The quenching effects of hot band annealing on grain-oriented electrical steel

Effect of Acid-Soluble Aluminum Content on Precipitates and Microstructure of Annealed Hot-Rolled Grain-Oriented Silicon Steel

“…The Goss orientation grains in subsurface of hot‐rolled band which have been proved as the origin of sharp Goss texture component in fully processed silicon steels were observed to still exist in the subsurface of annealed hot‐rolled band. Meanwhile, the uniform microstructure in subsurface of annealed hot‐rolled band is proved helpful to obtain uniform grains after primary recrystallization and hence enhance to stabilize the secondary recrystallization, which means that the uniform microstructure in subsurface is also an important factor for obtaining preferable resulting microstructure and magnetic property. Consequently, some studies were done on the microstructure in subsurface of annealed hot‐rolled band and the results are shown in Figure .…”

“…Two kinds of hot band annealing process are known to be used for obtaining a large amount of fine AlN. One is the one‐stage cooling: the steel is held at a higher temperature and cooled to a phase transformation temperature with a lower cooling rate, then cooled in boiling water . Another one is the two‐stage cooling which has been used in the present experiments: the steel was rapidly cooled to a phase transformation temperature from a higher temperature and then held for several minutes, finally cooled in boiling water .…”

“…Besides the intensity of Goss texture component in subsurface, the uniform grain structure in subsurface of annealed hot‐rolled band is another important factor that results in preferable magnetic property . The grain size is well known to be affected by the particle diameter and volume fraction of precipitates, so the MnS and AlN that precipitates before and during hot band annealing, respectively, can have a significant influence on the microstructural evolution during hot band annealing.…”

“…Two different ways: hot band annealing before cold rolling and nitriding during primary recrystallization annealing, were developed to produce the finely distributed precipitates of AlN. Although, nitriding is now widely used for getting more and finer AlN, hot band annealing is also necessary for producing grain‐oriented silicon steel with lower slab heating temperature . It has been proved that not only the precipitation behavior of AlN which precipitates primarily during the phase transformation of γ → α in hot band rolling, but also the microstructure of annealed hot‐rolled band can be promoted by controlling hot band annealing conditions, such as cooling way and cooling rate during hot band annealing .…”

“…Although, nitriding is now widely used for getting more and finer AlN, hot band annealing is also necessary for producing grain‐oriented silicon steel with lower slab heating temperature . It has been proved that not only the precipitation behavior of AlN which precipitates primarily during the phase transformation of γ → α in hot band rolling, but also the microstructure of annealed hot‐rolled band can be promoted by controlling hot band annealing conditions, such as cooling way and cooling rate during hot band annealing . Moreover, the content of acid soluble aluminum (Al s ) which consists of metallic aluminum and the aluminum in aluminum nitride in steel can also be thought to have a significant effect on the precipitation behavior of AlN and microstructure of annealed hot‐rolled band, but researches about the effect of Al s content on them are rather limited.…”