either a deformable billet, or during the use of a cold-worked product [2]. Therefore,
new additional technological operations should be introduced into the technological
process of steel products hardening, which ensure the elimination of the danger of
destruction due to a change in the mechanism of dislocation movement and the
obtainment of new types of the dislocation structures with a reduced value of the stored
elastic energy and other features. These new technological operations are based on steel
alloying with a certain non-equilibrium concentration of vacancies [3, 4]. The
technological parameters used to ensure the formation of the structural state, are: the
degree of cold deformation (the scheme of cold deformation), the alloying of steel at
certain stages of the technological process with the non-equilibrium concentration of
vacancies.
Thermomechanical hardening [1, 5].
For all types of thermomechanical hardening the sufficient effect is achieved by
increasing the concentration of dislocations and surface defects in different ratios,
depending on the version of this hardening. The combinations of the heat and
mechanical hardening methods involve hot, warm and cold deformation. In this case,
the deformation occurs in stable or metastable phases, obtained by heating or
quenching. The obtained dislocation structure is taken by steel in the process of
martensite, bainite, and phase transformations of the solid solutions breakdown. This
makes it possible, to some extent, to take advantage of the mechanical hardening and
substantially expand the spectrum of the obtained structural states. However, the above
mentioned downsides of the heat hardening, that are related to the need for heating and
high-speed cooling, as well as isothermal equalizing and the need for accuracy to a
certain chemical composition of steels, are proper for the combination methods of the
heat and mechanical hardening. Perhaps, only the method of thermomechanical heat
treatment (TMHT) [6] suggested during the 1980s of the past century allows to
maximize the advantages of the mechanical hardening by cold deformation during the
forming technological deformation with the minimal negative technological influence
of the disadvantages of the heat hardening methods.
The comparison of the methods of heat hardening, thermomechanical hardening
and the technologies based on them with the method of mechanical hardening and the
new technology of steel products hardening based on it suggests the advantages of the
latter. But to justify the possibility of practical realization of the stated advantages, it
is necessary to do a more detailed study of the theoretical principles of the new
technological process.
As it was already noted above, there are several basic technological operations
with the corresponding parameters in the development of the new technology for
manufacturing steel products hardened by the cold deformation.
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