Graphite steel wire rod, steel wire, graphite steel, and method for manufacturing the same, all with excellent cutting performance.

Abstract

The present invention provides a graphite steel wire rod, steel wire, and graphite steel having excellent cutting performance, and a manufacturing method thereof. [Solution] The graphite steel wire rod of the present invention is characterized by comprising, by weight, 0.60-0.90% carbon (C), 2.0-2.5% silicon (Si), 0.1-0.6% manganese (Mn), 0.015% or less phosphorus (P) (excluding 0), 0.031-0.3% sulfur (S), 0.01-0.05% aluminum (Al), 0.005-0.02% titanium (Ti), 0.0005-0.0020% boron (B), 0.0030-0.0150% nitrogen (N), with the remainder being Fe and unavoidable impurities.

Description

Technical Field

[0001] The present invention relates to a graphite steel wire, steel wire, graphite steel having excellent cutting performance, and a method for manufacturing the same, and more particularly, to a graphite steel wire, steel wire, graphite steel added with sulfur, and a method for manufacturing the same, which have better cutting performance than general free-cutting steel.

Background Art

[0002] Generally, as a material for mechanical parts and the like that require machinability, free-cutting steel added with machinability-imparting elements such as Pb, Bi, and S is used. In order to improve the machinability of steel materials, low-melting-point machinability-imparting elements such as Pb and Bi are added to the steel to utilize the liquid metal embrittlement phenomenon, or a large amount of MnS is formed in the steel. Such free-cutting steel is very excellent in the machinability of steel such as surface roughness, chip disposal property, and tool life during cutting.

[0003] However, in the case of Pb-added free-cutting steel with the best cutting performance, harmful substances such as toxic fumes are discharged during cutting operations, which is harmful to the human body and also disadvantageous for the recycling of steel materials. Therefore, in order to replace this, the addition of S, Bi, Te, Sn, etc. has been proposed, but there are problems that cracks are likely to occur during the production of steel materials and production is very difficult, or it is known that cracks are often caused during hot rolling. Graphite steel can be cited as a free-cutting steel developed to solve the above problems. Graphite steel is a steel containing fine graphite grains inside a ferrite base or a ferrite and pearlite base. The fine graphite grains inside act as crack supply sources during cutting and serve as chip breakers, so it is a steel having good machinability.

[0004] However, despite these advantages of graphite steel, it is not currently commercially available. This is because when carbon is added to steel, cementite, a metastable phase, precipitates even though graphite is a stable phase. It is difficult to precipitate graphite without a separate heat treatment of 10 hours or more, and this long heat treatment process causes decarburization, which negatively affects the performance of the final product.

[0005] Furthermore, even if graphite particles are precipitated through graphitization heat treatment, if they are irregularly shaped and unevenly distributed, the physical properties will be uneven during cutting, resulting in poor chip processing and surface roughness, shortened tool life, and making it difficult to obtain the advantages of graphite steel. Therefore, there is a need to provide a method for manufacturing graphite free-cutting steel with excellent cutting performance by using graphite particles and utilizing MnS-based inclusions. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide graphite steel wire, steel wire, graphite steel, and a method for manufacturing the same, which have excellent machinability. [Means for solving the problem]

[0007] The graphite steel wire rod of the present invention is characterized by comprising, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities.

[0008] The present invention relates to a method for manufacturing graphite steel wire rod, characterized by comprising the steps of: manufacturing a billet consisting of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities; heating the billet; hot rolling the heated billet to manufacture a wire rod; and cooling the wire rod.

[0009] The graphite steel wire of the present invention is characterized by comprising, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities.

[0010] The graphite steel of the present invention is characterized by having, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities, and having a microstructure in which graphite particles are distributed in a ferrite matrix, with a degree of graphitization of 95% or more, and containing a total of 5% or less of MnS inclusions and pearlite.

