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研究了采用薄板坯连铸连轧生产DC04热轧板卷过程中氧化铁皮的变化规律。以采集连铸坯均热前后铸坯上、下表面及热轧板卷附着的氧化铁皮作为试验材料,利用M21X超大功率X射线衍射仪对氧化铁皮的形貌及氧化铁皮粉末XRD物相进行了分析。其结果表明:铸坯进均热炉前,氧化铁皮较薄为100μm,铸坯经过均热炉加热后,氧化铁皮增厚到200~300μm。与氧化铁皮-基体界面比较,氧化铁皮的气体-氧化铁皮界面具有较多的孔洞,甚至裂缝,结构很疏松;氧化铁皮XRD定性分析表明,铸坯入炉前后、上下表面氧化铁皮均含有Fe3O4、Fe2O3和FeO共3种物相。SEM分析表明,在线热取样和冷取样下,热轧板氧化铁皮与基体之间因体积效应产生的内应力而形成了裂缝,铁皮结构呈现出疏松、多孔特点,有利于带钢表面酸洗。热取样氧化铁皮厚度比冷取样氧化铁皮厚度薄,冷卷尾样铁皮比冷卷头样厚。热取样氧化铁皮厚度与热轧板厚度成正比例关系。卷取温度在600~680℃范围内,热取样氧化铁皮厚度、物相相对含量变化不明显。
The variation regularity of scale in the process of producing DC04 hot rolled coil by thin slab continuous casting and rolling was studied. In order to collect the upper and lower surfaces of slab before and after the billet slab and the hot rolled coil attached to the scale as a test material, the use of M21X ultra-high power X-ray diffractometer of the oxide scale morphology and oxide scale powder XRD phase analysis. The results show that the thickness of the scale is 100μm before the slab enters the soaking bed and the thickness of the scale is increased to 200-300μm after the slab is heated by the soaking furnace. Compared with the oxide scale-matrix interface, the gas-scale interface of the scale has many holes and even cracks, and the structure is very loose. The XRD qualitative analysis of the scale shows that the oxide scales on the upper and lower surfaces contain Fe3O4, Fe2O3 and FeO total of 3 phases. The SEM analysis shows that cracks are formed due to the internal stress generated by the volume effect between the hot rolled sheet and the substrate due to the hot sample and cold sampling. The metallic structure of the hot metal sheet is characterized by porosity and porosity, which is good for pickling on the strip surface. The thickness of the hot-sampled scale is thinner than the cold-sampled scale and the cold-rolled tail is thicker than the cold-rolled tip. The thickness of hot sample scale is proportional to the thickness of hot rolled strip. Coiling temperature in the range of 600 ~ 680 ℃, the thermal sample thickness of the scale, the relative content of the phase change is not obvious.