The Study Of Decarburization Process In The Oriented Silicon Steel Production

With increasingly stringent requirements of environmental protection and energy saving,the stability of magnetic properties for oriented silicon steel in the process of serving is more and more attention.Research shows that carbon is the main reason that causes the magnetic aging for oriented silicon steel in the serving process,so the lower the content of carbon in the finished product is better.But grain oriented silicon steel in hot rolling process must maintain a certain carbon content to makes hot-rolled microstructure is small and uniform,so extra decarburization annealing is needed to remove the excess carbon in the steel strip.Through the research of the decarburization kinetics on the steel surface and the mechanism of carbon diffusion in the steel,the mathematical model for decarburization process of oriented silicon steel is build.According the appropriate boundary conditions,the effect of atmosphere,temperature,initial carbon content and the thickness and other factors on decarburization rate is analyzed.Decarburizing annealing experiments for high temperature oriented silicon steel were performed to assisted verification.The results show that when the P_H2O/P_H2 ratio above 0.3,the diffusion of carbon in the steel strip is restricted part for the decarburization process,raise the annealing temperature can help accelerate decarburization rate.With the increase of P_H2O/P_H2 ratio,the oriented silicon steel decarburization rate speed up at first and then slow down,there is a maximum value in decarburization rate appearing at P_H2O/P_H2 =0.37.The best annealing conditions:830℃annealing temperature+45℃dewpoint+25%H₂,after 2.5min annealing time,the residual carbon content is reduced to about 10 ppm.Comparison with the experimental results,the calculated value is smaller than the measured value,particularly in high annealing temperature and a high water-hydrogen ratio condition,the deviation of calculation results and the actual results is very large,the influence of surface oxidation decarburization cannot be ignored.