WO2013099179A1 - High strength steel plate having excellent brittle crack arrestability and method for manufacturing same - Google Patents
High strength steel plate having excellent brittle crack arrestability and method for manufacturing same Download PDFInfo
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- WO2013099179A1 WO2013099179A1 PCT/JP2012/008176 JP2012008176W WO2013099179A1 WO 2013099179 A1 WO2013099179 A1 WO 2013099179A1 JP 2012008176 W JP2012008176 W JP 2012008176W WO 2013099179 A1 WO2013099179 A1 WO 2013099179A1
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- 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
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
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- 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
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
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- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- 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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- 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
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- 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
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- 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
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- 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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- 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
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
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- 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
- C21D2201/00—Treatment for obtaining particular effects
- C21D2201/05—Grain orientation
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- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/002—Bainite
Definitions
- the present invention provides brittle crack propagation arrestability (brittle crack arrestability) suitable for thick steel plates exceeding 50mm in thickness used for large structures such as ships, marine structures, low-temperature storage tanks, and construction / civil engineering structures.
- the present invention relates to an excellent high-strength steel plate and a method for producing the same.
- Patent Document 1 proposes a steel material in which the structure of the surface layer portion is ultrafine-grained in order to improve the brittle crack propagation stopping characteristics without increasing the alloy cost.
- the steel material having excellent brittle crack propagation stopping characteristics described in Patent Document 1 is effective in improving the brittle crack propagation stopping characteristics due to shear lips (plastic deformation region shear-lips) generated in the steel layer when the brittle crack propagates.
- it is characterized in that the propagation energy possessed by the propagating brittle crack is absorbed by refining the crystal grains of the shear lip portion.
- ferrite structure ferrite structure
- bainite structure bainite structure
- both surface portions of the steel material have an equivalent grain size (average grain diameter a circle): 5 ⁇ m or less, aspect ratio (of the grain): It is composed of a layer having 50% or more of ferrite structure having two or more ferrite grains, and it is important to suppress the variation of ferrite grain size.
- a suppression method it is described that a maximum reduction ratio (rolling reduction ratio) per pass during finish rolling is set to 12% or less to suppress a local recrystallization phenomenon.
- the steel materials excellent in brittle crack propagation stopping characteristics described in Patent Documents 1 and 2 are obtained by recooling only the steel surface layer part and then recovering the heat, and by applying processing during the recuperation, a specific structure is obtained.
- control is not easy, and in particular, a thick material with a plate thickness exceeding 50 mm is a process with a heavy load on the rolling and cooling equipment.
- Patent Document 3 attention is paid not only to the refinement of ferrite crystal grains but also to subgrains formed in ferrite crystal grains, and a technique on the extension of TMCP that improves brittle crack propagation stop characteristics. Is described.
- Patent Document 4 discloses that (110) plane X-ray intensity ratio (X-ray diffraction intensity according to (110) plane) is 2 or more by controlled rolling, and equivalent circle diameter (average grain diameter equivalent to a circle). It is described that the brittle fracture resistance is improved by making coarse grains of 20 ⁇ m or more 10% or less.
- Patent Document 5 is characterized in that, as a welded structural steel having excellent brittle crack propagation stopping performance in a joint part, the (100) plane X-ray plane strength ratio in the rolled surface inside the plate thickness is 1.5 or more. Steel sheet is disclosed, and it is described that it has excellent brittle crack propagation stoppage characteristics due to the deviation of the angle between the stress load direction and the crack propagation direction due to the texture development. Further, Patent Documents 6 to 9 suspend brittle crack propagation that develops a texture in each part in the sheet thickness direction (1/4 part of sheet thickness, center part of sheet thickness, etc.) by defining the average rolling reduction in controlled rolling. A method for producing welded structural steel with excellent performance is described.
- the Kca value at a use temperature of ⁇ 10 ° C. is less than 3000 N / mm 3/2.
- a hull structure to which a steel plate having a thickness exceeding 50 mm is applied it has been suggested that ensuring safety is an issue.
- Patent Documents 1 to 5 are mainly targeted for a plate thickness of about 50 mm based on manufacturing conditions and disclosed experimental data, and when applied to thick materials exceeding 50 mm It is unclear whether a predetermined characteristic can be obtained, and the characteristics against crack propagation in the thickness direction necessary for the hull structure have not been verified at all.
- Patent Documents 6 to 9 since it is necessary to set a high rolling reduction per pass at the time of rolling in order to develop a texture in the central part of the plate thickness, various factors such as manufacturing conditions and steel plate size are required. As a result, there was a need for improvement.
- the present invention is a brittle crack propagation stoppage that can be stably produced by an industrially very simple process that optimizes rolling conditions and controls the texture in the thickness direction even for thick steel plates with a thickness exceeding 50 mm.
- An object is to provide a high-strength thick steel plate having excellent characteristics and a method for producing the same.
- the inventors of the present invention have earnestly researched a high-strength thick steel plate having excellent brittle crack propagation stopping characteristics even in a thick steel plate having a thickness exceeding 50 mm and a manufacturing method for stably obtaining the steel plate.
- the region having the texture where the (211) plane X-ray intensity ratio in the plane parallel to the steel sheet surface is 1.0 or more is the center of the plate thickness. It was found that excellent brittle crack propagation stopping characteristics can be obtained by existing in a region of 1/3 or more of the total thickness of the plate. And in order to obtain such a thick steel plate, it turned out that it is preferable to manufacture combining the chemical component of a specific range, and the manufacturing conditions of a specific range, especially the rolling and cooling conditions of a sheet thickness center part. .
- the present invention has been made by further studying the obtained knowledge, that is, the present invention, 1.
- the (211) plane X-ray intensity ratio in the plane parallel to the steel plate surface has a texture of 1.0 or more, Brittle crack propagation stopping characteristics characterized in that the bainite fraction in the center is 80% or more and the Charpy fracture transition temperature at 1 ⁇ 4 position of the plate thickness is -40 ° C or less Excellent high-strength thick steel plate.
