WO2020085855A1 - High manganese steel having excellent oxygen cutting properties, and manufacturing method therefor - Google Patents

Abstract

The high manganese steel having excellent oxygen cutting properties, according to one aspect of the present invention, comprises 0.1-0.5 wt% of carbon (C), 20-26 wt% of manganese (Mn), 0.05-0.4 wt% of silicon (Si), at most 2.0 wt% of aluminum (Al), and at most 4 wt% of chromium (Cr), with the remainder being Fe and other unavoidable impurities, and has a cutting sensitivity (Sc), calculated according to [relational expression 1] below, of at least 430 and may comprise at least 95 area% of austenite as a microstructure. [Relational expression 1] Cutting sensitivity (Sc) = 1742 - 662*[C] - 19.2*[Mn] + 1.6*[Al] - 140*[Cr] (In [relational expression 1], [C], [Mn], [Al], and [Cr] represent the respective percentages by weight of C, Mn, Al, and Cr included in the steel and, if the elements concerned are not included, represent 0.)

Description

High manganese steel with excellent oxygen cutting properties and method for manufacturing the same

The present invention relates to a high-manganese steel material and a method for manufacturing the same, and more particularly, to an austenitic high-manganese steel material having excellent oxygen cutting property and a method for manufacturing the same.

The austenitic high-manganese steel material is characterized by having high toughness as the austenite is stable even at room temperature by adjusting the content of manganese (Mn) and carbon (C), which are elements that increase the stability of austenite. Austenite is a paramagnetic material with low permeability and excellent non-magnetic properties compared to ferrite. In general, materials used for transformers, switchboards, etc. have a permeability of 1.05 or less, while austenitic high manganese steels have a permeability of 1.02 or less, so it can be seen that they have superior non-magnetic properties compared to conventional materials.

In addition, in the case of a high-manganese steel having austenite as the main structure, it has a ductile fracture property at low temperature, and thus has a technical advantage of having excellent low-temperature toughness.

However, in order to use austenitic high-manganese steel as a structure, cutting and processing of the material by oxygen cutting are essential, but since high-manganese steel contains a large amount of alloying components, the cutting surface is caused by sparks during oxygen cutting. Heating problems exist. That is, it is not preferable from the viewpoint of productivity because the steel is pre-heated or the cutting speed is adjusted in advance to improve the cutability. Accordingly, there is a need to develop an austenitic high-manganese steel material having economical and effective oxygen cutting processing characteristics.

(Advanced technical literature)

(Patent Document 1) Republic of Korea Patent Publication No. 10-2010-0064473 (2010.06.15. Public)

According to an aspect of the present invention, a high-manganese steel material having excellent oxygen cutting properties and a method for manufacturing the same can be provided.

The subject of this invention is not limited to the above-mentioned content. Those skilled in the art will have no difficulty in understanding the additional subject matter of the present invention from the general contents of this specification.

The high-manganese steel material having excellent oxygen-cutting properties according to an aspect of the present invention, in weight percent, carbon (C): 0.1-0.5%, manganese (Mn): 20-26%, silicon (Si): 0.05-0.4% , Aluminum (Al): 2.0% or less, Chromium (Cr): 4% or less, including residual Fe and other inevitable impurities, and the cutability sensitivity (Sc) calculated by the following [Relational Formula 1] is 430 or more, and 95 area % Or more of austenite.

[Relationship 1]

Cutting sensitivity (Sc) = 1742-662 * [C]-19.2 * [Mn] + 1.6 * [Al]-140 * [Cr]

(In [Relational Formula 1], [C], [Mn], [Al], and [Cr] mean the weight percent of C, Mn, Al, and Cr included in the steel, respectively, and 0 when the corresponding component is not added. Means.)

The steel material, by weight, may further include 0.0005 to 0.01% boron (B).

The magnetic permeability of the steel material may be 1.02 or less.

The yield strength of the steel material is 240MPa or more, the tensile strength is 720MPa or more, and the elongation may be 25% or more.

When oxygen-cutting the steel with a gas pressure of 0.3 to 0.9 Mpa and a maximum cutting speed of 300 to 700 mm / min, the average surface roughness of the steel cutting surface may be 0.5 mm or less.

