JP3536684B2 - Steel wire with excellent wire drawing workability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel wire rod excellent in wire drawability. More specifically, for example, the present invention relates to a steel wire rod excellent in drawability suitable for applications such as wire rope, PC steel wire, bead wire, and steel cord.

[0002]

2. Description of the Related Art In general, a wire rope and a PC steel wire are subjected to wire drawing to a steel wire obtained by hot rolling (hereinafter, "steel wire" is simply referred to as "wire") and further subjected to quenching and tempering. It is manufactured by subjecting it to a tempering treatment or a bluing treatment. An ultrafine steel wire for a steel cord used as a reinforcing material for a radial tire of an automobile is manufactured by the following process. That is, a wire rod having a diameter of about 5.5 mm adjusted and cooled after hot rolling is subjected to a primary drawing to a diameter of about 3 mm, then subjected to a patenting process, and further subjected to a secondary drawing to obtain a wire having a diameter of about 1 mm. The diameter is about 0.5 mm. After this, a final patenting process is performed, and then
Brass plating is performed and final wet drawing is performed to a diameter of 0.2 to 0.4 mm. The steel cord is manufactured by twisting a plurality of the extra-fine steel wires obtained in this manner by twisting into a twisted steel wire.

In general, when a wire is broken into a steel wire when it is broken, productivity and yield are greatly reduced. Therefore, wires belonging to the above technical field, at the time of wire drawing,
In particular, in the case of producing a steel cord, it is strongly required not to break the wire at the time of wet drawing in which strong cold working is performed.

Further, in the case of manufacturing a steel cord, many intermediate processing steps are required to convert a hot-rolled 5.5 mm-diameter wire into a steel wire having a diameter of about 1.5 mm, thereby increasing the manufacturing cost. Inviting. Therefore, there is an increasing demand from the industry to simplify the manufacturing process without deteriorating the performance of the final product. For this reason, for a relatively low-strength carbon steel wire rod having a C content of less than 0.7%, a technique for directly drawing a wire from 5.5 mm to 1.5 mm in diameter without intermediate treatment has been developed. ing.
In addition, the true strain amount in the wire drawing is 2.60. Here, the true strain (ε) is represented by the following equation (i) using the diameter (d ₀ ) of the wire and the diameter (d) of the drawn steel wire.

Ε = 2log _e (d ₀ / d) (i) On the other hand, in recent years, there has been an increasing movement to reduce the weight of steel cords and the like for various purposes. For this reason, high strength is required for the various products described above, and the above C
With a carbon steel wire having a content of less than 0.7%, a desired high strength cannot be obtained. For this reason, there is an extremely large demand for a wire rod which has a high C content and can secure a high strength to a steel wire, and which has excellent drawability such that the intermediate treatment can be omitted.

In the case of products having a large diameter such as a wire rope and a PC steel wire, a hot-rolled wire is drawn to a final product diameter. Therefore, if the degree of cold working can be increased by increasing the wire drawing workability, it is possible to obtain a product having higher strength than before, and thus a reduction in weight can be expected. For this reason, even for a product having a large diameter, a demand for a wire rod having excellent cold-drawability is increasing.

[0007] In response to the above-mentioned demands from the industry in recent years, there has been proposed a technique of controlling segregation and microstructure to enhance the wire drawing workability of a wire.

For example, Japanese Patent Publication No. 7-11060 discloses a "high-strength steel wire excellent in wire drawing workability" for controlling the segregation of Mn in the wire. However, the technique proposed in this publication is to increase the pressure reduction ratio by increasing the slab size in order to reduce the Mn segregation peak width in the wire, and to increase the degree of superheat of molten steel during casting in order to improve center segregation. Special treatments such as lowering the temperature, performing electromagnetic stirring in the mold, applying pressure to the slab at the end of solidification, and heating the slab in a soaking furnace to diffuse segregated elements are required. For this reason, when the manufacturing process or manufacturing equipment of a wire is different, it cannot necessarily be applied, and even if it can be applied, the manufacturing cost increases. Furthermore,
Controlling the segregation of Mn also contributes to the improvement of the drawing of the hot-rolled wire rod, but was insufficient to omit the patenting as the intermediate treatment described above.

