SOLIDIFICATION PROCESS OF HIGH-SPEED TOOL STEEL TYPE CAST-IRON FOR ROLLS

The phase diagram and the solidification processes are investigated on a series of alloy specimens containing 5%Cr, 5%Mo, 5%W, 0 similar to 11%V and 1.0 similar to 4.4%C. delta, gamma, MC and M(3)C appeare as primary phases, and eutectics of gamma+MC and gamma+M(3)C crystallize at boundary compositions between liquidus surfaces of the constituent phases. The compositional extent of each liquidus surface is similar to those of Fe-V-C and Fe-5%Cr-V-C alloy system. M(2)C and M(7)C(3) crystallize as eutectic carbides because of segregation of Mo, W and Cr to residual liquid, though they don't appear in the diagram. The species and amount of carbides of this alloy system are estimated on the basis of the diagram and the analysis of redistribution of alloying elements.