变成中间坯和成品钢板的带状偏析。硫化锰夹杂是在钢液凝固过程产生的,根据化学成分和硫化锰的形貌推断,这种均质呈带状分布的硫化锰夹杂是形成于用铝脱氧但又无其他过多合金元素的镇静钢中。通过控制硫含量、电磁搅拌、钢种成分微调等研究工作,目前直装轧制钢板内的条带状硫化锰夹杂已经减少,铸坯成分偏析也得到相应改善。Cold bending crack appeared on Q345B steel thick plate after using direct rolling process.The metallographic structure,inclusions,precipitates in hot charging rolling and direct charging slab were studied,and the results showed that banded structure and MnS inclusions in thick plates were the mainly reasons which caused cold bending crack in direct charging plates.Precipitates in direct charging plate were less which could not give enough strengthening effect.Carbon and other elements generated dendritic segregation during solidification process,and then dendritic segregation transformed into banded structure during rolling process.MnS inclusions were generated during solidification process,which formed in Al-killed steel without other deoxidation elements according to the appearance and chemical composition of inclusions.The banded MnS inclusions have been reduced,and segregation has also been improved accordingly throught sulfur content controlling,electromagnetic stirring application and chemical composition adjustment.

关 键 词：直装轧制 冷弯裂纹 金相组织 夹杂物 

分 类 号：TF704.7[冶金工程—钢铁冶金]