The role of chemical wear in machining iron based materials by PCD and PCBN super-hard tool materials

The chemical compatibility of PCBN and PCD tool materials with iron has been evaluated by means of the static interaction diffusion-couples technique. Experiments were undertaken at different temperatures (700 °C, 900 °C, 1100 °C and 1300 °C) in order to establish the maximum temperature at which the tool and workpiece materials are chemically compatible. Computational equilibrium thermodynamics was used to calculate the chemical solubility of the different tool materials in iron and to identify the interaction phases formed. The agreement between the experimental results and the thermodynamic calculations was excellent. Machining tests were performed in order to assess the relative importance of the chemical wear on the overall rate of tool wear. The results of these machining tests agreed perfectly with the chemical compatibility study, thereby indicating that under certain machining conditions, chemical wear is the main wear mechanism for these materials in machining iron based materials.