THE DEPENDENCE OF THE AUSTENITIZATION KINETICS ON THE TYPE OF INITIAL SPHEROIDIZED STRUCTURE IN LOW-ALLOY STEEL

The kinetics of austenitization were measured in Fe-2wt.%Si-2wt.%Mn-1wt.%Cr steel for the structure after soft annealing and it was proved that these kinetics are three to four orders of magnitude slower than in plain carbon steels. The exact shape of the austenitization curves (ferrite volume fraction vs. time relation) depends on the initial structure, i.e. on the procedure for its preparation, especially on the ferrite grain size and shape and location of the cementite (grain boundary or grain interior). The results are interpreted on the basis of inhomogeneous distribution of alloying elements and their effect on carbon activity.