Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2
Concepts on the rhomboidity formation nature for continuously cast billets were developed and detailed within the framework of the approach proposed earlier. At the same time, the practical orientation of the research results was a priority goal. The adduced regularities and mechanisms of the rhombo...
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| author | Писарський, Сергій Смірнов, Олексій Біктагіров, Фаріт |
| author_facet | Писарський, Сергій Смірнов, Олексій Біктагіров, Фаріт |
| author_institution_txt_mv | [
{
"author": "Сергій Писарський",
"institution": "Дослідник-фрілансер"
},
{
"author": "Олексій Смірнов",
"institution": "Фізико-технологічний інститут металів та сплавів НАН України"
},
{
"author": "Фаріт Біктагіров",
"institution": "Інститут електрозварювання ім. Є.О. Патона НАН України"
}
] |
| author_sort | Писарський, Сергій |
| baseUrl_str | https://www.metalsandcasting.com/index.php/mcu/oai |
| collection | OJS |
| datestamp_date | 2026-07-22T12:09:42Z |
| description | Concepts on the rhomboidity formation nature for continuously cast billets were developed and detailed within the framework of the approach proposed earlier. At the same time, the practical orientation of the research results was a priority goal. The adduced regularities and mechanisms of the rhomboidity initiation and growth processes are based on the provisions known from technical mechanics and strength of materials. Operation and maintenance experience for billet continuous casting machines was also taken into account. The achieved level of understanding of these regularities allowed to explain the increased addiction for medium carbon steel billets to rhomboidity. Moreover, the mechanism of occurrence for the extremely undesirable so-called "autocatalytic" character of the rhomboidity formation process was explained. Based on the research results, new solutions to reduce the billet rhomboidity were also proved and proposed. A noticeable improvement in the rhomboidity billet quality was achieved during the implementation of technical, technological and organizational measures, both known and new. The average annual sorting index on the rhomboidity for medium carbon steel billets 125x125 mm was reduced from 1.79 to 0.08 % for 5 years after the start of research and measures implementation. Those measures that, due to objective reasons, were not implemented, including for operational (during casting) reduction of rhomboidity, can be transferred to interested structures. |
| first_indexed | 2026-03-12T15:49:49Z |
| format | Article |
| fulltext |
35ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
“Starvation” over the past decades of the rhomboid-
ity problem for billet CCMs is largely due to the lack of a
clear understanding of the regularities of the rhomboidity
formation process activation, the influence mechanisms
for a variety of factors, as well as the available opportuni-
ties for active counteraction to them. The current situa-
tion, in our opinion, is partly due to the fact that the SCC
technology is located at the junction of various fields of
knowledge, including those that are quite far from those
that form the foundation of metallurgical science. To
this we can add the obvious fact that the peak of inter-
est to the applied research in metallurgy is in the past.
Considering that now this research is carried out mainly
at technical universities, one can note that the lack of
researcher’s production experience, unfortunately, can-
not be compensated by the high theoretical level of their
U
nderstanding of the nature and regularities of vari-
ous phenomena that reduce the technological pro-
cesses efficiency in metallurgy, including steel con-
tinuous casting (SCC), is a necessary condition for
their improvement. The phenomenon of spontaneous (in
the casting process) transformation of a square profile of
continuously cast billets (CCB) into a rhombic one, stud-
ied in this article, reduces not only the productivity of bil-
let continuously cast machines (CCM), but also the yield
index. The need for increased attention to adjustment
and maintenance of the CCM’s casting arc equipment,
including mould, its oscillation mechanism, monitoring
the mould copper tubes state, foot and support guid-
ing rolls, branch pipes and water sprayers of secondary
cooling (SC), water quality, etc. complicates the CCM’s
operation, requires highly qualified personnel.
ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022, № 2 (329), 35-46
https://doi.org/10.15407/steelcast2022.02.035
UDC 621.746
S.M. Pisarskyi, freelance researcher, e-mail: serge.pisarsky@gmail.com, https://orcid.org/0000-0002-2737-4518
O.M. Smirnov1, Dr. Sci. (Engin.), Professor, Head of the Department, e-mail: stalevoz@i.ua,
https://orcid.org/0000-0001-5247-3908, Web of Science ResearcherID: N-1890-2017
F.K. Biktagirov2, Dr. Sci. (Engin.), Senior Research Scientist, Leading Researcher, e-mail: biktagirov@paton.kiev.ua,
https://orcid.org/0000-0001-7843-4261
1Physico-technological Institute of Metals and Alloys of the NAS of Ukraine (Kyiv, Ukraine)
2 E.O. Paton Electric Welding Institute of the NAS of Ukraine (Kyiv, Ukraine)
Analysis and development of modern concepts on the
rhomboidity formation nature for continuously cast billets. Part 2
Concepts on the rhomboidity formation nature for continuously cast billets were developed and detailed within the
framework of the approach proposed earlier. At the same time, the practical orientation of the research results was a
priority goal. The adduced regularities and mechanisms of the rhomboidity initiation and growth processes are based on
the provisions known from technical mechanics and strength of materials. Operation and maintenance experience for
billet continuous casting machines was also taken into account. The achieved level of understanding of these regulari-
ties allowed to explain the increased addiction for medium carbon steel billets to rhomboidity. Moreover, the mechanism
of occurrence for the extremely undesirable so-called "autocatalytic" character of the rhomboidity formation process
was explained. Based on the research results, new solutions to reduce the billet rhomboidity were also proved and pro-
posed. A noticeable improvement in the rhomboidity billet quality was achieved during the implementation of technical,
technological and organizational measures, both known and new. The average annual sorting index on the rhomboidity
for medium carbon steel billets 125x125 mm was reduced from 1.79 to 0.08 % for 5 years after the start of research and
measures implementation. Those measures that, due to objective reasons, were not implemented, including for opera-
tional (during casting) reduction of rhomboidity, can be transferred to interested structures.
Key words: rhomboidity, spatial deformation, thermoelastic stresses, coefficient of linear thermal expansion (com-
pression), complex strength, bending and torsion strains, stability, linear and angular displacements, tolerances.
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
36 ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
formed billet profile relatively to the mould tube and, as a
result, triggers its distortion process.
