Pearlite growth kinetics and partitioning in a Cr−Mn eutectoid steel

The partitioning of manganese and chromium between cementite and ferrite during the austenite-pearlite transformation in a 1 pct Mn, 1 pct Cr eutectoid steel has been examined using analytical electron microscopy. Simultaneous segregation of both manganese and chromium to cementite was observed to occur at the reaction front for temperatures down to 600°C. Although the extent of partitioning decreased as the temperature was decreased, no-partitioning temperatures were not identified for either element. Calculations based on growth rate and interlamellar spacing measurements made on the alloy supported the view that the partitioning observed was kinetically feasible. Partitioning behind the pearlite front increased with time, and solute distributions which approached the equilibrium values were achieved after a few hours. The lack of experimentally observable no-partition temperatures for the Cr−Mn steel is discussed in the light of previous partitioning studies on eutectoid steels containing chromium or manganese. S. A. AL-SALMAN, formerly Graduate Student, University of Manchester