KR20200062951A - High carbon steel wire rod having excellent drawability and metheod for manufacturing thereof - Google Patents

Abstract

Disclosed are a high-carbon wire having a cementite arrangement suitable for drawing and a manufacturing method thereof. The high-carbon wire having excellent drawability according to one embodiment of the present invention includes: 0.8 to 1.0 wt% of C; 0.15 to 1.5 wt% of Si; 0.2 to 0.8 wt% of Mn; 0.2 to 0.8 wt% of Cr; equal to or less than 0.05 wt% of Al; and the balance Fe and unavoidable impurities. An area fraction of colonies having an acute angle of equal to or more than 60° formed between a center line and the cementite alignment direction among pearlite colonies where the center line passes in the longitudinal cross-section including the center line is equal to or less than 20%.

Description

High carbon wire with excellent freshness and its manufacturing method {HIGH CARBON STEEL WIRE ROD HAVING EXCELLENT DRAWABILITY AND METHEOD FOR MANUFACTURING THEREOF}

The present invention relates to a high carbon wire having a cementite arrangement suitable for fresh processing and a method for manufacturing the same.

The high-strength wire produced with a wire diameter of 5 to 15 mm is heat-treated and processed to provide automotive tire cords or cables for bridges, PC steel wires used for concrete reinforcement, cables for large buildings or structures, anchor ropes supporting offshore oil fields or various structures ( Anchor rope).

When processing high-strength wires into steel wires, they are usually drawn, since the allowable amount of cold work is greater than other processing conditions, so that the hardening effect can be maximized. The drawing process is very advantageous when the microstructure is controlled by pearlite composed of a layered structure of ferrite and cementite. This is a process hardening effect due to active generation of dislocation at the interface between ferrite and cementite during cold working, and it is also very hard to secure strength, but cementite, which is known to be weak in brittleness, is activated under hydrostatic strain conditions during fresh processing. This is because plasticity is also secured by the slip system.

On the other hand, the pearlite structure before processing is composed of a collection of colonies (colony), which is a unit region in which the layering direction of the cementite is constant. As the amount of fresh processing increases, the deformation behavior of the cementite inside the colony depends on the initial cementite alignment direction. Differences appear. That is, if the initial alignment direction of cementite is not significantly different from the direction of drawing, the layer of pearlite is maintained even if the amount of processing increases, and thus the plastic processing ability described above can be secured. Otherwise, the possibility of segmentation of cementite increases and eventually microcavity The probability of causing defects such as (Microvoid) increases.

As described above, in order to improve the workability of drawing, it is required to secure a fraction of colonies having a cementite array in a specific direction so as to be advantageous for drawing.

The present invention is to provide a high carbon wire having excellent workability by forming a pearlite colony having a cementite arrangement suitable for drawing, and a method for manufacturing the same.

High carbon wire having excellent freshness according to an embodiment of the present invention, by weight, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al : Area fraction (A _center ) of colonies having an acute angle between the center line and the cementite alignment direction of 60° or more among pearlite colonies passing through the center line of the longitudinal cross-section including 0.05% or less, the remaining Fe and inevitable impurities, and having a center line 20% or less.

In addition, according to an embodiment of the present invention, the parallel line at a position of ±0.5R (R: radius of the wire) parallel to the center line of the longitudinal cross-section of the pearlite colony passes through the parallel line and the acute angle between the cementite array direction is 60° The area fraction (A _0.5R ) of the above colony may be 25% or less.

In addition, according to an embodiment of the present invention, an area fraction (A _0.5R ) of colonies having an acute angle between the parallel line and the cementite alignment direction of 60° or more among pearlite colonies passing through a parallel line at a position of ±0.5R parallel to the center line is equal to or greater than 60°. And the difference between the area fractions (A _center ) of the colonies having an acute angle of 60° or more between the center line and the cementite alignment direction of the pearlite colonies passing through the center line (A _0.5R -A _center ) may be 5% or less.

In addition, according to an embodiment of the present invention, B: 0.0004 to 0.0008% and Co: 0.01 to 0.015% may further include one or more.

Method for producing a high-carbon wire having excellent freshness according to an embodiment of the present invention, by weight, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8 %, Al: 0.05% or less, winding the wire including the remaining Fe and unavoidable impurities; And cooling by immersing the wound wire rod in 400 to 550°C molten nitrate and cooling, wherein the molten nitrate contains 0.02 to 0.25% by weight of moisture.

