KR20160149647A - Shape steel and manufacturing method thereof - Google Patents
Shape steel and manufacturing method thereof Download PDFInfo
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- KR20160149647A KR20160149647A KR1020150086971A KR20150086971A KR20160149647A KR 20160149647 A KR20160149647 A KR 20160149647A KR 1020150086971 A KR1020150086971 A KR 1020150086971A KR 20150086971 A KR20150086971 A KR 20150086971A KR 20160149647 A KR20160149647 A KR 20160149647A
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 110
- 239000010959 steel Substances 0.000 title claims abstract description 110
- 238000004519 manufacturing process Methods 0.000 title abstract description 24
- 238000005096 rolling process Methods 0.000 claims abstract description 58
- 239000010955 niobium Substances 0.000 claims abstract description 24
- 238000005098 hot rolling Methods 0.000 claims abstract description 15
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 14
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 claims abstract description 14
- 238000000034 method Methods 0.000 claims abstract description 13
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 12
- 239000012535 impurity Substances 0.000 claims abstract description 10
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 9
- 239000011593 sulfur Substances 0.000 claims abstract description 9
- 238000001816 cooling Methods 0.000 claims abstract description 7
- 239000000463 material Substances 0.000 claims description 24
- 239000010936 titanium Substances 0.000 claims description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 13
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 10
- 238000003303 reheating Methods 0.000 claims description 10
- 229910052719 titanium Inorganic materials 0.000 claims description 10
- 239000011572 manganese Substances 0.000 abstract description 20
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 abstract description 11
- 229910052748 manganese Inorganic materials 0.000 abstract description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 10
- 229910052710 silicon Inorganic materials 0.000 abstract description 10
- 239000010703 silicon Substances 0.000 abstract description 10
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 6
- 229910052698 phosphorus Inorganic materials 0.000 abstract description 6
- 239000011574 phosphorus Substances 0.000 abstract description 6
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 abstract description 3
- 229910000975 Carbon steel Inorganic materials 0.000 abstract 1
- 239000010962 carbon steel Substances 0.000 abstract 1
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 22
- 230000000694 effects Effects 0.000 description 11
- 229910052757 nitrogen Inorganic materials 0.000 description 11
- 230000007423 decrease Effects 0.000 description 4
- 238000007670 refining Methods 0.000 description 4
- 229910000859 α-Fe Inorganic materials 0.000 description 4
- 229910000746 Structural steel Inorganic materials 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 229910001566 austenite Inorganic materials 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 230000008569 process Effects 0.000 description 3
- 230000002708 enhancing effect Effects 0.000 description 2
- 230000001965 increasing effect Effects 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910001200 Ferrotitanium Inorganic materials 0.000 description 1
- MKYBYDHXWVHEJW-UHFFFAOYSA-N N-[1-oxo-1-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propan-2-yl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(C(C)NC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 MKYBYDHXWVHEJW-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910052755 nonmetal Inorganic materials 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/46—Roll speed or drive motor control
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/74—Temperature control, e.g. by cooling or heating the rolls or the product
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The present invention relates to a steel sheet and a manufacturing method thereof. The method for manufacturing a steel sheet according to the present invention is a method for manufacturing a steel sheet which comprises the steps of preparing carbon steel (C), silicon (Si), manganese (Mn), phosphorus (P), sulfur (S), aluminum (Al), niobium (Nb) N), and a remaining amount of iron (Fe) and other unavoidable impurities; Hot-rolling the hot-rolled section steel at a rolling starting temperature of 1000 ° C to 1050 ° C to produce an intermediate formed body having a web portion and a flange portion; And cooling the intermediate formed body.
Description
The present invention relates to a section steel and a manufacturing method thereof. More particularly, to a high-strength and high-strength section steel through controlled rolling temperature and a manufacturing method thereof.
In recent years, the demand for marine structural steel, which is highly demanded due to the growth of offshore plant sector, is increasing. The H-shaped steel may be used for the structural steel for marine structure. The H-shaped steel is a rolled steel material composed of a flange, which is two horizontal members, and a web, which is a vertical member. Such H-shaped steel keeps the outer and inner parts of the flange at a constant thickness, and thus has an excellent sectional performance and an advantage of easy combination and joining of sections.
