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基于钢种氧化铁皮结构差异性的酸洗机理研究

Study on the pickling mechanism based on structural differences of oxide scale in steel grades

  • 摘要: 针对热轧带钢酸洗效率与表面质量的协同控制难题,本文选取低碳铝镇静钢、碳锰钢和冷轧高强钢3类典型钢种,系统分析了带钢表面氧化铁皮结构与酸洗行为之间的关联机制。结果表明,低碳铝镇静钢带钢表面氧化铁皮以疏松多裂纹的共析组织(FeO+Fe3O4)为主,酸洗60 s即可高效去除,表面光亮无缺陷;碳锰钢带钢表面氧化铁皮主要由致密的先共析Fe3O4构成,酸洗需180 s,碳锰钢易因氧化铁皮残留导致带钢表面发黑;冷轧高强钢因缓冷工艺析出Fe单质颗粒并伴生15 μm厚晶间氧化层,酸洗时间长达400 s,这是由于Fe颗粒阻碍了酸液渗入,晶间氧化加速了晶界腐蚀,且因Cl-残留易引起带钢表面发黄问题。研究结果明确了氧化铁皮结构差异对酸洗动力学行为的关键影响,为差异化酸洗工艺制定提供了理论依据。

     

    Abstract: To address the synergistic control challenge of pickling efficiency and surface quality of hot rolled strip, this study selects three typical steel grades i.e.low carbon aluminum killed steel, carbon manganese steel, and cold rolled high strength steel,and systematically investigates the correlation between the oxide scale structure on the strip surface and its pickling behavior. The results indicate that the oxide scale on low carbon aluminum killed steel is primarily composed of a loose and cracked eutectoid structure (Fe+Fe3O4), which can be efficiently removed within 60 s, yielding a bright and defectfree surface. In contrast, the oxide scale on carbon manganese steel mainly consists of dense proeutectoid Fe3O4, requiring 180 s for complete pickling, and tends to leave residual scale that causes surface darkening. For cold rolled high strength steel, slow cooling leads to the precipitation of Fe particles and the formation of a 15 μm thickness intergranular oxidation layer, extending the pickling time to 400 s. This is attributed to the Fe particles hindering acid penetration and the intergranular oxidation accelerating grain boundary corrosion, while residual Cl- may induce surface yellowing. The findings clarify the critical influence of oxide scale structural differences on pickling kinetics, providing a theoretical basis for developing differentiated pickling processes.

     

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