- the chemical composition of steel is mass%, C: 0.03-0.20%, Si: 0.03-0.50%, Mn: 0.50-2.20%, P: 0.030% or less , S: 0.010% or less, Al: 0.005 to 0.08%, N: 0.0045% or less, and the carbon equivalent (Ceq) represented by the following formula (1) is 0.34% or more 1.
- Ceq C + Mn / 6 + (Cu + Ni) / 15 + (V + Mo + Cr) / 5 (1)
- each element symbol represents the content (% by mass) of each component.
- the chemical composition of the steel is, by mass, Ti: 0.005 to 0.030%, Nb: 0.005 to 0.050%, Cu: 0.01 to 0.50%, Ni: 0.01 ⁇ 1.00%, Cr: 0.01 ⁇ 0.50%, Mo: 0.01 ⁇ 0.50%, V: 0.001 ⁇ 0.10%, B: 0.0030% or less, Ca: 0 1.
- the steel material having the chemical composition described in 4.2 or 3 is heated to a temperature of 900 to 1200 ° C, and the temperature at the center of the plate thickness in hot rolling is accumulated in a temperature range of (Ar 3 points +100) ° C or higher.
- the rolling reduction is 30% or more, the temperature at the center of the plate thickness is (Ar 3 points + 60) ° C. or less, the cumulative rolling reduction is 50% or more in the temperature range of Ar 3 points or more, and the average value of the rolling reduction per pass is 6 It is characterized by being cooled to 450 ° C. or lower at a cooling rate of 4.0 ° C./s or higher after rolling at a reduction rate range of 5.0% or higher and 5.0 to 20.0% in each pass.
- the texture is appropriately controlled according to each position in the plate thickness direction, so that it has excellent brittle crack propagation stopping characteristics.
- Applying the present invention to a steel plate having a plate thickness of 50 mm or more, preferably more than 50 mm, more preferably 55 mm or more, and even more preferably 60 mm or more is more prominent than steels according to the prior art. Effective because it demonstrates its superiority.
- a structural member for ships for example, it contributes to improving the safety of ships by applying it to deck members joined to hatch side combing in strong deck structures such as container ships and bulk carriers. It is extremely useful.
- the (211) plane X-ray intensity ratio in the plane parallel to the steel sheet surface is greater than 1/3 of the total thickness including the thickness center. It shall have a texture of 1.0 or more.
- the above-described effect that microscopic cracks are generated prior to crack growth and resistance to crack growth is that the region having the texture is a region that is 1/3 or more of the total thickness including the thickness center Therefore, the upper limit is not specified. If the area having the texture increases, the above-described effect can be further exhibited. However, even if the area is increased beyond 3/4 of the total thickness, the increase in the effect is saturated. Therefore, it is not necessary to increase the region having the texture beyond 3/4 of the total thickness. However, it goes without saying that the above-described effects are exhibited even when the total thickness of the plate is the texture.
- the (211) plane X-ray intensity ratio is a numerical value representing the (211) crystal plane integration degree (X-ray diffraction intensity ratio of texture) of the target material, and the (211) reflection X-ray diffraction of the target material.
- the intensity (I (211)) the ratio of the random standard sample (211) reflection of X-ray diffraction intensity with no texture (I 0 (211)) ( I (211) / I 0 (211)) the Point to.
- the bainite fraction in the central portion of the plate thickness having a cross section parallel to the rolling direction is at least 80%.
- the bainite fraction is expressed as an area fraction.
- the (211) plane in the plane parallel to the steel sheet surface is developed by transformation of the austenite structure processed during rolling into a ferrite or bainite structure.
- a ferrite-cementite structure there is an effect such as recovery, so this texture does not develop in a wide range in the thickness direction.
- the microstructure in the center portion of the plate thickness means a microstructure in the region of at least 1/3 portion of the plate thickness including the center portion of the plate thickness.
- the present invention includes a steel plate whose entire cross section in the thickness direction is the microstructure.
- the position representative of the material of the steel sheet is from 1/4 position of the plate thickness. Specifies the Charpy fracture surface transition temperature in the Charpy impact test using the collected Charpy specimens.
- C 0.03 to 0.20%
- C is an element that improves the strength of steel. In the present invention, it is necessary to contain 0.03% or more in order to ensure a desired strength, but if it exceeds 0.20%, the weldability deteriorates. As well as adversely affecting toughness. Therefore, C is preferably specified in the range of 0.03 to 0.20%. More preferably, it is 0.05 to 0.15%.
- Si 0.03-0.50% Si is effective as a deoxidizing element and as a strengthening element for steel, but if its content is less than 0.03%, it has no effect. On the other hand, if it exceeds 0.50%, not only the surface properties of the steel are impaired, but also the toughness is extremely deteriorated. Therefore, the content is preferably 0.03% or more and 0.50% or less. More preferably, it is 0.05 to 0.45%.
- Mn 0.50 to 2.20% Mn can be contained as a strengthening element. If it is less than 0.50%, the effect is not sufficient, and if it exceeds 2.20%, the toughness and weldability of the base metal deteriorate and the steel material cost also rises, so 0.50% or more and 2.20% or less It is preferable that More preferably, it is 0.60 to 2.15%.
- P, S P and S are inevitable impurities in the steel, but P exceeds 0.030%, and if S exceeds 0.010%, the toughness deteriorates. Therefore, 0.030% or less and 0.010%, respectively. The following are desirable, and 0.020% or less and 0.005% or less are more desirable respectively.
- Al acts as a deoxidizer, and for this purpose, it is preferable to contain 0.005% or more. However, when it contains exceeding 0.08%, while reducing toughness, when welding, the toughness of a weld metal part will be reduced. For this reason, Al is preferably specified in the range of 0.005 to 0.08%. More preferably, it is 0.02 to 0.04%.