BACKGROUND OF THE INVENTION [0002] The background art of the present invention is disclosed in Korean Patent Publication No. 2007-0095373 (published on September 28, 2007, entitled "High-Strength Steel Having Excellent Delay-Failure Property and Method for Manufacturing the Same").
According to one embodiment of the present invention, there is provided a method of manufacturing a steel strip excellent in rigidity and toughness.
According to one embodiment of the present invention, there is provided a method of manufacturing a steel strip excellent in low-temperature impact resistance.
According to one embodiment of the present invention, there is provided a method of manufacturing a steel sheet, which prevents shape deformation of a section steel and prevents a material deviation in each section.
According to an embodiment of the present invention, there is provided a section steel produced by the section steel manufacturing method.
One aspect of the present invention relates to a method of manufacturing a steel section. In one embodiment, the steel sheet manufacturing method comprises the steps of: 0.08 to 0.10 wt% carbon (C), 0.16 to 0.20 wt% silicon (Si), 1.46 to 1.50 wt% manganese (Mn) (N), 0.028 to 0.033% by weight of niobium (Nb), 0.016 to 0.02% by weight of titanium (Ti), 0.01% by weight or less of nitrogen (N) (Fe) and other unavoidable impurities; Hot-rolling the hot-rolled section steel at a rolling starting temperature of 1000 ° C to 1050 ° C to produce an intermediate formed body having a web portion and a flange portion; And cooling the intermediate formed body.
In one embodiment, the reheating may be performed at a temperature of 1100 ° C to 1200 ° C.
In one embodiment, when the thickness of the flange portion of the intermediate formed body is 7 mm or less, the steel material is allowed to stand for 15 to 45 seconds and then rolled at a rolling speed of 3.5 to 4.5 m / s, If the thickness exceeds 7 mm, the steel sheet may be allowed to stand for 85 to 110 seconds and then rolled at a rolling speed of 2.5 to 3.5 m / s.
In one embodiment, when the thickness of the flange portion of the intermediate formed body is 7 mm or less in the hot rolling, the steel material is rolled at a rolling finish temperature of 810 ° C to 850 ° C, and the thickness of the intermediate flange portion of the intermediate formed body exceeds 7 mm , The section steel can be rolled under the rolling finish temperature: 840 ° C to 880 ° C.
Another aspect of the present invention relates to a section steel produced by the section steel manufacturing method. In one embodiment, the section steel comprises 0.08 to 0.10 wt% carbon (C), 0.16 to 0.20 wt% silicon (Si), 1.46 to 1.50 wt% manganese (Mn) (N), 0.028 to 0.033 wt% of niobium (Nb), 0.016 to 0.02 wt% of titanium (Ti), 0.01 wt% or less of nitrogen (N) ) And other unavoidable impurities.
In one embodiment, the section steel has a tensile strength (TS) of 450 MPa or more, a yield strength (YS) of 345 MPa or more, an elongation (El) of 18% The impact absorbing energy at the surface may be 80 J or more.
The section steel produced by the method of the present invention has a minimized shape deformation, less material variation, excellent stiffness and toughness, and excellent low-temperature impact properties, especially for use in offshore structures such as poles .
1 shows a method of manufacturing a steel sheet according to one embodiment of the present invention.
2 shows an intermediate molded body manufactured according to one embodiment of the present invention.
Hereinafter, the present invention will be described in detail. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to be exemplary, self-explanatory, allowing for equivalent explanations of the present invention.
One aspect of the present invention relates to a method of manufacturing a steel section. (A) a step of reheating a steel sheet; (b) a hot rolling step; And (c) a cooling step. 1 shows a method of manufacturing a steel sheet according to one embodiment of the present invention. 1, the method for manufacturing a steel sheet according to the present invention comprises 0.08 to 0.10% by weight of carbon (C), 0.16 to 0.20% by weight of silicon (Si), 1.46 to 1.50% by weight of manganese (Mn) Or less of nitrogen (N), 0.005 wt% or less of sulfur (S), 0.2 to 0.3 wt% of aluminum (Al), 0.028 to 0.033 wt% of niobium (Nb), 0.016 to 0.02 wt% , And a remaining amount of iron (Fe) and other unavoidable impurities; Hot-rolling the hot-rolled section steel at a rolling starting temperature of 1000 ° C to 1050 ° C to produce an intermediate formed body having a web portion and a flange portion; And cooling the intermediate formed body.