Japanese Unexamined Patent Publication (Kokai) No. 6-73502 discloses that the upper bainite structure obtained by the two-stage transformation has an area ratio of 80%.
"High carbon steel wire or steel wire with excellent wire drawability"
Is disclosed. However, in order to obtain an upper bainite structure by two-stage transformation, it is necessary to immerse the wire directly in molten salt after hot rolling and cool it, and it is necessary to provide special equipment for this treatment. This leads to higher costs. Further, when the above-mentioned cooling using the molten salt as a medium is performed, the cooling salt adheres to the surface of the wire, and a step of removing the attached salt is required, which further increases the production cost.

[0010] Japanese Patent Publication No. 7-11060 and Japanese Unexamined Patent Publication No.
According to the technique proposed in Japanese Patent No. 73502, a wire rod excellent in wire drawing workability can be obtained. However, as described above, there is a major problem that equipment costs and manufacturing costs increase.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object the object of the present invention to provide a wire rope, a PC,
High-carbon steel wire with excellent drawability suitable for applications such as steel wire, bead wire, and steel cord. Above all, the wire may break even if it is drawn with a true strain of more than 2.60. The aim is to provide a low-carbon steel wire rod without any cost.

[0012]

SUMMARY OF THE INVENTION The gist of the present invention resides in a wire excellent in wire drawing work shown in the following (1) and (2).

(1) C: 0.7 to 1.1% by weight,
Si: 0.1 to 1.5%, Mn: 0.2 to 1.0%, A
l: 0.001 to 0.003%, Cr: 1.0% or less ,
N : 0.006% or less, Cu: 1.0% or less, Ni:
2.0% or less, Mo: 0.5% or less, Co: 4.0% or less, V: 0.4% or less, Nb: 0.1% or less, Ti:
0.1% or less, B: 0.005% or less, P: 0.05%
Hereinafter, S: 0.05% or less, rare earth element: 0.10% or less, Ca: 0.01% or less, Mg: 0.01% or less, the balance being a crossing of a steel wire rod composed of Fe and unavoidable impurities. In the surface, the average value of the C content in a region from the outer periphery to a position at a depth of 1/50 of the radius of the steel wire rod is 0.
A steel wire excellent in wire drawability characterized by being 6 to 0.9 × C% (where C is the C content of the steel wire).

(2) C: 0.7 to 1.1% by weight,
Si: 0.1 to 1.5%, Mn: 0.2 to 1.0%, A
l: 0.001 to 0.003%, Cr: 1.0% or less ,
N : 0.006% or less, Cu: 1.0% or less, Ni:
2.0% or less, Mo: 0.5% or less, W: 0.5% or less, Co: 4.0% or less, V: 0.4% or less, Nb:
0.1% or less, Ti: 0.1% or less, Zr: 0.1% or less, B: 0.005% or less, P: 0.05% or less, S:
0.05% or less, rare earth element: 0.10% or less, Ca:
0.01% or less, Mg: 0.01% or less, with the balance being from the outer periphery to a position at a depth of 1/50 of the radius of the steel wire in the cross section of the steel wire made of Fe and inevitable impurities. The average value of the C content in the region is 0.6 to 0.9.
× C% (where C is the C content of the steel wire), wherein the steel wire is excellent in wire drawability.

The "cross-section" of the wire in the present invention refers to a surface cut perpendicular to the rolling direction of the wire. or,
The “average value of the C content in a region from the outer periphery of the wire to a position at a depth of 1/50 of the radius of the wire” means, for example, the outer periphery of the wire (surface layer portion) using a wavelength-dispersive electron beam microanalyzer. 4/250, 3/250, and 2/25 of the radius from the outer circumference when a line analysis of the C content was performed.
It indicates the average value of the C content at the positions of 0 and 1/250 depth.

