Page 19 - Апрель

METALWORKING EQUIPMENT AND TOOLS

corrosion-mechanical destruction and reduce the resistance of protective coatings, as well as
affect the rate of relaxation of the properties of the surface layer and its softening.
Since the set of properties of the processed surface characterizes the quality of the surface
layer of the processed part or the quality of processing, many researchers around the world have
been studying the influence of cutting conditions and the geometry of the cutting tool on these
properties. It was found that the properties of the surface layer begin to form in the advanced
hardening zone in front of the cutting edge of the tool. The development of a dislocation structure
in the form of slip bands, an increase in the density of dislocations lead to hardening of the
surface layer [1 - 4]. The intensity of hardening of the surface layer, determined by the density
of dislocations, depends on the level of the applied load and the time of its action. In turn, the
dislocation density is closely related to the increase in the hardness of the hardened material
and the degree of its work hardening. It was shown in [5] that an increase in the hardness of a
work-hardened material is associated with an increase in the dislocation density by a power-law
dependence:
HV = Gbk-1ρ0,5,
where G is the shear modulus, b is the value of the Burgers vector, k is the coupling
coefficient for the hardened material, and ρ is the dislocation density.

Fig. 1. Spectra of VA signals during turning with sharp (spectrum 1) and blunt (spectrum 2) plates; in the inset, the change
in the values of the parameter Kf with an increase in the effect of wear on deformation of the surface layer (plate numbers are
given).

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