A method of manufacturing a high-manganese steel material having excellent oxygen-cutting properties according to an aspect of the present invention, in weight percent, carbon (C): 0.1-0.5%, manganese (Mn): 20-26%, silicon (Si): 0.05 ~ 0.4%, aluminum (Al): 2.0% or less, chromium (Cr): 4% or less, including residual Fe and other unavoidable impurities, and the slab sensitivity (Sc) of 430 or more calculated by [Relational Formula 1] below Re-heating in the temperature range of 1050 ~ 1300 ℃; Hot rolling the reheated slab to a finish rolling temperature of 800 to 1050 ° C to provide a hot rolled material; And cooling the hot rolled material to a temperature range of 600 ° C. or less at a cooling rate of 1 to 100 ° C./s.

 [Relationship 1]

Cutting sensitivity (Sc) = 1742-662 * [C]-19.2 * [Mn] + 1.6 * [Al]-140 * [Cr]

(In [Relational Formula 1], [C], [Mn], [Al], and [Cr] mean the weight percent of C, Mn, Al, and Cr included in the steel, respectively, and 0 when the corresponding component is not added. Means.)

The slab, by weight, may further include 0.0005 to 0.01% boron (B).

The solving means of the above problems does not list all the features of the present invention, and various features of the present invention and the advantages and effects thereof may be understood in more detail with reference to specific embodiments below.

According to a preferred aspect of the present invention, an austenitic high-manganese steel material having excellent oxygen cutting properties and a method for manufacturing the same can be provided.

FIG. 1 (a) is a photograph of whether a spark is generated during oxygen cutting in Example 2 and a cut surface due to oxygen cutting, and FIG. 1 (b) shows whether spark is generated during oxygen cutting in Comparative Example 2 and when oxygen is cut. This is a photograph of the cut surface.

The present invention relates to a high-manganese steel material having excellent oxygen-cutting properties and a method for manufacturing the same, and the following describes preferred embodiments of the present invention. The embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. These embodiments are provided to those skilled in the art to further detail the present invention.

Hereinafter, the steel composition of the present invention will be described in more detail. Hereinafter, unless otherwise indicated,% representing the content of each element is based on weight.

The high-manganese steel material having excellent oxygen-cutting properties according to an aspect of the present invention, in weight percent, carbon (C): 0.1-0.5%, manganese (Mn): 20-26%, silicon (Si): 0.05-0.4% , Aluminum (Al): 2.0% or less, chromium (Cr): 4% or less, the balance may include Fe and other unavoidable impurities.

Carbon (C): 0.1 ~ 0.5%

Carbon (C) is an effective element for stabilizing austenite of steel and securing strength by solid solution strengthening, so the present invention can limit the lower limit of the carbon (C) content to a certain range in order to secure low-temperature toughness and strength. . In other words, when the carbon (C) content is below a certain level, the stability of austenite is insufficient and stable austenite cannot be obtained at room temperature, and it is easily processed into ε-martensite and α'-martensite by external stress. This is because it can reduce the toughness and strength of the steel. Therefore, the present invention can limit the lower limit of the carbon (C) content to 0.1%. The lower limit of the preferred carbon (C) content is 0.15%, and the lower limit of the more preferred carbon (C) content may be 0.17%. On the other hand, when the carbon (C) content exceeds a certain range, the cutting surface may be deteriorated by the occurrence of sparks during oxygen cutting of the steel, or the productivity may be inferior by lowering the cutting speed. The upper limit of can be limited to 0.5%. The upper limit of the preferred carbon (C) content may be 0.47%, and the upper limit of the more preferred carbon (C) content may be 0.45%.

Manganese (Mn): 20-26%

Manganese (Mn) is an important element that plays a role in stabilizing austenite, so the present invention can limit the lower limit of the manganese (Mn) content to 20% to achieve this effect. That is, the present invention can effectively increase the austenite stability because it contains 20% or more of manganese (Mn), thereby inhibiting the formation of ferrite, ε-martensite and α'-martensite, and nonmagnetic properties of steel and It can effectively secure low-temperature toughness. On the other hand, when the manganese (Mn) content exceeds a certain level range, the effect of increasing the stability of austenite is saturated, while the manufacturing cost is greatly increased, and surface oxidation may be deteriorated due to excessive internal oxidation during hot rolling. , The present invention can limit the upper limit of the manganese (Mn) content to 26%. Therefore, the manganese (Mn) content of the present invention may be 20 to 26%, and a more preferable manganese (Mn) content may be 20 to 24%.