[0011] The present invention relates to a method for producing graphite steel, comprising the steps of: producing a wire rod consisting of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities; and performing graphitization heat treatment on the produced wire rod. [Effects of the Invention]

[0012] According to the present invention, the graphite steel of the present invention has excellent cutting performance, can replace conventional free-cutting steel materials, and can be used as an environmentally friendly free-cutting steel that eliminates harmful elements such as Pb. [Modes for carrying out the invention]

[0013] A graphite steel wire rod according to one embodiment of the present invention consists of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities.

[0014] The following describes in detail the graphite steel wire rod, steel wire, graphite steel, and the manufacturing method of the present invention, which have excellent cutting performance. [Graphite steel wire] A graphite steel wire rod according to one embodiment of the present invention consists of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities. Unless otherwise specified, the unit is weight percent. Furthermore, when any part is said to "contain" a certain component, this does not mean excluding other components, but rather that it may contain other components, unless otherwise stated. [Range of ingredients]

[0015] Carbon (C): 0.60~0.90% by weight Carbon is an essential element for forming graphite particles. If the carbon content is less than 0.60% by weight, the machinability improvement effect is insufficient, and the distribution of graphite particles becomes uneven even after graphitization is complete. If the content is excessive, at 0.90% by weight or more, the graphite particles are formed coarsely, the aspect ratio increases, and there is a risk that the machinability, especially the surface roughness, will decrease. Therefore, it is preferable that the upper limit of the carbon content is 0.90% by weight.

[0016] Silicon (Si): 2.0-2.5% by weight Silicon is an essential component as a deoxidizing agent in the production of molten steel. It is a graphitization-promoting element that destabilizes cementite in steel, causing carbon to precipitate as graphite, and is therefore added actively. In order to exhibit these effects in the present invention, the silicon content is preferably 2.0% by weight or more. On the other hand, if the content is excessive, not only will the effect saturate, but the hardness will increase due to the solid solution strengthening effect, tool wear will be accelerated during cutting, brittleness will be induced due to an increase in nonmetallic inclusions, and excessive decarburization may be induced during hot rolling. Therefore, the upper limit of the silicon content is preferably 2.5% by weight.

[0017] Manganese (Mn): 0.1-0.6% by weight Manganese improves the strength and impact properties of steel, and by combining with sulfur in the steel, it forms MnS inclusions, contributing to improved machinability. In order to exhibit these effects in the present invention, it is preferable that the manganese content be 0.1% by weight or more. On the other hand, if the content is excessive, it may inhibit graphitization, delay the completion time of graphitization, increase strength and hardness, and decrease machinability. Therefore, it is preferable that the upper limit of the manganese content be 0.6% by weight.

[0018] Phosphorus (P): 0.015% by weight or less (excluding 0) Phosphorus is an unavoidable impurity. Even though phosphorus weakens the grain boundaries of steel and improves machinability, it increases the hardness of ferrite through a considerable solid solution strengthening effect, reduces the toughness and delayed fracture resistance of the steel, and promotes the occurrence of surface defects. Therefore, it is preferable to control its content to the lowest possible level. Theoretically, it is advantageous to control the phosphorus content to 0% by weight, but it is inevitably included in the manufacturing process. Therefore, it is important to control its upper limit, and in this invention, that upper limit is controlled to 0.015% by weight.

[0019] Sulfur (S): 0.031~0.3% by weight Sulfur improves machinability by promoting MnS formation, but if present in excess, mechanical anisotropy occurs due to the stretching of MnS during rolling. In this invention, sulfur was added in a range that contributes to improving machinability without causing mechanical anisotropy, thereby inducing MnS formation. Specifically, when the sulfur content is in the range of 0.031 to 0.3% by weight, MnS is formed, improving machinability and resulting in 100% cutting performance compared to lead free-cutting steel. However, if the sulfur content is controlled to less than 0.031% by weight, it is not possible to create enough MnS inclusions to improve cutting performance. Furthermore, if it exceeds 0.3% by weight, the anisotropy of the material increases, leading to breakage during machining and posing a danger to workers.

