[go: up one dir, main page]

WO2018030790A1 - Feuille d'acier laminée à chaud haute résistance ayant une faible inhomogénéité et une excellente qualité de surface, et son procédé de fabrication - Google Patents

Feuille d'acier laminée à chaud haute résistance ayant une faible inhomogénéité et une excellente qualité de surface, et son procédé de fabrication Download PDF

Info

Publication number
WO2018030790A1
WO2018030790A1 PCT/KR2017/008640 KR2017008640W WO2018030790A1 WO 2018030790 A1 WO2018030790 A1 WO 2018030790A1 KR 2017008640 W KR2017008640 W KR 2017008640W WO 2018030790 A1 WO2018030790 A1 WO 2018030790A1
Authority
WO
WIPO (PCT)
Prior art keywords
steel sheet
rolled steel
hot rolled
surface quality
less
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/KR2017/008640
Other languages
English (en)
Korean (ko)
Inventor
공종판
최윤석
방종근
박교선
박경미
정제숙
차경세
고영주
조용석
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Posco Holdings Inc
Original Assignee
Posco Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Posco Co Ltd filed Critical Posco Co Ltd
Priority to JP2019505026A priority Critical patent/JP2019527774A/ja
Priority to CN201780048797.4A priority patent/CN109563601A/zh
Publication of WO2018030790A1 publication Critical patent/WO2018030790A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Images

Classifications

    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/46—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting
    • B21B1/463—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling metal immediately subsequent to continuous casting in a continuous process, i.e. the cast not being cut before rolling
    • 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
    • B21B3/02—Rolling special iron alloys, e.g. stainless steel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
    • B21B45/04—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing
    • B21B45/08—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for de-scaling, e.g. by brushing hydraulically
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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
    • C21D2211/005—Ferrite