Silicon (Si): 0.05 ~ 0.4%

Silicon (Si) is an element that is indispensably added in trace amounts as a deoxidizer, such as aluminum (Al). However, when silicon (Si) is excessively added, an oxide is formed at a grain boundary to reduce high temperature ductility, and there is a fear that surface quality may be lowered by causing cracks, etc., so that the present invention has an upper limit of the silicon (Si) content. It can be limited to 0.4%. The upper limit of the more preferable silicon (Si) content may be 0.3%. On the other hand, an excessive cost is required to reduce the silicon (Si) content in the steel, so the present invention can limit the lower limit of the silicon (Si) content to 0.05%. The lower limit of the more preferable silicon (Si) content may be 0.1%.

Aluminum (Al): 2.0% or less

Aluminum (Al) is a representative element added as a deoxidizer. However, aluminum (Al) may form precipitates by reacting with carbon (C) and nitrogen (N), and the hot workability may be deteriorated by these precipitates, and the present invention provides an upper limit of the aluminum (Al) content. It can be limited to 2.0%. The preferred content of aluminum (Al) may be 0.01 to 2.0%, and the more preferred content of aluminum (Al) may be 0.01 to 1.95%.

Chromium (Cr): 4% or less

Chromium (Cr) is a winso that stabilizes austenite up to a range of an appropriate addition amount, thereby contributing to the improvement of non-magnetic properties, and is employed in austenite to increase the strength of steel. In addition, chromium (Cr) is also an element that improves the corrosion resistance of steel materials. Therefore, the present invention can add chromium (Cr) to achieve this effect. However, chromium (Cr) increases the melting temperature of the oxide during oxygen cutting, and as the added content increases, the tendency for oxygen cutting property to deteriorate tends to deteriorate. In the present invention, the upper limit of the chromium (Cr) content is limited to 4%. May be, the upper limit of the more preferred chromium (Cr) content may be 3.5%.

The non-magnetic high-manganese steel material having excellent oxygen-cutting properties according to an aspect of the present invention may include residual Fe and other unavoidable impurities in addition to the above-described components. However, in the normal manufacturing process, unintended impurities from the raw material or the surrounding environment may inevitably be mixed, and therefore cannot be entirely excluded. Since these impurities are known to anyone skilled in the art, they are not specifically mentioned in this specification. In addition, addition of effective ingredients other than the above composition is not entirely excluded.

In addition, the high-manganese steel material having excellent oxygen cutting property according to an aspect of the present invention, by weight, may further include 0.0005 to 0.01% boron (B), and 0.03% or less phosphorus (P), 0.05% It may include one or more of the following sulfur (S) and less than 0.02% nitrogen (N).

Boron (B): 0.0005 ~ 0.01%

Boron (B) is a grain boundary strengthening element for strengthening the austenite grain boundary, and is an element capable of effectively lowering the high temperature cracking sensitivity of steel materials by strengthening the austenite grain boundary even with a small amount added. Therefore, in order to achieve this effect, the present invention can limit the lower limit of the boron (B) content to 0.0005%. The lower limit of the more preferred boron (B) content may be 0.001%. On the other hand, when the content of boron (B) exceeds a certain range, it causes segregation at the austenite grain boundary, thereby increasing the sensitivity of high temperature cracking of the steel, so the surface quality of the steel may be lowered. ) The upper limit of the content can be limited to 0.01%. The upper limit of the more preferred boron (B) content may be 0.006%.

Phosphorus (P): 0.03% or less

Phosphorus (P) is not only an element that is inevitably introduced into the steel, but is an element that is easily segregated and causes cracking during casting or degrades weldability. Therefore, the present invention may limit the upper limit of the phosphorus (P) content to 0.03% to prevent deterioration of castability and deterioration of weldability, and the upper limit of the more preferable phosphorus (P) content may be 0.02%.