The present inventors have repeatedly conducted investigations and studies on the effect of the structure of the hot-rolled high carbon steel wire rod, particularly the surface layer structure, on the drawability. As a result, the following findings were obtained.

(A) Unlike the bending and forging, the cold drawing is performed in multiple steps and with a large degree of work. Therefore, if a soft ferrite structure exists in the surface layer, workability is rather deteriorated. However, disconnection is likely to occur during wire drawing. That is, JP-A-56-55520 and JP-A-8-109 attempt to enhance cold workability and forgeability by having a soft ferrite structure in the surface layer of a steel material.
Even if the technology proposed in Japanese Patent No. 437 is applied to wire drawing, the wire drawing workability cannot be improved. However, if the hardness of the surface layer (near the outer periphery) of the wire is lower than the hardness of the base material (hereinafter referred to as the hardness of the central portion), the deformation resistance during cold wire drawing decreases, so that the wire drawing is performed. Can be enhanced.

(B) In order to lower the hardness near the outer periphery of the wire than the hardness at the center, the carbon content near the outer periphery may be reduced.

(C) When the average value of the carbon content in the vicinity of the outer periphery is set to 0.6% by weight or more, proeutectoid ferrite does not precipitate in the structure. Can be enhanced.

(D) From the above (a) to (c), if the carbon content in the vicinity of the outer periphery is in an appropriate range, it is possible to enhance the wire drawing workability. Thus, the life of a die used for cold drawing can be improved.

The present invention has been completed based on the above findings.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. In addition, “%” of the content of the chemical component means “% by weight”.

(A) Chemical composition C of the wire rod: 0.7 to 1.1% C is an element effective for securing the strength. But,
If the content is less than 0.7%, wire rope, P
It is difficult to stably give high strength to final products such as C steel wire, bead wire, and steel cord.
On the other hand, if the content of C is too large, the steel material becomes hard and causes a reduction in cold workability. In particular, when the C content exceeds 1.1%, not only the wire becomes hardened, but also proeutectoid cementite (that is, cementite along the prior austenite grain boundary).
It is difficult to prevent the formation of manganese, and the wire drawing workability is reduced. For this reason, even if the carbon content in the vicinity of the outer periphery is controlled to a range described later, disconnection occurs frequently if the wire is drawn at a large working ratio such that the true strain exceeds 2.60. Therefore, the content of C is set to 0.7 to 1.1%.

Si: 0.1-1.5% Si is an effective element for increasing the strength. Further, it is an element necessary as a deoxidizing agent. However, if the content is less than 0.1%, the effect of addition is poor. On the other hand, if the content exceeds 1.5%, the critical workability in wire drawing decreases, and the true strain exceeds 2.60. If the wire is drawn at the degree of processing, disconnection frequently occurs. Therefore, the Si content is set to 0.1 to 1.5.
%.

Mn: 0.2-1.0% In addition to the effect of increasing the strength, Mn reduces S in steel to MnS
And has the effect of preventing hot brittleness. However, if the content is less than 0.2%, it is difficult to obtain the above effects. On the other hand, Mn is an element that is easily segregated. If it exceeds 1.0%, Mn is segregated particularly at the center of the wire, and martensite and bainite are generated at the segregated portion, so that wire drawing workability is reduced. . Therefore, the Mn content is 0.2 to
1.0%.

Cr: 1.0% or less Cr may not be added. If added, it has the effect of reducing the lamella spacing of pearlite and increasing the strength after rolling and after patenting. Also, since it has the function of increasing the work hardening rate during cold working such as wire drawing,
High strength can be obtained even at a relatively low processing rate by adding. To ensure such an effect, the content of Cr should be set to 0.1.
The content is preferably 1% or more. On the other hand, if Cr is added excessively, the time required for the pearlite transformation to end is increased, and martensite and bainite are generated at the center of the wire after hot rolling, so that the frequency of breakage during wire drawing increases. In particular, when the Cr content exceeds 1.0%,
If the wire is drawn with a large working degree such that the true strain exceeds 2.60, disconnection frequently occurs. Therefore, if the content of Cr is 1.
0% or less.