Definitions

  • the present invention relates to a high strength hot rolled steel sheet having a low material deviation and excellent surface quality, and a method of manufacturing the same.
  • the new steel manufacturing process which is recently attracting attention, is a process called manufacturing thin slabs (mini-mill), which can produce morphological steel with good material deviation due to the small temperature deviation in the width and length directions of the strip. It is attracting attention as a process with potential.
  • the conventional mini mill steel sheet manufacturing method is a thin slab 50 ⁇ 150mm thickness in the continuous casting machine (10) (a) is manufactured, rolled into a bar plate of a predetermined thickness or less in the roughing mill 20, and then wound in a coil box in front of the finishing mill 50 to compensate for the difference between the playing speed and the rolling speed. Finish rolling.
  • Patent Document 1 there are three major problems when producing a steel sheet according to Patent Document 1.
  • edge surface temperature drops sharply below 800 ° C because thin slabs manufactured in continuous casting machines do not have a slab reheating process before rough rolling.
  • high-strength hot-rolled high burring steel has a high sensitivity of edge defect generation due to high temperature ductility deterioration when the edge portion temperature is low because many components such as Nb, V, and Ti, which are precipitate generating elements, are added.
  • Patent Document 1 Korean Unexamined Patent Publication No. 2012-0049992
  • One aspect of the present invention is to secure the inherent characteristics of the high burring steel, such as excellent hole expansion properties by using the continuous continuous rolling mode in the play-rolling direct connection process and at the same time excellent surface quality significantly reduced the width, longitudinal material deviation of the steel sheet It is to provide a high strength hot rolled steel sheet and a method of manufacturing the same.
  • One aspect of the present invention is by weight, C: 0.02 ⁇ 0.06%, Mn: 1.0 ⁇ 2.0%, Si: 0.1 ⁇ 0.3%, P: 0.025% or less, S: 0.01% or less, Cr: 0.001 ⁇ 0.5%, Al: 0.05% or less, Ti: 0.001-0.1%, Nb: 0.001-0.03%, N: 0.001-0.012%, remaining Fe and other unavoidable impurities,
  • the microstructure relates to a high-strength hot rolled steel sheet having a low material deviation and excellent surface quality including 60% to 90% ferrite, 5% to 35% bainite, and 5% MA (martensite / austenite) as an area fraction.
  • another aspect of the present invention is by weight, C: 0.02 ⁇ 0.06%, Mn: 1.0 ⁇ 2.0%, Si: 0.1 ⁇ 0.3%, P: 0.025% or less, S: 0.01% or less, Cr: 0.001 ⁇ 0.5%, Al: 0.05% or less, Ti: 0.001-0.1%, Nb: 0.001-0.03%, N: 0.001-0.012%, molten steel containing the remaining Fe and other unavoidable impurities continuously in a thin slab with a thickness of 50-150 mm Casting;
  • Removing the scale by sequentially passing the bar plate through two rows of spraying cooling water at a pressure of 50 to 200 bar and one row of spraying cooling water at a pressure of 50 to 100 bar;
  • winding the cooled hot rolled steel sheet at 300 ⁇ 500 °C; includes,
  • Each of the above steps relates to a method for producing a high strength hot rolled steel sheet having a low material deviation and excellent surface quality.
  • the present invention by using the continuous continuous rolling mode in the performance-rolling direct connection process, while ensuring the inherent characteristics of the high burring steel, such as elongation hole expansion properties, while significantly reducing the material deviation in the width and length direction of the steel sheet, It is possible to produce a high strength hot rolled steel sheet having excellent thickness of 3.0mmt or less.
  • the hot rolled steel sheet produced by the present invention is a thin material (3.0mmt or less) and the edge portion and the surface scale quality is good, it is possible to manufacture high-quality PO materials by the general hot-rolling pickling process, only hot-rolled after-roll material (more than 3.0mmt) This is different from the existing mini mill process, which is excellent in price competition and can significantly increase added value.
  • 1 is a view showing a conventional mini mill process.
  • FIG. 2 is a view showing a play-rolling direct connection process according to the present invention.
  • FIG. 3 is a photograph of the surface of the PO material coil tip portion of Inventive Example 1.
  • FIG. 4 is a photograph of the surface of the PO material coil tip portion of Comparative Example 3.
  • FIG. 5 is a photograph taken with an optical microscope of the microstructure of Inventive Example 1.
  • FIG. 7 is a photograph taken with a transmission electron microscope (TEM) of the microstructure of Inventive Example 1.
  • TEM transmission electron microscope
  • the present inventors have studied in depth to solve the conventional mini-mill process, it is difficult to produce a hot rolled steel sheet of a thin (3.0mmt or less), and problems such as edge defects, surface quality degradation may occur.
  • High-strength hot-rolled steel sheet having a low material deviation and excellent surface quality is a weight%, C: 0.02 to 0.06%, Mn: 1.0 to 2.0%, Si: 0.1 to 0.3%, P: 0.025% or less, S: 0.01% or less, Cr: 0.001-0.5%, Al: 0.05% or less, Ti: 0.001-0.1%, Nb: 0.001-0.03%, N: 0.001-0.012%, and the remaining Fe and other unavoidable impurities, Microstructures comprise 60 to 90% ferrite, 5 to 35% bainite and 5% or less MA (martensite / austenite) by area fraction.
  • MA martensite / austenite
  • the unit of each element content is weight%.
  • Carbon (C) is an element that forms carbide or is dissolved in ferrite to increase strength.
  • C content is less than 0.02% it may be difficult to secure the strength targeted in the present invention.