Sulfur (S): 0.05% or less

Sulfur (S) is not only an element that is inevitably introduced into the steel, but is also an element that causes hot brittle defects by inclusion formation. Therefore, the present invention can limit the upper limit of the sulfur (S) content to 0.05% to suppress the occurrence of hot embrittlement, the upper limit of the more preferred sulfur (S) content may be 0.02%.

Nitrogen (N) 0.02% or less

Nitrogen (N) is not only an element inevitably introduced into steel, but also an element contributing to solid solution strengthening. However, if the content of nitrogen (N) is excessive, there is a problem of lowering the strength of the steel by forming a coarse nitride, so the present invention can limit the upper limit of the nitrogen (N) content to 0.02%.

In the high-manganese steel material having excellent oxygen snow-setting properties according to an aspect of the present invention, the cutability sensitivity (Sc) calculated by the following [Relational Formula 1] may be 430 or more. More preferably, the cutting sensitivity (Sc) calculated by the following [Relational Formula 1] may be 460 or more.

[Relationship 1]

Cutting sensitivity (Sc) = 1742-662 * [C]-19.2 * [Mn] + 1.6 * [Al]-140 * [Cr]

(In [Relational Formula 1], [C], [Mn], [Al], and [Cr] mean the weight percent of C, Mn, Al, and Cr included in the steel, respectively, and 0 is not added. Means.)

The inventors of the present invention have conducted an in-depth study in relation to the oxygen-cutting property of high-manganese steel, while aluminum (Al) is an element that positively affects the oxygen-cutting property of high-manganese steel, whereas carbon (C) and manganese (Mn) ) And chromium (Cr) were found to be elements that negatively affect the oxygen-cleavability of high-manganese steels.

In addition, the inventors of the present invention have conducted a study on the correlation of these carbon (C), manganese (Mn), chromium (Cr), and aluminum (Al) contents, and the sensitivity to cutability (Sc) ) Was more than a certain level, it was confirmed that it has excellent oxygen cleavage.

That is, the high manganese steel material having excellent oxygen cutting property according to this aspect of the present invention controls the alloy composition content so that the cutability sensitivity (Sc) by [Relational Formula 1] satisfies 430 or more, so the average of the steel cutting surface during oxygen cutting The surface roughness can be managed at a level of 0.5 mm or less.

A high-manganese steel material having excellent oxygen-cutting properties according to an aspect of the present invention may include at least 95% by area of austenite as a microstructure, thereby effectively securing non-magnetic properties and low-temperature properties of the steel material. In addition, the average grain size of austenite may be 5 to 150 μm. The average grain size of austenite that can be implemented in the manufacturing process is 5 µm or more, and when the average grain size is greatly increased, the strength of the steel material may be lowered, so the grain size of austenite may be limited to 150 µm or less.

The austenitic high-manganese steel material having excellent oxygen cleavability according to an aspect of the present invention may include carbide and / or ε-martensite as a structure that may exist in addition to austenite. When the fraction of carbide and / or ε-martensite exceeds a certain level, the toughness and ductility of the steel may be rapidly reduced. In the present invention, the fraction of carbide and / or ε-martensite is less than 5 area%. Can be limited.

As described above, a high-manganese steel material having excellent oxygen cutting properties according to an aspect of the present invention is provided with an optimal alloy composition, and thus may have an excellent cutting surface during oxygen cutting. That is, since the occurrence of sparks is minimized when oxygen is cut, it is possible to minimize the phenomenon that the cut surface is non-uniform due to melting of the steel material. In addition, the high-manganese steel material having excellent oxygen cutting property according to an aspect of the present invention can effectively prevent a decrease in cutting speed when cutting oxygen, thereby optimizing work efficiency and maximizing productivity.

A high-manganese steel material having excellent oxygen cutting properties according to an aspect of the present invention may have a permeability of 1.02 or less, a yield strength of 240 MPa or more, a tensile strength of 720 MPa or more, and an elongation of 25% or more.

Hereinafter, the manufacturing method of the present invention will be described in more detail.