Al: 0.001 to 0.003% When the content of Al exceeds 0.05%, oxide inclusions containing Al ₂ O ₃ as a main component become coarse, and during the wire drawing. Disconnection occurs frequently. In particular, 0.5 at a linear diameter of the final product diameter
In the case of not more than mm, even if the oxide-based inclusions containing Al ₂ O ₃ as a main component are fine, they may cause disconnection at the time of final drawing. For this reason , the Al content of the wire is set to 0.001 to 0.1.
003%.

N: 0.006% or less N adheres to dislocations during cold drawing and increases the strength of the steel wire, but decreases the drawability. However, this adverse effect of N can be prevented by reducing the content to 0.006% or less. Therefore, the N content is set to 0.1.
006% or less.

Cu: 1.0% or less Cu may not be added. If added, it has the effect of increasing corrosion resistance. To ensure this effect, Cu should be 0.0
Preferably, the content is 5% or more. However, if the content exceeds 1.0%, segregation at crystal grain boundaries causes cracks and flaws to be noticeable during hot working such as bulk rolling of steel ingots and hot rolling of wires. Therefore, the content of Cu is set to 1.0% or less.

Ni: 2.0% or less Ni may not be added. If added, it has the effect of forming a solid solution in the ferrite and improving the toughness of the ferrite. To ensure this effect, the content of Ni is preferably set to 0.2% or more. However, if the content exceeds 2.0%, the quenchability becomes too high, so that martensite is easily formed and the wire drawing workability is deteriorated. Therefore, the content of Ni is set to 2.0% or less.

Mo: 0.5% or less Mo may not be added. If added, it precipitates as fine carbides by heat treatment and has the effect of increasing strength and fatigue properties. To ensure this effect, it is preferable that the content of Mo be 0.05% or more. On the other hand, if the content exceeds 0.5%, the above effect is saturated and the cost is increased. Therefore, the content of Mo is set to 0.5% or less.

W: 0.5% or less W may not be added. If added, it has the effect of precipitating as fine carbides by heat treatment and increasing the strength. W also effectively acts on improving corrosion resistance. In order to surely obtain these effects, the content of W is preferably set to 0.05% or more. On the other hand, if the content exceeds 0.5%, the above effect is saturated and the cost is increased. Therefore, the content of W is set to 0.5% or less.

Co: 4.0% or less Co may not be added. When added, it has the effect of preventing precipitation of proeutectoid cementite and further reducing the pearlite to increase the strength. To ensure this effect, C
It is preferable that the content of o is 0.2% or more. However, even if the content exceeds 4.0%, the above effect is saturated and the cost is increased. Therefore, the content of Co is set to 4.0% or less.

V: 0.4% or less V may not be added. If added, it has the effect of refining austenite crystal grains and increasing ductility and toughness. In order to surely obtain this effect, it is preferable that the content of V is 0.05% or more. However, even if the content exceeds 0.4%, the above effect is saturated and the cost is increased. Therefore, the content of V is set to 0.4 % or less.

Nb: 0.1% or less Nb may not be added. If added, it has the effect of refining austenite crystal grains and increasing ductility and toughness. To ensure this effect, Nb is 0.001%
It is preferable to set the content as described above. But 0.1%
If the content exceeds the above range, the above effect is saturated and the cost is increased. Therefore, the content of Nb is 0.1%
The following was set.

Ti: 0.1% or less Ti need not be added. If added, it has the effect of refining austenite crystal grains and increasing ductility and toughness. To ensure this effect, the content of Ti is preferably set to 0.01% or more. However, even if the content exceeds 0.1%, the above effect is saturated and the cost is increased. Therefore, the content of Ti is set to 0.1% or less.

Zr: 0.1% or less Zr may not be added. If added, it has the effect of refining austenite crystal grains and increasing ductility and toughness. In order to surely obtain this effect, the content of Zr is preferably set to 0.01% or more. However, even if the content exceeds 0.1%, the above effect is saturated and the cost is increased. Therefore, the content of Zr is set to 0.1% or less.

