WO2024136173A1 - Fil machine en fibre d'acier d'armature pour béton non soumis à un traitement thermique, fibre d'acier et procédés de fabrication associés - Google Patents

Fil machine en fibre d'acier d'armature pour béton non soumis à un traitement thermique, fibre d'acier et procédés de fabrication associés Download PDF

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WO2024136173A1
WO2024136173A1 PCT/KR2023/019121 KR2023019121W WO2024136173A1 WO 2024136173 A1 WO2024136173 A1 WO 2024136173A1 KR 2023019121 W KR2023019121 W KR 2023019121W WO 2024136173 A1 WO2024136173 A1 WO 2024136173A1
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wire rod
wire
reinforcing steel
relational expression
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PCT/KR2023/019121
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English (en)
Korean (ko)
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양요셉
김재환
전성렬
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주식회사 포스코
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Publication of WO2024136173A1 publication Critical patent/WO2024136173A1/fr

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  • the present invention relates to wire rods and steel fibers for concrete reinforcing steel fibers used as concrete reinforcing materials in tunnels, floors, etc., and methods for manufacturing them.
  • Steel fibers have different diameters and lengths depending on their intended use, such as tunnels and flooring. In the case of tunnels, the diameter is thin and the length is short because it is used as a short, whereas in the case of flooring, the diameter is relatively thick and the length is long.
  • Steel fibers are wire-drawn (dry, wet) using wires with a diameter of 5.0 to 7.0 mm, and because the diameter is thin, a structure that can withstand high processing volume is required. Ultra-low carbon steel with a maximum carbon content of 0.03% or 0.035% is used. This is because ferrite has the best wire-drawing properties. Pearlite may be formed at grain boundaries, but when the fraction increases, defects occur in the light pearlite, making processing difficult. This is because it causes a disconnection.
  • constant temperature heat treatment (lead patenting), which can restore ductility and refine grains during wire drawing, is being introduced.
  • the problem is that constant temperature heat treatment is not suitable in terms of environmental pollution because it consists of lead, and the additional heat treatment process increases manufacturing costs.
  • the purpose of the present invention to solve the above-mentioned problems is to control relational equation 1 and microstructure through alloy composition and manufacturing method to achieve a tensile strength of more than 1700 MPa and 90 degree bending 10 times through dry drawing and wet drawing processing without LP heat treatment.
  • the object is to provide wire rods and steel fibers for concrete reinforcing steel fibers that do not break when repeatedly applied, and methods for manufacturing them.
  • the wire for concrete reinforcing steel fiber according to an embodiment of the present invention has a weight percent content of C: 0.005-0.035%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.2%, P: 0.05% or less. , S: 0.05% or less, includes the remaining Fe and other unavoidable impurities, and satisfies the following relational equation 1.
  • microstructure of the wire for concrete reinforcing steel fibers according to an embodiment of the present invention includes more than 98% to less than 100% of quasi polygonal ferrite and more than 0 to less than 2% of cementite in terms of area fraction. It can be included.
  • the wire rod for concrete reinforcing steel fiber according to an embodiment of the present invention may have an average grain size of the quasi-polygonal ferrite in the range of 1/4D based on the cross section, exceeding 0 to 35 ⁇ m or less. (Here D means the diameter of the wire.)
  • the tensile strength of the wire for concrete reinforcing steel fibers according to an embodiment of the present invention may be 850 MPa or more.
  • the method of manufacturing a wire for concrete reinforcing steel fiber according to an embodiment of the present invention is C: 0.005-0.035%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.2%, P: Maintaining a billet containing 0.05% or less, S: 0.05% or less, the remaining Fe and other inevitable impurities at a temperature range of 1,000 to 1,250°C for 90 to 120 minutes, and then rolling to produce a wire rod; Winding the manufactured wire rod at a temperature range of 880 to 950°C; The cooling step after winding includes a first cooling step of cooling the wire to 800°C at a rate of 1°C/s or less; And a second cooling step of cooling at 20°C/s or more to 300°C.
  • the wire satisfies the following relational equation 1.
  • Concrete reinforcing steel fibers according to an embodiment of the present invention are C: 0.005-0.035%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.2%, P: 0.05% or less, S : 0.05% or less, contains the remaining Fe and other inevitable impurities, satisfies the following relational equation 1, and the tensile strength may be 1700 MPa or more.
  • the concrete reinforcing steel fiber according to an embodiment of the present invention may not fracture when 90 degree bending is repeatedly applied 10 or more times.
  • the method for producing concrete reinforcing steel fibers according to an embodiment of the present invention is C: 0.005-0.03%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.0%, P: 0.05% by weight.
  • S 0.05% or less, the remaining Fe and other unavoidable impurities, and dry drawing a wire rod that satisfies the following relational expression 1;
  • LP heat treatment is omitted after the dry drawing but before the wet drawing, and the tensile strength may be 1700 MPa or more.