In the general case, the profile deviation can be ad-
duced as a result of its linear displacements in the trans-
verse direction (in the YOX plane) and angular rotation
(relatively to the longitudinal Z axis) (Fig. 2). As evidence
indicating the presence of such deviations, one can cite
facts well known from the practice of billet CCM. For ex-
ample, this is indicated by such a fact as the unequal lu-
nule depths on the mould tube outward surfaces from the
centering screws along the perimeter. This is observed
at "rhombic" strands. The lunule depths from the center-
ing screws indention on some faces can reach 1–2 mm,
while on another faces they may be absent. In addition,
the fact of extremely uneven (along the profile perimeter)
wear of the inward working surface of some mould tubes
is well known.
Precision tube positioning in the mould is performed
using two or three rows of centering screws spaced apart
in height (Fig. 3). It is necessary both to ensure tube con-
centricity with the strand longitudinal axis, and to equal-
ize the conditions for its cooling (primary cooling circuit).
The thermal gaps adjustment differing somewhat ac-
cording to the screw rows is provided (during the mould
training. Meanwhile, production experience, as will be
shown below, is an important condition for the develop-
ing objective concepts about the nature of this undesir-
able phenomenon (rhomboidity of CCB).
Let us consider in detail those provisions that follow
from the approach proposed in the first part of this article
[1]. Remind, that the violation of the uniform contact con-
ditions for the billet and mould, that triggers the profile
distortion process, should be considered, first of all, as
a result of the billet three-dimensional elastic deforma-
tion within CCM’s casting arc. To determine this defor-
mation, it is necessary to study "Mould – Billet – Sec-
ondary Cooling Zone" (M-B-SCZ) system (Fig. 1). In this
case, various technical (design features of the M-B-SCZ
system elements, level of their maintenance and condi-
tion, precision of their positioning and adjustment, etc.)
and technological (temperature-speed mode of casting,
cooling parameters, steel chemical composition, etc.)
factors, that, as practice shows, greatly affect both the
occurrence probability and rhomboidity magnitude, are
easily integrated into concepts in question. The billet
deviation from the nominal position (technological axis
of the strand) is a consequence of its spatial deforma-
tion. This deviation violates the concentric position of the
M-B-SCZ system on the example of DANIELI billet CCM (type 3BLC08/06), put into operation at MMZ ISTIL UKRAINE in
1999 (1 – mould; 2 – lever type mould oscillation unit (MOU) with electromechanical drive; 3 – oscillating supporting table; 4 – pneu-
matic springs to balance the oscillating masses; 5 – set of foot rolls; 6 – support guiding rolls; 7 – centering pinch rolls; 8 – withdrawal
and straightening unit (WSU); 9 – SCZ with water sprayers sets installed on stainless steel branch pipes arranged on the 4 sides of
the billet; 10 – guiding delimiters of billet lateral deviation; 11 – base curvature center; 12 – strand base radius R; 13 – billet)
Fig. 1.
37ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
assembly) under the manual in order to compensate the
tube thermal expansion. In general, used mould design
solutions provide the possibility of some tube position
correction (so-called "self-alignment") during the casting
process. Billet rhomboidity during the casting of several
heats series, as a rule, gradually decreases and stabi-
lizes for this reason. This circumstance explains such
fact, well known from practice, that for CCMs, where on-
ly one billet profilesize is cast, the rhomboidity problem
sharpness is practically absent. At MMZ ISTIL UKRAINE
100 % of CCB was produced for sale, the portfolio of
orders included 5 square profilesizes and 5 round pro-
filesizes. Change of profilesizes under this circumstance
was carried out up to 5–6 times a month, so the rhom-
boidity problem was topical.
The results from the measurement protocols per-
formed using the VATRON MoldChecker laser measur-
ing device were analyzed at MMZ ISTIL UKRAINE to
identify the features of the mould tubes wear character.
This device provides both 3-d picture of the billet work-
ing surface wear relatively to billet initial profile (at the
time of supply), and the foot rolls actual position (Fig. 4).
Possible linear and angular deviations for the billet
profile (normal cross section) in the mould (1 – billet profile;
2 – working (contact) perimeter of the mould tube; XOZ – verti-
cal plane, in which the axis of the strand is located; XOY – plane
of normal cross section (transverse); double-edged arrows
show possible billet profile displacements in the XOY plane)
Fig. 2. Centering tube in the billet CCM mould (1 – stainless
steel "jacket" of the mould; 2 – mould tube; 3 – centering screw
with a lock nut; 4 – adjustable thermal gap with thickness of
0.3–0.4 mm; 5 – water "jacket" with thickness of 3–4 mm
Fig. 3.
Graphic files from the measurement protocols of the VATRON MoldChecker for the mould tubes wear and the foot rolls
position on "rhombic" strands: a – isometry of the tube working surface wear; b and c – the tube surface involutes for intense wear
of the near-corner zones; d – foot rolls position
Fig. 4.
38 ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
of the tundish metal jet concentricity with the longitudi-
nal axis of the mould or features of the natural convec-
tion development in the billet liquid core at radial CCM.
These factors are responsible for uneven heat transfer
along the billet profile perimeter and heat fluxes at the
solidification front. It, in turn, leads to thermal asymmetry
of billet profile, that amplifies with an increasing in the
casting speed and cast steel overheat. Thermal asym-
metry is also caused by factors that result in non-uniform
heat removal from the billet both in the mould and in the
SCZ. These factors include uneven mould tube wear and
tube misalignment in the mould, clogging and misalign-
ment of the SC water sprayers, unstable casting speed
and forced short-term stops during casting, for example,
due to steel castability deterioration [2], etc.
It is important to note that the spatial deformation that
triggers the billet profile distortion process can be caused
by factors of both the first and second groups. At the
same time, some factors of the second group can arise
both independently and as result of the first group fac-
tors action, i. e. be secondary or induced. Therefore, the
rhomboidity formation process can have a various and
multifactor character. If, as shown in [3], it is accompa-
nied by a constant change in the rhomboidity magnitude
and direction (sign), then it is obviously that periodically
there is both some growth and subsequent weakening of
the profile distortion process. It is also obviously that the
conditions necessary for the appearance of such rhom-
boidity “evolution” mode should differ from the conditions
under which the profile distortion process is able to take,
according to the some researchers, the so-called “auto-
catalytic”, i. e. self-supporting character of the process
with the end result in the form of nonchanging direction
(sign) high rhomboidity [4].
Fig. 5 shows a noticeable transverse displacement
(up to the prop against the roll flange) of the billet con-
tact track on the 4th support guiding roll of the SCZ,
disclosed at the "rhombic" strand. Such noticeable bil-
let displacement from the strand axis is accompanied by
In the course of this analysis, it was found that the si-
multaneous wear of all four near-corner tube zones at
all operation stages is a fairly typical phenomenon (Fig.
