Effects of Hot Band Annealing on the Precipitation of Copper Sulfide in Fe-3%Si Steel

Hot bands of Fe-3%Si steel containing 0.24%Cu were characterized to examine the precipitation of copper sulfides following different heat treatment schedules. It was found that copper sulfides were dominantly in a sphere shape. From 950°C to 1050°C, the precipitates were the complex of copper sulfides and aluminum nitrides. The size of the precipitates decreased and the distribution increased as the temperature increased. However, from 1050°C to 1150°C, the precipitates size increased and the distribution decreased with the rise of temperature. The precipitates were mainly complex copper-manganese sulfides. When the sample was annealed at 1050°C, air cooled to 900°C and boiling water quenched, the most fine and disperse precipitates were obtained. The average size and distribution of the precipitates was 37nm and 2.72μm-2, respectively.