Analysis On Crack Of Non-oriented Silicon Steel During Thin Slab Casting And Rolling Process

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.