热轧酸洗板表面黑斑缺陷成因及机理研究  

Study on the cause and mechanism of black spot defect on the surface of hot rolled pickled plate

作　　者：黄浩 徐桂丽 黄鹏 祖国胤 HUANG Hao;XU Guili;HUANG Peng;ZU Guoyin(School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学材料科学与工程学院,辽宁沈阳110819

出　　处：《轧钢》2024年第1期32-39,共8页Steel Rolling

基　　金：辽宁省兴辽英才计划项目(XLYC1902097)。

摘　　要：针对国内某钢厂生产的热轧酸洗板表面出现黑斑缺陷而严重影响后续酸洗质量的问题,对黑斑缺陷的形成原因及机理进行了研究。采用场发射扫描电镜和电子探针、X射线衍射仪、维式硬度计对黑斑缺陷的微观形貌、元素分布和相成分进行了分析,并对不同轧制工艺下残留氧化铁皮压入规律进行了研究。结果表明:黑斑缺陷部位与无缺陷部位氧化铁皮都为两层结构,但黑斑缺陷部位氧化铁皮更厚,并在交界处出现了“C”形厚度渐变趋势;黑斑内氧化层处Si元素以Fe_(2)SiO_(4)形式富集,Fe_(2)SiO_(4)对氧化铁皮产生钉扎作用导致除鳞困难,形成氧化铁皮压入缺陷,外侧更厚的Fe_(3)O_(4)层致使压入缺陷表面呈现黑色;在模拟残留氧化铁皮压入的实验中,残留氧化铁皮在粗轧和精轧温度下压入基体都会导致热轧板表面出现黑斑,随着压下率的增大,黑斑与基体结合会更紧密;黑斑缺陷表面微观形貌表现为氧化铁皮压入形式,并且表面硬度与残留氧化铁皮压入形成的黑斑表面硬度接近,都远大于基体硬度。出现黑斑缺陷的根本原因是Fe_(2)SiO_(4)引起的氧化铁皮压入,因此可以通过改进除鳞工艺以及控制Fe_(2)SiO_(4)的形成来降低黑斑缺陷的发生率。Aiming at the problem that the black spot defect on the surface of hot rolled pickled plate produced in a domestic steel mill seriously affects the subsequent pickling quality,the microscopic morphology,element distribution and phase composition of the black spot defect were analyzed by field emission scanning electron microscopy,electron probe,X-ray diffractometer and dimensional hardness tester,and the residual oxide scale pressing-in rule under different rolling processes was studied.The results show that the oxide scales at black spot defect position and no defect position are both two-layer structure,but the oxide scale at black spot defect position are thicker,and there is a"C"shape thickness gradient trend at the junction.Si elements of the oxide layer inside black spot is enriched in the form of Fe_(2)SiO_(4),which has a pinning effect on the oxide scale,resulting in difficulty in descaling and the formation of oxide scale pressing defects,and the outer thicker Fe3O_(4) layer resulting that the defect surface appears black.In the experiments simulating residual oxide scale pressing-in,residual oxide scale pressed into the matrix at both roughing and finishing rolling temperatures will lead to black spot on the surface of the hot rolled plate,and with the increase of the reduction rate,the black spot will be more closely combined with the matrix.The surface microscopic morphology of the black spot defect shows the form of oxide scale pressing-in,and the surface hardness is close to the black spot formed by residual oxide scale pressing-in,both much greater than the matrix hardness.The fundamental reason of the black spot defect is the oxide scale pressing-in caused by Fe_(2)SiO_(4),and the incidence of black spot defect can be reduced by improving the descaling process and controlling the formation of Fe_(2)SiO_(4).

关 键 词：热轧酸洗板 黑斑缺陷 残留氧化铁皮 Fe_(2)SiO_(4) Fe_(3)O_(4) 压下率 

分 类 号：TG335.11[金属学及工艺—金属压力加工]