B: 0.005% or less B may not be added. If added, it has the effect of promoting the growth of cementite in pearlite and increasing the ductility of the wire. To ensure this effect, B is 0.00
The content is preferably at least 03%. However, if the content exceeds 0.005%, cracks are likely to occur during hot or warm working. Therefore, the content of B is set to 0.005% or less.

P: 0.05% or less P lowers the drawability. In particular, when the content exceeds 0.05%, the wire drawing workability is significantly reduced.
Therefore, the content of P is set to 0.05% or less.

S: 0.05% or less S reduces the drawability. In particular, when the content exceeds 0.05%, the wire drawing workability is significantly reduced.
Therefore, the content of S is set to 0.05% or less.

Rare earth element: 0.10% or less Rare earth element need not be added. If added, it has the effect of increasing hot workability. To ensure this effect, the content of the rare earth element is preferably 0.002% or more. However, even if the rare earth element is contained in an amount exceeding 0.10%, the above effect is saturated and the cost is increased. Therefore, the content of the rare earth element is 0.10%
The following was set. The “content of the rare earth element” in the present invention indicates “the total content of the rare earth element”.

Ca: 0.01% or less Ca may not be added. If added, it has the effect of increasing hot workability. To ensure this effect, Ca
Is preferably 0.0005% or more.
However, even if Ca is contained in an amount exceeding 0.01%, the above-mentioned effect is saturated, and the cost is increased. Therefore, the content of Ca is set to 0.01% or less.

Mg: 0.01% or less Mg need not be added. If added, it has the effect of increasing hot workability. To ensure this effect, use Mg
Is preferably 0.0005% or more.
However, even if Mg is contained in an amount exceeding 0.01%, the above effect is saturated, and the cost is increased. Therefore, the content of Mg is set to 0.01% or less.

(B) Carbon Content Distribution in the Cross Section of the Wire In the present invention, the radius of the wire from the outer periphery of the wire is 1%.
The average value of the C content in the region up to the depth of / 50 is defined as 0.6 to 0.9 × C%. This is for the following reason.

The deformation at the time of cold drawing of the wire is large near the outer periphery, that is, closer to the surface layer. In particular, in the cross section, the deformation at a depth of 1/50 of the radius from the outer periphery is large. . The present invention is characterized in that the hardness of the above-mentioned region is made lower than the hardness of the central portion to reduce the deformation resistance at the time of cold drawing and to enhance the drawability. in this case,
If the average value of the C content in the region exceeds 0.9 × C%, the decrease in deformation resistance during cold drawing is small, and the drawing workability cannot be improved. As described above, “C” indicates “C content of the wire rod”.
For example, it means a ladle analysis value. On the other hand, if the average value of the C content in the region is less than 0.6%, pro-eutectoid ferrite precipitates and the deformation stress concentrates on this soft eutectoid ferrite during wire drawing, so that the critical workability decreases. Therefore, if the wire is drawn with a large working degree such that the true strain exceeds 2.60, disconnection frequently occurs. Therefore, the average value of the C content in the region from the outer periphery of the wire to a position at a depth of 1/50 of the radius of the wire is set to 0.6 to 0.9 × C%.

The "average value of the C content in the region from the outer periphery of the wire to a position at a depth of 1/50 of the radius of the wire" is calculated, for example, using a wavelength-dispersive electron beam microanalyzer. When the line analysis of the C content of the part (near the surface layer part) was performed, 4/250, 3 /
As described above, it indicates the average value of the C content at the depths of 250, 2/250, and 1/250.