A method of manufacturing a high-manganese steel material having excellent oxygen-cutting properties according to an aspect of the present invention, in weight percent, carbon (C): 0.1-0.5%, manganese (Mn): 20-26%, silicon (Si): 0.05 ~ 0.4%, aluminum (Al): 2.0% or less, chromium (Cr): 4% or less, including residual Fe and other unavoidable impurities, and the slab sensitivity (Sc) of 430 or more calculated by [Relational Formula 1] below Re-heating in the temperature range of 1050 ~ 1300 ℃; Hot rolling the reheated slab to a finish rolling temperature of 800 to 1050 ° C to provide a hot rolled material; And cooling the hot rolled material to a temperature range of 600 ° C. or less at a cooling rate of 1 to 100 ° C./s.

[Relationship 1]

Cutting sensitivity (Sc) = 1742-662 * [C]-19.2 * [Mn] + 1.6 * [Al]-140 * [Cr]

(In [Relational Formula 1], [C], [Mn], [Al], and [Cr] mean the weight percent of C, Mn, Al, and Cr included in the steel, respectively, and 0 when the corresponding component is not added. Means.)

In addition, the slab, by weight, may further include 0.0005 to 0.01% boron (B), 0.03% or less phosphorus (P), 0.05% or less sulfur (S), and 0.02% or less nitrogen (N).

Slab reheating

Since the steel composition of the slab provided in the manufacturing method of the present invention corresponds to the steel composition of the high-manganese steel material having excellent oxygen-cutting property, the description of the steel composition of the slab will be replaced by the description of the steel composition of the steel material described above. do.

The slab provided with the above-described steel composition can be reheated in a temperature range of 1050 to 1300 ° C. When the reheating temperature is less than a certain range, the problem of excessive rolling load during hot rolling may occur, or a problem that the alloy component is not sufficiently dissolved may occur, so that the present invention can limit the lower limit of the slab reheating temperature range to 1050 ° C. have. On the other hand, if the reheating temperature exceeds a certain range, the grains may grow excessively and the strength may decrease, or the re-heating may exceed the solidus temperature of the steel material, thereby deteriorating the hot rolling property of the steel material. The upper limit of the range can be limited to 1300 ° C.

Hot rolled

The hot rolling process includes a rough rolling process and a finish rolling process, and the reheated slab may be hot rolled and provided as a hot rolled material. At this time, the hot finish rolling is preferably carried out in a temperature range of 800 ~ 1050 ℃. If the hot finish rolling temperature is less than a certain range, excessive rolling load due to an increase in the rolling load may be a problem, and if the hot finish rolling temperature exceeds a certain range, the grains grow coarsely and the target strength cannot be obtained.

Cooling

The hot rolled hot rolled material may be cooled to a cooling stop temperature of 600 ° C. or less at a cooling rate of 1 to 100 ° C./s. If the cooling rate is less than a certain range, the ductility of the steel may be reduced due to carbides precipitated at the grain boundary during cooling, and thus deterioration of abrasion resistance may be a problem. Therefore, the present invention can limit the cooling rate of the hot rolled material to 1 ° C / s or more. have. The lower limit of the more preferable cooling rate may be 10 ° C / s, and accelerated cooling may be applied. However, the faster the cooling rate is, the more advantageous the effect of suppressing the precipitation of carbides, but considering the circumstances in which the cooling rate exceeding 100 ° C / s in normal cooling is difficult to implement due to the characteristics of the facility, the present invention sets the upper limit of the cooling rate to 100 ° C. Can be limited to / s.

In addition, even if the hot-rolled material is cooled by applying a cooling rate of 10 ° C./s or more, when the cooling is stopped at a high temperature, there is a high possibility that carbides are generated and grown, so the present invention limits the cooling stop temperature to 600 ° C. or less. You can.

The high-manganese steel with excellent oxygen-cutting properties prepared as described above contains 95% by area or more of austenite as a microstructure, has a permeability of 1.02 or less, a yield strength of 240MPa or more, a tensile strength of 720MPa or more, and an elongation of 25% or more, At the same time as having an excellent cutting surface during oxygen cutting, it is possible to effectively prevent a decrease in productivity of the oxygen cutting operation.

