Qualitative study of carbides in liquid phase sintered M3:2 high speed steel

Abstract

The microstructure of liquid phase sintered M3:2 high speed steel and the effect of adding carbon and silicon on the microstructure was characterized by scanning electron microscopy, dispersive spectrometry, and X-ray diffraction. Various types of carbides were formed depending on the added carbon and/or silicon, the sintering atmosphere and the cooling rate. The microstructure of sintered M3:2 high speed steel samples in vacuum conditions without the addition of Si and graphite is composed mainly of MC and M6C carbides inside cells and primarily at cell boundaries. The M2C eutectic carbides in these samples were formed at cell boundaries and their amounts and morphology depends on the cooling rate. Sintered samples in N2 atmosphere with added carbon and silicon, M6C eutectic and M7C3 eutectic carbides were dominantly formed while carbonitrides were formed in smaller amounts.

Keywords

• High speed steel
• Primary carbides
• Eutectic carbides
• Microstructure
• Carbide-forming elements