1/50 of the radius of the wire from the outer circumference of the wire
In order to make the average value of the C content in the region up to the position of the depth of 0.6 to 0.9 × C%, for example, a billet having almost no decarburized layer is converted into natural gas (main component is methane (CH 2
₄ ) When heating in a heating furnace using fuel,
The billet was charged into a furnace maintained at a temperature of 1100 ° C. and maintained for 30 to 40 minutes.
After hot rolling at 870 ° C., it may be cooled to a temperature of 500 ° C. or lower at a cooling rate of 5 to 10 ° C./sec. When the billet has a decarburized layer, the temperature of the furnace and the time in the furnace may be changed according to the degree of the decarburized layer.

The chemical composition described in the above (A) and the present (B)
The wire having the distribution of the carbon content described in the section is subjected to wire drawing in the usual way, and then subjected to tempering and bluing to finish the final product such as wire rope and PC steel wire. Can be Alternatively, wire drawing is performed in a usual manner, and then final heat treatment and final wire drawing are performed to finish a bead wire or a steel wire for a steel cord.

Hereinafter, the present invention will be described in detail with reference to examples.

The steels B to M having the chemical compositions shown in Table 1 were
It was melted using a 50 kg vacuum furnace. Steel B in Table 1 ,
C, E, G, I, L and M are examples of the present invention in which the chemical composition is within the range of the content specified in the present invention. On the other hand, steel D,
F, H, J and K are comparative examples in which any one of the components is out of the range of the content specified in the present invention.

[0051]

[Table 1]

Next, these steels were hot-forged in a usual manner into round bars having a diameter of 60 mm,
The decarburized layer was completely removed by mechanical grinding until completely. Thereafter, the above-mentioned round bar having a diameter of 50 mm is divided into six equal parts, heated at 1050 ° C. for 30 minutes while controlling the atmosphere in a heating furnace, and hot-rolled by a usual method to obtain a wire rod having a diameter of 5.5 mm or 10 mm. I made it. Each of the hot-rolled wires mainly had a pearlite structure.

An electric furnace was used for heating before hot rolling, and the atmosphere in the furnace was composed of CO, H ₂ , N ₂ and CO ₂ .
By changing (CO partial pressure) ² / (CO ₂ partial pressure),
The C content in the outer peripheral portion was adjusted.

A transverse sample was taken from the hot-rolled wire rod,
The C content in the outer peripheral portion (near the surface layer portion) was measured. That is, using a wavelength dispersion type electron beam microanalyzer, a line analysis of the amount of C was performed, and 4/250 of the radius from the outer periphery was obtained.
The C content at the depths of 3/250, 2/250, and 1/250 is read from the measurement chart, and the average value of these four points is obtained, whereby the position at a depth of 1/50 of the radius from the outer circumference is obtained. The average value of the C content in the region up to was obtained. FIG.
Table 2 shows the measurement results of Test No. 8 in Table 2 described below as an example of the C content in the outer peripheral portion (near the surface layer portion). In addition,
In this figure, A = 0.65% is the average value of the above-mentioned C content.

The hot-rolled wire obtained as described above is pickled by a usual method, and after applying a lubricant, the wire is broken according to a pass schedule in which the area reduction rate in each die is 20% on average. Wire drawing was performed up to. At this time, when the wire was not broken even when the wire was drawn at a true strain of 2.60 or more, the wire drawing was evaluated to be good.

Tables 2 and 3 summarize the atmosphere conditions of the heating furnace, the size of the hot-rolled wire rod, and the results of the above-mentioned investigations. In Tables 2 and 3, the atmosphere conditions of the heating furnace are such that (partial pressure of CO) ² / (partial pressure of CO ₂ ) is 120, 60, 30, 15, and 5 in the order of conditions 1 to 5. Is shown.

