Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Title of the Invention
High strength and high toughness steel bar, rod
and wire and the process of producing the same.
1 Background of the Inventlon
This invention relates to a manufacturing process of
high strength and tough steel bar, rod and wire hereinafter
briefly referred to as wire and the process of producing the
same.
Brief Des~ription of the Drawings
Fig. 1 shows the relationship among tensile strength,
torsion value, and reduction in area, Fig~ 2 and Fig. 3
respectively show the relationship between tensile
strength and carbon equival~ént, and Fig. 4 is a sectional
view of the equipment for drawing and cooling. Fig. 5
shows the relationship between the torsion value and
tensile strength and reduction in area in the manufac-
turing of conventional steel wires and the steel wires
by this invention, Fig. 6 shows the relationship
between number of passes of drawing and torsion value.
Fig. 7 is to show the relationship between torsion
value and the drawing speed, Fig. 8 is to show the
relationship among tensile strength and xeduction
in area, Fig, 9 is to show the relationship between
the torsion value and the number of passes of drawiny,
and Fig, 10 shows the relationship between the torsion
value and drawing speed. Fig. 11 is a sectional view
of a rope, and Fig. 12 shows the relationship between
= 25 the tensile strength and wire diameter and indicates
the area of poor toughness and poor ductility.
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1 Increase in total reduction in area for drawing or
increase in the strength of raw material is generally
adopted in order to attain high strength steel wire. In
case the total reduction in area is increased to attain
higher strength wire, however, the toughness is sharply
lowered when the strength of wires reaches the area
shaded in Fig. 12. In other words delamination takes
place at torsion test. As the bending property also
deteriorates, it can also cause breakage of ropes,
aluminium cables steel reinforced and PC strand at the
stage of stranding or closing, breakage at the stage of
forming spring, or breakage of wire in the middle of drawing.
Cr has also been used to increase the strength
of raw material after patenting~ Addition of Cr,
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1 however, increases, smut at the pickling process before
drawing. Pxoductivity and efficiency in the drawing
process is lowered due to lonyer pickling time and
defective lubrication film caused by smut.
In order to attain the plated high carbon hard drawn
s~eel wire or piano wire as specified in Japan
Industrial Standard (JIS), it is necessary to increase
strength of the steel wixe before plating as the strength
is greatly lowered by galvanizing.
According to JIS, high carbon steel wire is specified
by diameter and tensile strength, for example hard drawn
steel wire is specified by the tensile strength of 220
kgf/mm or higher for 1.0 mm diameter and smaller, and by
over 200 kgf/mm2 for 2.5 mm diameter and smaller. Where
the diameter is over 3.5 mm, however, 210 kgf/mm2 can
hardly be attained even with piano wire. This is because
the torsion value of wire with the diameter of 3.5 mm and
over is diminished to an abnormal level when tensile
strength of piano wire exceeds 220 kgf/mm2 or delamination
takes place in torsion test, is higher deformation to
attain the tensile strength exceeding (240 -68 log d) kgf/
mm2 and it makes the manufacturing difficult~ For hard
drawn steel wires of lower grade, in particular, it is
very hard to maintain high toughness with the strength of
over 210 kgf/mm2 for the wire with the diameter of 1.5 mm
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1 and larger as the required reduction of impurity at
manufacturing is not so strict as is required for piano
wire.
Accordingly, to the uncoated stress-relieved steel
wire and strand for prestressed concrete of JIS G3536
(ASTMA421), the practical tensile strength has been 197
kgf/mm2 or higher for wire of 2.9mm ~iameter, 165 kgf/mm2 or
higher ~or S mm diameter, and 189 kgf/mm2 ~r higher even
for strand wires. Particularly, manufacturing of large
10 diameter strand wires of 12.4 mm, 15.2 mm and 17.5 mm
diameters have been difficult as they are made of large
diameter wires of 4.2 mm or larger twist~d together.
The ropes of large diameter made of two or more
wires twisted together require strands of
1.5 mm and larger in most cases, and the toughness is
deteriorated by the use of large diameter wire.
