THE INFLUENCE OF SOLIDIFICATION RATE ON P OWDER HIGH-SPEED STEELS MICROSTRUCTURE

The work deals with microstructure formation of powder high speed stee ls produced via nitrogen atomization in conditions of rapid solidifica tion. For investigated AISI M2 and T15 high speed steels powders we ha ve estimated physical and technological properties and performed optic al mickroscopy, REM and X-ray analysis. The solidification rate was es timated using the method of dendrit second arms distances measuring. W e have found out that the powder particles of size under 40 mum were c ooled at the rate 10(6) - 10(8) Ks-1. When solidification rate raised, the structure became more dendritic and quantitative portion of phase s alpha, gamma and carbides changed.