低合金热轧钢带冷弯开裂的分析与改进  

Analysis and Improvement of Cold Bending Cracking of Low Alloy Hot Rolled Steel Strip

作　　者：孙乾 Sun Qian(Technical Center of Laiwu Iron and Steel Group Yinshan Section Steel Co.,Ltd.,Jinan Shandong 271104)

机构地区：[1]莱芜钢铁集团银山型钢有限公司技术中心,山东济南271104

出　　处：《山西冶金》2023年第4期38-41,共4页Shanxi Metallurgy

摘　　要：针对低合金热轧钢带弯折后导角开裂的实际问题,经合理取样,采用金相显微镜微观组织观察、扫描电镜分析、力学性能检验等方法对试样进行综合分析,探讨低合金热轧钢带弯折开裂的可能原因。结果表明:钢带为11.75 mm,规格较厚,基体组织为珠光体和铁素体,晶粒细小均匀,强度偏高,经剪切后,边缘存在细小毛刺,弯曲时折弯半径过小,易形成应力集中导致折裂,外层金属变形程度超过变形极限是弯折开裂的主要原因;厚规格钢带表面存在氧化铁皮,表面质量较差;心部位置存在一定珠光体偏析,加剧了开裂可能。实际生产中,合理控制材料强度及铸坯偏析;弯折加工时,做好钢带表面及切边精度处理,降低应力集中可能;选择恰当的工艺方案及合理的圆角半径,使折弯过程中钢材流动阻力减小。通过采取以上措施,可有效避免低合金热轧钢带在弯折制管过程中出现的导角开裂问题。In view of the actual problem of leading angle cracking of low alloy hot rolled steel strip after bending,after reasonable sampling,the samples were comprehensively analyzed by means of metallographic microscope microstructure observation,scanning electron microscope analysis and mechanical property inspection,and the possible causes of bending cracking of low alloy hot rolled steel strip were discussed.The results show that the steel strip is 11.75 mm thick,the matrix structure is pearlite and ferrite,the grain is fine and uniform,the strength is high,after shearing,there are fine burrs on the edge,the bending radius is too small when bending,which is easy to form stress concentration and lead to fracture,the deformation degree of the outer metal exceeds the deformation limit is the main reason for the fracture,at the same time,there is iron oxide scale on the surface of thick steel strip,and the surface quality is poor.And there is pearlite segregation in the center,which aggravates the possibility of cracking.The material strength and billet segregation should be controlled reasonably in actual production.During the bending process,the surface and trimming accuracy of the steel strip shall be well treated to reduce the possibility of stress concentration.The appropriate process scheme and reasonable fillet radius shall be selected to reduce the flow resistance of steel during the bending process,which can effectively avoid the leading angle cracking of low alloy hot rolled steel strip during the bending process.

关 键 词：低合金 热轧钢带 弯折 导角开裂 偏析 

分 类 号：TG142.1[一般工业技术—材料科学与工程]