- N 0.0045% or less N combines with Al in the steel, adjusts the crystal grain size during rolling, and strengthens the steel. However, if it exceeds 0.0045%, the toughness deteriorates, so 0.0045% or less is preferable. More preferably, it is 0.0040% or less.
- Carbon equivalent (Ceq) 0.34% or more and 0.49% or less
- the carbon equivalent is an important index for predicting the strength, transformation behavior and the like of the structure. If the carbon equivalent is less than 0.34%, it is difficult to obtain the above-mentioned bainite fraction at the center of the plate thickness. Further, if it exceeds 0.49%, the toughness deteriorates, so it is preferable to set it to 0.34% or more and 0.49% or less. More preferably, it is 0.35 to 0.48%.
- the above is the preferred basic component composition in the present invention, and the balance is Fe and inevitable impurities.
- an inevitable impurity for example, O is allowed to be 0.0050% or less.
- Ti 0.005 to 0.030%, Ti has the effect of forming nitrides, carbides, or carbonitrides due to the inclusion of a small amount, and making the crystal grains finer to improve the base material toughness. The effect is obtained when the content is 0.005% or more. However, if the content exceeds 0.030%, the toughness of the base metal and the weld heat affected zone is lowered. A range of 0.030% is preferable. More preferably, it is 0.008 to 0.028%.
- Nb 0.005 to 0.050%
- Nb precipitates as NbC at the time of ferrite transformation or reheating, and contributes to the increase in strength.
- it has the effect of expanding the non-recrystallized region in rolling in the austenite region, and contributes to the refinement of ferrite, so it is also effective in improving toughness.
- the effect is obtained by containing 0.005% or more, but if it exceeds 0.050%, coarse NbC precipitates and conversely causes a decrease in toughness, so when Nb is contained, the upper limit is It is preferable to set it as 0.050%. More preferably, it is 0.008 to 0.040%.
- Cu, Ni, Cr, Mo Cu, Ni, Cr, and Mo are all elements that enhance the hardenability of steel. While contributing directly to strength enhancement after rolling, it can be included for functional improvements such as toughness, high-temperature strength, or weather resistance, but excessive inclusion degrades toughness and weldability, so if included
- the upper limits of Cu are preferably 0.50% for Cu, 1.00% for Ni, 0.50% for Cr, and 0.50% for Mo. More preferably, the upper limit is 0.45% for Cu, 0.95% for Ni, 0.45% for Cr, and 0.45% for Mo.
- the content of each element is preferably 0.01% or more.
- V 0.001 to 0.10%
- V is an element that improves the strength of the steel by precipitation strengthening as V (CN), and may be contained by 0.001% or more in order to exert this effect. However, when it contains exceeding 0.10%, toughness will fall. For this reason, when V is contained, the content is preferably in the range of 0.001 to 0.10%. More preferably, it is 0.008 to 0.095%.
- B 0.0030% or less
- B is an element that enhances the hardenability of steel in a small amount, and the effect is exhibited with a content of 0.0006% or more. However, if it exceeds 0.0030%, the toughness of the welded portion is lowered. Therefore, when B is contained, the content is preferably 0.0030% or less. More preferably, it is 0.0028% or less.
- REM 0.01% or less Ca
- REM is necessary because it refines the structure of the weld heat-affected zone and improves toughness, and even if contained, the effect of the present invention is not impaired. It may be contained accordingly. However, when it is excessively contained, coarse inclusions are formed and the toughness of the base material is deteriorated. When it is included, the upper limit of the amount is preferably 0.005% and 0.01%, respectively.
- the manufacturing conditions specify slab heating conditions, hot rolling conditions, and cooling conditions after hot rolling.
- the molten steel having the above composition is melted in a converter or the like, made into a steel material (slab) by continuous casting or the like, heated to 900 to 1200 ° C., and then hot-rolled. If the heating temperature is less than 900 ° C., sufficient time for rolling in the austenite recrystallization temperature region cannot be secured, and if it exceeds 1200 ° C., the austenite grains become coarse, leading to a decrease in toughness and significant oxidation loss. Since the yield is lowered, the heating temperature is set to 900 to 1200 ° C. From the viewpoint of toughness, the preferred heating temperature range is 1000 to 1150 ° C, more preferably 1000 to 1050 ° C.
- the final microstructure is refined by rolling the austenite at a temperature of (Ar 3 points +100) ° C or higher at a central thickness of 30% or more, and austenite.
- the cumulative rolling reduction in this temperature range is more preferably 35% or more.
- the Ar 3 point (° C.) is obtained by the following equation.
- Ar 3 points 910-273C-74Mn-57Ni-16Cr-9Mo-5Cu
- each element symbol is the content (% by mass) in steel, and 0 if not contained.
- the cumulative reduction rate is 50% or more and the average value of the reduction rate per pass is 6.0% or more. Rolling. If the cumulative rolling reduction in this temperature range is less than 50%, the toughness of the steel sheet deteriorates. Further, in order to set the (211) plane X-ray intensity ratio to 1.0 or more, the cumulative reduction ratio is 50% or more in the temperature range of (Ar 3 points + 60) ° C. or lower, which is an unrecrystallized austenite region, and Ar 3 points or higher. To do. The cumulative rolling reduction in this temperature range is more preferably 55% or more.
- the region where the (211) plane X-ray intensity ratio in a plane parallel to the steel plate surface tends to be 1.0 or more tends to be narrowed. Therefore, in the present invention, the temperature at the center of the plate thickness is (Ar 3 points + 60) ° C. or less, the average value of the rolling reduction per pass in the temperature range of Ar 3 points or more is 6.0% or more, and each pass The rolling reduction range is specified to be 5.0 to 20.0%. As a result, the region where the (211) plane X-ray intensity ratio is 1.0 or more can be made a region including the plate thickness center and 1/3 or more of the total thickness.
- the toughness decreases and the (211) plane X A region where the line intensity ratio is 1.0 or more cannot be a region including the center of the plate thickness and 1/3 or more of the total thickness.