[0020] Aluminum (Al): 0.01-0.05% by weight Aluminum is an element that promotes graphitization after silicon. This is because when aluminum exists as dissolved Al, it destabilizes cementite. Therefore, it is necessary to exist as dissolved Al. In order to exhibit such an effect in the present invention, it is preferably contained at 0.01% by weight or more. On the other hand, when the content is excessive, not only does the effect saturate, but there is also a risk of inducing clogging of the nozzle during continuous casting. AlN is generated at the austenite grain boundary, and graphite nucleated by this is distributed non-uniformly at the grain boundary. Therefore, the upper limit of the aluminum content is preferably 0.05% by weight.

[0021] Titanium (Ti): 0.0051 to 0.02% by weight [[ID=]7]<0>

[0022] Nitrogen (N): 0.0030 to 0.0150% by weight Nitrogen combines with titanium, boron, and aluminum to form TiN, BN, AlN, etc. In particular, nitrides such as BN and AlN are mainly formed at austenite grain boundaries. During graphitization heat treatment, graphite may be formed with such nitrides as nuclei, causing a non-uniform distribution of graphite. Therefore, an appropriate amount of addition is required. If the nitrogen addition amount is too large and does not combine with nitride-forming elements but exists in the steel as dissolved nitrogen, it has an adverse effect of increasing strength, stabilizing cementite, and delaying graphitization. Therefore, in the present invention, the nitrogen content is limited with a lower limit of 0.0030 wt% and an upper limit of 0.0150 wt% so as to be consumed to form nitrides that act as graphite nucleation sites and not remain as dissolved nitrogen.

[0023] Boron (B): 0.0005 - 0.0020% It combines with N to form BN, acts as a nucleus for graphite crystallization, and promotes graphitization, so it is actively added. However, if it is less than 0.0005 wt%, the effect is small. Also, when added in excess of 0.0020 wt%, excessive BN is formed at austenite grain boundaries, not only causing a non-uniform distribution of graphite grains after graphitization heat treatment but also making the grain boundaries brittle and causing a problem of significantly reducing hot rolling ductility. Therefore, it is preferably contained in the range of 0.0005 - 0.0020 wt%.

[0024] The remaining components of the present invention are iron (Fe) and inevitable impurities. However, in the normal steel manufacturing process, unintended impurities may unavoidably be mixed in from raw materials or the surrounding environment, and thus they cannot be excluded. Since these impurities can be known to any engineer in the normal steel manufacturing process, all of their details are not particularly mentioned in this specification.

[0025] Furthermore, according to one embodiment of the present invention, the wire for graphitization heat treatment can have a perlite area fraction of 95% or more. In the present invention, graphite particles are generated by the decomposition of perlite, so if the area fraction of perlite is low, the fraction of graphite particles will also be low, resulting in an undesirable, non-uniform distribution. A high area fraction of perlite is advantageous for ensuring uniform and fine graphite particles, so there is no particular upper limit to it. [Method of manufacturing wire]

[0026] A method for manufacturing graphite steel wire rod according to one embodiment of the present invention involves the steps of producing a billet consisting of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities. In the step of heating the billet, The steps include: hot rolling the heated billet to produce a wire rod, and This includes the step of cooling the aforementioned wire. Wire heating process

[0027] Furthermore, according to one embodiment of the present invention, the heating step may include heat treatment by maintaining the temperature in the range of 1050 ± 100°C for 60 minutes or more. Before wire rolling, the billet is maintained at a temperature of 1050 ± 100°C for at least 60 minutes. Heating the billet to a temperature below 950°C can increase the load during rolling, potentially reducing rolling productivity, thus presenting disadvantages to lower heating temperatures. Heating to a temperature exceeding 1150°C is undesirable because it not only increases costs but also accelerates decarburization, resulting in a thicker decarburized layer that remains in the final product. The reason for maintaining the heating time at 60 minutes or more is that maintaining it for less than 60 minutes makes it difficult to ensure a uniform temperature distribution inside and outside the billet for wire rolling. Wire rolling process