4 b, с). Significant wear of the tube near-corner zones
with a cast tonnage of less than 1000 tons is shown in
Fig. 4 b. Tubes with high wear of the near-corner zones
are usually decommissioned ahead of schedule despite
a small operation life (steel cast tonnage), since the use
of such tubes significantly increases the billet rhombo-
idity probability, especially from medium carbon steel.
The use of such tubes for casting of high-carbon steel
can also lead to the formation of both near-corner cracks
and longitudinal compression on the billet surface.
Obviously, that this wear type can be caused, first of
all, by the angular deviation (rotation) of the billet pro-
file relatively to the longitudinal Z axis through the billet’s
torsion. This moment deserves special attention when
studying the features of stresses and strains in the billet
under the action of various factors. Active1 and passive
forces act on the billet in the M-B-SCZ system. Active are
the potential forces of thermoelasticity, gravity, as well as
the forces acting from the pinch centering rolls. Passive
forces are the so-called reactions from various type sup-
ports. The following assumptions can be used when pre-
paring the calculation scheme for the M-B-SCZ system.
A billet formed within the billet CCM casting arc can,
in the first approximation, be considered as a tubular bar
with a curved axis and a changeable (along the length)
rigidity seeing its changeable shell (wall) thickness. The
longitudinal bar axis is a plane curve lying in the vertical
XOZ plane. It should nominally coincide with the strand
technological axis. Billet parts located in the mould and
WSU can in the first approximation be considered, re-
spectively, as having a slide and rigidly fixed supports.
Support guiding rolls No. 2, 4 in the calculation scheme
for the M-B-SCZ system shown in Fig. 1 can be defined as
hinged movable supports, and No. 1, 3 (depending on the
upper pinch rolls design) – as slide or bi-slide supports.
The described M-B-SCZ system is statically indetermi-
nate. A detailed analysis of the calculation scheme for this
system and the solution methods known from the strength
of materials are far beyond the frame of this study. So we
will restrict ourselves to considering only those provisions
that are necessary to understand the mechanisms and
regularities of billet spatial deformation.
The stresses that arise in the formed billet and cause
its spatial deformation can be created by two groups of
factors. The first group includes factors caused by devia-
tions of various elements of the M-B-SCZ system (mould
tube; foot, centering pinch and support guiding rolls;
WSU) relatively to their nominal position and uneven
wear of their surfaces contacting with billet. The second
group includes factors that influence the billet thermal
state. For the second group factors the billet spatial defor-
mation takes place only if its formation process is accom-
panied by the appearance of an asymmetric temperature
distribution in billet normal cross section. The following
factors can be attributed to the second group: violation
1Here and further in the text, the terms used in the relevant chapters of
technical mechanics and strength of materials are in italics
Transverse displacement of the billet contact track on
the 4th support guiding roll
Fig. 5.
39ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
uneven SC of the billet, since the SC water sprayers are
aligned strictly relatively to this axis. Such displacement
creates guaranteed conditions for the billet spatial de-
formation and the rhomboidity generation. It is important
to emphasize that the billet spatial deformation process
activation and subsequent profile distortion in the mould
can be due to the factors of both groups indicated above,
but achieving a self-supporting character for the profile
distortion process requires specific conditions, that will
be discussed below.
An explanation of increased addiction for billets from
medium carbon steel to rhomboidity that fully fits into the
proposed approach framework and the provisions formu-
lated on its basis seems to be as following. So, it is logi-
cally to assume that the reason for such addiction can be
associated with the intensity of spatial deformation, pri-
marily due to the uneven billet cooling. The elementary
volumes of an unevenly cooled elastic body cannot free-
ly shrink, that leads to the appearance of thermoelastic
stresses in it. In this case for isotropic material Hooke’s
law be generalized to include thermal effects. The total
strain e of each elementary volume in this case is the
sum of its thermal e(T) and mechanical e(M) strains: e =
= e(M) + e(T) [5, p. 405]. Then, for the projection of the total
strain on the X axis will be equal to:
ex = e(M)
x + e(T)
x = [σx – ν(σy + σz)]/E + al·DT.
Here al – CLTE(C) – coefficient of linear thermal expan-
sion (compression), °C−1; DT – temperature change, °С;
σX, σY, σZ – projections of normal stresses along the X,
Y, Z axes; ν – Poisson's ratio for steel; E – modulus of
elasticity, MPa.
Considering that e(T)
X = e(T)
y = e(T)
z = al·DT, the formulas
for determining the projections of the total deformation
of elementary volume ey and ez on the Y and Z axes will
be similar for ex, but differ only in the part that defines
e(M)
y and e(M)
z .
It can be seen from the above formulas that CLTE(C) al
is a physical characteristic that determines the deforma-
tion magnitude of an elastic body due to thermoelastic
stresses. One can assume that this physical character-
istic of the material is precisely the link that indicates the
cause for the increased addiction for medium carbon steel
billets to rhomboidity. Indeed, a check on the known data
[6, 7] confirmed the presence of the supposed nonlinear
dependence of CTE(C) for carbon steel on the carbon
content al = f ([С]). Fig. 6 shows that this dependence has
an explicit local maximum in the range of contents [C] =
= 0.30–0.32 %. Disclosed local maximum coincides with
the maximum in the graph of the rhomboidity depend-
ence on the carbon content in steel [1]. Considering the
fact that the phase transition Feg → Fea in steel occurs in
the temperature range T ≈ (700–900) °C with the steel
volumetric expansion, this interval was excluded from
consideration when plotting graphical dependences al =
= f ([C]). It can also be assumed that the dependence al =
= f ([С]) retains an extreme character with a local maximum
in the indicated carbon contents region at temperatures
above 1000 °C. One can note that the CLTE(C) al values
during steel cooling are higher than during its heating.
We cannot exclude that, along with the proposed,
also additional mechanisms may be for the influence of
other chemical elements in steel on its addiction to rhom-
boidity. For example, for boron and manganese steels,
such addiction, in our opinion, can be associated with
the fact that with an increasing in the content of Mn and
B in steel, its elastic limit increases. This ultimately leads
to an increase in steel deformation due to thermoelastic
stresses.