In addition, according to an embodiment of the present invention, B: 0.0004 to 0.0008% and Co: 0.01 to 0.015% may further include one or more.

In addition, according to an embodiment of the present invention, the cooled wire rod is a colony having an acute angle of 60° or more formed between the center line and the cementite alignment direction of the pearlite colonies passing through the center line of the longitudinal section including the center line at an area fraction of 20 %.

The present invention can provide a high-strength wire having excellent workability by forming a pearlite colony having a cementite arrangement suitable for drawing.

1 is a view showing the position of the center line and ±0.5R parallel line of the longitudinal section of the wire rod of radius R (Longitudinal section).
FIG. 2 is a view showing an angle θ formed between the wire rod central direction and the alignment direction of cementite in the pearlite colony.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are presented to sufficiently convey the spirit of the present invention to those of ordinary skill in the art. The present invention is not limited only to the embodiments presented herein, but may be embodied in other forms. In order to clarify the present invention, the drawings may omit the illustration of parts irrelevant to the description, and the size of components may be exaggerated to help understanding.

In the present invention, after researching on a method of appropriately controlling the arrangement of the cementite of pearlite colonies in a fresh direction when producing a wire rod having a pearlite microstructure by hot rolling or cooling after heat treatment, after the pearlite phase transformation, It was found that as the thermal gradient was minimized, the tendency of the colony's cementite arrangement to develop in the longitudinal direction of the wire increased. Currently, the principle is not clearly revealed, but when the phase transformation proceeds, if the thermal gradient between the surface and the center of the material is large, the lengthening of the cementite is biased in the direction of the thermal gradient, and the arrangement of the cementite inside the material eventually leads to the longitudinal direction of the material. It is estimated that the degree of deviation from the (fresh direction of the material in the future) increases.

In order to satisfy the above-mentioned thermal gradient conditions, a cooling method in which the material contacts the cooling fluid is required rather than the conventional blowing cooling method in terms of heat transfer efficiency on the material surface.

In the present invention, by studying the above phenomenon in depth, it was confirmed that the alloy component and the cooling manufacturing conditions were optimized to provide the direction of the cementite array inside the colony in the length direction of the wire rod, and the present invention has been completed.

High carbon wire having excellent freshness according to an embodiment of the present invention, by weight, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al : 0.05% or less, including the remaining Fe and unavoidable impurities.

Hereinafter, the reason for the numerical limitation of the alloying element content in the embodiment of the present invention will be described. In the following, unless otherwise specified, the unit is% by weight.

The content of C is 0.8 to 1.0%.

C is an element that forms cementite in a steel wire, and the cementite forms ferrite with a layered structure together with ferrite. Since cementite is higher in strength than ferrite, the higher the fraction of cementite, the greater the strength of the material. In addition, the more uniform and fine the spacing between the layered structures, the more the strength of the material can be improved.

Increasing the C content increases the fraction of cementite, and the lamellar interlayer spacing becomes fine, which is very effective in improving the strength of the wire. To this end, in the present invention, it is preferable to add C at 0.8% or more. However, when the content of C exceeds 1.0%, there is a problem in that the fraction of cementite cementite becomes excessive and ductility decreases.

Therefore, in the present invention, it is preferable to control the content of C to 0.8 to 1.0%.

The content of Si is 0.15 to 1.5%.

Si is employed in ferrite which is a matrix structure to strengthen steel, and when wire is processed into steel wire, it suppresses cementite fragmentation to maintain a healthy lamella structure even after fresh processing. In order to sufficiently obtain the above-described effect, it is preferable to add Si in an amount of 0.15% or more, but if the content is excessive and exceeds 1.5%, there is a fear that martensite is generated even after cooling by greatly increasing the quenching property.

Therefore, in the present invention, it is preferable to control the content of Si to 0.15 to 1.5%.

The content of Mn is 0.2 to 0.8%.

Mn is an element that retards pearlite transformation, and has an effect of allowing fine pearlite to be easily generated even at a slightly slower cooling rate. For the above-described effect, it is preferable to add Mn at 0.2% or more. However, when the Mn content exceeds 0.8%, the quenching property is greatly increased, and there is a fear that martensite is generated after cooling.

Therefore, in the present invention, it is preferable to control the Mn content to 0.2 to 0.8%.

The content of Cr is 0.2 to 0.8%.