[0028] Furthermore, according to one embodiment of the present invention, the step of hot rolling to manufacture a wire rod is preferably performed at a temperature range of 900 to 1150°C. The reason for setting the wire rod rolling temperature in the range of 900 to 1150°C is that below 900°C, surface defects easily occur during hot rolling, or the rolling load increases, making rolling difficult. On the other hand, above 1150°C, the Austenite Grain Size (AGS) becomes coarser, which can lead to a longer graphitization heat treatment time after wire rod rolling. cooling process

[0029] Furthermore, according to one embodiment of the present invention, the cooling step is preferably performed by cooling to 500°C at a cooling rate of 0.1 to 10.0°C / s. Furthermore, according to one embodiment of the present invention, it is preferable to include a step of air cooling after the cooling step. If the cooling rate exceeds 10.0°C, a hard phase such as martensite may form, which can cause wire breakage during cold drawing, the next step after wire rolling, and is therefore undesirable. If the cooling rate is less than 0.1°C, excessive proteremination phase formation occurs, which can reduce the fraction of pearlite, coarseen the grain size, and result in a non-uniform distribution of graphite grains after the graphitization heat treatment, which is also undesirable. [Graphite steel wire]

[0030] A graphite steel wire according to one embodiment of the present invention consists of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities. [Graphite steel]

[0031] が、 が

[0032] The degree of graphitization refers to the ratio of carbon content present in graphite state to carbon content added to the steel, and is defined by the following [Relationship Formula 1]. Graphitization of 95% or more means that most of the added carbon was consumed to produce graphite (the amount of carbon dissolved in ferrite and fine carbides is extremely small and therefore not considered), and that there is no undecomposed pearlite, meaning that the ferrite matrix has a microstructure in which graphite particles are distributed. [Relationship 1] Graphitization degree (%) = (1 - Carbon content in undecomposed pearlite / Carbon content in steel) × 100 (If there is no undecomposed perlite, the degree of graphitization will be 100%.) [Manufacturing method for graphite steel]

[0033] A method for producing graphite steel according to one embodiment of the present invention includes the steps of: producing a wire rod consisting of, by weight percent, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities; and graphitizing heat treatment of the produced wire rod.

[0034] Furthermore, according to one embodiment of the present invention, the graphitization heat treatment step can be performed at a temperature range of 700 to 800°C for 5 hours or more. Maintaining a heat treatment at 700-800°C for more than 5 hours can achieve a graphitization degree of 95% or higher. However, below 700°C, the graphitization heat treatment time becomes longer, exceeding 10 hours. Above 800°C, not only does the graphitization time become longer, but austenite is generated by the reverse transformation of pearlite, and further pearlite may be formed during cooling, which is undesirable. The present invention will be described in more detail below based on examples. The following embodiments are provided to fully convey the concept of the present invention to those who have ordinary skill in the art to which the present invention pertains. The present invention is not limited to the embodiments presented herein and may be embodied in other forms. (Examples)

[0035] A billet containing the components listed in Table 1 below was maintained at the heating temperature for 90 minutes and then rolled at high speed to produce a wire with a diameter of 19 mm. The wire cooling rate, the area fraction of perlite in the wire, the graphitization heat treatment time, and the degree of graphitization are shown in Table 1 below. In Tables 1 and 2, Examples 1 to 11 correspond to graphite steel wire rods that satisfy the alloy composition range and manufacturing conditions of the present invention, while Comparative Examples 1 to 7 correspond to wire rods that do not satisfy the alloy composition range and / or manufacturing conditions of the present invention.

[0036] [Table 1] *Cutting performance is a value based on the cutting performance of leaded free-cutting steel (100% means an equivalent level).

[0037] [Table 2] The microstructure of *(100%-graphitization degree) consists of MnS inclusions and pearlite, while the graphitized microstructure consists of ferrite + graphite particles. The area fraction of pearlite and the degree of graphitization can be confirmed to be achieved under the wire and graphitization manufacturing conditions as shown in Table 2 above.