- the maximum value of each pass reduction ratio exceeds 20.0%, the toughness deteriorates on the contrary due to the influence of processing strain.
- the average value of the rolling reduction per pass in this temperature range is more preferably 6.5% or more, and the rolling reduction range of each pass is more preferably 5.5 to 18.0%. In hot rolling, rolling outside the specified temperature range may be performed. Rolling including the specified cumulative rolling reduction may be performed in the temperature range specified above.
- the rolled steel sheet is cooled to 450 ° C. or lower at a cooling rate of 4.0 ° C./s or higher.
- the cooling rate is less than 4.0 ° C. /, the transformation to bainite does not proceed sufficiently. Therefore, the region where the (211) plane X-ray intensity ratio is 1.0 or more includes the thickness center and the total thickness of the plate. Further, a desired microstructure, that is, a structure having a bainite fraction of 80% or more in the central portion of the plate thickness cannot be obtained.
- the cooling stop temperature exceeds 450 ° C., the transformation to bainite does not proceed sufficiently, so that a desired microstructure cannot be obtained.
- a cooling method methods such as water cooling and gas cooling can be used. According to the manufacturing conditions described above, not only the desired texture is obtained, but also the fracture facet size in the Charpy impact test is miniaturized, and the Charpy fracture surface transition temperature at 1 ⁇ 4 position of the plate thickness is ⁇ 40 ° C. or lower. Is achieved.
- the temperature at the center of the plate thickness is obtained by heat transfer calculation from the plate surface temperature measured with a radiation thermometer.
- the temperature condition for cooling after hot rolling is also the temperature at the center of the plate thickness.
- a ⁇ 14 JIS14A test piece having a longitudinal direction in the direction orthogonal to the rolling direction is taken from 1/4 part of the plate thickness, a tensile test is performed, yield strength (YS), tensile strength (TS) was measured.
- a JIS No. 4 impact test specimen was taken from 1/4 part of the plate thickness so that the longitudinal axis direction of the test specimen was parallel to the rolling direction, and a Charpy impact test was conducted to determine the fracture surface transition temperature ( vTrs) was determined.
- the Charpy fracture surface transition temperature at 1 ⁇ 4 part of the plate thickness was within the scope of the present invention within the range of ⁇ 40 ° C.
- the (211) plane X-ray intensity ratio in a plane parallel to the steel plate surface is measured every 1 mm from the front surface to the back surface of the steel plate.
- Table 3 shows the results of these tests.
- the (211) plane X-ray intensity ratio in a plane parallel to the steel plate surface was 1.0 or more at the central portion of the plate thickness.
- the region where the transition temperature of the Charpy impact test at 1 ⁇ 4 part of the plate thickness, the bainite fraction at the center of the plate thickness, and the (211) plane X-ray intensity ratio in the plane parallel to the steel plate surface is 1.0 or more.
- Kca ( ⁇ 10 ° C.) showed excellent brittle crack propagation stopping performance of 7000 N / mm 3/2 or more.
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Abstract
Description
しかし、Ni量の増加はコストの大幅な上昇を余儀なくさせるため、LNG貯槽タンク以外の用途には適用が難しい。 As a means to improve the brittle crack propagation stopping characteristics of steel materials, a method of increasing the Ni content has been conventionally known. In a liquefied natural gas (LNG) storage tank, 9% Ni steel is commercially available. Used on a scale.
However, since the increase in the amount of Ni necessitates a significant increase in cost, it is difficult to apply to applications other than the LNG storage tank.
1.板厚中心部を含め板厚全厚の1/3以上の領域において、鋼板表面に平行な面における(211)面X線強度比が1.0以上となる集合組織を有し、板厚の中央部におけるベイナイト分率が80%以上であり、かつ板厚の1/4位置におけるシャルピー破面遷移温度(fracture transition temperature)が-40℃以下であることを特徴とする脆性き裂伝播停止特性に優れた高強度厚鋼板。 The present invention has been made by further studying the obtained knowledge, that is, the present invention,
1. In the region of 1/3 or more of the total thickness including the thickness center, the (211) plane X-ray intensity ratio in the plane parallel to the steel plate surface has a texture of 1.0 or more, Brittle crack propagation stopping characteristics characterized in that the bainite fraction in the center is 80% or more and the Charpy fracture transition temperature at ¼ position of the plate thickness is -40 ° C or less Excellent high-strength thick steel plate.
Ceq=C+Mn/6+(Cu+Ni)/15+(V+Mo+Cr)/5 (1)
ただし、各元素記号は各成分の含有量(質量%)をあらわす。 2. The chemical composition of steel is mass%, C: 0.03-0.20%, Si: 0.03-0.50%, Mn: 0.50-2.20%, P: 0.030% or less , S: 0.010% or less, Al: 0.005 to 0.08%, N: 0.0045% or less, and the carbon equivalent (Ceq) represented by the following formula (1) is 0.34% or more 1. A high-strength thick steel plate excellent in brittle crack propagation stopping property according to 1, wherein the content is 0.49% or less, and the balance is Fe and inevitable impurities.
Ceq = C + Mn / 6 + (Cu + Ni) / 15 + (V + Mo + Cr) / 5 (1)
However, each element symbol represents the content (% by mass) of each component.
本発明では、圧延方向または圧延直角方向など板面に平行な方向に伝播するき裂に対してき裂伝播停止特性を向上させるため、鋼板表面に平行な面に、すなわち、圧延面に平行に(211)面を発達させる。板厚中央部で鋼板表面に平行な面において(211)面を発達させると、き裂進展に先立ち微視的なクラックが発生し、き裂進展の抵抗となる。 1. In the present invention, in order to improve the crack propagation stop property for cracks propagating in the direction parallel to the plate surface, such as the rolling direction or the direction perpendicular to the rolling direction, in the plane parallel to the steel plate surface, that is, rolling A (211) plane is developed parallel to the plane. When the (211) plane is developed in a plane parallel to the steel sheet surface at the center of the plate thickness, a microscopic crack is generated prior to the crack propagation, which becomes resistance to crack propagation.
