连铸坯热酸蚀检验反应机理及过程优化  

Reaction mechanism and process optimization of hot acid etching inspection of continuous casting slab

作　　者：郭坤辉 侯自兵[1,2] 曾子航 郭东伟 彭治强 GUO Kun-hui;HOU Zi-bing;ZENG Zi-hang;GUO Dong-wei;PENG Zhi-qiang(College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学材料科学与工程学院,重庆400044 [2]重庆大学钒钛冶金及新材料重庆市重点实验室,重庆400044

出　　处：《钢铁》2022年第11期87-98,共12页Iron and Steel

基　　金：国家自然科学基金资助项目(52274318)。

摘　　要：热酸蚀法是连铸坯质量检验的一种常用方法,但目前使用效果不稳定,检验过程中容易出现过腐蚀或腐蚀不够的现象,其反应机理也存在争议。以高碳钢为例,探索一种热酸蚀检验反应机理的研究方法,旨在确定热酸蚀检验的具体反应机理,并对热酸蚀检验的过程优化提供理论指导。首先原位分析组织形貌在酸蚀过程中的变化规律,然后对酸蚀前后物相变化和酸蚀过程中不同物相对应的腐蚀行为观察分析,结合对酸蚀过程进行的数值模拟、极化曲线测量及电化学理论,共同分析热酸蚀过程的反应机理,并由此展开过程优化。结果表明,热酸蚀检验机理可以用不同物相间的微电池反应解释,即铸坯中的Fe_(3)C相可以与周围基体发生微电池反应,碳浓度高的偏析区域Fe_(3)C较多,微电池分布密度大,在热酸蚀过程中腐蚀速率较快,铸坯中腐蚀速率的差异导致不同区域腐蚀形貌的不同,最终显示出铸坯的低倍组织及缺陷情况。并根据反应机理得出酸蚀效果随酸蚀时间的增长存在拐点,且所研究钢种最佳反应时间为300 s,同时发现适当提高温度可以增大铸坯中不同区域在酸蚀过程中腐蚀速率的差异,有利于改善酸蚀效果。这对连铸坯质量优化及高品质钢质量稳定性的提升具有重要意义,同时所提出的研究方法对类似检验的过程优化也具有参考价值。The thermal acid etching test method is a common method for the quality inspection of continuous casting slabs,but the current test effect is not stable,and the phenomenon of over-corrosion or insufficient corrosion is prone to occur during the inspection process,and its reaction mechanism is also controversial.Taking high carbon steel as an example,a systematic research method of thermal acid etching inspection mechanism was explored.The purpose is to determine the specific reaction mechanism of thermal acid etching inspection and provide theoretical guidance for process optimization of thermal acid etching inspection.Firstly,the change law of the microstructure and morphology during the acid etching process was analyzed in situ,and then the phase change and the corrosion behavior corresponding to different phase were observed and analyzed,and the acid etching process was numerically simulated,polarization curve was measured and combining the electrochemical theory,the reaction mechanism of the thermal acid etching process was jointly analyzed,and the process optimization was carried out based on this mechanism.The results showed that the thermal acid corrosion test mechanism could be explained by the microbattery reaction between different phases,that is,the Fe_(3)C phase in the slab could react with the surrounding matrix,and the segregation area with high C concentration had more Fe_(3)C,and the distribution density of the microbattery was large,in the process of thermal acid etching,the corrosion rate was faster,and the difference in corrosion rate led to different corrosion morphology in different regions,and the solidification structure and defects of the slab were shown finally.According to the reaction mechanism,it was concluded that the acid etching effect has an inflection point with the increase of acid etching time and the optimum reaction time of the steel studied was 300 s.It is also found that an appropriate increase in temperature can increase the difference in the corrosion rate of different reg

关 键 词：低倍组织 偏析 热酸蚀 微电池腐蚀 连铸 高碳钢 

分 类 号：TF777[冶金工程—钢铁冶金]