The Study of Deformation and Failure Processes in the Cut Layer of Material Based on the Atomic Approach

The atomic approach to the processes of deformation and failure of chips is described in the article. The resistance of the cut layer to plastic deformation depends on the crystal lattice of the machined material, its stacking fault energy and the presence of additives at the grain boundaries. The effect of these variables is manifested through the kinds of dissipative structures formed in the process of cut layer deformation, and determining its location. Carbon is the main additive in carbon steels. Located at the grain boundaries, it can promote grain embrittlement. With the increase of temperature, diffusion mobility of carbon increases too, which simplifies grain slippage, enlarges and changes the shape of the chips. This article presents the results of quantum-mechanical calculations on the role of additives in the processes of deformation and shape formation of the chips, as well as the change of the dislocation structure under chip element shear. It has been established that the consistency of shear resistance when the cutting conditions are changed is linked to the achievement of the dislocation density limit in the crystal lattice, breakage of the interatomic bonds, and amorphization of the deformed volumes.  Ways of improving the cutting process efficiency are proposed.

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