Cr makes the gap between the lamellar layers of pearlite fine, and plays a role of suppressing fragmentation of cementite when drawing like Si. In order to sufficiently obtain the above-described effect, it is necessary to add Cr to 0.2% or more. However, if the content exceeds 0.8%, there is a fear that the quenching property is greatly increased to generate martensite after cooling, and there is a problem in that manufacturing cost increases as an expensive element.

Therefore, in the present invention, it is preferable to control the content of Cr to 0.2 to 0.8%.

The content of Al is 0.05% or less (excluding 0%).

Al is an element that is easy to react with O, and is a representative element utilized in the deoxidation reaction of steelmaking. However, if such Al is present in the steel, there is a possibility of promoting the formation of an inclusion, so it is preferable to control so that it does not remain in the steel as much as possible. In addition, Al is involved in the diffusion behavior of C at high temperature to suppress the reaction of C dissolving from cementite to ferrite during austenite heating and high temperature maintenance, thereby promoting the phenomenon of unrefined cementite remaining.

In consideration of this, in the present invention, it is preferable to add Al to 0.05% or less, and 0% is excluded.

According to an embodiment of the present invention, B: 0.0004 to 0.0008% and Co: 0.01 to 0.015% may further include one or more.

The content of B is 0.0004 to 0.0008%.

B is segregated at the austenite grain boundary and has the effect of delaying phase transformation. In the present invention, it is necessary to appropriately control the phase transformation time point in order to secure a time during which the thermal gradient between the center and the surface generated while the material is cooled at a high temperature can be resolved. In this aspect, B is an applicable element. However, if the added amount is less than 0.0004%, the effect is negligible. If it is more than 0.0008%, B compound may be formed at the grain boundary to impair physical properties.

The content of Co is 0.01 to 0.015%.

Co, like B, has the effect of stabilizing grain boundary energy and delaying phase transformation. However, if the addition amount is less than 0.01%, the effect is minimal, and if it is more than 0.015%, the phase transformation delay effect is very large, affecting the overall material level as well as being an expensive element, which is disadvantageous in terms of economic efficiency.

The remaining component of the present invention is Fe. However, in the normal manufacturing process, impurities that are not intended from the raw material or the surrounding environment may be inevitably mixed, and therefore cannot be excluded.

The high carbon wire of the present invention that satisfies the above-described alloy composition has a pearlite phase as a microstructure and a base structure, and the centerline and cementite array among pearlite colonies (hereinafter referred to as the center) passing through the centerline of the longitudinal section including the centerline. The area fraction of colonies having an acute angle of 60° or more in the direction is 20% or less.

In addition, according to an embodiment of the present invention, in a longitudinal cross section including a center line of a wire rod having a radius of R, among the pearlite colonies (hereinafter, referred to as surface layer parts), parallel lines of ±0.5R parallel to the center line of the longitudinal section pass. The area fraction of the colonies having an acute angle of 60° or more formed by the parallel line and the cementite alignment direction may be 25% or less.

1 is a view showing the center line and ±0.5R parallel line position of the longitudinal section of the wire rod (Longitudinal section) of the radius R, Figure 2 is a view showing the angle (θ) between the center direction of the wire rod and the alignment direction of cementite in the pearlite colony .

With reference to FIGS. 1 and 2, the angle θ between the longitudinal direction of the wire rod and the direction of cementite alignment among the pearlite colonies of the center portion and the surface layer portion of the present invention and the significance of the area fraction of the corresponding pearlite colonies will be described.

The regions A in FIG. 1 represent a central portion and a surface layer portion, and FIG. 2 shows a microstructure composed of pearlite colonies observed by enlarging the region A. The center line of the center and the parallel line of the surface layer portion at the position of ±0.5R with the center line as the origin are all in the same direction as the length direction of the wire rod. In the present invention, the area fraction of the colonies having an acute angle of 60° or more formed between the longitudinal direction of the wire rod and the cementite alignment direction is within the entire length of the pearlite colony passing through the center line or parallel line (center line or parallel line) and within the pearlite colony. It means the fraction of pearlite colonies whose acute angle θ formed by the cementite array direction is 60° or more.

The cementite having an acute angle of 60° or more is segmented by bending deformation as the fresh processing progresses. In this process, micro-crack may be induced at the interface between cementite and ferrite. In addition, the segmented cementite remains in a spherical shape. In this case, when a subsequent deformation proceeds, microvoids are generated at the interface and then act as a crack starting point. In order to reveal a significant difference in physical properties by the above mechanism, it is necessary to control the area fraction of colonies satisfying the corresponding conditions to be 20% or less.