Accordingly, wires for ropes of over 210 kgf/mm and of
over 1.5 mm diameter are not manufactured, which makes the
practical application of large diameter high strength
rope difficult.
Of the galvanized steel wires for the aluminium
cables steel reinforced is specified in JIS C3110
(ASTM B498), those of 2.6 mm diameter with tensile
strength of over 180 kgf/mm2 are produced in large
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1 quantity. When the tensile strength exceeds 210kg~/mm2,
however, the torslonal characteristic deteriorates and
practical application has not been made possible at the
present situation.
When the ordinary high carbon steel wire rod is
drawn under the conditions of 8 passes of drawing, 200
m/minute of drawing speed, and 90% reduction in area
for example, the torsion value is greatly reduced and
the following problems are raised to respective
products.
(A) PC wire
At the final taking up of wire after drawing, the
wire is broken at the turn roller and the coil
straightening roller, thus making the manufacturing
impossible. Even if the wire can be manufactured without
breakage, the wire is often broken by the anchoring
chuck during tensioning at the stage of introducing
prestressing force, thus making commercialization
impossible.
(B) PC strand
Besides the problem mentioned above br~akage occurs
at the stage of stranding if the embrittlement is
excessive and thus manufacturing of PC strand is
practically impossible. The merit of processing
for high strength wire is not obtained
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1 because the anchoring efficiency of the strand wire is
low due to the brittleness of wire.
(C) Galvanized steel wire
As to the galvanized steel wire for ACSR laluminium
cables steel reinforced) torsion value is specified at
the value of more than 16 turns or more than 20 turns.
Embrittled steel wires do not meet the specified
torsional value due to delamination. As a low torsion
value leads to a low fatigue strength it makes
co~nercialization difficult.
(D) Rope
A low torsion value makes stranding impossible. The
bending fatigue strength which is an important
characteristic for wire rope is also low, and it may lead
to serious trouble due to breakage during use.
To prevent embrittlement of steel wires, cold
drawing methods are also enmplyed in which the wire, after
drawing~ is cooled directly with water together with the
rear face of the dies to reduce heat generation from the
wire at draw ng and to cool the wire quickly. For
manufacturing of high strength and high toughness wire,
however, such methods as the compositions, number of
passes of drawing, total reduction in area, pa-tenting, and
cold drawing are combined systematically have not been
adopted so far.
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1 Summary of the Invention
In view of the prior art described above, it is a
general object of this invention to provide a manufacturing
method of steel wires which have properties of high
strength, with the tensile strength exceeding (240 - 68 log
4) kgf/mm2, and high toughness.
This invention describes that the compositions of
high carbon steel wire rods can be advantageously adjusted
by adding Si~ Si-Cr, Si-Mn, Si-Mn-Cr, Si-Mn-Al and Si-Mn-Cr-
Al to obtain a quality product by using a very specific
process. In this process the patenting strength is improved
by heat treatment at the optimum patenting condition. The
wire rods are subjected to cold drawing while limiting total
reduction in area, the number of passes of drawing, and the
drawing speed.
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1 Detailed Description o~ the Invention
As shown in Fig. 1, the ~ensile strength indicated
by line 1 of a conventional material increases as
reduction in area increases but the number of times of
twisting indicated by line 2 reduces sharply when tensile
strength exceeds a certain level and embrittlement is
accelerated.