  • the wire rod for concrete reinforcing steel fiber, the steel fiber, and their manufacturing method according to an embodiment of the present invention increase the initial material strength and work hardening rate by adding a high content of Cr of 1.0% or more, which has excellent solid solution strengthening effect, and other solid solution strengthening effect. It is possible to reduce manufacturing costs by minimizing the Si and Mn content, which has little effect or deteriorates scale peeling properties. By omitting LP heat treatment and processing with wire drawing only, it not only reduces costs in the manufacturing process, but also reduces construction time by omitting the use of reinforcing bars in concrete. can be shortened. Furthermore, because scale is removed through mechanical peeling instead of pickling, it can be competitive in the global market by strengthening the image of an eco-friendly product.
  • the wire rod for concrete reinforcement steel fiber, steel fiber, and their manufacturing method according to an embodiment of the present invention omit LP heat treatment during processing and have a tensile strength of 1700 MPa or more and 90 degree bending repeated 10 or more times through dry and wet drawing processing. Breakage may not occur upon application.
  • Figure 1 is a photograph observing the microstructure of Inventive Example 4.
  • the wire for concrete reinforcing steel fiber according to an embodiment of the present invention has a weight percent content of C: 0.005-0.035%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.2%, P: 0.05% or less. , S: 0.05% or less, may include the remaining Fe and other unavoidable impurities.
  • the content of C may be 0.005 to 0.035% by weight.
  • C is an element that greatly improves strength when forming pearlite or cementite, but when the C content increases, there is a problem of pearlite that causes processing breakage during wet drawing. Therefore, it is difficult to achieve the strength target when the C content is added below 0.005%, and when it exceeds 0.035%, disconnection occurs during wire drawing due to the formation of grain boundaries of cementite with an area fraction of 2% or more, so it is preferable to control it below that amount.
  • the Si content may be 0.07 to 0.3% by weight.
  • Si has the advantage of improving strength as a ferrite hardening element, but is disadvantageous in terms of scale peeling ability due to the formation of Fe 2 SiO 4 , which has excellent bonding power with the base material. Therefore, if the Si content exceeds 0.3%, scale peeling property is inferior, and it is desirable to control it to 0.07% or more due to the limit due to the inflow of extraneous slag.
  • the content of Mn may be 0.07 to 0.2% by weight.
  • Mn is an element that improves solid solution strengthening and hardenability and can combine with S present in the steel to form MnS, so it can be included in more than 0.07%. However, since it has little effect on increasing strength and may increase the cost, the maximum content is set to 0.2%. It is desirable.
  • the content of Cr may be 1.0 to 2.2% by weight.
  • Cr is a major solid solution strengthening element that exists in ferrite and increases material strength.
  • the tensile strength can be increased by about 40 MPa.
  • the strain hardening rate during drawing can be increased by more than 300 by adding Cr, it is possible to increase the strength of the final product. If the Cr content is less than 1.0%, it is difficult to achieve the target strength, and if it exceeds 2.2%, if the bloom is charged into a high-temperature heating furnace at a low temperature after playing, cracks may occur due to the stress difference between the surface and the center due to the formation of martensite in the center. Therefore, it is desirable to control it below that level.
  • the content of P and S may be 0.05% by weight or less.
  • P and S are harmful elements, and if they exceed 0.05%, they will break during wire drawing due to central segregation, so it is desirable to control them below that amount.
  • the remaining component of the present invention is iron (Fe).
  • Fe iron
  • the wire for concrete reinforcing steel fibers according to an embodiment of the present invention may satisfy relational equation 1.
  • C, Mn, and Cr are elements related to the strength of the material.
  • the initial material strength and work hardening rate can be increased by adding a high content of Cr of 1.0% or more, which has an excellent solid solution strengthening effect.
  • this Cr content is excessively added, internal cracks may occur when the billet is cooled and then charged into the heating furnace, causing it to break within the heating furnace, or cobbles may occur during rolling. Therefore, the relational expression 1 is a relational expression regarding the appropriate C, Mn, and Cr contents. If the relational expression 1 is greater than 0, billet cracks may occur and cobbles may occur during wire rod rolling, so it is preferable to control it below that value.
  • the microstructure of the wire for concrete reinforcing steel fibers according to an embodiment of the present invention may include more than 98% to less than 100% of quasi polygonal ferrite and more than 0 to less than 2% of cementite in terms of area fraction. You can.
  • the main structure of the steel is composed of quasi-polygonal ferrite, a low-temperature transformation structure with a large amount of Cr content, aggravated disconnection can be prevented even if LP heat treatment is omitted, and it is possible to prevent stretching, etc., compared to when the main structure is composed of polygonal ferrite.
  • the decrease in strength can be suppressed without interference, and higher tensile strength can be obtained.
  • carbides such as CrC due to the addition of Cr
  • the formation of cementite is less than without the addition of Cr, which may reduce the probability of wire breakage during drawing.
  • the microstructure of the wire rod has more than 2% cementite as an area fraction, breakage may occur during wire drawing due to the formation of grain boundaries in cementite, so the area fraction of cementite should be controlled to exceed 0 to less than 2%. It is desirable.