Let us mention the main provisions that must be
taken into account for the considered M-B-SCZ sys-
tem without going deeply into the determining stresses
and strains methods known from strength of materials
and technical mechanics. So, the assumption about the
strain smallness (compared with the dimensions of the
body itself) is used for the body subjected to loading that
do not go beyond the elastic region [5]. Further, the fol-
lowing analogy with the action of external forces is used
when formulating problems of thermoelasticity in strains
(displacements): displacements and strains in a heated
body arise the same as in an unheated one (from the
same material and the same shape), if equivalent exter-
nal forces (volumetric and superficial) are applied to it. In
the general case, these forces are determined by known
formulas and they take into account the thermophysical
characteristics of the material, including CLTE(C), modu-
lus of elasticity, thermal conditions, etc. [5, p. 407].
The main regularities that cause billet spatial defor-
mation within the CCM casting arc, including the mould,
are following. It is known [8, p. 345; 9] that the bending
of a curved bar in the case when the forces acting on it
do not lie in the principal plane of inertia (that in our case
coincides with the bar longitudinal axis plane or, in other
words, with the plane of its initial curvature), leads to the
complex strength appearance. Complex strength is char-
acterized by the presence of more than two force factors
in bar normal cross-sections. In the general case, load-
ing of the small curvature bar by an arbitrary load leads
to the simultaneous occurrence in its cross-sections of all
six internal force factors, namely: normal force N, shear-
ing forces Qy, Qx, torque Mz and bending moments Mx,
Dependence of the CLTE(C) on the [C] and tempera-
ture for carbon steels according to [6, 7] (Ar3 is the polymorphic
transformation (Feg → Fea) beginning temperature during steel
cooling)
Fig. 6.
40 ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
My. Normal (from bending) and shear (from bending and
torsion) stresses arise under the action of the indicated
force factors. Since shear stresses from shear forces Q
and due to bar bending are in most cases significantly
less than shear stresses from torsion, they are usually
disregarded. For the same reason, normal stresses from
the bar compression-tension forces N are often disre-
garded. Therefore, the combination of torsion with pure
bending is actually considered in the calculations. The
displacement of the cross section center along the X and
Y axes is determined by the Mohr’s method. With regard
to the problem under consideration, the view of the force
factors acting in certain normal sections of the billet can
be as shown in Fig. 7.
The bar axis curvature has some effect on the stress
distribution in its cross sections, but its influence be-
comes significant only for a large curvature bar, when
the ratio of the axis curvature radius to the height of its
profile (cross section) is less than 5. The influence of the
axis curvature on the stresses and strains in the bar of
small curvature is insignificant; therefore, the calculation
of such bars for bending with sufficient accuracy can be
performed using the formulas for a rectilinear bar [9].
If the external acting forces plane (force plane) coin-
cides with the bar curvilinear axis plane then the planar
bend for such bar is unstable under certain conditions.
In particular, the stability loss for a curved bar is possible
when small deviations of the acting force from the princi-
ple plane of inertia lead to lateral deflection and torsion
of the curved bar. Bar bending in this case also occurs
in a plane that is perpendicular to the force plane, with
its cross-section rotating by a certain angle. Instead of
a planar bend, a bend in two planes with simultaneous
torsion of the bar cross section takes place. Bar axis de-
viation from the nominal position in this case can lead
to the tilting moment appearance. The loss of bar stabil-
ity occurs when the tilting moment becomes higher than
the moment of stability. When the body loses stability, it
tends to take a position with minimal potential energy. All
existing restrictions on possible linear (in the transverse
direction) and angular (relatively to the longitudinal axis)
billet displacements for the investigated M-B-SCZ sys-
tem should be taken into account.
As an example of such a loss of stability for a curved
bar we can give the following from everyday life. So, when
you try to unbend a curved bar because of the action
in its normal cross-sections along with the bending mo-
ment also arising torque, its position becomes extremely
unstable. One can assume that this kind of instability is
one of the main reasons for the "autocatalytic" mode of
the rhomboidity formation process. Its result is high and
difficult to eliminate rhomboidity of nonchanging direction
(sign). It is obvious that such situation is possible under
certain conditions. According to our estimates, it is pos-
sible, for example, if the deformations under the action of
the bending moment My in the vertical XOZ plane tend to
reduce the bar curvature. Both technological and techni-
cal factors can lead to the appearance of such situation.
It is obvious that the ranking of various factors affect-
ing the billet rhomboidity and the optimization of meas-
ures foreseen to reduce the probability of its occurrence
and subsequent steady growth should be carried out
taking into account the presented theoretic provisions.
Priority can be considered those measures, the imple-
mentation of which reduces the probability of an "auto-
catalytic" mode of the rhomboidity formation. It is also
obvious that the number of factors that can provoke the
transition to the indicated mode are less than those that
contribute the rhomboidity initiation.
Complex strength may also arise in a rectilinear bar
with the so-called planar and spatial unsymmetric bend-
ing [5, p. 237]. In the first case, the force plane does not
coincide with its principal planes of inertia. In the second,
external forces act in different planes. The bar curved
axis for these cases is, respectively, planar or spatial
curve. Сonsequently, the considered mechanisms and
regularities of spatial deformation of curved and rectilin-
ear bars are applicable to billets cast at CCMs of both
radial and rectilinear types. The latter were built in the
last century and they were also characterized by the bil-
let rhomboidity problem. Thus, the presented provisions
from the field of technical mechanics and strength of ma-
terials for stresses and strains in rectilinear and curved
bars are clue in understanding the causes of the billet
spatial deformation that initiates its profile distortion pro-
cess and can, under certain conditions, go into an unde-
sirable "autocatalytic" mode.
According to the analysis results of theoretical and
practical aspects for the rhomboidity problem there is
reason to believe that:
1) the rhomboidity initiation can be due to both factors
that cause some initial uneven cooling (for example, due
to linear or angular deviation of the tube relatively to the
strand axis, clogging of water sprayers, etc.), and factors
that cause billet initial spatial deformation (for example
due to various kinds of deviations and inconsistencies in
the M-B-SCZ system elements position) and, as a result,
complex strength in the solidified billet with its subsequent
additional spatial deformation;
Scheme of force factors acting in the normal cross-
section of a curved bar when it is loaded with an arbitrary load
without taking into account the shearing Q and normal N forces
(P – principal plane of inertia; OX and OY – principal central
axes of inertia for normal cross section; Mz – torque; Mx, My –
bending moments)
Fig. 7.
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ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
2) depending on the actual conditions determined by
a combination of acting factors, some initial rhomboidity
can both steady grow and spontaneously weaken with
change of direction (sign);
3) the factor of uneven cooling (both primary and sec-
ondary) plays a determining role in the noticeable (ex-
ceeding the permissible limits) rhomboidity formation.
