780CF钢表面裂纹形成原因分析  

Analysis on the Cause and Mechanism of Surface Crack Formation of 780CF Steel

作　　者：刘宏春 李杰 付冬阳 毛文文 高宇 郭恒斌 LIU Hongchun;LI Jie;FU Dongyang;MAO Wenwen;GAO Yu;GUO Hengbin(HBIS Materials Technology Research Institute,Shijiazhuang 052100,China;HBIS Group Wusteel Company,Pingdingshan 462500,China)

机构地区：[1]河北河钢材料技术研究院有限公司,河北石家庄052100 [2]河钢集团舞钢公司,河南平顶山462500

出　　处：《工业加热》2025年第1期68-71,78,共5页Industrial Heating

摘　　要：通过裂纹样品的光学显微组织观察,电子探针的方法,对780CF中厚板表面裂纹成因进行了分析研究。光学显微组织观察显示,钢板表层约303μm厚度存在粗大的铁素体、贝氏体等异常组织,裂纹多产生在异常组织区域内或与基体组织边的界处;电子探针分析表明,裂纹两侧C元素分布均匀,钢板表层无明显脱碳特征,裂纹间隙存在轧制过程中压入的氧化铁,铸坯扒皮未发现明显裂纹,基本可以排除铸坯原始裂纹原因造成;同时在裂纹周边未检测到Cu元素的富集,钢中添加一定量的Cu元素并不是此种裂纹产生的直接原因;钢的表层出现了混晶组织,在粗轧阶段未能消除,轧制过程中粗晶区先于细晶区变形,不协调的形变导致了表面裂纹的产生,在随着加工变形比的增大及钢板的热连轧,裂纹不同程度的扯开或者黏合,从而逐渐演变成从外向内扩展的表面裂纹。热送热装过程中,控制好粗终轧温度是有效控制此种裂纹产生的关键。The cause of surface cracking in the 780CF plate was investigated through optical microstructure observation and electron probe anal-ysis.The optical microstructure observation revealed the presence of coarse ferrite,bainite,and other abnormal structures on the surface of the steel plate with a thickness of approximately 303μm,Cracks were predominantly observed in areas with abnormal tissue or at boundaries with the matrix.Electron probe analysis indicated that there was a uniform distribution of carbon C element on both sides of the crack,without any significant decarburization features on the steel plate's surface.Iron oxide was found within the crack gap,while no obvious cracks were detec-ted in the billet skin.Additionally,no enrichment of copper Cu element was detected around the crack,suggesting that adding a certain a-mount of Cu to the steel did not directly cause these cracks.A mixed crystal structure appeared on the steel's surface during rough rolling stage and could not be eliminated.During rolling process,deformation occurred first in coarse crystal zones before fine crystal zones leading to unco-ordinated deformation and subsequent formation of surface cracks.With increased processing deformation ratio and hot continuous rolling of the steel plate,these cracks gradually expanded from outside to inside as they either pulled apart or bonded to different degrees.In order to effec-tively control such cracks during hot feeding and charging processes,it is crucial to regulate temperature during final rough rolling stage.

关 键 词：混晶 形变 表面裂纹 

分 类 号：TG142.2[一般工业技术—材料科学与工程]