Abstract
Specimens (30mmφ×70mm) were solidified unidirectionally in exothermic molds on a watercooled copper chill plate. The chemical composition of the specimens varied : 1.8-3.8%C, 1-5%Cr, 1-3%Mn, 0.25-1%Mo and 0.5-1%V.
The size of a group of primary dendrite cells, having a constant crystallographic orientation, became finer with increase of the content of alloying elements, while the dendrite cell size was not affected by any alloying elements. The secondary dendrite arm spacing became finer with increase of the chromium content because it reduced the amount of primary austenite. In each specimen, ledeburite solidified with a cellular morphology and presented a colony structure. The size of the colony became larger with increase in the chromium and molybdenum content probably because they extended the freezing range of the eutectic. In low carbon specimens, less than 3.0%C, the eutectic cementite was inclined to become more massive by the addition of molybdenum.