上述の板厚中央部における好適な集合組織を得るため、圧延方向に平行な断面の板厚の中央部におけるベイナイト分率を少なくとも80%とする。ベイナイト分率は面積分率で表すものとする。 2. Microstructure in the central portion of the plate thickness In order to obtain a suitable texture in the central portion of the plate thickness described above, the bainite fraction in the central portion of the plate thickness having a cross section parallel to the rolling direction is at least 80%. The bainite fraction is expressed as an area fraction.
母材靭性が、良好な特性を有することが脆性き裂の進展を抑制する前提となるので、本発明に係る鋼板では鋼板の材質を代表する位置として板厚の1/4位置から採取したシャルピー試験片によるシャルピー衝撃試験におけるシャルピー破面遷移温度を規定する。 3. Base material toughness Since the base material toughness has the premise of suppressing the progress of brittle cracks since it has good characteristics, in the steel sheet according to the present invention, the position representative of the material of the steel sheet is from 1/4 position of the plate thickness. Specifies the Charpy fracture surface transition temperature in the Charpy impact test using the collected Charpy specimens.
Cは鋼の強度を向上する元素であり、本発明では、所望の強度を確保するためには0.03%以上の含有を必要とするが、0.20%を超えると、溶接性が劣化するばかりか靭性にも悪影響がある。このため、Cは、0.03~0.20%の範囲に規定することが好ましい。なお、より好ましくは0.05~0.15%である。 C: 0.03 to 0.20%
C is an element that improves the strength of steel. In the present invention, it is necessary to contain 0.03% or more in order to ensure a desired strength, but if it exceeds 0.20%, the weldability deteriorates. As well as adversely affecting toughness. Therefore, C is preferably specified in the range of 0.03 to 0.20%. More preferably, it is 0.05 to 0.15%.
Siは脱酸元素として、また、鋼の強化元素として有効であるが、0.03%未満の含有量ではその効果がない。一方、0.50%を超えると鋼の表面性状を損なうばかりか靭性が極端に劣化する。従ってその含有量を0.03%以上、0.50%以下とすることが好ましい。より好ましくは、0.05~0.45%である。 Si: 0.03-0.50%
Si is effective as a deoxidizing element and as a strengthening element for steel, but if its content is less than 0.03%, it has no effect. On the other hand, if it exceeds 0.50%, not only the surface properties of the steel are impaired, but also the toughness is extremely deteriorated. Therefore, the content is preferably 0.03% or more and 0.50% or less. More preferably, it is 0.05 to 0.45%.
Mnは、強化元素として含有することができる。0.50%より少ないとその効果が十分でなく、2.20%を超えると母材の靭性や溶接性が劣化し、鋼材コストも上昇するため、0.50%以上、2.20%以下とすることが好ましい。より好ましくは、0.60~2.15%である。 Mn: 0.50 to 2.20%
Mn can be contained as a strengthening element. If it is less than 0.50%, the effect is not sufficient, and if it exceeds 2.20%, the toughness and weldability of the base metal deteriorate and the steel material cost also rises, so 0.50% or more and 2.20% or less It is preferable that More preferably, it is 0.60 to 2.15%.
P、Sは、鋼中の不可避不純物であるが、Pは0.030%を超え、Sは0.010%を超えると靭性が劣化するため、それぞれ、0.030%以下、0.010%以下が望ましく、それぞれ、0.020%以下、0.005%以下がさらに望ましい。 P, S
P and S are inevitable impurities in the steel, but P exceeds 0.030%, and if S exceeds 0.010%, the toughness deteriorates. Therefore, 0.030% or less and 0.010%, respectively. The following are desirable, and 0.020% or less and 0.005% or less are more desirable respectively.
Alは、脱酸剤として作用し、このためには0.005%以上含有することが好ましい。しかし、0.08%を超えて含有すると、靭性を低下させるとともに、溶接した場合に、溶接金属部の靭性を低下させる。このため、Alは、0.005~0.08%の範囲に規定することが好ましい。なお、より好ましくは、0.02~0.04%である。 Al: 0.005 to 0.08%
Al acts as a deoxidizer, and for this purpose, it is preferable to contain 0.005% or more. However, when it contains exceeding 0.08%, while reducing toughness, when welding, the toughness of a weld metal part will be reduced. For this reason, Al is preferably specified in the range of 0.005 to 0.08%. More preferably, it is 0.02 to 0.04%.
Nは、鋼中のAlと結合し、圧延加工時の結晶粒径を調整し、鋼を強化する。しかし、0.0045%を超えると靭性が劣化するため、0.0045%以下とすることが好ましい。より好ましくは、0.0040%以下である。 N: 0.0045% or less N combines with Al in the steel, adjusts the crystal grain size during rolling, and strengthens the steel. However, if it exceeds 0.0045%, the toughness deteriorates, so 0.0045% or less is preferable. More preferably, it is 0.0040% or less.
炭素当量は組織の強度、変態挙動等を予測するための重要な指標となる。炭素当量が0.34%未満では板厚中心部において、前述のベイナイト分率が得難い。また0.49%超えでは靭性が劣化してしまうため、0.34%以上、0.49%以下とすることが好ましい。より好ましくは、0.35~0.48%である。
なお、炭素当量(Ceq)は、以下に示す式で得られるものとする。
Ceq=C+Mn/6+(Cu+Ni)/15+(V+Mo+Cr)/5
各元素記号は含有量(質量%)、含有しない場合は0とする。 Carbon equivalent (Ceq): 0.34% or more and 0.49% or less The carbon equivalent is an important index for predicting the strength, transformation behavior and the like of the structure. If the carbon equivalent is less than 0.34%, it is difficult to obtain the above-mentioned bainite fraction at the center of the plate thickness. Further, if it exceeds 0.49%, the toughness deteriorates, so it is preferable to set it to 0.34% or more and 0.49% or less. More preferably, it is 0.35 to 0.48%.