Hereinafter, a method of manufacturing a steel sheet according to the present invention will be described in detail.
(a) Shape steel Reheat step
The above step is a step of reheating the steel material. In an embodiment, the section steel may be a beam blank for producing H-section steel. For example, the molten steel produced by the electric furnace steelmaking process using the above-mentioned steel material can be manufactured by the refining process and the beam blank can be manufactured by the continuous casting process.
In one embodiment of the present invention, the steel sheet comprises 0.08 to 0.10 weight% of carbon (C), 0.16 to 0.20 weight% of silicon (Si), 1.46 to 1.50 weight% of manganese (Mn) (N), 0.028 to 0.033 wt% of niobium (Nb), 0.016 to 0.02 wt% of titanium (Ti), 0.01 wt% or less of nitrogen (N) ) And other unavoidable impurities.
The carbon (C) is included to improve the material strength of the present invention. The carbon is contained in an amount of 0.08 to 0.10% by weight based on the total weight of the steel material. When the carbon content is less than 0.08% by weight, the strength of the steel is lowered. When the carbon content is more than 0.10% by weight, the ductility and flange formability may be deteriorated. 0.08 to 0.09% by weight, for example.
The silicon (Si) is an element added for solid solution strengthening and deoxidation for the purpose of enhancing the activity of the carbon and facilitating formation of ferrite at a high temperature. The silicon is contained in an amount of 0.16 to 0.20% by weight based on the total weight of the steel material. If the silicon content is less than 0.16 wt%, the strength of the ferrite decreases, the oxidation and carbonation inclusion inhibition effect decreases, and surface defects due to the inclusion scale exceeding 0.20 wt% may occur. For example, 0.18 to 0.20% by weight.
The manganese (Mn) is included for the purpose of improving the strength and toughness and stabilizing the austenite structure to increase the incombustibility. The manganese is contained in an amount of 1.46 to 1.50% by weight based on the total weight of the steel material. When manganese is contained in an amount of less than 1.46% by weight, pearlite is easily produced at high temperature, and strength and ductility are liable to be deteriorated. When the content exceeds 1.50% by weight, workability is lowered and the amount of nonmetal inclusions is increased, . For example, from 1.46 to 1.48 wt%.
The phosphorus (P) contributes partly to the strength improvement, but is a typical element that lowers the secondary process embrittlement. The phosphorus is contained in an amount of 0.015% by weight or less based on the total weight of the steel sheet. When the phosphorus is contained in an amount exceeding 0.015% by weight, secondary processing brittleness occurs, and weldability may also be deteriorated. For example, 0.001 to 0.015% by weight.
The sulfur (S) reacts with manganese (Mn) to form precipitates of fine MnS, thereby improving workability. The sulfur content is 0.005% by weight or less based on the total weight of the steel sheet. When sulfur is contained in an amount exceeding 0.005% by weight, the content of sulfur dissolved may be too high, so that ductility and moldability may be deteriorated. For example, 0.001 to 0.005% by weight.
Aluminum (Al) is included for the purpose of enhancing solubility and refining grain refinement by fine-precipitating nitride (AlN) by bonding with nitrogen together with deoxidation effect for removing an acid contained in the steel. The aluminum is contained in an amount of 0.2 to 0.3% by weight based on the total weight of the steel material. When the amount of aluminum is less than 0.2% by weight, the deoxidizing effect is insignificant. When the aluminum is contained in an amount exceeding 0.3% by weight, Al 2 O 3 is formed, and impact toughness may be lowered. For example, 0.25 to 0.3% by weight.
The niobium (Nb) bonds with carbon (C) and nitrogen (N) at a high temperature to form carbide or nitride. Niobium-based carbides or nitrides improve grain strength and low-temperature toughness by suppressing grain growth during rolling and making crystal grains finer. The niobium is contained in an amount of 0.028 to 0.033% by weight based on the total weight of the steel sheet. When the content of niobium is less than 0.028 wt%, the effect of improving the low-temperature toughness and grain refining effect may be deteriorated. When the niobium is contained in an amount exceeding 0.033% by weight, impact toughness may be lowered. For example, 0.028 to 0.031% by weight.
