Thermodynamics and Kinetics for the Pearlite Reaction in Chromium Steels

Abstract

<p>The phase equilibria in the Fe-C-Cr system, essential for the understanding of the pearlite reaction in low chromium steels, has been calculated from the thermodynamic data. The experimentally determined tie-lines are in good agreement with the calculated phase diagrams.</p> <p>The pearlite growth rates and interlamellar spacings in a series of low chromium Fe-C-Cr alloys have been experimentally determined. The growth rates in these alloys are explained in terms of chromium partitioning and chromium phase boundary diffusion control at low supersaturations and in terms of the local equilibrium no-partition mechanism and carbon volume diffusion control at high supersaturations.</p> <p>The relative effect of Cr, Mn, and Ni on the pearlite reaction is qualitatively discussed in terms of the above mechanisms, established for the chromium steels. The results have an application to the hardenability problem in steels.</p>