【作者】 石虎珍；

【导师】 王国栋； 李长生；

【作者基本信息】 东北大学 ， 材料加工工程， 2008， 硕士

【摘要】 本文回顾了目前国内外对薄板坯连铸连轧技术的发展状况以及国内利用薄板坯连铸连轧工艺开发无取向硅钢的研究开发情况,针对采用薄板坯连铸连轧工艺生产无取向硅钢过程中出现的裂纹缺陷问题进行了研究。本文在实验室模拟了薄板坯连铸连轧生产中高牌号无取向硅钢的生产过程,利用光学显微镜、扫描电镜及动态拉伸台及多功能热模拟实验机对制得的无取向硅钢热轧带钢进行了研究,观察了热轧试样的原始形貌和裂纹的形核与扩展情况,研究了无取向硅钢的室温性能与高温塑性,对不同加热与轧制工艺下的组织进行了对比分析,得出有利于预防和减缓裂纹缺陷的工艺参数。研究表明,钢中的氧化夹杂与析出物MnS等和带钢的附加应力是导致裂纹的主要因素。轧制过程中带钢宽度方向上温降不均匀,边部冷却过快,硬度增大,脆性增加,析出物在外力作用下成为裂纹的形核部位,随着变形的增加沿不同路径扩展成为宏观裂纹；在稳定轧制区域内低开轧温度与高终轧温度,有利于裂纹现象的缓解。保温时间与变形速率并非越短越好或越大越好,有一个最佳范围的问题；并提出了实行热轧工艺润滑、控制轧制温度、采用立辊轧制、边部加热、增加保温罩等裂纹预防或减缓措施。裂纹的形核与扩展对于实际生产中成材率的提高起着非常重要的作用。针对薄板坯连铸连轧生产线研究不同工艺参数对裂纹的影响,为实际开发无取向硅钢产品制定控制轧制工艺提供了理论基础。更多还原

【Abstract】 This paper reviews the situation of internal and external development about the merit and demerit of the technology of continuous casting and rolling, and the exploitation of non-oriented silicon steel with the process. The crack defects during the compact technology are mainly researched.Thin slab continous rolling process is simulated to produce non-oriented silicon steel of middle and high grades in the lab on the basis of investigation on campact strip production line. And main contents of this paper are as follows:hot rolled microstructure amd original crack are researched by optical and scanning electrical microscope, and nuclearation and expansion are emphasized. Meanwhile mechanical properties in room temperature and high temperature are surveyed. Processes of different parameters are compared to get better microstructure, and some methods of prevention and reduction are brought forward which are proposed to be helpful in coming real production.The results of investigation are summarized as:oxide inclusion, precipitation MnS and addional stress are main factors. Inhomogeneity of temperature drop leads to ono-uniform temperature along the width of strip, thus, the edge region is cooled fastly so that its hardness and embritttlement get increased. Precipitation becomes nucleation site by the effect of external force. The microcrack gets expansed into invisible crack along varied ways with deformation. Lower starting temperature and higher finishing temperature in steady rolling process can slow down the crack expansion. The soaking time and deformation rate have a optimized range which can reduce the crack phemonimen. Messures such as reasonable lubrication in hot roll stage, controlled cooling, rolling of different mill speed and so on are mentioned to decrease the crack defects.The regularity of nucleation and expansion of crack plays a very important role for the actual production process control. It is crucial to study the affection of different conditions of hot rolling in the compact slab process.更多还原