The titanium (Ti) forms a carbide upon reheating to inhibit the growth of austenite grains and to refine the texture of the steel. 0.016 to 0.02% by weight based on the total weight of the titanium steel sheet. When the amount of titanium is less than 0.016 wt%, the effect of refining may be lowered. When the titanium is contained in an amount exceeding 0.02 wt%, carbonized precipitates become coarse and the effect of suppressing grain growth is lowered. 0.018 to 0.02% by weight, for example.
The nitrogen (N) is another unavoidable impurity, and there is a problem that inclusions such as AlN and TiN are formed and the quality of the steel is deteriorated. The nitrogen content is 0.01% by weight or less based on the total weight of the steel sheet. If the nitrogen is contained in an amount exceeding 0.01% by weight, the elongation and moldability may be deteriorated. For example, 0.0001 to 0.01% by weight.
In one embodiment, the reheating may be performed at a temperature of 1100 ° C to 1200 ° C. The reheating is carried out in order to reuse the segregated components in the casting of the section steel. It is possible to prevent the coarsening of the austenite grains and ensure the mechanical strength without causing a large rolling load during reheating in the above temperature range. For example, at a temperature of 1140 ° C to 1180 ° C. The reheating time may be from 100 minutes to 240 minutes. For example, 100 minutes to 220 minutes.
(b) hot rolling step
The step of hot-rolling the reheated steel material at a rolling starting temperature of 1000 ° C. to 1050 ° C. to manufacture an intermediate formed body having a web portion and a flange portion.
The steel sheet can be rolled into a specific shape by the hot rolling. For example, the intermediate formed body can be rolled into an H-shape. 2 shows an intermediate molded body manufactured according to one embodiment of the present invention. Referring to FIG. 2, the intermediate formed
In one embodiment, the starting rolling temperature (SRT) in the hot rolling may be 1000 ° C. to 1050 ° C. In the above range, it is possible to secure the toughness, high rigidity and low-temperature impact properties of the steel material during hot rolling. When the rolling start temperature is less than 1000 ° C, the load during rolling increases. When the rolling starting temperature exceeds 1050 ° C, the reduction amount in the non-recrystallized region exceeds 30%, and the low- Can be lowered. For example, 1000 ° C to 1030 ° C.
The finish rolling temperature (FRT) during the hot rolling may be 810 to 880 ° C. The cumulative rolling reduction in the non-recrystallized region can be ensured at the end of the hot rolling at the temperature within the above-mentioned range, and the effect of grain refinement resulting therefrom is excellent, so that the rigidity, low temperature impact property and toughness of the intermediate formed body can be secured at the same time.
According to one embodiment of the present invention, the rolling end time and the rolling speed can be controlled according to the thickness of the flange portion of the intermediate formed body to achieve the rolling finish temperature.
On the other hand, the movement of the steel material from the inlet side to the outlet side of the rolling mill or from the outlet to the inlet side is referred to as a pass. In the present invention, before the hot rolling, After the reheated steel sheet is left to stand for a predetermined time, rolling can be performed.
In one embodiment, if the thickness of the flange portion of the intermediate formed body is 7 mm or less, the steel sheet can be left to stand for 15 to 45 seconds and then rolled at a rolling speed of 3.5 to 4.5 m / s. When the above-described waiting time and rolling speed are applied, the steel material can pass through the pass, and the low temperature rolling effect can be obtained, so that the rigidity, low temperature impact property and toughness of the intermediate molded body can be secured at the same time. For example, when the thickness of the intermediate formed body flange portion is 0.1 mm or more to 7 mm or less, the steel sheet may be allowed to stand for 15 to 30 seconds and then rolled at a rolling speed of 3.5 to 4.0 m / s.
In one embodiment, when the thickness of the flange portion of the intermediate formed body exceeds 7 mm, the steel sheet may be left to stand for 85 to 110 seconds and then rolled at a rolling speed of 2.5 to 3.5 m / s. When the above-described waiting time and rolling speed are applied, the steel material can pass through the pass, and the low temperature rolling effect can be obtained, so that the rigidity, low temperature impact property and toughness of the intermediate molded body can be secured at the same time. For example, when the thickness of the intermediate formed body is more than 7 mm and not more than 25 mm, the steel sheet can be left to stand for 95 to 105 seconds and then rolled at a rolling speed of 2.5 to 3.3 m / s.
