Two 52100 steels, one containing 0.009 pct P, the other 0.023 pct P, were homogenized at 1150 °C, slowly cooled to form proeutectoid carbides and pearlite, partially spheroidized, austenitized at 850 °C for one hour, oil quenched, and tempered at 200 °C. Light microscopy and transmission electron microscopy of carbon extraction replicas showed that cementite particles were retained as three different morphologies in the fine-grained austenite formed during the 850 °C intercritical austenitizing treatment. The morphologies are characterized as follows: (1) closely spaced intragranular carbides most of which are less than 0.25 μm in diameter, (2) carbides about 1 μm in diameter, located on austenite grain boundaries, and (3) branched proeutectoid carbides arranged in networks corresponding to the coarse, 130 μm diameter austenite grains formed during homogenizing. The major effect of high phosphorus content was to retard the spheroidization of the retained carbides.