Sintering characteristics and properties of WC-10AISI304 (stainless steel) hardmetals with added graphite

WC-Co hardmetals are widely used in the cutting industry. Due to several disadvantages of Co binder, many research studies have been carried out to find the suitable binders to replace Co metal. In the present research, AISI304 stainless steel was used as the binder phase to replace Co in WC-based hardmetals. When WC-10AISI304 hardmetals were ball-milled prior to consolidation at 1350 °C for 1 h in a vacuum furnace, brittle η-phase (Fe3W3C) was observed to be formed during sintering. The addition of 1.5-2 wt% graphite to the composition prior to ball milling completely eliminated η-phase formed during sintering of WC-10AISI304 hardmetal. Addition of 2 wt% graphite improves the densification and mechanical properties of the sintered samples by obtaining higher Vickers hardness (HV30) and fracture toughness (KIC) of 1625 kg/mm2 and 10.2 MPa m1/2, respectively. However, the free graphite increases while both hardness and fracture toughness were found reduced beyond this value (2 wt% Cgr).