If the strength as being patented is increased,
the tensile strength will therefore increase as shown by
line 3. The torsion value mainly depends not on the
initial tensile strength of the patented wire, but on
the total reduction in area of drawing. Accordingly, a
high torsion value is obtained even at a high strength
of over 210 kgf/mm provided that such drawing method is
employed as the toughness is not deteriorated. The
chemical composition by which high tensile strength as
patented can be attained and which are practical are
therefore specified as shown below:
(Si - Mn series)
C: 0.70 ~ 1.00 %
Si: 0.50 - 3.0 %
Mn: 0.3 ~ 2.0 %
(Si - Mn - Cr series~
C: 0.70 ~ 1.00 %
Si: ~.50 ~ 3.0 %
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1 Mn: 0.30 - 2.0 %
Cr: 0.10 ~ 0.50 %
(Si - Mn - Al series)
C: 0.70 ~ 1.00
Si: 0.50 ~ 3.0 %
Mn: 0.30 ~ 2.0 %
~1: 0.02 ~ 0.10 %
N: 0.003 ~ 0.015 %
(Si - Mn - Cr - Al series)
C. 0.70 ~ 1.00 ~
Si: 0.50 ~ 3.00 %
Mn: 0.30 ~ 2.00%
Cr: 0.10 ~ 0.50 %
Al: 0.020 ~ 0.100 %
N: 0.003 ~ 0.015 %
P and S are also included as unavoidable impurities
for steel making and the rest is Fe. The reasons to limit
the components to the above are;
C: The patenting strength is increased by 16 kgf/mm2
2n per 1% of C and the required strength is not obtained at
0.7% or lower content. Higher C% is, therefore,
advantageous to increase the strength. When the content
exceeds 1.00%, however, network cementite is precipitated
in the grainboundary affecting the toughness.
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1 Si: The patenting strength is increased by 12 kgf/mm2
per 1% addition of Si and heat resistive strength is also
increased by Si addition. When the content exceeds 2%,
however, solid hardening of ferrite increases,
decarburizing tends to happen at rolling and at reheating,
and the elongation and con~raction properties are lowered
sharply. The upper limit, therefore, is set at 2%. The
materials specified in JIS ordinarily include 0.3% Si
and the lower limit in this invention is 0.2% higher than
this, and at least 6 kgf/mm2 or higher increase in the
patenting strength is intended.
Mn: As the result of improvement in hardenability,
Mn content moves the rate of transformation to the side
of longer time, generates fine pearlite even with steel
wires of large diameter, and serves for strength
improvement. At 0.3~ or lower content, however, the
effect is insignificant. When the content exceeds 2%,
however, the time requierd to hold in a lead bath in order to co~plete
pearlite transformation at patenting becomes too long~
which is not practical.
Cr: Cr is a effective element for strengthening
as it is adequately dissolved into ferrite matrix, and
also into Fe3C being an element producing carbide, and
the strength of Fe3C is increased, the reaction of
pearlite transformation is delayed serving to move the
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1 transformation to the side of longer time and making it
easier to obtain fine pearlite even with larger diameter
wire rods. When 0.5% is exceeded, however, completion
of pearlite transformation during patenting takes too
lon~ to make pearlite transformation practical.
Therefore, the upper limit is set at 0.5~ for Si - Cr and
Si - Mn - Cr, but the lower limit is set at 0.1% as the
effect of strengthening is not expectable if the
addition is less than 0~ To Si - Mn series, no Cr
is added because the time to complete transformation
becomes too long.
Al: Al is added at ordinary steel making for
deoxidation and 0.02% or more is added to make grain
size of crystal finer and to improve the toughness.
Addition of 0.02% Al or more greatly improves twist
characteristic after drawing and bending workability and
reduces breakage at machining and use of the products.
Addition of Al, however, is kept within the range from
0.02 to 0.100~ as addition of over 0.100% increases
A12O3, which reduces drawability.
N is effect~ve to improve toughness after drawing
if included by more than 0.003~ within the range of Al
addition mentioned above. If the content exceed 0.015%,
however, the effect of improvement is lowered and
drawability is affected. Accordingly, addition of N is
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1 kept within the range from 0.003 to 0.015~.
It is also possible to add one or more o~ Ti, Nb, V,
Zr, B and ~1 within the limit of 0.3% in total quantity
to obtain fine grain slze. Addition of over 0.3% only
saturates effect of fine grain size of austenite
crystal and results in deterioration of toughness.
Accordingly, the total quantity is kept at 0.3~ maximum.
The control by addition of Ca or rare earth elements
and steels processed to reduce impurities such as P, S,
N, and 0 do not spoil the effect of the present invention
either.
