Formation of Edge Crack in 1.4% Si Non-oriented Electrical Steel during Hot Rolling

Microstructure evolution, dynamic recrystallization, high temperature oxidation and hot ductility of 1.4% Si non-oriented electrical steel sheets were investigated to reduce edge cracking. The causes of cracking were found to be coarse as-cast microstructure, grain boundary oxidation in reheating furnace, lack of dynamic recrystallization during hot rolling and increase of temperature, resulting in reduced hot ductility in strip edge region. Countermeasures against the edge crack are proposed accordingly. Lowering reheating temperature and reducing holding time reduced oxidation and decarburization. Hot charging temperature was increased to decrease reheating temperature. And using an edger can refine microstructure in strip edge region. Finally, edge heater can be added to increase edge region formability by inducing dynamic recrystallization and ductility by increasing temperature.