On the other hand, since the surface of the material is expected to have a large thermal gradient due to the temperature difference between the outside and the material where heat exchange is directly generated, the acute angle formed by the longitudinal direction of the wire rod colony tends to be greater than that of the center. However, the surface layer portion has a favorable aspect in arranging the cementite in the fresh direction without fragmentation of the cementite compared to the center because shear deformation is concentrated during the fresh processing. For this reason, the area fraction of pearlite colonies having an acute angle of 60° or more formed in the longitudinal direction allowed by the surface layer portion is slightly higher than that of the center portion, but if the difference is wide, it is disadvantageous in terms of material deviation between the material center portion and the surface layer portion.

In the present invention, when observing the center portion and the surface layer portion (±0.5R point), the area fraction of the colonies having an acute angle between the wire rod length direction and the cementite arrangement direction inside the colony of 60° or more should be controlled to be 5% or less. If the difference in fraction exceeds 5%, it may affect securing properties of the final steel wire.

According to an embodiment of the present invention, the area fraction of colonies having an acute angle between the parallel line and the cementite alignment direction of 60° or more among pearlite colonies passing parallel lines of ±0.5R parallel to the center line of the longitudinal section is 25% or less. Can be.

Next, a method of manufacturing a high-carbon wire having excellent freshness according to the present invention will be described.

The method of manufacturing a high-carbon wire having excellent freshness according to an embodiment of the present invention is manufactured through a series of processes for manufacturing a wire having the above-described alloy composition, and then winding it under a controlled temperature condition and then cooling it. Can be produced.

The high carbon wire according to the present invention can be produced through various wire production techniques commonly known in the art, but is preferably produced through a series of processes described below.

First, it is preferable to prepare a billet that satisfies the above-described alloy composition and then undergo a heating process to homogenize it. It is preferable to make the microstructure of the billet austenite single phase through a heating process. To this end, heating may be performed in a temperature range of 950 to 1,100°C. If the heating temperature is less than 950° C., it is difficult to secure a temperature range required for subsequent wire rolling, whereas when the temperature exceeds 1,100° C., there is a problem in that the surface quality is inferior due to the occurrence of scale and decarburization.

After rolling the billet heated as above, it is preferable to cool it to produce a wire rod.

At this time, it is preferable that the wire rod is subjected to finish rolling in a temperature range of 900 to 1,000°C. If the finish rolling temperature is less than 900°C, there is a fear that the rolling roll is damaged by the rolling load, whereas when the finish rolling temperature exceeds 1,000°C, the austenite grains become coarse, and there is a problem that it is difficult to secure the target strength.

It is preferable that the rolled wire is wound in a ring shape. In the present invention, the winding step may be performed in a temperature range of 750 to 950°C. Here, the winding temperature is based on the temperature of the surface of the wire rod.

After winding, a cooling method in which the material contacts the cooling fluid is required, and the cooling fluid at this time is preferably 400 to 550°C molten nitrate. When the temperature of the nitrate is less than 400°C, the possibility of inhibiting physical properties is increased by forming a bainite structure rather than pearlite on the surface layer, whereas when the temperature of the nitrate exceeds 550°C, the cooling rate of the entire material is slow, which is disadvantageous in terms of strength.

Further, the molten nitrate may include 0.02 to 0.25% by weight of moisture. When the molten nitrate contains water, the efficiency of cooling increases as the action of taking away the heat of vaporization from the material and the stirring action of the molten salt due to bubbles occur due to the phenomenon that the water vaporizes on the surface of the material. It can contribute to suppressing gradients. When the moisture content is less than 0.02% by weight, vaporization does not occur sufficiently to realize the above effect, and when it exceeds 0.25% by weight, vaporization occurs very vigorously, causing high temperature molten salt to scatter to the outside. Not suitable for use as Therefore, the moisture content of the molten nitrate is preferably in the range of 0.02 to 0.25% by weight.

Hereinafter will be described in more detail through a preferred embodiment of the present invention.