[0038] The examples and comparative examples are evaluated below with reference to Tables 1 and 2. Examples 1 to 11 confirmed that by satisfying the alloy composition range and manufacturing conditions of the present invention, the area fraction of pearlite in the graphite steel wire rod was 95% or more, the degree of graphitization was 98.5% or more, and the cutting performance was 100% compared to lead free-cutting steel.

[0039] On the other hand, the cutting performance of Comparative Example 1, a graphite steel with a sulfur content of only 0.005% by weight and virtually no boron, was 88% lower than that of lead free-cutting steel. Furthermore, the manufacturing method of the wire rod in Comparative Example 1 involved cooling at a cooling rate of 0.05°C / s, resulting in a wire rod containing a 93% area fraction of pearlite, and the heat treatment was maintained for 1.5 hours, resulting in a low degree of graphitization of 75%. Furthermore, the cutting performance of the graphite steel in Comparative Example 2, which contained only 0.003% by weight of sulfur and only 0.0002% by weight of boron, was 95% lower than that of lead free-cutting steel. The manufacturing method for the wire rod in Comparative Example 2 involved cooling at a cooling rate of 12.0°C / s. A wire rod containing 93.5% pearlite area fraction was produced and maintained for 2.5 hours during heat treatment, resulting in a low degree of graphitization of 85%. Furthermore, the cutting performance of the graphite steel in Comparative Example 3, which contained only 0.006% by weight of sulfur and only 0.0004% by weight of boron, was 89% lower than that of lead free-cutting steel. The manufacturing method of the wire rod in Comparative Example 3 involved cooling at a cooling rate of 11.5°C / s, producing a wire rod containing 94.2% pearlite area fraction, and the heat treatment was maintained for 3.0 hours, resulting in a low degree of graphitization of 86%.

[0040] Furthermore, the cutting performance of the graphite steel in Comparative Example 4, which had a carbon content of 0.95 wt%, a sulfur content of 0.007 wt%, and a boron content of 0.0025 wt%, was 92% lower than that of lead free-cutting steel. In the manufacturing method of the wire rod in Comparative Example 4, the cooling rate was 0.07 °C / s, resulting in the production of a wire rod containing a 93.2% area fraction of pearlite, and the heat treatment was maintained for 2.5 hours, resulting in a low degree of graphitization of 85%.

[0041] Furthermore, the cutting performance of the graphite steel in Comparative Example 5, which had a carbon content of 0.55 wt%, a silicon content of 2.6 wt%, a sulfur content of 0.4 wt%, a titanium content of 0.025 wt%, and a boron content of 0.0025 wt%, was 91% lower than that of lead free-cutting steel. The wire rod manufacturing method for Comparative Example 5 involved cooling at a cooling rate of 15.5°C / s, producing a wire rod containing a 93.5% pearlite area fraction, which was then maintained under heat treatment for 3.4 hours, resulting in a low degree of graphitization of 86%. Furthermore, the cutting performance of the graphite steel in Comparative Example 6, which had a silicon content of 2.75 wt%, a manganese content of 0.9 wt%, a sulfur content of 0.45 wt%, a titanium content of 0.03 wt%, and a boron content of 0.0024 wt%, was 93% lower than that of lead free-cutting steel. The manufacturing method of the wire rod in Comparative Example 6 involved cooling at a cooling rate of 14.0°C / s, producing a wire rod containing a 94.1% pearlite area fraction, which was then maintained under heat treatment for 4.2 hours, resulting in a low degree of graphitization of 84%.

[0042] Furthermore, Comparative Example 7, a graphite steel with a silicon content of 2.8 wt%, manganese content of 0.8 wt%, sulfur content of 0.35 wt%, titanium content of 0.002 wt%, and boron content of 0.003 wt%, had cutting performance that was 90% lower than that of lead free-cutting steel. From the evaluation of each example and comparative example described above, it can be seen that if the range of alloy composition and manufacturing conditions of the present invention are met, all the properties of the graphite steel wire and graphite steel of the present invention can be satisfied. [Industrial applicability]

[0043] The graphite steel according to the present invention has excellent cutting performance, can replace conventional free-cutting steel materials, and can be used as an environmentally friendly free-cutting steel by replacing harmful elements such as Pb, thus demonstrating its potential for industrial use.