Such unevenness can be both a consequence of vari-
ous violations in the operation of cooling systems and
a consequence of the billet spatial deformation due to
complex strength because of the reasons noted above
and associated with tolerance violations for the M-B-SCZ
system elements positioning. This provision correlates
with the above proposed explanation of the nature of the
increased addiction to rhomboidity for medium-carbon
steel billets;
4) the rhomboidity formation process gets an ex-
tremely undesirable "autocatalytic" mode in the presence
of factors that provoke the loss of billet static stability.
Since the rhomboidity initiation can be provoked by
even a slight deviation of any M-B-SCZ system element
from the nominal position, the relevant design and tech-
nological documentation establishes fairly tight toler-
ances for all dimensions, including linear and angular,
that determine their position relatively to the base radius
arc. Support guiding and pinch centering rolls, located
along the base radius arc are mounted on roller bear-
ings. They ensure the billet positioning strictly in the
required location. The upper rolls pinch the billet to the
lower rolls using a pneumatic system. A spatial system
of datum marks, relevant geodetic equipment, a special
template, a measuring tool are used for precise mount-
ing and alignment of support guiding rolls. These proce-
dures, including the actual position periodic checks of the
M-B-SCZ system elements and their adjustments, are
quite laborious, require the qualified personnel involve-
ment, reduce the productivity of the CCM and increase
the billet cost.
Since the mould is structurally an assembly unit, and
the billet in the mould is in contact with the copper tube
and foot rolls, their precise positioning is a responsible
procedure performed in accordance with a special man-
ual. The tube position error relatively to the CCM strand
base radius arc is determined by the total error of the
corresponding dimensional chains. The foot rolls block
is mounted on the mould lower flange. Individual adjust-
ment of each roll is made relatively to the previously
centered (in the mould body frame) tube by adjusting
the angular position of their eccentric axes. In this case
the special template is applied. For this procedure steel
shrinkage is taken into account.
Tolerances for mounting dimensions that determine
the position of the MOU and the mould itself on the MOU
are ± 0.15 mm. Tolerances for the mating dimensions of
the mould parts (upper and lower flanges, "jacket", etc.),
that determine the position of the tube in the mould body
frame, are set according to the eighth tolerance grade
IT8 (quality class). For comparison, we note that the tol-
erance for the deviation of the tube actual profile from the
specified one (determined by the value of steel shrink-
age) is ± 0.1 mm, and the tolerances for various shape
deviations in the tube internal profile (convexity, concav-
ity, non-parallelism, misalignment or skewness, etc.) are
0.15–0.25 mm per side. The angular deviation tolerances
for the various SCZ rolls are: for foot rolls – 0.1 mm per
roll length (or 0.04–0.05 degrees), for support guiding
rolls – 0.2 and 0.5 mm per 1000 mm (or 0.01 and 0.03
degrees) respectively in the longitudinal and transverse
planes (Fig. 8 a). Practice shows (Fig. 4 d) that the actual
angular deviations of the foot rolls on "rhombic" strands
can significantly exceed the specified tolerance (respec-
tively 0.4–0.6 degrees versus 0.04–0.05 degrees). The
foot rolls with such deviations cannot ensure the con-
centric position of the billet top relatively to the tube in
case of the billet spatial deformation. The linear devia-
tion tolerances for the M-B-SCZ system elements rela-
Tolerances for angular (a) and linear (b) deviations of the support guiding rolls for DANIELI typical billet CCM with base
radius R = 8 m (1 – lower support guiding roll; 2 – upper pinch centering roll)
Fig. 8.
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ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
tively to the CCM base radius arc during their mounting
and alignment are: for the tube – ± 0.25 mm, for support
guiding rolls No. 1–3 and the WSU rolls – 0… + 0.5 mm
(Fig. 8 a), for support guiding roll No. 4 – ± 0.25 mm.
In practice, the enterprise’s mechanical service for
various reasons, for example, through the lack of a spe-
cial template, may not abide by these requirements or
recommendations, simplify the design of units or proce-
dures for checking and positioning, replace alloyed steel
grades with usual carbon grades, etc. Such actions can
negatively affect the rhomboidity situation. One can note
that the factors associated with the unsatisfactory main-
tenance and adjustment of the casting arc equipment at
many enterprises are considered as priorities in obtain-
ing rhomboidity. Therefore, the main responsibility for
the loss of billet quality indicators by rhomboidity in the
absence of obvious violations in steel production techno-
logy, including continuous casting (increased sulfur and
phosphorus content, violation of the temperature and
speed casting condition, violation of the SC parameters,
etc.) is laid on the mechanical services of the shop and
CCMs.
One can note that the mould deviation, as a dynamic
element of the M-B-SCZ system, from the nominal posi-
tion can have not only a constant (like for all other ele-
ments), but also a variable (changing during the oscil-
lation cycle) components. Primarily the MOU technical
state and the results of foreseen balancing procedure
(by means of pressure change in the MOU pneumatic
springs) influence the variable component value. The
conditions for transverse wave formation on the metal
mirror in the mould and, as a result, a noticeable increase
in the magnitude of metal level fluctuations are created
under a significant magnitude of the variable component
for transverse deviation (the so-called vibration displace-
ment) along the X and Y axes due to the dynamic inter-
action of mould with billet. As noted earlier [1], such wave
formation under certain conditions can also contribute to
the rhomboidity occurrence.
Various methods of vibrodiagnostics are used to es-
timate the MOU technical condition. Vibrodiagnostics
using a specialized Oscillation.Checker device from the
Austrian company VATRON, in our opinion, is the most
informative and visual (Fig. 9 a). This device provides
continuous measurement of movement parameters in
three planes, visualization and recording of results. It al-
lows to determine the actual oscillation parameters (for
example, the NST parameter, the mould lead, etc.), as
well as the vibrodisplacement magnitudes, vibrovelocity,
vibroaccelerationes in 3 axes, to identify the presence of
phase distortion and mould torsional oscilations around
the longitudinal Z axis.
Fig. 9 b, c, d shows the mould vibrodisplacement
graphs in the transverse XOY plane, taken from the
MOU vibrodiagnostic protocols for the lever type MOU.
The presented results were obtained using simultane-
ously two sensors installed on the oscillation supporting
table on the right and left (along the Y axis) of the mould.
