The method allows to individualize the processing of objects in a given batch, to
reduce the dispersion of product properties in a given batch, to remove from the process
the potentially defective objects and, thus, to increase the nondefective yield.
For the products hardened by cold deformation both ready-made and while in the
technological process as billets, there is a variety of uses of coercive field
measurements, a characteristic that depends not only on the density but also on the
volume distribution of dislocations [23, 24], and as the basis for the obtained
correlation dependences between the mechanical properties and coercive field, which
provides the operative non-destructive testing of properties, both for the technological
process and finished products, which also increases the nondefective yield and provides
not a selective destructive, but 100% control of properties of the finished products with
a noticeable saving of metal and other resources.
The subject of the final testing of the finished steel products manufactured
according to the developed technology project. To ensure the non-destructive testing
of properties of the finished products, it is necessary, as is known, to perform full-scale
tests with obtaining sufficiently large samples of the characteristics of the finished
products (their mechanical and physical properties), that is why the general
methodology for determining the former is provided below.
Final tests of the cold-worked products, manufactured applying both the known
technologies, and the developed new variants, have their own specifics. The usual
characteristics of the plastic deformation resistance under uniaxial tension with the
recording of the technical diagram of deformation and fracture and consideration of its
nature are determined in a known way. Known methods are also used to determine the
resistance to brittle failure: impact ductility at various temperatures and the fracture
toughness parameter, crack resistance К
Ic
. In such tests, the following requirement must
be met: the maximum approximation of the massiveness of tested objects to the
massiveness of products. New approaches have also been developed to determine the
characteristics of the ductile failure resistance, the importance of which increases with
the reduction in cross-sectional area of products, when the risk of ductile failure by
brittle type increases [25].
The determination of the stored elastic energy, which is a function of the formed
by this technology structural state of the finished product Q
e
т
, is, presumably, for the
first time introduced into the system of the final testing. The value of Q
e
т
during
operation is summed with the elastic energy associated with the level of service loads
Q
e
serv.
(if its relaxation is not essential). The admissible limit value of this total energy
Ʃ Q
e
should not exceed the permissible value, at and above which the growth of defects
(cracks) to their critical dimensions is statistically probable. The methodology and the
necessary equipment for determining the Q
e
т
values are not considered in this article
(the subject of a separate paper), and the Q
e
serv.
value is preset.
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