Example

After casting the ingot (70Kg) having the alloy component composition (% by weight) as described in Table 1 below, heated in a heating furnace at 1,100°C for about 2 hours, and then extracted in a heating furnace to have a wire diameter of 13 mm at a temperature of 900°C or higher. The wire rod was rolled. Thereafter, the rolled wire rod was cooled by water, wound at 850°C, and then immersed in a 400 to 550°C nitric acid salt bath prepared in advance for 5 minutes and then taken out to observe the material longitudinal section.

division Alloy composition [% by weight] C Si Mn Cr Al B Co Inventive Example 1 0.8 0.15 0.2 0.8 0.03 - - Inventive Example 2 0.9 0.15 0.5 0.5 0.03 - - Inventive Example 3 1.0 1.5 0.8 0.8 0.03 - - Inventive Example 4 0.8 0.15 0.2 0.2 0.05 0.0004 - Inventive Example 5 0.8 0.15 0.2 0.8 0.03 - 0.01 Inventive Example 6 0.8 1.5 0.2 0.8 0.04 0.0006 Inventive Example 7 0.8 1.5 0.8 0.2 0.01 - 0.012 Inventive Example 8 0.8 1.5 0.8 0.8 0.05 0.0008 - Inventive Example 9 0.9 0.15 0.2 0.5 0.01 - 0.015 Inventive Example 10 0.9 0.15 0.2 0.8 0.01 0.0004 - Inventive Example 11 0.9 0.15 0.5 0.5 0.03 - 0.01 Inventive Example 12 0.9 0.15 0.8 0.2 0.01 0.0006 - Inventive Example 13 0.9 0.9 0.5 0.8 0.03 - 0.012 Inventive Example 14 0.9 0.9 0.8 0.8 0.01 0.0008 - Inventive Example 15 0.9 1.5 0.2 0.2 0.03 - 0.015 Inventive Example 16 0.9 1.5 0.8 0.2 0.01 0.0004 - Inventive Example 17 0.9 1.5 0.8 0.5 0.03 - 0.01 Inventive Example 18 1.0 0.15 0.8 0.2 0.01 0.0006 - Inventive Example 19 1.0 0.15 0.8 0.2 0.05 - 0.012 Inventive Example 20 1.0 1.5 0.8 0.8 0.03 0.0008 - Comparative Example 1 0.8 0.15 0.2 0.8 0.03 - 0.015 Comparative Example 2 0.9 0.15 0.5 0.5 0.03 0.0004 - Comparative Example 3 1.0 0.15 0.8 0.2 0.01 - 0.01 Comparative Example 4 0.8 1.5 0.2 0.8 0.04 0.0006 -

division Molten nitrate
Salt bath temperature
[℃] nitrate
Moisture content
[weight%] With wire rod length direction
The angle formed by the cementite array direction
Perlite colony fraction over 60°
[area%] center Surface layer Inventive Example 1 450 0.12 20 25 Inventive Example 2 450 0.19 20 25 Inventive Example 3 450 0.25 20 25 Inventive Example 4 400 0.25 20 24 Inventive Example 5 450 0.19 17 21 Inventive Example 6 500 0.12 20 24 Inventive Example 7 550 0.02 17 21 Inventive Example 8 400 0.25 18 23 Inventive Example 9 450 0.19 20 24 Inventive Example 10 500 0.12 19 24 Inventive Example 11 550 0.02 16 21 Inventive Example 12 400 0.25 20 25 Inventive Example 13 450 0.19 20 25 Inventive Example 14 500 0.12 17 22 Inventive Example 15 550 0.02 16 21 Inventive Example 16 400 0.25 20 23 Inventive Example 17 450 0.19 19 24 Inventive Example 18 500 0.12 16 20 Inventive Example 19 550 0.02 19 24 Inventive Example 20 400 0.25 15 20 Comparative Example 1 395 0.02 20 27 Comparative Example 2 555 0.02 21 26 Comparative Example 3 500 0.01 22 29 Comparative Example 4 400 0.26 19 24

Inventive Examples 1 to 3 are weight %, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al: 0.05% or less, remaining Fe and unavoidable impurities. Including, it was prepared by a manufacturing method comprising the step of cooling by immersing the wound wire in 450 ℃ nitrate containing 0.02 to 0.25% moisture. Accordingly, when observing the pearlite colonies in the center of the longitudinal section, the area fraction of colonies having an acute angle of 60° or more formed between the wire length direction and the inner cementite alignment direction was 60% or less, and ±0.5R position When the surface layer colonies were observed, the difference in the area fraction of the colonies having acute angles of 60° or more formed between the wire length direction and the internal cementite alignment direction was less than 5%.