Fig. 2 shows the compositions of Si - Mn and Si - Cr
series in terms of carbon equivalent (Ceq = C + (Mn + Si)/
6 ~ Cr/4) and in relation to the strength after lead
15 patenting. The patenting strength is 140 kgf/mm2 - 160
kgf/mm at Ceq of 1.1 to 1.6 to Si - Mn and at 0 - 1.5 to
Si - Cr, which indicates the effect of strengthening.
Fig. 3 shows the components of Si and Si - Mn - Cr
series in terms o~ carbon equivalent (Ceq = C ~ (Mn + Si)/
6 ~ Cr/4) and in relation to the strength after lead
patenting. The patenting strength is 140 - 162 kgf/mm2
at Ceq of 0.93 - 1.60 to Si series as shown by line 14
and 0.99 - 1.95 to Si - Mn - Cr as shown by line 15, which
indicates the effect of strengthening.
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1 In the following description of the mcth~d o~ drawing
were rods of high patenting strength a~d having the
compositions described above for manu~acturing high
strength and high toughness steel wires, Si series and
Si - Mn - Cr series are not separated one from the other
as they show the same tendency.
Fig. ~ is an example of drawing and cooling device
to directly cool down heated steel wires by drawing. The
drawing and cool:lng device 2 has a die box 21, a die
case 22 retained by the die box 21, a case cap attached
to the die case 22, and a die 25 caught by a spacer 24
and the case cap 23 in the die case 22, and a cooling
! chamber 26 to cool the die 25 is provided in the ~ie
case 22 into which cooling water is lead. A cooling unit
3 is connected to the drawing unit 2, and a cooling
chamber 30 is made in the cooling unit 3. Cooling water
is lead into the cooling chamber through a cooling water
inlet 31 and discharged through an outlet 32. A guide
member 34 is provided at the back of the cooling unit
to feed air to the periphery o~ steel wires passing
through the guide from an air feed port 33 to dry the
wires. A steel wire 1 goes through the cap 23 and is
drawn by the die 25. The drawn steel wire 10 is cooled
immediately while going through the cooling chamber.
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1 Moisture on the periphery is removed by air while the
wire goes through ~he guide member 34.
Since the drawn wire 10 is cooled at the die outlet
in this manner, embrlttlement by strain aging is
prevented. The drawing by the die and water cooling
after drawing are repeated by the specified number of
passes. The use of the direct water cooling device
shown, as an example, in Fig. 4, can be omitted at one
or a few dies.
No adoption of direct water cooling is harmless for
wire properties at first die or for a few dies at early
stage of drawing.
This is because wire temperature rise at the early
stages of continuous drawing is usually smaller than
that at the latter stages of drawing, and the strain age
embrittlement hardly takes place.
Fig. 5 shows the relationship of tensile strength
and twisting to the change in total reduction in area
and in patenting strength when the device shown in
Fig. 4 is used for drawing. The wire of 133 kgf/mm2
patenting strength shown by line 6 is ordinary material
(conventional) with 0.82 C, 0.3 Si and 0.5 Mn componen~s,
and the wires of 142 kgf/mm2 shown by line 7 and of 160
kgf/mm2 shown by line 8 are respectively the materials of
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1 Si - Cr series and Si - Mn series according to this
invention. The one shown by line 9 and having 168 kgf/mm~
patenting strength contains 2.0% Si conten~, which is
larger than the limited range. The twisting of the
materials of line 6, 7, 8, and 9 is respectively as
shown by line 60, 70~ 80 and 90.
As the drawings indicate, the required torsion
value, 20 turns, is not met by ordinary steel material
when the tensile strength exceed (240-68 log d) kgf/mm2.
(d: diameter o wire) With the materials of this
invention, however, the required twisting of over 20
turns c~n be met even at high strength exceeding (240 - 68
log d) kgf~mm2 The material with increased Si content
to 3~ shows signiflcant embrittlement and very low
number of times of twlsting. For the materials of this
invention, it is necessary to limit reduction in area to
70 - 93~ as the tensile strength exceeds (240- 68 log d)
kgf/mm2 at 70% and over, and torsion value is less than
20 turns at over 93% of drawing.