  • C content is greater than 0.06%, molten steel outflow may occur because alloy steel is manufactured by high-speed playing, and a solidification cell having a non-uniform thickness may be formed, which may cause an operation accident. Therefore, it is preferable that C content is 0.02 to 0.06%.
  • Manganese (Mn) is an element that suppresses ferrite formation and enhances austenite stability, thereby facilitating the formation of low-temperature transformation phase and increasing the strength of steel.
  • Mn content is less than 1.0%, it may be difficult to secure the strength targeted in the present invention. On the other hand, when the Mn content is more than 2.0%, weldability, hot rolling property, and the like may be inferior. Therefore, it is preferable that Mn content is 1.0 to 2.0%.
  • Silicon (Si) is an element that increases the ductility of steel sheet by increasing ferrite solid solution strengthening and carbide formation to increase residual austenite stability.
  • Si content is less than 0.1%, it is difficult to secure the above-described effects sufficiently.
  • Si content is more than 0.3%, red scale is generated on the surface of the steel sheet, and traces may remain on the surface of the steel sheet after pickling, thereby degrading the surface quality. Therefore, it is preferable that Si content is 0.1 to 0.3%.
  • Phosphorus (P) may be segregated at grain boundaries and / or interphase boundaries as impurities to cause brittleness. Therefore, the content should be controlled as low as possible, preferably at 0.025% or less.
  • S Sulfur as impurities may segregate during MnS non-metallic inclusions and performance solidification in steel, causing hot cracks. Therefore, the content should be controlled as low as possible, preferably at 0.01% or less.
  • Chromium (Cr) is an element that increases the strength of steel by increasing its hardenability.
  • the Cr content is less than 0.001%, the above effects are insufficient.
  • the Cr content is more than 0.5%, there is a problem that the ductility of the steel sheet is lowered. Therefore, the Cr content is preferably 0.001 to 0.5%.
  • Aluminum (Al) may be concentrated on the surface of the steel sheet to degrade the plating property, while suppressing carbide formation to increase the ductility of the steel.
  • aluminum (Al) in the steel reacts with nitrogen (N) to precipitate AlN, which can degrade slab or hot rolled steel sheet by causing slab cracks in the slab cooling conditions in which these precipitates precipitate during thin slab manufacture. .
  • the content should be controlled as low as possible, preferably at 0.05% or less.
  • Titanium (Ti) is an element that increases the strength of steel as a precipitate and nitride forming element.
  • the Ti content is less than 0.001%, the above effects are insufficient.
  • the Ti content is more than 0.1%, the increase in manufacturing cost and the ductility of the ferrite may be reduced. Therefore, the Ti content is preferably 0.001 to 0.1%.
  • Niobium is an element which forms carbide and refines austenite grains at high temperature. It is also dissolved in ferrite to increase strength.
  • the Nb content is less than 0.001%, the above effects are insufficient.
  • the Nb content is more than 0.03%, excessive NbC, (Ti, Nb) CN, etc. may be formed to cause high or low temperature brittleness of the slab, which may cause edge defects of the hot rolled steel sheet. Therefore, the Nb content is preferably 0.001 to 0.03%.
  • Nitrogen (N) is an austenite stabilizing and nitride forming element.
  • the N content is less than 0.001%, the above effects are insufficient.
  • the N content is greater than 0.012%, it increases the precipitation strengthening effect by reacting with the precipitate-forming element, but may cause a sharp drop in ductility.
  • N content is 0.001-0.012%.
  • the remaining component of the present invention is iron (Fe).
  • impurities which are not intended from the raw material or the surrounding environment may be inevitably mixed, and thus cannot be excluded. Since these impurities are known to those skilled in the art, all of them are not specifically mentioned in the present specification.
  • one or more of Cu, Ni, Mo, Sn, and Pb may be included, and the sum thereof may be 0.2% by weight or less.
  • the tramp element is an impurity element derived from scrap used as a raw material in the steelmaking process, and when the sum is more than 0.2%, the surface crack of the thin slab and the surface quality of the hot rolled steel sheet may be reduced.
  • Ceq represented by the following formula (1) may be 0.10 to 0.24.
  • each element symbol is a value representing each element content in weight%.
  • Equation (1) is a component relational formula for securing weldability of the steel sheet.
  • Ceq value 0.10 to 0.24
  • excellent spot weldability can be ensured and excellent mechanical properties can be given to the welded portion. .
  • Ceq is less than 0.10, there is a problem in that the hardenability is low, making it difficult to secure strength. On the other hand, if Ceq is greater than 0.24, the weldability may deteriorate and the physical properties of the weld portion may deteriorate.
  • the microstructure of the hot rolled steel sheet according to the present invention includes 60 to 90% ferrite, 5 to 35% bainite and 5% or less MA (martensite / austenite) in area fraction.
  • the ferrite fraction is greater than 90%, it is difficult to secure the target strength, and if the ferrite fraction is less than 60%, the remaining bainite and MA tissue fractions are high, thereby making it difficult to secure hole porosity.
  • bainite structure is an effective structure that can secure both strength and hole expansion at the same time, the above-mentioned effect is insufficient when the bainite fraction is less than 5%, and the strength is too high when the bainite fraction is more than 35%, the hole expandability There may be difficulties in securing it.
  • the fraction of MA is preferably 0%.