[0057]

[Table 2]

[0058]

[Table 3]

As is clear from Tables 2 and 3, in the case of the test numbers using the steels D, F, H, J and K of the comparative examples, that is, test number 16 in which the C content exceeds 1.1%. ~ 2
0, Test numbers 26 to 3 in which the Si content exceeds 1.5%
0, Test numbers 36 to 4 in which the Mn content exceeds 1.0%
0, Test No. 46 to 5 with Cr content exceeding 1.0%
Test Nos. 51 to 5 with 0, N content exceeding 0.006%
In No. 5, the wire drawing workability was low, and the true strain amount did not reach 2.60, and the wire was broken. Test numbers 16, 26, 36, 4
6, 47 and 51 have an average C content of 0.9 × C in a region from the outer periphery to a position at a depth of 1/50 of the radius.
%, The drawability is extremely poor. Test numbers 20, 30, 40, and 55 are 1/5 of the radius from the outer circumference.
Since the average value of the C content in the region up to the position of the depth of 0 is less than 0.6%, proeutectoid ferrite is generated in the surface layer portion of the wire, and the drawability is extremely poor.

[0060] Also the chemical composition is a steel within the range of the content defined in the present invention, the test number 6, 7,11,21,
31, 41, 42, 56, 57 and 61 have drawbacks in that the average value of the C content in the region from the outer periphery to the position at a depth of 1/50 of the radius exceeds 0.9 × C%. Was low, and the disconnection occurred without reaching the true strain of 2.60.

[0061] Also, the chemical composition is a steel within the range of the content defined in the present invention, the test numbers 10, 14, 1
Nos. 5, 25, 34, 35, 60, and 65 have a primary deposition on the surface of the wire rod because the average value of the C content in the region from the outer periphery to a position at a depth of 1/50 of the radius is less than 0.6%. Ferrite was generated, and therefore, the wire drawing workability was low, and the wire was broken without reaching the true strain of 2.60.

In contrast to the above comparative example, in the case of the present invention which satisfies the conditions defined in the present invention, the wire drawing workability was good, and the true strain exceeded 2.60. No disconnection occurred.

[0063]

Since the wire of the present invention is excellent in wire drawing workability, it is possible to provide a wire rope, a spring, a PC steel wire, a bead wire, a steel cord and the like with a high yield with high productivity by using the wire as a material. Can be. This wire is relatively easy to manufacture with ordinary equipment and does not require special equipment, so its manufacturing cost is low.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a measurement result of a C content in a cross section of a wire rod by a wavelength dispersion type electron beam microanalyzer.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22C 38/00 301 C22C 38/54

Claims (2)

(57) [Claims] C .: 0.7 to 1.1% by weight, Si:
0.1-1.5%, Mn: 0.2-1.0%, Al:
0.001 to 0.003%, Cr: 1.0% or less , N :
0.006% or less, Cu: 1.0% or less, Ni: 2.0
%, Mo: 0.5% or less, Co: 4.0% or less,
V: 0.4% or less, Nb: 0.1% or less, Ti: 0.1
%, B: 0.005% or less, P: 0.05% or less,
S: 0.05% or less, rare earth element: 0.10% or less, C
a: 0.01% or less, Mg: 0.01% or less,
In the cross section of the steel wire rod composed of Fe and unavoidable impurities, the average of the C content in the region from the outer periphery to a position at a depth of 1/50 of the radius of the steel wire rod is 0.6 to 0.6%.
A steel wire having excellent drawability, characterized by being 0.9 × C% (where C is the C content of the steel wire). 2. C .: 0.7 to 1.1% by weight, Si:
0.1-1.5%, Mn: 0.2-1.0%, Al:
0.001 to 0.003%, Cr: 1.0% or less , N :
0.006% or less, Cu: 1.0% or less, Ni: 2.0
%, Mo: 0.5% or less, W: 0.5% or less, C
o: 4.0% or less, V: 0.4% or less, Nb: 0.1%
Hereinafter, Ti: 0.1% or less, Zr: 0.1% or less, B:
0.005% or less, P: 0.05% or less, S: 0.05
%, Rare earth element: 0.10% or less, Ca: 0.01
% And Mg: 0.01% or less, and the balance is C in a region from the outer periphery to a position at a depth of 1/50 of the radius of the steel wire in the cross section of the steel wire made of Fe and unavoidable impurities. The average value of the content is 0.6 to 0.9 × C%
(Where C is the C content of the steel wire), wherein the steel wire is excellent in wire drawing workability.