It is also necessary to limit the patenting strength
over 140 kgf/mm2 as the torsion value of over 20 turns is
met at tensile strength exceeding (240 -68 log d) kgf/mm2.
Ordinary wire materials are also affected by cooling
after drawing and when no cooling is applied after
drawing, the material having the char~cteristic of line
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1 61 is embrittled slgnificantly as shown by line 62. Wire
materials of the present lnvention also show the same
tendency and the cooling as described in Fig. 4 or
other comparable direct cooling methods is therefore
essential. The number of times of drawing is set at 16
as reduction in area per one die is too much if the
number of passes of drawing is 6 or less and the
embrittlement as shown in Fig. 6 is resulted due to
excessive heat generation. If the number of times of
drawing is too much, on the other hand, the economical
performance becomes lower though there is no problem in
the characteristicsO
Fig. 7 shows the relationship between torsion value
and drawing speed of the wires showing tensile strength
exceeding (240 -68 log d) kgf/mm . The drawing speed of
550 m/minute max. is desirable as wires are broken at
higher speed than 550 m/minute. The lower limit of
drawing speed is set at 50 m/minute and ~aster though
the drawing is free from embrittlement at lower speed
side and the economical performance becomes lower at a
slower speed than 50 m/minute. According to the results
described above, this invention is to be composed as
follows:
Compositions ...... As described above
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1 Drawing method ~ Drawing and cooling immediately
after drawiny
Patenting strength ...... Over 140 kgf/~m2
Number of times of drawing ...... 7 - 16 times
Drawing speed O~ 50 - 550 m/minute
Reduction in area ...... 70 - 93 ~
High tension and highly tough steel wires having
tensile strength exceeding (240 - 68 log d) kgf/mm2 and
number of times of twisting of over 20 turns can be
manufactured by limlting each one of the above stated
conditions within a specific range.
Fig. 8 shows tensile strength and torsion value
against total redustlon in area when the device shown
in Fig. 4 is used for drawing to the wire materials of Si
series and Si - Mn - Cr series except for the first die.
The wire material of 133 kgf/mm2 patenting strength shown
by line 16 is ordinary material (conventional) with the
compositions of 0.82 C, 0.3 Si and 0.5 Mn, while the
materials of 143 kgf/mm2 patenting strength shown by line
17 and of 162 kgf/mm2 shown by line 18 are respectively
the materials by this invention of Si series and Si -
Mn ~ Cr series. The one with 170 kgf/mm2 patenting
strength shown by line 19 includes 4.0~ of Si content.
The torsion value of the above materials shown by line
17
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1 16, 17, 18, and 19 are respectively as indicated by line
81, 84, 85 and 86.
As is known clearly from the drawing, ordinary wire
materials fails to meet the required torsion value of
20 turns when the tenslle strength exceed (240 -68 log d)
kgf/mm2 (17 turns to line 81). With the wire materials
by this invention, however, torsion value of more than
20 turns can be met even at higher tensile strength than
(240 -68 log d) ~g~/mm2. (28 times with line 84, and 27
times with line 85.) With the material of higher Si
content of 4~, embrittlement is significant and the
torsion value is very low (several times with line 86).
To the wire materials of this invention, it is necessary
to limit reduction in area to 70 - 93~ and the tensile
strength exceeds (240 -68 log d) kgf/mm2 at lower
reduction in area than 70% and the twisting is less than
20 turns at higher reduction in area than 93~.
It is also necessary to limit patenting strength
over 140 kgf/mm2 because the tensile strength exceeding
(248 -68 log d) kgf/mm2 and twisting of over 20 turns can
be met when the patenting strength is kept at this level.
Ordinary wire materials are affected by cooling after
drawing and when no cooling is applied after drawing, the
material having the characteristic of line 82 is
embrittled significantly as shown by line 83. Since the
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1 wire materials of this invention show the same tendency,
the cooling as described in Fig. 4 is essentialO The
lower limit of the number of passes of drawing is set
at 7 as the reduction in area per one die is too much
at less than 6 turns and sharp embrittlement is resulted
as shown by line 50 in Fig. 9 due to excessive heat
generation. I~ on the other hand, the number of times
of drawing is too much, the economical performance
becomes lower though it is free ~rom any problem in the
characteristics. Accordingly, the upper limit is set
at 16 times.
