Mechanical behavior is the macroscopic expression of the microscopic process of plastic deformation. Early metal cutting theoretical models did not consider the effect of microstructure on the cutting force. Based on the dislocation density material model, a 6061-T6 aluminum alloy orthogonal cutting force prediction model is established, and the influence of dislocation motion based plastic deformation mechanism on the cutting force with different cutting parameters is analyzed. By combining the model of equal division shear zones and unequal division shear zones, we construct a multi-physics field calculation method for the first deformation zone, and propose an analytical model of microstructure evolution caused by plastic deformation during chip formation. The feasibility of the model is preliminarily verified by measuring the cutting force and the size of grain in the chip. The results show that the material increase involved in the dislocation slip caused by the length of the shear zone is the main reason for the increase of the feed rate, which further leads to the increase of the cutting force. The decrease in the cutting force caused by the increasing cutting speed is not the result of a single variable, but the joint effect of the number reduction of dislocations induced by the strain reduction and the annihilation increase resulted from temperature increase. The non-divided shear zone model correctly reflects the temperature and stress distribution characteristics of the first deformation zone, and is consistent with the two-dimensional finite element model. The analytical model of the microstructure evolution of the first deformation zone can predict the dislocation density and grain size in the chip.
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