The carbon equivalent (Ceq) is obtained by the following formula.
Ceq = C + Mn / 6 + (Cu + Ni) / 15 + (V + Mo + Cr) / 5
Each element symbol is the content (% by mass), and 0 when not contained.
Tiは微量の含有により、窒化物、炭化物、あるいは炭窒化物を形成し、結晶粒を微細化して母材靭性を向上させる効果を有する。その効果は0.005%以上の含有によって得られるが、0.030%を超える含有は、母材および溶接熱影響部の靭性を低下させるので、Tiを含有させる場合には、0.005~0.030%の範囲にするのが好ましい。より好ましくは、0.008~0.028%である。 Ti: 0.005 to 0.030%,
Ti has the effect of forming nitrides, carbides, or carbonitrides due to the inclusion of a small amount, and making the crystal grains finer to improve the base material toughness. The effect is obtained when the content is 0.005% or more. However, if the content exceeds 0.030%, the toughness of the base metal and the weld heat affected zone is lowered. A range of 0.030% is preferable. More preferably, it is 0.008 to 0.028%.
Nbは、NbCとしてフェライト変態時あるいは再加熱時に析出し、高強度化に寄与する。また、オーステナイト域の圧延において未再結晶域を拡大させる効果をもち、フェライトの細粒化に寄与するので、靭性の改善にも有効である。その効果は0.005%以上の含有により得られるが0.050%を超えて含有すると、粗大なNbCが析出し逆に、靭性の低下を招くので、Nbを含有させる場合にはその上限は0.050%とするのが好ましい。より好ましくは、0.008~0.040%である。 Nb: 0.005 to 0.050%
Nb precipitates as NbC at the time of ferrite transformation or reheating, and contributes to the increase in strength. In addition, it has the effect of expanding the non-recrystallized region in rolling in the austenite region, and contributes to the refinement of ferrite, so it is also effective in improving toughness. The effect is obtained by containing 0.005% or more, but if it exceeds 0.050%, coarse NbC precipitates and conversely causes a decrease in toughness, so when Nb is contained, the upper limit is It is preferable to set it as 0.050%. More preferably, it is 0.008 to 0.040%.
Cu、Ni、Cr、Moはいずれも鋼の焼入れ性を高める元素である。圧延後の強度アップに直接寄与するとともに、靭性、高温強度、あるいは耐候性などの機能向上のために含有させることができるが、過度の含有は靭性や溶接性を劣化させるため、含有させる場合には、それぞれ上限をCuは0.50%、Niは1.00%、Crは0.50%、Moは0.50%とすることが好ましい。それぞれ上限をCuは0.45%、Niは0.95%、Crは0.45%、Moは0.45%とすることがより好ましい。一方、各元素の含有量が0.01%未満であるとその効果が現れないため、含有させる場合には、各元素について0.01%以上の含有とすることが好ましい。 Cu, Ni, Cr, Mo
Cu, Ni, Cr, and Mo are all elements that enhance the hardenability of steel. While contributing directly to strength enhancement after rolling, it can be included for functional improvements such as toughness, high-temperature strength, or weather resistance, but excessive inclusion degrades toughness and weldability, so if included The upper limits of Cu are preferably 0.50% for Cu, 1.00% for Ni, 0.50% for Cr, and 0.50% for Mo. More preferably, the upper limit is 0.45% for Cu, 0.95% for Ni, 0.45% for Cr, and 0.45% for Mo. On the other hand, since the effect does not appear when the content of each element is less than 0.01%, when it is contained, the content of each element is preferably 0.01% or more.
Vは、V(CN)としての析出強化により、鋼の強度を向上させる元素であり、この効果を発揮させるために0.001%以上含有してもよい。しかし、0.10%を超えて含有すると、靭性を低下させる。このため、Vを含有させる場合には、0.001~0.10%の範囲の含有とすることが好ましい。より好ましくは、0.008~0.095%である。 V: 0.001 to 0.10%
V is an element that improves the strength of the steel by precipitation strengthening as V (CN), and may be contained by 0.001% or more in order to exert this effect. However, when it contains exceeding 0.10%, toughness will fall. For this reason, when V is contained, the content is preferably in the range of 0.001 to 0.10%. More preferably, it is 0.008 to 0.095%.
Bは微量で鋼の焼入れ性を高める元素であり、その効果は0.0006%以上の含有で発揮される。しかし、0.0030%を超えて含有すると溶接部の靭性を低下させるので、Bを含有させる場合には0.0030%以下とすることが好ましい。より好ましくは、0.0028%以下である。 B: 0.0030% or less B is an element that enhances the hardenability of steel in a small amount, and the effect is exhibited with a content of 0.0006% or more. However, if it exceeds 0.0030%, the toughness of the welded portion is lowered. Therefore, when B is contained, the content is preferably 0.0030% or less. More preferably, it is 0.0028% or less.
Ca、REMは溶接熱影響部の組織を微細化し靭性を向上させ、含有しても本発明の効果が損なわれることはないので必要に応じて含有してもよい。しかし、過度に含有すると、粗大な介在物を形成し母材の靭性を劣化させるので、含有させる場合にはその量の上限をそれぞれ0.005%、0.01%とするのが好ましい。 Ca: 0.005% or less, REM: 0.01% or less Ca, REM is necessary because it refines the structure of the weld heat-affected zone and improves toughness, and even if contained, the effect of the present invention is not impaired. It may be contained accordingly. However, when it is excessively contained, coarse inclusions are formed and the toughness of the base material is deteriorated. When it is included, the upper limit of the amount is preferably 0.005% and 0.01%, respectively.