Claims

1. In mass percent, the composition is: carbon (C): 0.60–0.90%, silicon (Si): 2.0–2.5%, manganese (Mn): 0.1–0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031–0.3%, aluminum (Al): 0.01–0.05%, titanium (Ti): 0.005–0.02%, boron (B): 0.0005–0.0020%, nitrogen (N): 0.0030–0.0150%, with the remainder being Fe and unavoidable impurities. A graphite steel wire rod with excellent cutting performance, characterized by a microstructure in which graphite particles are distributed within a ferrite matrix, with a degree of graphitization of 95% or more, and containing a total of 5% or less of MnS inclusions and pearlite.

2. The process involves manufacturing a billet consisting of, by mass%, carbon (C): 0.60–0.90%, silicon (Si): 2.0–2.5%, manganese (Mn): 0.1–0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031–0.3%, aluminum (Al): 0.01–0.05%, titanium (Ti): 0.005–0.02%, boron (B): 0.0005–0.0020%, nitrogen (N): 0.0030–0.0150%, with the remainder being Fe and unavoidable impurities. In the step of heating the billet, The steps include: hot rolling the heated billet to produce a wire rod, and The step includes cooling the aforementioned wire, A method for producing graphite steel wire rod with excellent cutting performance, characterized in that, as a microstructure, graphite particles are distributed in a ferrite matrix, the degree of graphitization is 95% or more, and it contains a total of 5% or less of MnS inclusions and pearlite.

3. The method for producing graphite steel wire with excellent cutting performance according to claim 2, characterized in that the heating step is performed by maintaining the temperature in the range of 1050 ± 100°C for 60 minutes or more during the heat treatment.

4. The method for producing graphite steel wire rods with excellent cutting performance according to claim 2, characterized in that the step of hot rolling to produce the wire rod is performed at a temperature range of 900 to 1150°C.

5. The method for producing graphite steel wire with excellent cutting performance according to claim 2, characterized in that the cooling step is performed by cooling to 500°C at a cooling rate of 0.1 to 10.0°C / s.

6. The method for producing graphite steel wire with excellent cutting performance according to claim 2, further comprising a step of air cooling after the cooling step.

7. In mass percent, the composition is: carbon (C): 0.60–0.90%, silicon (Si): 2.0–2.5%, manganese (Mn): 0.1–0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031–0.3%, aluminum (Al): 0.01–0.05%, titanium (Ti): 0.005–0.02%, boron (B): 0.0005–0.0020%, nitrogen (N): 0.0030–0.0150%, with the remainder being Fe and unavoidable impurities. A graphite steel wire with excellent cutting performance, characterized by a microstructure in which graphite particles are distributed within a ferrite matrix, with a degree of graphitization of 95% by mass or more, and containing a total of 5% by mass or less of MnS inclusions and pearlite.

8. The process of manufacturing a wire rod consisting of, by mass%, carbon (C): 0.60-0.90%, silicon (Si): 2.0-2.5%, manganese (Mn): 0.1-0.6%, phosphorus (P): 0.015% or less (excluding 0), sulfur (S): 0.031-0.3%, aluminum (Al): 0.01-0.05%, titanium (Ti): 0.005-0.02%, boron (B): 0.0005-0.0020%, nitrogen (N): 0.0030-0.0150%, with the remainder being Fe and unavoidable impurities, and The process includes a step of graphitizing the manufactured wire, A method for producing graphite steel wire with excellent cutting performance, characterized in that, as a microstructure, graphite particles are distributed in a ferrite matrix, the degree of graphitization is 95% by mass or more, and it contains a total of 5% by mass or less of MnS inclusions and pearlite.

9. The method for producing graphite steel wire with excellent cutting performance according to claim 8, characterized in that the graphitization heat treatment step is performed by heat treatment at a temperature range of 700 to 800°C for 5 hours or more.

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