  • the MA is preferably limited to 5% or less because it is a structure that is advantageous for securing strength.
  • the average size of the crystal grains of the ferrite measured by the equivalent circle diameter may be 5 ⁇ m or less.
  • the hot rolled steel sheet of the present invention is 5 ⁇ 30 / ⁇ m 2 (Ti, Nb) (C, N) precipitates having an average size of 30nm or less measured by the equivalent diameter It may include.
  • (Ti, Nb) (C, N) precipitates are meant to include TiC, NbC, TiN, NbN, and composite precipitates thereof.
  • the size of the precipitate exceeds 30nm it may be difficult to effectively secure the strength.
  • the number of precipitates is 5 / ⁇ 2 If less than, it may be difficult to secure the target strength.
  • the number of precipitates is more than 30 / ⁇ m 2 , the elongation and hole expandability inferior to the increase in strength may cause cracks during processing.
  • the thickness of the hot rolled steel sheet of the present invention may be 3.0mmt or less.
  • the hot rolled steel sheet of the present invention may have a tensile strength of 590 MPa or more, a hole expandability of 80% or more, and a material deviation of tensile strength of 10 MPa or less.
  • a method of manufacturing a high-strength hot rolled steel sheet having a low material deviation and excellent surface quality may include continuously casting molten steel having the above-described alloy composition into a thin slab having a thickness of 50 to 150 mm; Heating the edge portion of the continuously cast thin slab to 900 to 1000 ° C .; Spraying coolant at a pressure of 150 bar or more to the heated thin slab to remove scale; Co-rolling the scaled thin slab to obtain a bar plate; Removing the scale by sequentially passing the bar plate through two rows of spraying cooling water at a pressure of 50 to 200 bar and one row of spraying cooling water at a pressure of 50 to 100 bar; Obtaining a hot rolled steel sheet by finishing rolling the bar plate from which the scale is removed at a temperature range of Ar1 to Ar3; Cooling the hot rolled steel sheet; And winding the cooled hot rolled steel sheet at 300 ° C. to 500 ° C., wherein each step is performed continuously.
  • Figure 2 shows an example of the play-roll direct connection process of the present invention for overcoming the problems of the existing mini mill process.
  • a thin slab (a) having a thickness of 50 to 150 mm is manufactured, and the slab is further heated in the heater 200 to secure the edge temperature above 900 ° C., thereby lowering the edge defect sensitivity and improving the quality. Let's do it.
  • Roughing scale scale breaker 300 (roughly called 'RSB') in front of roughing mill 400 and finishing mill scale breaker (500) (FSB ') in front of finishing mill 600 It is easy to remove the surface scale, so it is possible to produce PO (Pickled & Oiled) material with excellent surface quality when pickling hot rolled steel sheet in post process.
  • PO Powderled & Oiled
  • isothermal isothermal rolling with a rolling speed difference of less than 5% in one steel plate in the finish rolling step through a performance-rolling direct connection process. It is possible to produce high-strength hot rolled high burring steel with excellent material variation by precise cooling control in 'runout table'.
  • the molten steel having the alloy composition described above is continuously cast into a thin slab having a thickness of 50 to 150 mm.
  • the casting speed of the continuous casting may be 5.0mpm or more.
  • the reason why the casting speed is 5.0mpm or more is because in the present invention, since the continuous casting and the rolling process are performed continuously, a certain casting speed is required to secure a target rolling temperature.
  • the edge portion of the continuous cast thin slab is heated to 900 ⁇ 1000 °C.
  • the edge portion When the temperature of the edge portion is less than 900 ° C., a large amount of Nb (C, N) and AlN precipitates are generated, and thus there is a problem in that the edge crack generation sensitivity is very high as the ductility decreases. On the other hand, if the edge temperature is more than 1000 ° C., the center temperature of the thin slab becomes too high, resulting in a large number of arithmetic scales, resulting in poor surface quality after pickling.
  • Cooling water is sprayed to the heated thin slab at a pressure of 150 bar or more to remove scale.
  • the surface scale thickness may be removed to 300 ⁇ m or less by spraying a cooling water of 40 ° C. or less with a pressure of 150 bar or more from a roughing mill scale breaker (RSB) nozzle.
  • RTB roughing mill scale breaker
  • the thin slab from which the scale has been removed is roughly rolled to obtain a bar plate.
  • the rough rolling may be performed so that the bar plate thickness is 10 ⁇ 40mm. This is because the bar plate thickness is preferably 10 to 40 mm in the rough rolling step in order to secure the thickness of the final hot rolled steel sheet to 3.0 mmt or less.
  • the bar plate is sequentially removed through one row for spraying the coolant at a pressure of 50 to 100 bar and two rows for spraying the coolant at a pressure of 50 to 200 bar to remove scale.
  • the first and second row nozzles of the finishing mill scale breaker 500 may be used to remove surface scale thicknesses of 50 ⁇ m or less prior to rolling the bar plate. Can be.
  • the pressure of the first row and the second row nozzles is less than 50 bar, the scale is insufficient to be removed, and a large amount of fusiform and scale scales are generated on the surface of the steel sheet after finishing rolling, resulting in inferior surface quality after pickling.
  • the pressure of the first row nose is more than 100 bar or the pressure of the second row nozzle is more than 200 bar, the finishing rolling temperature is too low to obtain an effective austenite fraction, and thus it is difficult to obtain a target tensile strength.