Inventive Examples 4 to 20 are weight %, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al: 0.05% or less, and B or Co. It contains a species or more, and was prepared by a manufacturing method comprising immersing and winding the wound wire in 400 to 550°C nitrate containing 0.02 to 0.25% moisture. Accordingly, when observing the pearlite colonies in the center of the longitudinal section, the area fraction of colonies having an acute angle of 60° or more formed between the wire length direction and the inner cementite alignment direction was 60% or less, and ±0.5R position When the surface layer colonies were observed, the difference in the area fraction of the colonies having acute angles of 60° or more formed between the wire length direction and the internal cementite alignment direction was less than 5%.

In Comparative Example 1, the temperature of the nitrate immersed for cooling after coiling was 395°C and less than 400°C, resulting in bainite in the microstructure, and was unsuitable for freshness.

In Comparative Example 2, the temperature of the nitrate immersed for cooling after coiling was 555°C, exceeding 550°C, making it difficult to secure high strength, and when the colonies in the center of the longitudinal section were observed, the lengthwise direction of the wire rod and the direction of the arrangement of cementite inside were formed. The area fraction of colonies having an acute angle of 60° or more exceeded 20%.

In Comparative Example 3, when the content of nitrate was less than 0.02% by weight, and the colonies in the center of the longitudinal section were observed, the area fraction of the colonies having a sharp angle between the wire length direction and the internal cementation direction of 60° or more exceeded 20%. , The area fraction of colonies having an acute angle of 60° or more on the surface layer also exceeded 25%, and the difference was found to be 7%, which was confirmed as a material having low fresh suitability.

In Comparative Example 4, the nitrate had a moisture content exceeding 0.25% by weight, resulting in scattering of nitrate, and it was confirmed that it was difficult to apply it to manufacturing.

As described above, although exemplary embodiments of the present invention have been described, the present invention is not limited thereto, and a person skilled in the art does not depart from the concept and scope of the following claims. It will be understood that various modifications and variations are possible.

Claims (8)

In weight percent, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al: 0.05% or less, including the remaining Fe and unavoidable impurities,
Among the pearlite colonies passing through the center line of the longitudinal cross-section including the center line, a high-carbon wire having excellent freshness with an area fraction of 20% or less in colonies having an acute angle of 60° or more formed between the center line and the cementite array direction. According to claim 1,
Of pearlite colonies in which parallel lines at a position of ±0.5R (R: radius of wire) parallel to the center line of the longitudinal section pass, the colonies having an acute angle of 60° or more formed between the parallel lines and the cementite alignment direction are 25% or less in area fraction High-carbon wire with excellent properties. According to claim 1,
B: 0.0004 to 0.0008% and Co: 0.01 to 0.015%, high carbon wire having excellent freshness, further comprising at least one. In weight percent, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al: 0.05% or less, including the remaining Fe and unavoidable impurities,
In the longitudinal section including the center line,
The area fraction (A _center ) of the colonies having an acute angle of 60° or more formed between the center line and the cementite alignment direction among the pearlite colonies passing through the center line is 20% or less,
The difference between the area fraction (A _0.5R ) of the colony having an acute angle between the parallel line and the cementite alignment direction of 60° or more among pearlite colonies passing through a parallel line at a position of ±0.5R parallel to the center line (R: radius of the wire) A _0.5R - _{center of} A) High carbon wire with excellent freshness of 5% or less. The method of claim 4,
B: 0.0004 to 0.0008% and Co: 0.01 to 0.015%, high carbon wire having excellent freshness, further comprising at least one. In weight percent, C: 0.8 to 1.0%, Si: 0.15 to 1.5%, Mn: 0.2 to 0.8%, Cr: 0.2 to 0.8%, Al: 0.05% or less, winding the wire rod containing the remaining Fe and unavoidable impurities step; And
Including the step of cooling by immersing the wound wire 400 to 550 ℃ molten nitrate;
The molten nitrate is a method for producing a high-carbon wire rod excellent in freshness containing 0.02 to 0.25% by weight of moisture. The method of claim 6,
B: 0.0004 to 0.0008% and Co: 0.01 to 0.015% of the method for producing a high-carbon wire rod excellent in freshness further comprising at least one. The method of claim 6,
The cooled wire rod,
Of the pearlite colonies passing through the center line of the longitudinal cross-section including the center line, a method of manufacturing a high-carbon wire having excellent freshness in which an area having an acute angle of 60° or more formed between the center line and the cementite alignment direction is 20% or less in an area fraction.

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