The rolling start temperature and the rolling finish temperature of the present invention can be achieved by adjusting the rolling stand-by time and the rolling speed according to the thickness of the intermediate formed body flange portion as described above. Thus, the present invention provides a steel sheet excellent in rigidity, toughness, Can be manufactured.
In one embodiment of the present invention, the rolling finish temperature may be varied depending on the thickness of the flange portion of the intermediate formed body.
In one embodiment, when the thickness of the flange portion of the intermediate formed body is 7 mm or less, the steel material may be rolled under the rolling finish temperature: 810 ° C to 850 ° C. When rolling at the rolling finish temperature, it is possible to secure the rigidity, low-temperature impact property and toughness of the steel sheet according to the present invention, and to prevent the phenomenon that coarse pro-eutectoid ferrite is formed on the surface of the steel to decrease the strength. For example, when the thickness of the intermediate formed body flange portion is 0.1 mm or more to 7 mm or less, the steel sheet can be rolled under the rolling finish temperature: 810 ° C to 850 ° C.
When the thickness of the intermediate flange portion of the intermediate formed body exceeds 7 mm, the steel material can be rolled under the rolling finish temperature: 840 캜 to 880 캜. When rolling at the rolling finish temperature, it is possible to secure the rigidity, low-temperature impact property and toughness of the steel sheet according to the present invention, and to prevent the phenomenon that coarse pro-eutectoid ferrite is formed on the surface of the steel to decrease the strength. For example, when the thickness of the intermediate formed body is more than 7 mm and not more than 25 mm, the section steel can be rolled under the rolling finish temperature: 840 캜 to 880 캜.
When the rolling finish temperature is controlled according to the thickness of the steel material as described above, an intermediate molded body having excellent rigidity, toughness and low-temperature impact properties can be manufactured.
(c) cooling step
The step is a step of cooling the intermediate formed body.
The present invention relates to a method for producing a steel sheet according to the present invention, which is excellent in productivity in the production of a steel sheet. Especially, the steel sheet has excellent low-temperature impact properties, Shaped steel can be manufactured.
Another aspect of the present invention relates to a section steel produced by the section steel manufacturing method. In embodiments, the section steel may be, but is not limited to, an H-section steel.
Wherein the steel sheet comprises 0.08 to 0.10 wt% of carbon (C), 0.16 to 0.20 wt% of silicon (Si), 1.46 to 1.50 wt% of manganese (Mn), 0.015 wt% or less of phosphorus (P) 0.2 to 0.3 wt% of aluminum (Al), 0.028 to 0.033 wt% of niobium (Nb), 0.016 to 0.02 wt% of titanium (Ti), 0.01 wt% or less of nitrogen (N) Impurities.
The tensile strength (TS) of the section steel may be 450 MPa or more. And may be suitable for use as a section steel for marine structures in the above range. For example, 450 to 550 MPa. For another example, it may be 460 to 540 MPa.
The yield strength (YS) of the section steel may be at least 345 MPa. And may be suitable for use as a section steel for marine structures in the above range. For example, from 350 to 450 MPa. For example, 400 to 450 MPa.
Elongation (El) of the section steel may be 18% or more. And may be suitable for use as a section steel for marine structures in the above range. For example, 18% to 31%.
The impact absorption energy of the section steel at -40 캜 may be 80 J or more. In the above range, it may be suitable to be used as a section steel for offshore structures in low temperature regions such as polar regions. For example, from 26% to 38%.
The shape steel produced by the method of the present invention has a minimized shape deformation, less material variation, excellent stiffness and toughness, and excellent low-temperature impact properties, particularly for use in off-shore structures such as poles .
Hereinafter, the configuration and operation of the present invention will be described in more detail with reference to preferred embodiments of the present invention. It is to be understood, however, that the same is by way of illustration and example only and is not to be construed in a limiting sense.