The vibrodisplacement of the mould cross section geo-
metric center along the X and Y axes is determined as
the arithmetic mean of the corresponding displacements
for the two sensors along these axes. Fig. 9 e, f shows
the vibrodisplacement graphs along the Y axis for the
oscillation cycle, corresponding to the graphs of Fig. 9 c,
d. They demonstrate the complex spatial movement of
the oscillating mould. The presented graphs show that
Oscillation.Checker sensor (а); the mould vibrodisplacements in the transverse XOY plane on strands Nos. 1, 2, 5 (b, c,
d); the mould vibrodisplacement along the Y axis for the oscillation cycle (graphs in the e, f-figures correspond to graphs in the c,
d-figures). Graphs notation: 1, 2 – graphs of the left and right Oscillation.Checker sensors
Fig. 9.
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ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
the mould during the oscillation process can move in the
Y axis direction (close to plane-parallel movement), and
also can perform torsional oscillations concerning the
longitudinal Z axis. Such torsional oscillations can, along
with the billet torsion, contribute to accelerated wear of
the mould tube near-corner zones and thereby contrib-
ute to the rhomboidity generation.
Vibrodisplacement along the X axis consists of two
components: 1) due to the mould movement along the
base radius arc and 2) due to the presence of gaps in
the MOU kinematic chain. The first component can be
determined by knowing the base radius R and the oscil-
lation stroke. The resulting vibrodisplacement in the XOY
transverse plane can be defined as the vector sum of
vibrodisplacements along the X and Y axes.
As for the critical value of the mould transverse (in the
XOY plane) vibrodisplacements, according to the experi-
ence of billet CCM operation at MMZ ISTIL UKRAINE, it
was determined at the level of 0.7–1.0 mm. With these
values the probability of casting stability violation as well
as the billet rhomboidity appearance increases sharply.
Casting at strand with such results of vibrodiagnostics
can be allowed after maintenance (rebalancing of the
MOU, replacement of the mould) or replacement of a
life-expired MOU. In order to reduce the mould vibro-
displacement magnitude, to reduce the dynamic loads
on the MOU and to increase its resource at MMZ ISTIL
UKRAINE in 2008 we began to use the amplitude-fre-
quency mode of mould oscillation with the lowest pos-
sible oscillation frequencies, that was unified for square
profilesizes of 120, 125, 130 and 150 mm. This measure
eliminated the need to perform the laborious procedure
of the oscillation amplitude changing when changing the
billet profilesize, provided a reduction of labor costs and
time for changing the billet profilesize, provided main-
tenance simplification and the MOU technical condition
improvement, the CCM productivity increasing, and also
billet rhomboidity reduction.
Thanks to advanced theoretical concepts about the
billet rhomboidity nature it became possible to explain
the influence of various factors and production situa-
tions on this typical shape defect, and most importantly,
to give certain recommendations on the priority of vari-
ous measures foreseen to reduce the billet rhomboid-
ity. Let us consider, for example, such a typical situation
for billet CCM as the start of a reserve strand or restart
of a working strand during serial casting. As practice
shows, in this situation, the billet rhomboidity is observed
quite often. Deviations of the actual flow characteristics
Q = f(P) from the nominal ones are detected in these
situations very often and mainly in the lower sectors of
the SC. One should note that each SC sector, equipped
with a certain number of water sprayers of a certain type-
size, has a known dependence of water flow Q on its
pressure P. Deviations from the nominal characteristics
indicate various kinds of violations. In particular, if at a
nominal water flow its pressure in the system is higher
than the nominal one, then clogging of the water spray-
ers takes place (mainly on the side of a small radius r).
This situation leads to insufficient billet cooling on the
r side and overcooling on the R side. This leads to the
thermoelastic stresses appearance that aspire to reduce
the billet curvature. Such deformation, as shown earlier,
contributes to the most severe "autocatalytic" mode of
the rhomboidity formation process.
The alignment of support guiding rolls Nos. 1–3
(Fig. 1) relatively to the base radius arc not in the positive
tolerance limit, as required by the technical documenta-
tion (Fig. 8 b), but in the minus zone will lead to a simi-
lar negative result. In this case, the billet is affected by
forces from the pinch rolls (supports Nos. 1, 3 in Fig. 1)
and billet weight itself, that causes stresses and strains
from bending in some billet cross sections. They aspire
to reduce the billet curvature and provoke the loss of
its stability. The stability loss can also be provoked by a
number of other factors that directly or indirectly (through
complex strength) cause torsional deformation. One
such factor, for example, could be the imperfect design
of the upper centering pinch rolls.
Such rolls, for example, at DANIELI billet CCMs are
traditionally made conical (Fig. 8 a). In addition to cen-
tering the billet, they must perform pinch function. See-
ing that billets of 5 square typosizes were cast at MMZ
ISTIL UKRAINE, centering pinch rolls of DANIELI design
had uneven and stepped wear of conical surfaces. The
pinch force for such rolls with wear may often not coincide
with the billet initial curvature plane, that leads to complex
strength and, as a result, billet torsion strain relatively to
its longitudinal axis Z. In fact, a wear roll of this design
can provoke the rhomboidity generation. That is why we
at one time recommended for MMZ ISTIL UKRAINE to
transfer to the use of pinch rolls with smooth barrels and
flanges. Pinch rolls of this design are successfully used by
a number of companies, such as CONCAST et al. Com-
parative tests on part of the CCM strands confirmed the
effectiveness of this solution. After that the replacement
of conical pinch rolls was performed on all CCM strands.
Also, as an example of technological measures that
were proposed taking into account advanced concepts,
one can advert the SC corrected mode. One should note
that for the SCZ lower sectors of the radial type billet
CCMs, the point of view on the need for a uniform (along
the perimeter) SC to a certain extent contradicts the
physical regularities for the natural convection develop-
ment in the liquid core of the billet and convective heat
transfer at the solidification boundary. The displacement
of the cross section thermal center relatively to the geo-
metrical one towards the small radius r side indicates a
lower solidification rate along the upper billet facet and,
as a result, the presence of a profile thermal asymmetry
[10]. Considering this, as well as the fact that the water
sprayers of the lower SC sectors on the small radius r
side are most addicted to clogging, we also proposed to
install water sprayers with increased flow characteristics
on the two lower SC sectors on the small radius r side.
This solution reduces the clogging probability and pro-
vides more intensive cooling of the upper billet facet. As a
result, conditions are created that reduce the probability
of billet static stability loss during its spatial deformation
due to the complex strength appearance in it. Tests of
this extraordinary technological solution fully confirmed
its effectiveness. It was introduced in 2010 with the en-
44 ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
tering of appropriate changes to the CCM technological
instruction.
