Growth of recrystallised grains in 1.8% Si steel in temperature range 650 to 850°C

Three different types of grain growth were observed: uniform growth producing a regular microstructure; fast individual grain growth and finally a fast secondary recrystallisation initiated by the decarburisation of steel. Uniform growth follows parabolic kinetics. Above appr. 800°C a lower rate of growth is observed than it would be expected by extrapolation from lower temperature. Individual grain growth occurs in areas depleted of cementite and austenite and follows also parabolic kinetics. Nuclea for this type of growth are produced by the coalescence of smaller grains with similar space orientation. An apparent activation energy of 26 kJ/mole was determined for the process of coalescence, while for the uniform growth of recrystallised grains an apparent activation energy of 171 kJ/mole was established. Experimental data show that the texture rich with grains of orientation near to (111) in strips plane results from the greater density of such grains in recrystallised steel and the resulting faster formation of near (111) nuclea of sufficient size suitable for fast growth.