  • the bar plate from which the scale is removed is finish rolled at a temperature range of Ar1 to Ar3 to obtain a hot rolled steel sheet. That is, austenite and ferrite two-phase rolling are performed between Ar1 and Ar3 transformation points.
  • the finishing rolling process a large number of strain-induced precipitates are formed to decrease the alloying elements to be precipitated at low temperature, thereby decreasing the strength.
  • the low-temperature finishing can increase the strength by grain refinement.
  • the finish rolling may be performed so that the sheet speed is 200 ⁇ 600mpm, the thickness of the hot rolled steel sheet is 3.0mmt or less.
  • martensite may form when a coiling temperature is less than 300 degreeC, and a pearlite may form when it exceeds 500 degreeC, and it is difficult to ensure a target material.
  • the cooling is T Fin -300 °C ⁇ T Fin
  • the T Fin means the finish rolling end temperature.
  • the present invention can be controlled to be wound at the above-mentioned winding temperature by cooling by using a weak cooling bank after the air cooling section because each step is performed continuously.
  • pickling the wound hot rolled steel sheet may further comprise the step of obtaining Pickled & Oiled (PO) material.
  • the pickling treatment which can be used in the present invention is not particularly limited since it can be applied if it is a treatment method that is generally used in the hot acid pickling process.
  • the molten steel having the component composition shown in Table 1 below was prepared.
  • Inventive Examples 1 to 3 and Comparative Examples 1 and 2 were applied to the production conditions shown in Table 2 to prepare a hot rolled steel sheet having a thickness of 2.0 mmt in the continuous continuous rolling mode in the performance-rolling direct connection process.
  • Ar3 temperature in Table 2 is the value computed using the commercial thermodynamic software JmatPro V-8.
  • Comparative Example 3 In Comparative Example 3 and the conventional example, 3.2 mmt thick hot rolled steel sheet was manufactured in a batch mode by applying the manufacturing conditions shown in Table 2.
  • Tensile strength and hole expandability are measured by measuring the JIS No. 5 specimen in the rolling perpendicular direction at the width w / 4 point, and material deviation is measured by the longitudinal and width directions of the coil. The maximum value minus the minimum value.
  • Hole expandability is a value calculated as a percentage of the original diameter (10.8mm) of the diameter of the hole that is expanded until the crack is formed on the circumference after punching the hole with a diameter of 10.8mm and pushing it up to the cone.
  • the surface quality of the PO material was evaluated by dividing it into a tip part, a middle part, and an end part.
  • the invention examples satisfying all of the conditions presented in the present invention satisfy both the target tensile strength (590 MPa class) and the hole expansion rate (more than 80%), and the surface quality of the PO material is also at the front end, the middle part, and the end part. It can be seen that excellent.
  • Comparative Examples 1 to 3 did not satisfy the RSB or FSB pressure presented in the present invention, the surface quality was inferior.
  • FIG. 3 is a photograph photographing the surface of the PO material coil tip of the invention example 1 (continuous rolling mode), and FIG. 4 is a photograph photographing the surface of the PO material coil tip of the comparative example 3 (batch mode).
  • Inventive Example 1 produced in the continuous rolling mode has excellent surface quality
  • Comparative Example 3 produced in the batch mode is inferior in surface quality.
  • the inferior tip quality of the PO coils manufactured in batch mode is that the bar plate is wound around the coil box during hot rolled material manufacturing, which results in poor temperature peelability due to a drop in temperature at this area. For this reason, the coils that are poorly treated are 50 to 100 m per average coil, which results in an average error rate of less than 85%. Therefore, in order to manufacture a 590MPa class high strength hot rolled steel sheet excellent in material deviation, surface quality, and error rate, it is preferable to manufacture in a continuous continuous rolling mode in a performance-rolling direct connection process.
  • Figure 5 is a microstructure of Inventive Example 1 (continuous mode) produced at 752 °C the finish rolling temperature is below Ar3
  • Figure 6 is a microstructure of Comparative Example 3 (batch mode) produced at 857 °C over Ar3 to be.
  • tissue white is ferrite tissue and black tissue is bainite or MA tissue.
  • the ferrite grain size of the invention example 1 is 2.65 ⁇ m
  • the ferrite grain size of Comparative Example 3 is 5.1 ⁇ m.
  • the grain size is the average grain size measured by the equivalent diameter of the circle using Image Pro Plus software after randomly taking 10 tissue photographs at a magnification of 1,000 times using an optical microscope. From this result, it can be seen that the ferrite grain size becomes very fine when the finish rolling temperature is lower than Ar3 in the continuous continuous rolling mode, and thus it is judged that the material deviation and hole expandability are excellent.
  • FIG. 7 is a photograph taken with a transmission electron microscope (TEM) of the microstructure of Inventive Example 1.
  • TEM transmission electron microscope
  • fine precipitates such as (Ti, Nb) (C, N) are uniformly distributed in the ferrite matrix structure.
  • the average precipitate size is 17 nm and the average number of precipitates is 16 / ⁇ m 2 .
  • the number of precipitates was made by a carbon replica method, and the number of precipitates present in a 1 ⁇ m ⁇ 1 ⁇ m square was measured in a tissue photograph taken at 50,000 ⁇ magnification by TEM, and 50 randomly Measured average value.
  • heating means 40 coil box