上記組成の溶鋼を、転炉等で溶製し、連続鋳造等で鋼素材(スラブ)とし、900~1200℃に加熱後、熱間圧延を行うことが好ましい。
加熱温度が900℃未満では、オーステナイト再結晶温度域における圧延を行う時間が十分に確保できず、また、1200℃超えではオーステナイト粒が粗大化し、靭性の低下を招くばかりか、酸化ロスが顕著となり、歩留が低下するので、加熱温度は900~1200℃とする。靭性の観点から好ましい加熱温度の範囲は1000~1150℃であり、より好ましくは1000~1050℃である。 [Slab heating]
It is preferable that the molten steel having the above composition is melted in a converter or the like, made into a steel material (slab) by continuous casting or the like, heated to 900 to 1200 ° C., and then hot-rolled.
If the heating temperature is less than 900 ° C., sufficient time for rolling in the austenite recrystallization temperature region cannot be secured, and if it exceeds 1200 ° C., the austenite grains become coarse, leading to a decrease in toughness and significant oxidation loss. Since the yield is lowered, the heating temperature is set to 900 to 1200 ° C. From the viewpoint of toughness, the preferred heating temperature range is 1000 to 1150 ° C, more preferably 1000 to 1050 ° C.
熱間圧延における板厚中央部の温度(板厚の1/2となる位置での温度で、以下同じとする)が(Ar3点+100)℃以上での累積圧下率、(Ar3点+60)℃以下、Ar3点以上の累積圧下率、(Ar3点+60)℃以下、Ar3点以上における1パス当りの圧下率の平均値、および、(Ar3点+60)℃以下、Ar3点以上における1パス当りの圧下率の範囲を規定することが好ましい。 [Hot rolling]
Cumulative rolling reduction when the temperature at the center of the plate thickness in hot rolling (the temperature at a position that is ½ of the plate thickness, hereinafter the same) is (Ar 3 points + 100) ° C. or more, (Ar 3 points + 60 ) ° C. or lower, Ar 3 points or higher cumulative reduction rate, (Ar 3 points + 60) ° C. or lower, average value of reduction rate per pass at Ar 3 points or higher, and (Ar 3 points + 60) ° C. or lower, Ar 3 It is preferable to define the range of the rolling reduction per pass above the point.
Ar3点=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu
式において各元素記号は鋼中含有量(質量%)で、含有しない場合は0とする。 In hot rolling, the final microstructure is refined by rolling the austenite at a temperature of (Ar 3 points +100) ° C or higher at a central thickness of 30% or more, and austenite. To improve the base material toughness. The cumulative rolling reduction in this temperature range is more preferably 35% or more. In the present invention, the Ar 3 point (° C.) is obtained by the following equation.
Ar 3 points = 910-273C-74Mn-57Ni-16Cr-9Mo-5Cu
In the formula, each element symbol is the content (% by mass) in steel, and 0 if not contained.
圧延が終了した鋼板は4.0℃/s以上の冷却速度にて450℃以下まで冷却する。冷却速度が4.0℃/未満では、ベイナイトへの変態が十分に進行しないため、(211)面X線強度比が1.0以上となる領域を、板厚中心を含み板厚全厚の1/3以上とすることができず、さらに所望のミクロ組織、すなわち、板厚の中央部におけるベイナイト分率が80%以上の組織も得られない。また、冷却停止温度が450℃を超えると、ベイナイトへの変態が十分に進行しないため、やはり、所望のミクロ組織が得られない。冷却方式としては、水冷、ガス冷却などの方式を用いることができる。
上述の製造条件により、所望の集合組織が得られるだけでなく、シャルピー衝撃試験における破面単位(fracture facet size)が微細化され、板厚1/4位置におけるシャルピー破面遷移温度-40℃以下が達成される。 [Cooling after hot rolling]
The rolled steel sheet is cooled to 450 ° C. or lower at a cooling rate of 4.0 ° C./s or higher. When the cooling rate is less than 4.0 ° C. /, the transformation to bainite does not proceed sufficiently. Therefore, the region where the (211) plane X-ray intensity ratio is 1.0 or more includes the thickness center and the total thickness of the plate. Further, a desired microstructure, that is, a structure having a bainite fraction of 80% or more in the central portion of the plate thickness cannot be obtained. In addition, when the cooling stop temperature exceeds 450 ° C., the transformation to bainite does not proceed sufficiently, so that a desired microstructure cannot be obtained. As a cooling method, methods such as water cooling and gas cooling can be used.
According to the manufacturing conditions described above, not only the desired texture is obtained, but also the fracture facet size in the Charpy impact test is miniaturized, and the Charpy fracture surface transition temperature at ¼ position of the plate thickness is −40 ° C. or lower. Is achieved.
Ar3点=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu
ただし、各元素記号は鋼中含有量(質量%)で、含有しない場合は0とする。 Molten steel (steel symbols A to T) of each composition shown in Table 1 is melted in a converter, made into a steel material (slab 280 mm thick) by a continuous casting method, hot rolled to a plate thickness of 50 to 75 mm, and then cooled. No. 1 to 28 test steels were obtained. Table 2 shows hot rolling conditions and cooling conditions. Ar 3 points (° C.) were calculated by the following equation.
Ar 3 points = 910-273C-74Mn-57Ni-16Cr-9Mo-5Cu
However, each element symbol is a steel content (mass%), and is 0 when not contained.
なお、No.1~28については、いずれも、鋼板表面に平行な面における(211)面X線強度比が板厚中央部において1.0以上であった。 Table 3 shows the results of these tests.
In addition, No. With respect to 1 to 28, the (211) plane X-ray intensity ratio in a plane parallel to the steel plate surface was 1.0 or more at the central portion of the plate thickness.
