1997 Volume 37 Issue 1 Pages 65-73
Dispersion microstructures in C-, Cr- and Mn-alloyed steels result from the precipitation and coarsening of carbide particles from the martensitic initial condition. The changes in the microstructure were observed at aging temperatures T=500, 600, 650 and 700°C and for the time t=1 to 4290 min by measuring the coercive field strength HC. The particle size analysis on scanning electron micrographs of M3C in the steels and of M6C (+MC) carbide particles in the case of the high-alloyed steel X80WMo6.5 yielded to a certain connection with HC. Thus HC can be taken as an indirect microstructural characteristic quantity insteed of directly observed microstructure data.
It was found that nucleation, growth and the dominating coarsening of the particles take place permanently in so-called generations. With increasing time the particle sizes in the one after another following generations become smaller because of the matrix depletion of the participated elements by precipitation. The Ostwald-ripening law is to apply separately to each generation. All the processes and relationships, which are connected with HC, can be written mathematically.