Landscapes

  • 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 Sheet Steel (AREA)

Abstract

La présente invention concerne une feuille d'acier laminée à chaud haute résistance et son procédé de fabrication, la feuille d'acier garantissant, afin de surmonter le problème d'un procédé de mini-usine existant, la présence de propriétés uniques de l'acier à ébavurage élevé, tel que la capacité d'extension de trou, à l'aide d'un mode de laminage sans fin dans un processus de laminage direct par coulée continue et, simultanément, réduisant remarquablement l'inhomogénéité dans le sens de la largeur et dans le sens de la longueur de la feuille d'acier et présentant une excellente qualité de surface.
PCT/KR2017/008640 2016-08-09 2017-08-09 Feuille d'acier laminée à chaud haute résistance ayant une faible inhomogénéité et une excellente qualité de surface, et son procédé de fabrication Ceased WO2018030790A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP2019505026A JP2019527774A (ja) 2016-08-09 2017-08-09 材質ばらつきが少なく表面品質に優れた高強度熱延鋼板及びその製造方法
CN201780048797.4A CN109563601A (zh) 2016-08-09 2017-08-09 具有低不均匀性和优异表面品质的高强度热轧钢板及其制造方法

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR10-2016-0101132 2016-08-09
KR1020160101132A KR101797383B1 (ko) 2016-08-09 2016-08-09 재질편차가 적고 표면품질이 우수한 고강도 열연강판 및 그 제조방법

Publications (1)

Publication Number Publication Date
WO2018030790A1 true WO2018030790A1 (fr) 2018-02-15

Family

ID=60386008

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2017/008640 Ceased WO2018030790A1 (fr) 2016-08-09 2017-08-09 Feuille d'acier laminée à chaud haute résistance ayant une faible inhomogénéité et une excellente qualité de surface, et son procédé de fabrication

Country Status (4)

Country Link
JP (1) JP2019527774A (fr)
KR (1) KR101797383B1 (fr)
CN (1) CN109563601A (fr)
WO (1) WO2018030790A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112996939A (zh) * 2018-10-01 2021-06-18 株式会社Posco 表面品质优异以及材质偏差少的超高强度热轧钢板及其制造方法
CN113834828A (zh) * 2020-06-08 2021-12-24 东芝三菱电机产业系统株式会社 产品品质分析支援系统
CN116145038A (zh) * 2023-02-22 2023-05-23 湖南华菱涟源钢铁有限公司 一种厚度均匀的热轧高强钢及其制备方法与应用
EP3998368A4 (fr) * 2019-07-10 2023-07-05 Nippon Steel Corporation Tôle en acier hautement résistante