In general, the work begun in 2007 at MMZ ISTIL
UKRAINE aimed at reducing losses associated with ob-
taining rhombic billets included both theoretical studies
and the implementation of various measures of an organi-
zational, technical and technological character, including
known and proposed according to new concepts. Imple-
mentation of most measures was carried out only after
positive results at the preliminary tests stage. As a result,
it was gradually possible to significantly reduce the bil-
let sorting on the "rhomboidity" defect. The table shows
the dynamics of rhomboidity sorting for billet 125x125
mm from medium carbon steel Grade St5sp ([C] = 0.28–
0.37 %) according to DSTU 2651:2005/GOST 380-2005
for the period 2007–2011. This billet profilegrade was the
most wholesale in production. To compare the achieved
indicators and their dynamics, as an example, we can
present the data from [11] on similar indicators of one of
the US plants before and after the implementation of new
mould tube type (WAVE MOULD). The KME Company,
that developed and manufactures such mould tubes, po-
sitions them as an innovative product. At the same time,
the reduction in the billet rhomboidity is highlighted by
the company's specialists as the most noticeable among
other advantages of such mould tubes [12]. So, if before
the implementation of WAVE MOULD the sorting level on
rhomboidity for billet 178x178 mm from steel AISI 4130
([C] = 0.28–0.33 %) according to the ASTM A29 standard
was 2.12 % (2012), then after of their implementation, it
decreased to 1.62 % (2013).
Since it was not possible to implement a number of
measures, primarily requiring funding, due to the gen-
eral deterioration in the enterprise working conditions
after 2011, the authors are ready to consider transfer-
ring these and other solutions to interested structures.
Among these solutions, for example, the technological
Dynamics of rhomboidity sorting for billet 125x125 mm from steel Grade St5sp ([C] = 0.28–0.37 %)
Profilegrade of
steel
Billet rhomboidity sorting, %*
2007 2008 2009 2010 2011
125х125 mm St5sp 1.79 1.48 0.82 0.33 0.08
* – from the annual production volume of this steel profilegrade
know-how to quickly reduce the rhomboidity in the cast-
ing process is present. It was assumed that this solu-
tion would be integrated with the automated system for
billet rhomboidity measuring during casting, developed
at MMZ ISTIL UKRAINE and presented earlier [1]. One
should note that such solutions could become an integral
part of the smart technology for billet CCMs. Their effec-
tiveness, according to our estimates, is beyond doubt.
Their implementation will minimize economic losses
from the CCB rhomboidity, will simplify the maintenance
of CCMs, and will reduce the personnel qualification re-
quirements.
CONCLUSIONS
The development of theoretical concepts on the CCB
rhomboidty nature is carried out using the provisions
known from technical mechanics and strength of materi-
als. Results in studies of the mechanisms and regulari-
ties of the rhomboidity initiation and growth processes
made it possible to explain the reason for the increased
addiction for medium carbon steel billets to rhomboid-
ity. The proposed mechanism of appearance for the ex-
tremely undesirable so-called "autocatalytic" mode of the
rhomboidity formation process, that contributes to the
formation of a noticeable nonchanging direction (sign)
rhomboidity, makes it possible to distinguish among the
various types of "antirhombic" measures those that are
able to prevent its appearance. An in-depth understand-
ing of the billet rhomboidity nature made it possible also
to propose new effective technical and technological so-
lutions aimed at reducing rhomboidity. Achieved during
the research and implementation of various measures
period the rhomboidity sorting reduction for the medium
carbon steel billet confirms the effectiveness of both
proposed concepts and the implemented "antirhombic"
measures.
1. Pisarskyi S.M., Smirnov O.M. Analysis and development of modern concepts on the rhomboidity formation nature for
continuously cast billets. Part 1. Метал та лиття України. 2021. Т. 29. № 2 (325). С. 31–40. DOI: https://doi.org/10.15407/
steelcast2021.02.031
2. Писарский С.Н., Смирнов А.Н., Лавренко Д.А., Рябый Д.В. Оценка технологических возможностей стабилизации ско-
рости разливки открытой струей на современной сортовой МНЛЗ. Сообщение 1. Металл и литье Украины. 2018.
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stabilization-casting-open-jet-modern-billet
ЛІТЕРАТУРА
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ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
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11. Bakshi I.A., Piwowar H.-D. (2014). WAVE Mould for Improved Billet Shape and Quality. URL: https://hobbydocbox.com/
Jewelry_Making/109538469-Wave-mould-for-improved-billet-shape-and-quality.html
12. URL: https://www.kme.com/en/specialdivision/melting-casting/innovation-products/mould-tubes
Надійшла 20.02.2022
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steelcast2021.02.031
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11. Bakshi, I.A., Piwowar, H.-D. (2014). WAVE Mould for Improved Billet Shape and Quality. URL:https://hobbydocbox.com/
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Received 20.02.2022
46 ISSN 2077-1304. Met. lit'e Ukr., vol. 30, 2022. № 2 (329)
ПРОЦЕСИ БЕЗПЕРЕРВНОГО РОЗЛИВАННЯ СТАЛІ
Анотація
С.М. Писарський, дослідник-фрілансер, e-mail: serge.pisarsky@gmail.com,
https://orcid.org/0000-0002-2737-4518
О.М. Смірнов1, д-р техн. наук, проф., зав. вiддiлу, e-mail: stalevoz@i.ua,
https://orcid.org/0000-0001-5247-3908, Web of Science
ResearcherID: N-1890-2017
Ф.К. Біктагіров2, д-р техн. наук, ст. наук. співр., пров. наук. співр.,
e-mail: biktagirov@paton.kiev.ua, https://orcid.org/0000-0001-7843-4261
1Фізико-технологічний інститут металів та сплавів НАН України
(Київ, Україна)
2Інститут електрозварювання ім. Є.О. Патона НАН України
(Київ, Україна)
Аналіз і розвиток сучасних уявлень з природи формування ромбічності
безперервнолитих сортових заготовок. Частина 2
У ході розвитку та деталізації уявлень відносно природи ромбічності в рамках запропонованого в частині 1 цієї публі-
кації підходу акцент зроблено на практичній спрямованості проведених досліджень. Запропоновані закономірності та
механізми процесів зародження та зростання ромбічності спираються на відомі з технічної механіки та опору матеріа-
лів положення, а також на результати та факти з досвіду експлуатації та обслуговування сортових машин безперервно-
го лиття заготовок (МБЛЗ). На основі цих положень вперше запропоновано пояснення природи підвищеної схильності
до ромбічності заготовок із середньовуглецевої сталі, а також механізму виникнення так званого «автокаталітичного»
характеру процесу формування ромбічності, який є вкрай небажаним. За результатами досліджень запропоновано
нові рішення для зниження ромбічності заготовок. У ході реалізації технічних, технологічних та організаційних заходів,
як відомих, так і вперше запропонованих, досягнуто помітне покращення якості заготовок з ромбічності. Середньо-
річний показник відсортування по ромбічності заготовок 125х125 мм із середньовуглецевої сталі протягом п'яти років
з початку досліджень та реалізації заходів був знижений з 1,79 до 0,08 %. Ті заходи, які з об'єктивних причин не були
реалізовані, зокрема з оперативного (по ходу розливання) зниження ромбічності, можуть бути передані зацікавленим
структурам.