  • the wire rod for concrete reinforcing steel fibers may have an average grain size of the quasi-polygonal ferrite in the range of 1/4D based on the cross section, exceeding 0 to 35 ⁇ m or less.
  • D means the diameter of the wire.
  • the average grain size of quasi-polygonal ferrite is greater than 0 and less than or equal to 35 ⁇ m, breakage during wire drawing can be prevented, and the 90-degree bending characteristics of the final steel fiber can be greatly improved to more than 10 times.
  • the wire rod for concrete reinforcing steel fiber according to an embodiment of the present invention can be manufactured by producing a billet having the above-described alloy composition and then going through the following processes: reheating, rolling the wire, winding, and cooling.
  • the method of manufacturing a wire for concrete reinforcing steel fiber according to an embodiment of the present invention is C: 0.005-0.035%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.2%, P: Maintaining a billet containing 0.05% or less, S: 0.05% or less, the remaining Fe and other inevitable impurities at a temperature range of 1,000 to 1,250°C for 90 to 120 minutes, and then rolling to produce a wire rod; Winding the manufactured wire rod at a temperature range of 880 to 950°C;
  • the cooling step after winding includes a first cooling step of cooling the wire to 800°C at a rate of 1°C/s or less; And it includes a second cooling step of finishing up to 300°C at a cooling rate of 20°C/s or more.
  • the heated billet is rolled under normal rolling conditions. That is, the wire rod is manufactured by performing hot rolling sequentially consisting of rough rolling, intermediate rough rolling/finish rolling, and finish rolling on the heated billet.
  • the scale is removed through mechanical peeling, so it is cooled to 800°C at less than 1°C/s to increase the scale thickness. If the cooling rate in the first cooling step exceeds 1° C./s, the desired scale thickness for mechanical peeling cannot be achieved.
  • the second cooling step After the first cooling step, in the second cooling step, it is necessary to suppress the scale transformation from FeO to Fe 2 O 4 to suppress the generation of fugitives, so it is cooled to 20°C with a reforming tube in the Stellmore cooling zone up to 300°C. This can be suppressed and the tensile strength increased by cooling above /s.
  • the cooling rate in the second cooling step may be 30°C/s or less. If the cooling rate exceeds 30°C/s, the tensile strength desired in the present invention cannot be achieved.
  • the concrete reinforcing steel fibers of the present invention contain, in weight percent, C: 0.005-0.035%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.2%, P: 0.05% or less, S: 0.05% or less, It contains the remaining Fe and other inevitable impurities, satisfies the following relational equation 1, and the tensile strength may be 1700 MPa or more.
  • the concrete reinforcing steel fibers of the present invention may not fracture when repeatedly subjected to 90-degree bending 10 or more times.
  • the concrete reinforced steel fiber of the present invention can be manufactured by drawing the wire for concrete reinforced steel fiber manufactured above.
  • the method for producing concrete reinforcing steel fibers of the present invention is C: 0.005-0.03%, Si: 0.07-0.3%, Mn: 0.07-0.2%, Cr: 1.0-2.0%, P: 0.05% or less, S: 0.05% by weight. % or less, the remaining Fe and other unavoidable impurities, and dry-drawing the wire rod that satisfies the following relational expression 1; and a step of wet drawing; LP heat treatment is omitted after the dry drawing and before the wet drawing, and the tensile strength can be secured at 1700 MPa or more.
  • the size of the wire rod is reduced through mechanical peeling and dry drawing, and the intermediate LP heat treatment can be omitted and finished by dry drawing followed by wet drawing.
  • Tables 1 and 2 show the test composition, microstructure and mechanical properties of the wire observed under an optical microscope in a 1/4D area based on the cross-section of the wire, where D refers to the diameter of the wire.
  • the average grain size of quasi-polygonal ferrite was defined by measuring the area of all grains measured at a magnification of
  • Figure 1 shows that the wire rod of Inventive Example 4, which satisfies the alloy composition of the present invention, has a microstructure of quasi-polygonal ferrite and cementite as a result of observation with an optical microscope.
  • Table 3 shows the characteristics of steel fibers manufactured by removing the scale existing on the surface of the wire rod prepared above using a mechanical peeling method, dry drawing it, and then wet drawing it without performing LP heat treatment.
  • the tensile test followed ISO6892-1 standards, and the tensile speed (cross head speed) was 50 m/min.
  • the length of the test piece was 300 mm, and the test piece was cut in succession (20 pieces) to measure its tensile strength and check the average and deviation.
  • the 90-degree bending test used a steel fiber with a length of 300 mm as a test material, fixed a pin with a size of 2.5R (R is the steel fiber diameter: 0.55 mm) in the center of the length, and then repeated 90-degree bending in one direction.
  • R is the steel fiber diameter: 0.55 mm
  • the number of times until fracture occurs during repeated 90-degree bending is shown in Table 3 below.
  • the Si content was 0.5% by weight, which was excessive, resulting in the formation of Fe 2 SiO 4 that deteriorates scale peeling properties, resulting in wire breakage during processing.
  • the Cr content is 0.5% by weight, and there is no problem in wire drawing, but the added Cr content is insufficient, so the tensile strength of the steel fiber is 1430 MPa, so it has inferior tensile strength compared to the invention example of the present invention.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Physics & Mathematics (AREA)
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  • Crystallography & Structural Chemistry (AREA)