Line No. 51 of Flg. 10 shows the relationship between
the torsion value and drawing speed of the wires having
tensile strength of exceeding ~240 - 68 log d) kgf/mm2.
The drawing speed of 550 m/minute maximum is desireable
as the torsion value is sharply reduced and wires are
broken at higher speed than 550 m/minute. The lower
limit of drawing ls set at 50 m/minute though the
drawing is free from embrittlement at low speed side but
the economical performance is lower. Accordingly, this
invention is to be composed as shown below:
Compositions ........ As described above
Drawing method ...... ..Drawing and cooling immediately
after the drawing
Patenting strength .. ......Over 140 ~gf/mm2
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1 Number of passes of drawin~ O 7 - 16 times
Drawing speed .. .. 50 - 550 m/minute
Reduction in area ...... 70 - 93%
High tension and highly tough steel wires having
tensile strength exceeding (240 -68 log d) kgf/mm2 and
torsion value of over 20 turns can be manufactured by
limiting each one of the above conditions to the specific
range.
Em~odiment - 1
The components are set at 0.87 C - 1.2 Si - 1.2 Mn -
0.020 P - 0.010 S, fox Si - Mn series, 0.84 C - 1.2 Si
- 0.50 Mn - 0.20 Cr - 0.021 P - 0.015 S for Si - Mn - Cr
series, and at 0.82 C - 0.50 Mn - 0.40 Si - 0.018 P
- 0.017 S for ordinary wire rod.
A high-frequency induction furnace is used for
melting, wire rods of 13 mm and 9.5 mm diameters are
made through ordinary blooming and rolling, and the
following wires are made of the rods.
(1) PC wire
The rods of 13 mm diameter are sub]ected to patenting
at 560C to Si - Mn and Si - Mn - Cr series and at 500C
to ordinary wire materials, each rod is made to the tensile
strength of 152 kgf/mm2, 154 kgf/mm2 and 131 kgf/mm2
respectively, subjected to pickling, phosphate coating
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1 and cooling, then drawn to 5 mm diameter at 180 m/minute
drawing speed and by 9 passes of drawing. (86% of drawing)
The ordinary materials are also drawn without cooling and
the wire materials of Si - Mn series and Si - Mn - Cr
series are also drawn at 10 m/minute, without cooling,
and by 6 passes of drawing to prepare samples for
comparison. The comparison is as shown in Table 1.
As Table 1 indicates, the materials by this invention
show a high strength, better toughness, and higher
fatigue strength, while with the ordinary materials,
the strength is lowered when the toughness is increased,
and the toughness deteriorates greatly if the
strength is increased. Even with materials of the
same components as that of the materials by this
invention, wires of high strength and also of high
toughness can't be o~tained if the drawing conditions
are not adequate.
(2~ Galvanized wire
The wires of 5 mm diameter made in the manner as
shown in Table 1 are subjected to galvanizing at 440C,
and the strength and toughness are as shown in Table 2.
As therein indicated, high strength and high toughness
are maintained even after galvani~ing. It i5 obvious
that the toughness after galvanizing is very low even
with the same compositions as those of the wire material
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1 by this invention if the drawing conditions are not sek
adequately.
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1 (3) PC strand
After drawing the rods of 13 mm diameter described
above to 11.4 mm and 10.9 mm diameters, those of Si - Mn
series and Si - Cr series are s~bjected to patenting at
560C and ordinary wire materials ~re at 510C to the
tensile strength of 156kgf/mm2, 155 kgf/mm2 and 133 kgf/mm2
respectively. After pickling, and phosphate coating,
cooling immediately after drawing is applied, the
materials of 11.4 mm diameter are drawn 8 passes at 200
m/minute speed to 4.40 mm and the materials of 10.9 mm
diameter to 4.22 mm (85% drawing). ordinary wire
materials are also made under the condition of no water
cooling. For Si - Cr series and Si - Mn series, wires
of 4.40 mm and 4.2 mm diameters are also made under the
conditions of 6 passes of drawing, 10 m/minute drawing
speed, and without cooling. Then PC strand of 7 wires,
0.5 inch size is prepared by using 4.40 mm wires as the
core and 4.22 mm wires as the sides. After bluing at
380C, the characteristics are compared as shown in
Table 3.
