Ferritic chromium steel as binder metal for WC cemented carbides

Fe-based alloys as alternative binders of cemented carbides are of increased research interest. We used ferritic chromium steel AISI430L as metallic component in cobalt and nickel free WC-FeCr cemented carbides. Composites with relatively high binder content of 30 wt% were under investigation. Our focus was on the effect of sintering temperature on the densification and phase evolution and on the influence of extra carbon. With the liquid phase formation around 1150 °C, the near full density of the composites was achieved at 1200 °C. During sintering, M6C η-phase and (Cr, Fe)xCy mixed carbides of different composition dependent on the carbon additions were formed. Addition of carbon to achieve over-stoichiometric carbon level proved opportunity to retard the formation of the η-phase and the (Cr, Fe)23C6 phase and favored microstructural homogeneity. However, final microstructure remained heterogeneous with binder rich areas consisting of Cr- and Fe-based carbides and α-Fe.