Premature failure mechanism of the cemented carbide blade in drilling Wansheng-limestone with water jet

The premature failure of the drill bit seriously influences the efficiency and security of rock drilling. The premature failure mechanism of the cemented carbide blade on the drill bit is studied in drilling Wansheng-limestone with water jet. Experiment results showed that transgranular fracture is the main morphology of premature failure of cemented carbide blades in drilling Wansheng-limestone with water jet. Based on the experimental results and mechanical model analysis of the impact stress of the quartz grain, it is showed that the high content of quartz grains in Wansheng-limestone and the excessive speed of the water jet are the main causes of brittle fracture of the cemented carbide blades. Furthermore, the cooling of excessive speed water jet brings more hcp-Co phases than fcc-Co phases in the blade which may put the cemented carbide blade at higher risks of brittle fracture by the impact of quartz grains.