Hereinafter, the present invention will be described in more detail through examples. However, it is necessary to note that the embodiments described below are only intended to further illustrate the present invention and are not intended to limit the scope of the present invention.

(Example)

The slab that satisfies the alloy composition of Table 1 below was reheated at a temperature of 1200 ° C, hot rolled under the conditions of Table 2 to produce a hot rolled material having a thickness of 12mm, and then cooled to a cooling stop temperature of 100 ° C at a cooling rate of 20 ° C / s. The specimen was prepared by accelerated cooling. The yield strength, tensile strength and elongation of each specimen were measured, and the permeability, the maximum cutting speed, and the cutting surface state are shown together in Table 2 below. The maximum cutting speed means the maximum cutting speed applicable when oxygen cutting is performed at an average gas pressure of 0.7 MPa. The cut surface scores were evaluated by dividing them into 1, 1.5, and 2. A rating of 1 means that the base material is not only melted during oxygen cutting, but also means that the average surface roughness of the cut surface is greater than 0.5 mm. A rating of 1.5 means that some of the base material is melted during oxygen cutting, but the average surface roughness of the cut surface is 0.5 mm. The following means the case, and a rating of 1 means that the base material is not melted during oxygen cutting and the average surface roughness of the cut surface is 0.5 mm or less. The cutability index in Table 2 means the value obtained by multiplying the maximum cutting speed of each specimen and the cutting surface rating.

division	Alloy composition (% by weight)								[Relationship 1]
	C	Mn	Si	P	S	Al	Cr	N
Example 1	0.41	21.7	0.27	0.017	0.003	0.013	2.01	0.013	772.6
Example 2	0.18	22.3	0.14	0.019	0.010	1.80	0.00	0.013	1197.6
Example 3	0.44	24.6	0.26	0.019	0.007	0.020	3.45	0.018	495.4
Example 4	0.18	21.8	0.21	0.016	0.003	0.026	2.00	0.016	924.3
Example 5	0.41	21.8	0.22	0.019	0.003	0.016	1.95	0.013	779.0
Example 6	0.40	21.6	0.20	0.018	0.003	0.025	0.00	0.014	1062.5
Example 7	0.41	21.9	0.21	0.019	0.003	0.027	4.00	0.016	490.1
Example 8	0.39	22.3	0.15	0.018	0.009	1.93	1.92	0.016	789.9
Example 9	0.2	22	0.2	0.018	0.002	0.025	0	0.015	1187.2
Example 10	0.2	20	0.2	0.018	0.002	0.025	0	0.015	1225.6
Example 11	0.2	25	0.2	0.018	0.002	0.025	0	0.015	1129.6
Comparative Example 1	0.45	24.4	0.22	0.019	0.003	0.012	3.95	0.018	422.6
Comparative Example 2	0.61	22.1	0.2	0.016	0.006	0.023	5.95	0.02	80.9
Comparative Example 3	0.8	22	0.21	0.015	0.008	0.026	3.65	0.019	279.0

division	Finish rolling temperature (℃)	YS (Mpa)	TS (Mpa)	El (%)	Permeability	Cutting speed (mm / min)	Cutting plane	Cleavage index
Example 1	925	457	980	52	1.003	400	1.5	600
Example 2	920	386	728	53	1.001	700	2	1400
Example 3	930	489	906	54	1.001	350	1.5	525
Example 4	917	399	834	33	1.003	400	1.5	600
Example 5	925	493	1050	62	1.002	400	1.5	600
Example 6	854	394	948	57	1.003	500	2	1000
Example 7	915	493	969	51	1.001	300	1.5	450
Example 8	920	495	803	54	1.004	400	1.5	600
Example 9	900	265	890	27	1.001	700	2	1400
Example 10	850	280	942	25	1.001	700	2	1400
Example 11	940	241	762	54	1.001	600	2	1200
Comparative Example 1	920	452	919	51	1.000	300	One	300
Comparative Example 2	920	633	1094	52	1.001	300	One	300
Comparative Example 3	925	629	1170	49	1.001	300	One	300

As shown in Table 1 and Table 2, in the case of Examples 1 to 11 satisfying the scope of the present invention, not only the average surface roughness of the cut surface is 0.5 mm or less, but also has excellent oxygen cutting property with a cutability index of 400 or more. On the other hand, in the case of Comparative Examples 1 to 3 that do not satisfy the scope of the present invention, it can be seen that not only the average surface roughness of the cut surface exceeds 0.5 mm, but also the cutability index is inferior to the oxygen cutability of 300 levels. .