Claims (4)
- 板厚中心部を含め板厚全厚の1/3以上の領域において、鋼板表面に平行な面における(211)面X線強度比が1.0以上となる集合組織を有し、板厚の中央部におけるベイナイト分率が80%以上であり、かつ板厚の1/4位置におけるシャルピー破面遷移温度が-40℃以下であることを特徴とする高強度厚鋼板。 In the region of 1/3 or more of the total thickness including the thickness center, the (211) plane X-ray intensity ratio in the plane parallel to the steel plate surface has a texture of 1.0 or more, A high-strength thick steel plate characterized by having a bainite fraction at the center of 80% or more and a Charpy fracture surface transition temperature at ¼ position of the plate thickness of -40 ° C or less.
- 鋼の化学成分が、質量%で、C:0.03~0.20%、Si:0.03~0.50%、Mn:0.50~2.20%、P:0.030%以下、S:0.010%以下、Al:0.005~0.08%、N:0.0045%以下、かつ、下記(1)式で示される炭素等量(Ceq)が0.34%以上0.49%以下であり、残部がFeおよび不可避的不純物からなることを特徴とする請求項1記載の高強度厚鋼板。
Ceq=C+Mn/6+(Cu+Ni)/15+(V+Mo+Cr)/5 (1)
ただし、各元素記号は各成分の含有量(質量%)をあらわす。 The chemical composition of steel is mass%, C: 0.03-0.20%, Si: 0.03-0.50%, Mn: 0.50-2.20%, P: 0.030% or less , S: 0.010% or less, Al: 0.005 to 0.08%, N: 0.0045% or less, and the carbon equivalent (Ceq) represented by the following formula (1) is 0.34% or more The high-strength thick steel plate according to claim 1, characterized in that it is 0.49% or less, and the balance consists of Fe and inevitable impurities.
Ceq = C + Mn / 6 + (Cu + Ni) / 15 + (V + Mo + Cr) / 5 (1)
However, each element symbol represents the content (% by mass) of each component. - 鋼の化学成分が、さらに、質量%で、Ti:0.005~0.030%、Nb:0.005~0.050%、Cu:0.01~0.50%、Ni:0.01~1.00%、Cr:0.01~0.50%、Mo:0.01~0.50%、V:0.001~0.10%、B:0.0030%以下、Ca:0.0050%以下、REM:0.010%以下から選ばれる1種または2種以上を含有することを特徴とする請求項2記載の高強度厚鋼板。 Further, the chemical composition of the steel is, by mass, Ti: 0.005 to 0.030%, Nb: 0.005 to 0.050%, Cu: 0.01 to 0.50%, Ni: 0.01 ~ 1.00%, Cr: 0.01 ~ 0.50%, Mo: 0.01 ~ 0.50%, V: 0.001 ~ 0.10%, B: 0.0030% or less, Ca: 0 The high-strength thick steel plate according to claim 2, comprising one or more selected from .0050% or less and REM: 0.010% or less.
- 請求項2または3に記載の化学成分を有する鋼素材を、900~1200℃の温度に加熱し、熱間圧延における板厚中央部の温度が(Ar3点+100)℃以上の温度域で累積圧下率30%以上、板厚中央部の温度が(Ar3点+60)℃以下、Ar3点以上の温度域において累積圧下率50%以上、かつ、1パス当りの圧下率の平均値が6.0%以上、かつ各パスの圧下率範囲が5.0~20.0%となる圧延を行った後、4.0℃/s以上の冷却速度にて450℃以下まで冷却することを特徴とする高強度厚鋼板の製造方法。 The steel material having the chemical component according to claim 2 or 3 is heated to a temperature of 900 to 1200 ° C, and the temperature at the center of the plate thickness in hot rolling is accumulated in a temperature range of (Ar 3 points +100) ° C or higher. The rolling reduction is 30% or more, the temperature at the center of the plate thickness is (Ar 3 points + 60) ° C. or less, the cumulative rolling reduction is 50% or more in the temperature range of Ar 3 points or more, and the average value of the rolling reduction per pass is 6 It is characterized by being cooled to 450 ° C. or lower at a cooling rate of 4.0 ° C./s or higher after rolling at a reduction rate range of 5.0% or higher and 5.0 to 20.0% in each pass. A method for producing a high-strength thick steel plate.
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US20170335424A1 (en) * | 2014-12-24 | 2017-11-23 | Posco | High-strength steel having superior brittle crack arrestability, and production method therefor |
JP2018503744A (en) * | 2014-12-24 | 2018-02-08 | ポスコPosco | High strength steel material excellent in brittle crack propagation resistance and manufacturing method thereof |
JP2018504523A (en) * | 2014-12-24 | 2018-02-15 | ポスコPosco | High strength steel material excellent in brittle crack propagation resistance and manufacturing method thereof |
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JP2018504524A (en) * | 2014-12-24 | 2018-02-15 | ポスコPosco | Structural heavy steel with excellent brittle crack propagation resistance and method for producing the same |
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JP2019501281A (en) * | 2015-12-04 | 2019-01-17 | ポスコPosco | High-strength steel material excellent in brittle crack propagation resistance and brittle crack initiation resistance of welds and method for producing the same |
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JP2019183205A (en) * | 2018-04-05 | 2019-10-24 | Jfeスチール株式会社 | Steel sheet and manufacturing method therefor |
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CN113528957A (en) * | 2021-06-30 | 2021-10-22 | 武汉钢铁有限公司 | High-strength container steel with excellent fatigue and corrosion resistance and manufacturing method thereof |
Also Published As
Publication number | Publication date |
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BR112014015789A8 (en) | 2017-07-04 |
BR112014015789B1 (en) | 2019-10-29 |
BR112014015789A2 (en) | 2017-06-13 |
KR20160021912A (en) | 2016-02-26 |
KR101614375B1 (en) | 2016-04-21 |
JP5733425B2 (en) | 2015-06-10 |
JPWO2013099179A1 (en) | 2015-04-30 |
TWI504759B (en) | 2015-10-21 |
CN104011247B (en) | 2016-11-02 |
KR101681491B1 (en) | 2016-12-01 |
CN104011247A (en) | 2014-08-27 |
KR20140113975A (en) | 2014-09-25 |
TW201333219A (en) | 2013-08-16 |
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