On the enhanced wear resistance of ultra-coarse WC-Co cemented carbides by WCoB addition

•Ultra-coarse cemented carbide with high wear resistance was developed.•Wear resistance mechanisms of the materials with and without WCoB are different.•WCoB addition protected WC grains from the fragmentation and pullout after Co removal.•WCoB addition is beneficial to homogeneous stress distribution in the material. The effect of the WCoB addition on the wear resistance of the ultra-coarse WC-8Co cemented carbides was studied by experiments and finite element simulations. The results showed that with the increase of the WCoB content, the wear resistance of the ultra-coarse cemented carbides was greatly improved. The cemented carbide containing 1.0 wt.% WCoB had a friction coefficient of 0.281 and a wear rate of 0.77 × 10−6 mm3/N⋅m, which was 72% and 46% of those of the WC-8Co counterpart. The reason of the significant reduction of the friction coefficient and wear rate was analyzed. WCoB with high hardness distributed homogeneously at WC/WC and WC/Co interfaces, which led to relatively homogeneous distribution of the stress in WC grains and supported the WC grains after Co removal. Consequently, the probability of brittle fracture and pull-out of the WC grains during wear process of the cemented carbides was decreased.