Example One
(C) 0.08 to 0.10 wt%, silicon (Si) 0.16 to 0.20 wt%, manganese (Mn) 1.46 to 1.50 wt%, phosphorus (P) 0.015 wt% or less, sulfur (S) 0.005 wt% or less 0.2 to 0.3 wt% of aluminum (Al), 0.028 to 0.033 wt% of niobium (Nb), 0.016 to 0.02 wt% of titanium (Ti), 0.01 wt% or less of nitrogen (N) A beam blank made of an impurity was reheated at 1150 占 폚. The reheated beam blank was left to stand for 20 seconds and then hot rolled at a rolling start temperature of 1017 ° C at a rolling speed of 4.0 m / s to finish rolling at the finish rolling temperature of 831 ° C to form a web portion and a layer having a thickness of 6.6 t Thereby preparing an intermediate molded body having a flange portion. The intermediate formed body was cooled to produce H-shaped steel.
Example 2 to 4
An H-shaped steel was produced in the same manner as in Example 1, except that the flange thickness and rolling conditions of the intermediate formed body in Table 1 were applied.
Comparative Example 1-4
An H-shaped steel was produced in the same manner as in Example 1, except that the flange thickness and rolling conditions of the intermediate formed body in Table 1 were applied.
Tensile strength, yield strength, elongation and impact absorption energy at -40 캜 were measured for the sections produced in Examples 1 to 4 and Comparative Examples 1 to 4, and the results are shown in Table 2 below.
Referring to Table 2, it was found that the H-shaped steels of Examples 1 to 4, in which rolling standby time and rolling start temperature were varied according to the thickness of the present invention, were excellent in strength, elongation and low temperature impact properties. However, in Comparative Examples 1 to 4, which were outside the rolling start temperature range of the present invention, the impact absorption energy values related to the high strength and low temperature impact properties were lowered, indicating that they were not suitable as the structural steel for marine structure in the low temperature regions such as the polar regions.
It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
10: web portion 20: flange portion
100: section steel
Claims (6)
Hot-rolling the hot-rolled section steel at a rolling starting temperature of 1000 ° C to 1050 ° C to produce an intermediate formed body having a web portion and a flange portion; And
And cooling the intermediate formed body.
Wherein the reheating is performed at a temperature of 1100 ° C to 1200 ° C.
When the thickness of the flange portion of the intermediate formed body is 7 mm or less, the steel sheet is allowed to stand for 15 to 45 seconds, rolled at a rolling speed of 3.5 to 4.5 m / s,
Wherein when the thickness of the flange portion of the intermediate formed body exceeds 7 mm, the steel sheet is allowed to stand for 85 to 110 seconds and then rolled at a rolling speed of 2.5 to 3.5 m / s.
When the thickness of the flange portion of the intermediate formed body is 7 mm or less in the hot rolling, the steel material is rolled under the conditions of the rolling finish temperature: 810 캜 to 850 캜,
Wherein when the thickness of the intermediate flange portion of the intermediate formed body exceeds 7 mm, the section steel material is rolled at a rolling finish temperature of 840 캜 to 880 캜.
The tensile strength (TS) of the section steel is 450 MPa or more, the yield strength (YS) is 345 MPa or more, the elongation (El) is 18% or more, And the energy is 80 J or more.
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020150086971A KR20160149647A (en) | 2015-06-18 | 2015-06-18 | Shape steel and manufacturing method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| KR1020150086971A KR20160149647A (en) | 2015-06-18 | 2015-06-18 | Shape steel and manufacturing method thereof |
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| KR20160149647A true KR20160149647A (en) | 2016-12-28 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109338239A (en) * | 2018-11-01 | 2019-02-15 | 宁波钢铁有限公司 | A kind of production method of low-cost and high-performance structural steel |
| CN109536828A (en) * | 2018-11-01 | 2019-03-29 | 宁波钢铁有限公司 | A kind of production method of low cost low yield strength ratio high tenacity Steels for High Rise Buildings |
-
2015
- 2015-06-18 KR KR1020150086971A patent/KR20160149647A/en not_active Application Discontinuation
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109338239A (en) * | 2018-11-01 | 2019-02-15 | 宁波钢铁有限公司 | A kind of production method of low-cost and high-performance structural steel |
| CN109536828A (en) * | 2018-11-01 | 2019-03-29 | 宁波钢铁有限公司 | A kind of production method of low cost low yield strength ratio high tenacity Steels for High Rise Buildings |
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