【作者】 王峰；

【导师】 袁武华；

【作者基本信息】 湖南大学 ， 材料加工工程， 2009， 硕士

【摘要】 钢铁腐蚀与防护是一个困扰钢铁工业的难题。全世界每年因腐蚀而报废的钢铁材料和设备的量约为金属年产量的1/4~1/3。热轧盘条轧制成形以后,在放置过程中,表面往往会产生不同程度的锈蚀,这造成了材料的损耗,也大大降低了盘条的产品质量。其在轧制过程中以及在之后的空冷过程中,表面会自然形成一层薄的氧化铁皮。这层氧化皮在后续深加工中,需要极力去除。但是,这层氧化皮在热轧盘条的保存,转运过程中能起到极好防护作用。因此研究这层氧化皮的成分,致密性,以及防腐性能对于指导工业生产有着重要的意义。本文首先采用红外光谱检测盘条氧化皮的物相组成,扫描电镜观察氧化皮的组织形貌和结构,电化学方法及加速腐蚀实验测量热轧盘条的耐腐蚀性能。通过对比几种不同表面质量的盘条氧化皮,总结了热轧盘条的氧化皮的不同厚度、致密性、以及与基体的结合性对盘条耐腐蚀性能影响的规律,得出了盘条易锈蚀的原因。结果表明:在存放条件,外界环境气氛以及盘条成分材料基本一致的情况下,表面质量就成为了影响盘条锈蚀的关键因素。表面质量好即氧化层完好,厚度均匀,致密性高,基体与氧化层的结合紧密都能提高热轧盘条防腐性。其次,因为控冷工艺是影响热轧盘条氧化皮表面质量的主要因素,本文采用GLEEBLE1500型热模拟试验机研究了热轧盘条生产过程中的加热温度、保温时间、吐丝温度、冷却速度等控冷工艺参数对氧化皮耐蚀性影响。实验中,以不同的吐丝温度,不同的冷却速度冷却到500℃后空冷。吐丝温度分别选取910℃、880℃、850℃,冷却速度分别选取0.5℃/S、1℃/S、2℃/S、3℃/S。并通过X射线衍射检测氧化皮的物相组成,扫描电镜观察氧化皮的表面形貌、厚度、致密度,加速失重腐蚀实验检测氧化皮的耐蚀性。实验结果表明:吐丝温度为850℃、冷却速度为2℃/S的冷却工艺能得到较理想的厚度适中,致密度高,与基体结合紧密的氧化皮。吐丝温度为910℃和880℃会导致氧化皮增厚并产生裂纹,冷却速度0.5℃/S、1℃/S也会导致氧化皮增厚,冷却速度为3℃/S则导致氧化皮薄,起不到保护作用。在上述试验研究基础上又对热轧盘条实际生产控冷工艺进行了改进。结果表明,现场控冷工艺参数优化后,精轧温度为880℃、吐丝温度为860℃的盘条氧化层表面形貌质量得到改善:厚度适中、氧化层与基体的结合较好、无明显裂纹、且氧化层致密,耐锈蚀性能明显提高。更多还原

【Abstract】 It is well know that the steel corrosion and protection is a big problem puzzling iron and steel industry. Every year, the metal yearly output of approximately a quarter to a third have been discarded by corrosion. Due to the surface corrosion of steel wire rolled and deposited in the air, the quality of steel wire will be decreased, meanwhile, the waste of material will be resulted. In the process of rolling machining and exposure to air, the hot-rolled wire will inevitably be formed a thin oxide scales on the surface. In the following machining of the hot-rolled wire, it’s necessary to remove the oxide scale. However, the oxide scale can be used against kinds of corrosion in the saving and transferring process before the next working procedure. Thus, it is significant for industrial manufacturin to research the oxide scale of composition, compacting and antisepsis capability.In this paper, the material component and morphology of oxide scale were respectively investigated by using the infrared absorption spectroscopy and SEM. Additionally, the anti-corrosive performance of steel scale on wire rod was also be researched by using the electrochemical potentiodynamic polarization curves and accelerated corrosion test. Comparing the oxide scale with different surface quality, a rule of anti-corrosive performance of steel scale was summarized by researching the influence of scale thickness, tightness and combines of substrate and steel scale on the anti-corrosive performance of steel scale. The results indicate that the surface quality of oxide scale can play an important role in effecting the anti-corrosive performance in the condition of constant air condition, deposited environment and material component. The high surface quality of oxide scale, including the thickness, well tightness and binding force between substrate and steel scale, can enhance the anti-corrosive performance of steel scale on wire rod.Due to the cooling process is an important effect on the surface quality of steel scale on wire rod, the influence of parameters in the process of producing the hot-rolled wire rod on corrosion resistance of iron oxide scale, such as the heating temperature, cooling rate and the cooling temperature was investigated by using the thermal simulator of GLEEBLE1500. The different cooling temperature of 910℃, 880℃and 850℃and cooling rate of 0.5℃/S,1℃/S,2℃/S and 3℃/S was respectively adopted in our experiments. Moreover, the scale composition was primarily analyzed through XRD. The scale surface feature, thickness and tightness were observed through SEM. The anti-corrosive performance of steel scale was investigated by accelerated corrosion test. The results indicate that when the temperature and cooling rate in the cooling process is 850℃and 2℃/S, the oxide scale with optimal thickness, tightness and binding force between substrate and steel scale can be obtained. The cooling temperature of 910℃and 880℃can increase the thickness of oxide scale and make the oxide scale crack. Moreover, the thickness of oxide scale also can be increased in the cooling rate of 0.5℃/S and 1℃/S. when the cooling rate is 3℃/S, the thickness of oxide scale will be decreased and lose the performance of corrosion resistance.Based on the above research, the practical production of steel wire rod was also be ameliorated. The results indicate that the surface quality of oxide scale including optimal thickness, tightness, the anti-corrosive performance, less crack, and binding force between substrate and steel scale, can be improved in the optimal process of rolling temperature at 880℃and cooling temperature at 860℃.更多还原