The anchoring efficiency in the table is determined
by the following equation.
Anchoring efficiency = (Tensile breaking load by
wedge fixing) x 100/(Breaking load of the strand
of ordinary test material)
- 25 -
.. - ~ , ~ - . . - '
. ' :
. . .
~ 3~ ~
1 The minimum stress and the stress width oE the
fatigue fracture ~est are constant at 0.6 times of the
tensile strength and 15 kg/mm2 respectively. As Table 3
indicates, the strength of the ordinary wire materials by
cooling and drawing is low and the fatigue characteris~ic
is not favourable either. When no cooling is applied
a~tex drawing, the ordinary materials show significant
embrittlement and no stranded wires can be manufactured.
It is also obvious that the elongation is low, the
anchoring efEiciency is low, and embrittlement is
significant even with the materials of Si - Mn or Si - Cr
series unless the drawlng conditions are set adequately.
While the materials o~ the present invention have ~ high
strength o~ around 220 kg/mm2 and evidently show exceeding
fatigue characterlstics.
(4) Galvanized steel wire for aluminium cable steel
reinforced (ACSR)
After primary drawing of the above described rods of
9.5 mm diameter to 8 mm, those of Si - Mn series and
Si - Mn - Cr series are subjected to patenting at 570C
and .he ordinary wire materials at 530C to make the
tensile strength to 160 kg/mm2, 158 kg/mm2 and 134 kg~mm2
respectively, then subjected further to pickling,
phospnate coating, and cooling after drawing. The wires
are drawn further to 2~52 mm ~90~ drawing) by 12 passes
., ~ '
.
- . : .
1 of drawing and at 2~0 m/minute drawing speed, then are
subjected to HCl trea-tmen-t, flux treatment, and Zn plating
at 4~2C to obtain Zn plated wires of 2.6 mrn diameter for
ACSR. With the ordlnary wires materials, the plated
wires of 2.6 mm diameter are also prepared without
cooling. The wire materials of Si - Mn series, and of
Si - Mn - Cr series are also drawn into 2.6 mm diameter
without water cooling by ~ passes of drawing, at 10 m/
minute drawing speed.
The results are as shown in Table 4. In the table,
unwinding means the repeated motion of winding and un-
winding and the plated wires are wound around and
unwounded Erom another wire of the same diameter to check
surface flaw. As to the winding property, the plated
wires are wound axound a rod with diameter of 15 times
larger than the diameter of the wire to be tested and
the property is judcJed from the condition. The table
indicates that the wire materials by this invention have
a high strength and high toughness.
- 27 -
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29 -
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q33 5
1 (5) Rope
The rods of 13 mm diameter described above are drawn
into wires of 10.85 mm and 10.45 mm diameters, then the
wires are subjected to patenting at 570C to those of
Si - Mn series and Si - Mn - Cr series, and at 550C to
ordinary wire materials. The results are as shown
respectively in Table 5.
After pickling, phosphate coating, and cooling
after drawing, the wires are drawn further to 90~ drawing;
the wires 10.85 mm to 3.43 mm and those of 10.45 mm to
3.30 mm respectively by 12 passes of drawing and at 250
m/minutes of drawlng speed. By using the wires of 3.43
mm diameter as the core, and those of 3.30 mm diameter as
the side wires, strand of 7 wires, and 6 pieces of such
stranded wires are twisted together into a rope 55 of 30 mm
outside diameter as shown in Fig. 11, With the ordinary
wire materials, ropes are also prepared without cooling
after drawing when the strands are made. The results
are shown in Table 6. The fatigue test is practiced
under the condition of 10.0 tons test load, 460 mm
sheave diameter, and 16 bending angle, and the number of
times of repetitive bending to break-down is found.
