Non-equilibrium solidification of high alloy ledeburitic type steel

The results of the research work concerning the rapid solidification of undercooled liquid droplets into small powder particles are presented. The iron base ledeburitic type alloy with 2.3% C, 4% Cr, 2% W, 7-8% V, 10-11% Co, 8% Mo chemical composition has been subjected to the experimental evaluation. Hypoeutectic solidification mechanism has been determined in the specimen obtained by 10 K.min(-1) cooling rate and also in RS powder with a particle size more than 100 mu m. With the increase in cooling fate represented by a decrease in powder size, the change in the mentioned mechanism to the hypereutectic one has been determined. As such, the microstructure of a material is characterized by occurrence of small primary carbides in the centres of eutectic colonies. The changes in phase composition as a function of powder particle size have been also found in RS material.