Ключові слова
Ромбічність, просторова деформація, термопружні напруги, коефіцієнт лінійного тепло-
вого розширення (стиснення), складний опір, деформації згинання та кручення, стійкість,
лінійні та кутові переміщення, допуски.
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| id | oai:oai.metalsandcasting.com:article-15 |
| institution | Metal and Casting of Ukraine |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-23T01:01:13Z |
| publishDate | 2023 |
| publisher | Physico-technological Institute of Metals and Alloys |
| record_format | ojs |
| resource_txt_mv | wwwmetalsandcastingcom/4f/c7a93a74c545c8bbaf8d869057b71a4f.pdf |
| spelling | oai:oai.metalsandcasting.com:article-152026-07-22T12:09:42Z Analysis and development of modern concepts on the rhomboidity formation nature for continuously cast billets. Part 2 Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 Писарський, Сергій Смірнов, Олексій Біктагіров, Фаріт rhomboidity spatial deformation thermoelastic stresses coefficient of linear thermal expansion (compression) complex strength bending and torsion strains stability linear and angular displacements tolerances ромбічність просторова деформація термопружні напруги коефіцієнт лінійного теплового розширення (стиснення) складний опір деформації згинання та кручення стійкість лінійні та кутові переміщення допуски Concepts on the rhomboidity formation nature for continuously cast billets were developed and detailed within the framework of the approach proposed earlier. At the same time, the practical orientation of the research results was a priority goal. The adduced regularities and mechanisms of the rhomboidity initiation and growth processes are based on the provisions known from technical mechanics and strength of materials. Operation and maintenance experience for billet continuous casting machines was also taken into account. The achieved level of understanding of these regularities allowed to explain the increased addiction for medium carbon steel billets to rhomboidity. Moreover, the mechanism of occurrence for the extremely undesirable so-called "autocatalytic" character of the rhomboidity formation process was explained. Based on the research results, new solutions to reduce the billet rhomboidity were also proved and proposed. A noticeable improvement in the rhomboidity billet quality was achieved during the implementation of technical, technological and organizational measures, both known and new. The average annual sorting index on the rhomboidity for medium carbon steel billets 125x125 mm was reduced from 1.79 to 0.08 % for 5 years after the start of research and measures implementation. Those measures that, due to objective reasons, were not implemented, including for operational (during casting) reduction of rhomboidity, can be transferred to interested structures. У ході розвитку та деталізації уявлень відносно природи ромбічності в рамках запропонованого в частині 1 цієї публікації підходу акцент зроблено на практичній спрямованості проведених досліджень. Запропоновані закономірності та механізми процесів зародження та зростання ромбічності спираються на відомі з технічної механіки та опору матеріалів положення, а також на результати та факти з досвіду експлуатації та обслуговування сортових машин безперервного лиття заготовок (МБЛЗ). На основі цих положень вперше запропоновано пояснення природи підвищеної схильності до ромбічності заготовок із середньовуглецевої сталі, а також механізму виникнення так званого «автокаталітичного» характеру процесу формування ромбічності, який є вкрай небажаним. За результатами досліджень запропоновано нові рішення для зниження ромбічності заготовок. У ході реалізації технічних, технологічних та організаційних заходів, як відомих, так і вперше запропонованих, досягнуто помітне покращення якості заготовок з ромбічності. Середньорічний показник відсортування по ромбічності заготовок 125х125 мм із середньовуглецевої сталі протягом п'яти років з початку досліджень та реалізації заходів був знижений з 1,79 до 0,08 %. Ті заходи, які з об'єктивних причин не були реалізовані, зокрема з оперативного (по ходу розливання) зниження ромбічності, можуть бути передані зацікавленим структурам. Physico-technological Institute of Metals and Alloys 2023-05-19 Article Article Рецензована Стаття application/pdf https://www.metalsandcasting.com/index.php/mcu/article/view/15 Metal and Casting of Ukraine; Vol. 30 No. 2 (2022): Metal and Casting of Ukraine Метал та лиття України ; Том 30 № 2 (2022): Метал та лиття України 2706-5529 2077-1304 en https://www.metalsandcasting.com/index.php/mcu/article/view/15/15 Авторське право (c) 2023 Сергій Писарський, Олексій Смірнов, Фаріт Біктагіров https://creativecommons.org/licenses/by/4.0 |
| spellingShingle | ромбічність просторова деформація термопружні напруги коефіцієнт лінійного теплового розширення (стиснення) складний опір деформації згинання та кручення стійкість лінійні та кутові переміщення допуски Писарський, Сергій Смірнов, Олексій Біктагіров, Фаріт Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 |
| title | Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 |
| title_alt | Analysis and development of modern concepts on the rhomboidity formation nature for continuously cast billets. Part 2 |
| title_full | Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 |
| title_fullStr | Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 |
| title_full_unstemmed | Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 |
| title_short | Аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. Частина 2 |
| title_sort | аналіз і розвиток сучасних уявлень з природи формування ромбічності безперервнолитих сортових заготовок. частина 2 |
| topic | ромбічність просторова деформація термопружні напруги коефіцієнт лінійного теплового розширення (стиснення) складний опір деформації згинання та кручення стійкість лінійні та кутові переміщення допуски |
| topic_facet | rhomboidity spatial deformation thermoelastic stresses coefficient of linear thermal expansion (compression) complex strength bending and torsion strains stability linear and angular displacements tolerances ромбічність просторова деформація термопружні напруги коефіцієнт лінійного теплового розширення (стиснення) складний опір деформації згинання та кручення стійкість лінійні та кутові переміщення допуски |
| url | https://www.metalsandcasting.com/index.php/mcu/article/view/15 |
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