应力比对WC-Co硬质合金疲劳性能的影响

采用三点弯曲疲劳法,研究了不同粘结相含量以及粘结相成分的硬质合金在两种不同应力比(R=0.1和R=0.5)加载时的疲劳行为,并结合SEM对疲劳机理进行了分析.结果表明:硬质合金疲劳断裂过程同时存在脆性断裂和韧性断裂.在两种应力比疲劳加载时都发现,增加钴含量,合金的疲劳敏感性先减小后增大,添加Ni和Cr能降低合金的疲劳敏感性.大应力比疲劳加载时,粘结相疲劳断裂过程由脆性断裂向韧性断裂转变.增大应力比对合金的疲劳敏感性也有影响.

Influence of Different Stress Ratios on Fatigue Behavior of WC Co Cemented Carbides

The three point bending fatigue behaviors of WC Co cemented carbides with different binder phase content and composition under cyclic loading at two different stress ratios (R=0.1 and R=0.5) were investigated. The characterization of the fracture surfaces was carried out by using a scanning electron microscope (SEM), and the fatigue mechanism was also studied. The results show that the macroscopic fracture morphology exhibited brittle fracture and toughness fracture. With the increase of Co content, the fatigue sensitivity decreased firstly and then increased. Cemented carbides with complex binder phase (Co + Ni + Cr) exhibited lower fatigue sensitivity than that of pure Co cemented carbides. The fracture mechanism transformed from brittle to ductile at the stress ratio changing from 0.1 to 0.5. With the increase of the stress ratio, the fatigue sensitivity was changed.