【作者】 赵亮；

【导师】 张晓明；

【作者基本信息】 东北大学 ， 材料加工工程， 2020， 硕士

【摘要】 近年来,汽车、机械、轻工等行业发展迅速,巨大的市场竞争力使得各企业对生产成本及产品质量的追求日益提高。热轧酸洗板以其低成本、高精度和表面光洁等特点被越来越多的用户所认可。但是,正是由于其较高的表面质量要求,热轧酸洗板的生产相对常规热轧生产要困难。氧化铁皮压入带钢、山水画、过酸洗等缺陷制约着国内热轧酸洗板的高效生产。尤其对于薄规格高强热轧酸洗板的生产,表面麻点缺陷严重影响了酸洗板的使用。目前,国内各钢铁企业对于麻点缺陷的控制并不稳定,尤其对于设备能力不足的老牌热轧生产线,其控制能力更加有限。本文以国内某企业1580 mm热轧生产线薄规格高强热轧酸洗板为研究对象,首先利用高温热重分析仪(TGA)、电子探针显微分析仪(EPMA)等检测设备研究了合金成分Si对实验钢氧化铁皮形成动力学的影响;然后使用C++语言设计并编写了国内某企业热轧生产线轧辊温度场的数值模拟计算程序,模拟计算了精轧机组轧辊冷却参数对辊温的影响;最后将实验与模拟结果应用于现场实践,并结合现场数据采集与跟踪,优化了相关生产工艺参数,较好地降低了国内某企业热轧酸洗板麻点缺陷的发生率。本论文获得的主要研究结果如下:(1)通过对实验钢在950～1050℃的高温氧化增重实验,研究了温度及Si含量对低Si(Si<0.1 wt.%)高强热轧酸洗板氧化铁皮形成动力学的影响规律,并建立了两种实验钢的氧化动力学模型。结果表明,随着实验钢Si含量的提升,慢速氧化阶段和快速氧化阶段的氧化速率常数均降低,且在其基体表面形成了少量的FeO·SiO2,这有助于改善实验钢的抗氧化性;随着氧化温度的升高,实验钢快速、慢速氧化阶段的速率常数均有所增大,且氧化铁皮与实验钢基体的结合能力变差。(2)使用有限差分法,建立了“准三维”轧辊温度场数值计算模型,并结合国内某企业的实际生产情况,着重模拟了水冷边界对轧辊温度变化的影响规律。结果表明,冷却水水压、水温、流量以及切水板积水对轧辊的辊温产生一定的影响,并研究了水冷边界条件的变化对于轧辊辊温的影响规律。(3)通过现场跟踪,研究了轧制生产工艺(排产、烫辊工艺、轧制节奏和轧辊磨削等)对麻点缺陷形成的影响规律。并结合氧化动力学实验和轧辊温度场的模拟结果,优化了现场生产工艺。结果表明,工艺参数调整前后,薄规格高强热轧酸洗板的麻点缺陷发生率由3.0%下降为0.5%,达到了预期的效果。更多还原

【Abstract】 In recent years,automobile,machinery,light industry and other industries develop rapidly,huge market competitiveness makes companies’ pursuit of production costs and product quality increasingly.With the characteristics of low cost,high surface quality,precision and surface smoothness,hot-rolled and pickled sheet has been recognized by an increasing number of users.However,due to the high surface quality requirement,it is more difficult to produce hot-rolled and pickled sheet than to produce common hot-rolled sheet.The high-efficient production of hot-rolled and pickled sheet has been restricted at home by the defects such as the press-in of scales on the surface of the steel plate,landscape painting and overpickling.Especially for the production of extreme-dimensioned high-strength hot-rolled and pickled sheet,the aesthetic measure has been severely affected by pitting defect on the surface of the steel plate.Up to now,the domestic iron and steel enterprises are still unable to stably control the pitting defect,particularly the old hot rolling production lines show more limited control ability due to the insufficient equipment capacity.In this paper,the extreme-dimensioned high-strength hot-rolled and pickled sheets are provided by a domestic enterprise and they are produced by a 1580 hot rolling production line of this enterprise.The effects of Si on scale formation kinetics were investigated using thermal gravimetric analyzer(TGA)and electron probe microanalyzers(EPMA).The numerical calculation program of roll temperature field of the hot rolling production line in a domestic enterprise was developed by the use of C++ programming language and the relationship between working roll temperature and cooling system of the finishing mill group in this enterprise was simulated using the developed program.Finally,the experimental and simulated results were applied in the field production and the production process parameters were optimized by tracking the production process,which significantly reduced the occurrence rate of pitting defect of the hot-rolled and pickled sheet produced by a domestic enterprise.The main works and results of this paper are as follows:(1)The effects of temperature and alloying element Si on scale formation kinetics of low Si(Si<0.1 wt.%)high-strength hot-rolled and pickled sheets were studied by carrying out a series of high temperature oxidation weight gain experiments in the temperature ranges of 950～1050℃ and the oxidation kinetics models of the experimental steels were also established.The results showed that with the increase in Si content,the oxidation rate constants corresponding to both slow and rapid oxidation stages decreased,which is due to the fact that Fe2SiO4 formed on the surface of the experimental steels can improve the resistance to oxidation of the experimental steels.With the increase in temperature,the oxidation rate constants corresponding to both slow and rapid oxidation stages increased and the binding ability of the scale to experimental steel matrix was worse.(2)A semi-3d numerical calculation model of roll temperature field was built by finite difference method and the water cooling interface was simulated according to the actual production condition of a domestic enterprise.The results indicated that the pressure,temperature and flow rate of cooling water and the stored water in water-cutting board could affect the temperature of rolls,the change of water-cooled boundary conditions to the roll temperature is also given.(3)The effects of rolling process on the formation of pitting defect were investigated by tracking the production process.And the effects of the roll grinding process,roasting roll process,production scheduling and rolling rhythm on the production of hot-rolled and pickled sheet were analyzed in detail.In addition,the rolling plans about cooling water supply,roasting roll process,production scheduling and rolling rhythm used in a domestic enterprise were improved referring to the results of oxidation kinetics experiments and the simulation calculation of roll temperature field.By tracking the production process,one thing is clear that the occurrence rate of pitting defect of extreme-dimensioned high-strength hot-rolled and pickled sheets produced from 3.0%to 0.5%,achieving the desired effect.更多还原