Effect of subgrain boundaries on the state of supercooled austenite

The dislocation walls composing the low-angle boundaries (theta less than or equal to 20 deg), acting as hydrodynamic funnels which are filled with carbon atoms due to the drift of these atoms in the attractive-force field are considered. The effects of misorientation angle on the amount of carbon going to the dislocation wall from the adjacent zone of the action of forces, on the time necessary for the saturation of subgrain boundary, and on the width of decarburized zone austenite are calculated. The time of the saturation of subgrain boundaries with carbon is shown to be dependent on misorientation angle and temperature. Three stages of this process are revealed. The first stage accomplished for 2 . 10(-6) a at 620 degrees C for theta = 10 deg results in maximum nonuniformity and instability of austenite. The extent of nonuniformity decreases with increasing isothermal-treatment time.