Abstract

La présente invention concerne : un fil machine en fibre d'acier d'armature pour béton, non soumis à un traitement thermique LP pendant l'étirage, qui ne se rompt pas lorsqu'il est plié de manière répétée à 90 degrés à 10 reprises ou plus, et qui présente une résistance à la traction de 1 700 MPa ou plus ; une fibre d'acier ; et des procédés de fabrication associés. Le fil machine en fibre d'acier d'armature pour béton selon un mode de réalisation de la présente invention comprend, en % en poids, 0,005 à 0,035 % de C, 0,07 à 0,3 % de Si, 0,07 à 0,2 % de Mn, 1,0 à 2,2 % de Cr, 0,05 % ou moins de P, 0,05 % ou moins de S, le reste étant constitué de Fe et d'autres impuretés inévitables, et satisfait la relation 1. [Relation 1] [C] + 0,17 * [Mn] + 0,25 * [Cr] - 0,62 ≤ 0 ([C], [Mn] et [Cr] représentant chacun un % en poids.)
PCT/KR2023/019121 2022-12-21 2023-11-24 Fil machine en fibre d'acier d'armature pour béton non soumis à un traitement thermique, fibre d'acier et procédés de fabrication associés WO2024136173A1 (fr)

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KR10-2022-0180140 2022-12-21
KR1020220180140A KR20240098409A (ko) 2022-12-21 2022-12-21 열처리 생략형 콘크리트 보강 강섬유용 선재, 강섬유 및 이들의 제조 방법

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20000042051A (ko) * 1998-12-24 2000-07-15 이구택 성형가공성이 우수한 콘크리트 보강용 강섬유선재의 제조방법
KR20050057267A (ko) * 2002-09-26 2005-06-16 가부시키가이샤 고베 세이코쇼 신선전의 열처리가 생략 가능한 신선가공성이 우수한 열간압연선재
JP2016056418A (ja) * 2014-09-10 2016-04-21 株式会社神戸製鋼所 冷間加工用鋼材
KR20200042118A (ko) * 2018-10-15 2020-04-23 주식회사 포스코 고강도 강섬유용 선재, 고강도 강섬유 및 이들의 제조방법
CN111690877A (zh) * 2020-06-30 2020-09-22 张家港联峰钢铁研究所有限公司 一种超低碳钢纤维用热轧盘条的生产方法
KR20220089479A (ko) * 2020-12-21 2022-06-28 주식회사 포스코 강도 및 가공성이 향상된 강섬유용 선재, 강선 및 그 제조 방법

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20000042051A (ko) * 1998-12-24 2000-07-15 이구택 성형가공성이 우수한 콘크리트 보강용 강섬유선재의 제조방법
KR20050057267A (ko) * 2002-09-26 2005-06-16 가부시키가이샤 고베 세이코쇼 신선전의 열처리가 생략 가능한 신선가공성이 우수한 열간압연선재
JP2016056418A (ja) * 2014-09-10 2016-04-21 株式会社神戸製鋼所 冷間加工用鋼材
KR20200042118A (ko) * 2018-10-15 2020-04-23 주식회사 포스코 고강도 강섬유용 선재, 고강도 강섬유 및 이들의 제조방법
CN111690877A (zh) * 2020-06-30 2020-09-22 张家港联峰钢铁研究所有限公司 一种超低碳钢纤维用热轧盘条的生产方法
KR20220089479A (ko) * 2020-12-21 2022-06-28 주식회사 포스코 강도 및 가공성이 향상된 강섬유용 선재, 강선 및 그 제조 방법

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