Study on the adhering failure mechanism of cemented carbide inserts and element diffusion model during the heavy-duty cutting of water chamber head

Abstract

In view of the serious adhering failure of cemented carbide inserts during the heavy-duty cutting of water chamber head, the adhering failure mechanism of inserts and the element diffusion model of the adhering process were investigated. First, based on cutting simulations, the cutting force was found to be as high as 45.2 kN while the maximum cutting temperature was 930 °C. Under the combined action of mechanical and thermal loads, element diffusion occurred between insert and workpiece and formed an adhering layer, resulting in the adhering failure of inserts. After that, the element diffusion dynamics equation of the adhering process was proposed according to Fick’s law. Based on the semi-infinite long-bar diffusion model and its initial conditions and boundary conditions, the dynamics equation was solved, with the element diffusion concentration model obtained. In the end, the experimental scheme of element diffusion was put forward, and the element diffusion between the cemented carbide insert and workpiece at elevated temperatures was experimentally investigated. The diffusion distance of Co in 508III steel was measured as 8 μm. The element diffusion concentration within the diffusion distance was compared with the value predicted by the model, with the effectiveness of the element diffusion model validated. The concentration distribution of diffusing elements in the diffusion cross section was characterized through experiments and compared with the theoretical concentration distribution. The research results can provide a basis for the in-depth study of the formation mechanism of insert-chip adhering layers and their influence on the cutting performance and service life of inserts.