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首钢现行工艺下IF钢热卷铁皮厚度达到10μm以上,边部铁皮略薄,中部铁皮较厚,随着卷取温度的升高,铁皮厚度增加且对应酸洗时间延长;不同卷取温度下的热卷酸洗后均发现小麻坑缺陷。本文利用差热分析手段研究了IF钢的高温氧化机理,发现IF钢抗氧化性低,随温度升高铁皮增厚明显,精轧区间以FeO铁皮结构为主,在1 150℃左右发生明显的内氧化,界面形成大颗粒氧化质点。综合分析得出:IF钢带钢连退后麻点缺陷产生的主要机理为热卷的铁皮较厚,热轧过程压入钢板表面所致。为此,提出了控制措施,即降低热轧过程温度,改变层冷模式,加大精轧用水量,提高精轧轧制速度,降低冷轧酸洗速度等,有效减少了麻点缺陷的发生概率。
In the current process of Shougang, the thickness of IF steel hot rolled coil is more than 10μm, the thickness of the side metal is slightly thinner and the thickness of the middle metal is thicker. With the increase of coiling temperature, the thickness of metal surface increases and the pickling time prolongs. After the hot-rolled pickling were found small defects. In this paper, the mechanism of high temperature oxidation of IF steel was studied by means of differential thermal analysis. It was found that the IF steel has low oxidation resistance and thickening of the iron skin with increasing temperature. The FeO metal structure is the main part of the finish rolling. Internal oxidation, the formation of large particle interface oxide particles. The results show that the main mechanism of the pitting defects after the continuous and reverse rolling of IF steel strip is that the hot metal is thick and the hot rolling process is caused by pressing the steel plate surface. Therefore, the control measures are put forward, which are to reduce the hot rolling process temperature, change the cooling mode, increase the water consumption of finishing rolling, increase the rolling speed of finish rolling and reduce the pickling speed of cold rolling, so as to effectively reduce the occurrence of pitting defects Probability.