热轧带钢“唇印结疤”缺陷形成机理分析

Formation mechanism of "lip print scarring" defects in hot rolled strip

在热轧产品中,某些厚板品种中部上表面出现横向裂纹缺陷,形状像嘴唇,即所谓"唇印结疤"。通过金相组织分析,裂纹分界处两边的组织晶粒大小存在较大差异,根据金属学和钢的热塑性变形原理,调查分析现场生产的实际情况和试验数据,发现唇印结疤的产生与中间坯轧制过程中冷却不均有关。

In the hot roiled products the lip shaped transverse cracks, the so called ＂Lip print scarring ＂ defects occur on the upper surface of the central section of certain hot roiled plates. By metallographical analysis on the structures it＇s found that great difference of grain sizes of the microstructures exists on the two sides of the grain boundary of the cracks. Upon completion of investigation of the on-site production conditions and test data analysis according to hot plasticity deformation principle and metallography it＇s determined that the ＂lip print scarring＂ is closely related to the uneven cooling in the seml-finished product rolling process.