FIG. 1 (a) is a photograph of whether a spark is generated during oxygen cutting in Example 2 and a cut surface due to oxygen cutting, and FIG. 1 (b) shows whether spark is generated during oxygen cutting in Comparative Example 2 and when oxygen is cut. This is a photograph of the cut surface. As shown in (a) and (b) of FIG. 1, in the case of Example 2, while having an excellent cutting surface, in the case of Comparative Example 2, excessive sparking occurs when oxygen is cut, resulting in melting of the base material, and thus not uniform It can be seen that an unsuccessful cut surface is realized.

Although the present invention has been described in detail through the above embodiments, other types of embodiments are possible. Therefore, the technical spirit and scope of the claims set forth below are not limited to the embodiments.

Claims (7)

1. In weight percent, carbon (C): 0.1-0.5%, manganese (Mn): 20-26%, silicon (Si): 0.05-0.4%, aluminum (Al): 2.0% or less, chromium (Cr): 4% Hereinafter, the remaining Fe and other inevitable impurities are included,

   The cutting sensitivity (Sc) calculated by the following [Relational Formula 1] is 430 or more,

   A high-manganese steel with excellent oxygen-cutting properties, containing more than 95% by area of austenite as a microstructure.

   [Relationship 1]

   Cutting sensitivity (Sc) = 1742-662 * [C]-19.2 * [Mn] + 1.6 * [Al]-140 * [Cr]

   (In [Relational Formula 1], [C], [Mn], [Al], and [Cr] mean the weight percent of C, Mn, Al, and Cr included in the steel, respectively, and 0 when the corresponding component is not added. Means.)
2. According to claim 1,

   The steel material, by weight%, further comprising 0.0005 to 0.01% boron (B), a high-manganese steel excellent in oxygen cutting.
3. According to claim 1,

   The permeability of the steel is 1.02 or less, a high-manganese steel excellent in oxygen cutting property.
4. According to claim 1,

   The yield strength of the steel material is 240MPa or more, the tensile strength is 720MPa or more, and the elongation is 25% or more, a high-manganese steel excellent in oxygen cutting property.
5. According to claim 1,

   When oxygen-cutting the steel with a gas pressure of 0.3 to 0.9 Mpa and a maximum cutting speed of 300 to 700 mm / min, the average surface roughness of the steel cutting surface is 0.5 mm or less, and a high-manganese steel with excellent oxygen cutting properties.
6. In weight percent, carbon (C): 0.1-0.5%, manganese (Mn): 20-26%, silicon (Si): 0.05-0.4%, aluminum (Al): 2.0% or less, chromium (Cr): 4% Hereinafter, a step of reheating a slab having a residual Fe and other unavoidable impurities and having a cutability sensitivity (Sc) of 430 or more calculated as [Relational Formula 1] at a temperature range of 1050 to 1300 ° C;

   Hot rolling the reheated slab to a finish rolling temperature of 800 to 1050 ° C to provide a hot rolled material; And

   Cooling the hot rolled material to a temperature range of 600 ℃ or less at a cooling rate of 1 ~ 100 ℃ / s; Method for producing a high-manganese steel material having excellent oxygen cutting.

   [Relationship 1]

   Cutting sensitivity (Sc) = 1742-662 * [C]-19.2 * [Mn] + 1.6 * [Al]-140 * [Cr]

   (In [Relational Formula 1], [C], [Mn], [Al], and [Cr] mean the weight percent of C, Mn, Al, and Cr included in the steel, respectively, and 0 when the corresponding component is not added. Means.)
7. According to claim 1,

   The slab, by weight%, further comprising 0.0005 to 0.01% boron (B), a method of manufacturing a high-manganese steel excellent in oxygen cutting.

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