Abstract
The effects of austenite deformation conducted below the recrystallization temperature on the subsequent isothermal transformation to pearlite in an eutectoid steel (SKD 6, H11) were quantitatively studied. The plastic deformation in the austenite condition led to marked acceleration of austenite-pearlite transformation. This acceleration was found to be mostly caused by the increase in the nucleation rate but not by the increase in the growth rate.
The increase in the nucleation rate per unit volume of specimen was attributed (1) to the increase in the austenite grain area by the elongation of grains, (2) to the increase in the nucleation rate per se per unit area of grain surface, and (3) to the formation of additional nucleation sites such as annealing twin boundaries, deformation bands, etc. In this study, the nucleation rate on the grain boundary surface was estimated to be increased about 27 times larger by 30% rolling. The average pearlite fraction nucleated within the grains was found to be 25% of the total transformed fraction.
