Effects of Temperature and Alloying Elements on γ Phase Fraction of Grain-oriented Silicon Steel

The effects of temperature and alloying elements on γ phase fraction of grain-oriented silicon steel, which contained 2.97—3.42 mass% Si and 0.028—0.058 mass% C, were studied by microstructure observation and statistics. Furthermore, the quantitative relationships of temperature as well as C, Si, and Mn contents to γ phase fraction were obtained by numerical fitting. The experimental results show that γ phase fraction firstly increases with increasing temperature, reaches a maximum and then decreases in the temperature range of 900—1250 °C. The temperature corresponding to the maximum γ phase fraction is about 1150—1200 °C. Meanwhile, the γ phase fractions in steels at the same temperature have some differences because of different contents of various alloying elements. The verification results show that the values of γ phase fractions to C, Si, and Mn contents at the specific temperatures, which were obtained by multiple linear regression method, agree well with the measured values. In addition, the values of γ phase fractions to C, Si, and Mn contents in the temperature range of 900—1250 °C, which were obtained by binomial regression method, agree with the measured values when the contents of Mn and soluble Al are not more than 0.320 mass% and 0.034 mass%, respectively. The obtained equations can carry out the approximate prediction of γ phase fractions of grain-oriented silicon steels during the hot rolling process.