As the tab~e indlcates, the materials of this
invention show a high strength and the fatigue life is
5 times longer than that of ordinary wire materials.
- 30 -
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,
.
- ~ '
~;~80~3~
Table 5
._ __ .
\ Components
\ Ordinary
\ Si-Mn Si-Mn-Cr wire
S Size ~ _ _ . material
10.85 ~ 154 kgf/mm 157 kgf/mm 133 kgf/rlm
. __ . . _ - _ .
10.45 ~ 1156 kgf/1rm2 158 kgf/mm2 135 kg:f/nm
-- 31 --
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1 Embodiment - 2
Wire materials of 12.7 mm diameter and of Si - Mn -
Al series are subjected to lead patenting to the tensile
strength of 139 kgf/mm2, 139 kgf/mm2, and ordinary material
for comparison 131 kgf/mm2 respectively. Then, they are
drawn to 3.7 mm~ wires by 91.5~ reduction, and are
subjected to bending ~est at 3 mm radius of curvature
after bluing at 350~C. The results are as shown in the
following table~
33 -
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1 Embocliment - 5
After applyinc3 lead patenting, 8 passes of drawing
and direct coolincJ (300 m/minute) to the wire materials
of above described Si - Mn series, stress-relieving is
performed at 400C in the lead bath, then copper is
deposited on the surEace by substitution plating, and
the wires are tested as shown in the following table.
In the table, sample 1 and sample 2 are respectively
3 mm and 5 mm in diameter with tensile strength of 150
kgf/mm2 after patenting, and are drawn to 0.96 mm and
1.6 mm respectively. The samples 3, 4 and 5 are subjected
to patenting at the diameters of 3 mm, 5 mm and 6 mm, and
the tensile streng-th is obtained at the values of 124
kgf~mm2, 130 kgf/mm2 and 129 kgf/mm2 respectively, and
15 such wires are drawn to 0.96 mm, 1.60 mm and 1.60 mm
diameter respectively.
Chemical compsitions of each sample is as
follows:
Sample No. 1: 0.83 C 1.2 Si - 0.70 Mn
Sample No. 2: 0.72 C - 0.25 Si - 0.50 Mn
Sample No. 3: 0.82 C - 1.15 Si - 0.72 Mn
Sample No. ~: 0.82 C - 0.20 Si - 0.55 Mn
Sample No. 5: 0.82 C - 0.24 Si - 0.51 Mn
- 37 -
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-- 38 --
- ~ .. . : , .
, . .
-
. .
: . ,
1 Effect of the Inventi.on
As described above, the presen-t invention is to
enable manufacturing s-teel wires of hiyh strength and
high toughness by adjusting the compositions such as C,
Si, Mn, Cr, Al and N adequately and by se-tting the
drawing conditions such as the number of passes of
drawings, drawing speed, direct water cooling and -total
reduction in area wi-thin the adequate range respectively.
This invention, in particular, leads to the
following results of each product.
(A) PC wire and PC strand
Economical effects corresponding to reduced
consumption of steel materials and corresponding to
reduced consumption of concrete introduction of high
prestressing force.
~B) Core wire for aluminium cable steel reinforced
Less consump-tlon of steel wire materials due to
increase in electrlc power transmission capacity
corresponding to increased area of aluminium conductor
b~ compact design of ACSR strand and due to compact
design of core steel wire.
(C) Rope
Economical effect corresponding to reduced
consumption of steel wire materials by reduced rope size~
and the effect of compact design of the whole equipment
- 39 -
-, . ~ . . :
.
~8~ 5
1 by reduced rope wei~ht owing to smaller rope size and by
smaller sheave.
This invention also enables to reduce consumption
of steel wire materials for such products as ~alvanized
steel wire for long-span suspension bridge, uncoated
wire for stay cables for bridges, bead wire, spring wire,
etc. and saving in the cost is expected.
~ - 40 -
- . . . . .
. .
' ~
.
- ' ~ ' ' . .