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102090549B1 (ko) * 2017-12-20 2020-03-18 주식회사 포스코 후물재의 헤드부 온도 제어 장치 및 제어 방법
CN110090861B (zh) * 2019-05-21 2020-02-07 东北大学 一种简单断面型钢的无头轧制方法
DE112020004399T5 (de) * 2019-09-19 2022-06-02 Baoshan Iron & Steel Co., Ltd. Nb-mikrolegierter Stahl mit hoher Festigkeit und hohem Lochaufweitungsvermögen und Herstellungsverfahren dafür
KR102307928B1 (ko) * 2019-12-02 2021-09-30 주식회사 포스코 내구성이 우수한 후물 복합조직강 및 그 제조방법
KR102321301B1 (ko) * 2019-12-09 2021-11-02 주식회사 포스코 내해수성이 우수한 구조용 강판 및 이의 제조방법
CN116083795A (zh) * 2022-12-23 2023-05-09 本钢板材股份有限公司 一种具有高r值的热轧高扩孔钢及其生产方法
CN120190209B (zh) * 2025-05-23 2025-08-26 华北理工大学 一种易切削钢及热轧方法

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011241456A (ja) * 2010-05-20 2011-12-01 Sumitomo Metal Ind Ltd 溶融めっき熱延鋼板およびその製造方法
KR20120052022A (ko) * 2010-11-15 2012-05-23 주식회사 포스코 인장강도 590ＭＰａ급의 가공성 및 재질편차가 우수한 고강도 열연 ＤＰ강의 제조방법
KR20120074154A (ko) * 2010-12-27 2012-07-05 주식회사 포스코 강판 표면 처리방법
KR20130116329A (ko) * 2011-03-18 2013-10-23 신닛테츠스미킨 카부시키카이샤 프레스 성형성이 우수한 열연 강판 및 그 제조 방법
KR20140085188A (ko) * 2012-12-27 2014-07-07 주식회사 포스코 열연강판 제조방법 및 이를 이용한 열연강판

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5735663A (en) * 1980-08-11 1982-02-26 Kobe Steel Ltd Hot rolled steel plate for rim of wheel
JP2000212687A (ja) * 1999-01-20 2000-08-02 Nisshin Steel Co Ltd 材質均一性及び穴拡げ性に優れた高張力熱延鋼板及びその製造方法
US6488790B1 (en) * 2001-01-22 2002-12-03 International Steel Group Inc. Method of making a high-strength low-alloy hot rolled steel
JP4692018B2 (ja) * 2004-03-22 2011-06-01 Ｊｆｅスチール株式会社 強度−延性バランスに優れた高張力熱延鋼板およびその製造方法
US10071416B2 (en) * 2005-10-20 2018-09-11 Nucor Corporation High strength thin cast strip product and method for making the same
WO2009072753A1 (fr) * 2007-12-04 2009-06-11 Posco Tôle d'acier à haute résistance avec une excellente ténacité à basse température et procédé de fabrication de celle-ci
JP5141811B2 (ja) * 2010-11-12 2013-02-13 Ｊｆｅスチール株式会社 均一伸びとめっき性に優れた高強度溶融亜鉛めっき鋼板およびその製造方法
CN103526116B (zh) * 2013-10-08 2015-07-08 武汉钢铁(集团)公司 抗拉强度590MPa级具有高扩孔性能的铁素体贝氏体钢及其生产方法
KR20150076994A (ko) * 2013-12-27 2015-07-07 현대제철 주식회사 건축용 강 부품 및 제조 방법
KR20160025185A (ko) * 2014-08-27 2016-03-08 현대제철 주식회사 고강도 열연도금강판 및 그 제조 방법

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2011241456A (ja) * 2010-05-20 2011-12-01 Sumitomo Metal Ind Ltd 溶融めっき熱延鋼板およびその製造方法
KR20120052022A (ko) * 2010-11-15 2012-05-23 주식회사 포스코 인장강도 590ＭＰａ급의 가공성 및 재질편차가 우수한 고강도 열연 ＤＰ강의 제조방법
KR20120074154A (ko) * 2010-12-27 2012-07-05 주식회사 포스코 강판 표면 처리방법
KR20130116329A (ko) * 2011-03-18 2013-10-23 신닛테츠스미킨 카부시키카이샤 프레스 성형성이 우수한 열연 강판 및 그 제조 방법
KR20140085188A (ko) * 2012-12-27 2014-07-07 주식회사 포스코 열연강판 제조방법 및 이를 이용한 열연강판

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112996939A (zh) * 2018-10-01 2021-06-18 株式会社Posco 表面品质优异以及材质偏差少的超高强度热轧钢板及其制造方法
CN112996939B (zh) * 2018-10-01 2023-07-28 浦项股份有限公司 表面品质优异以及材质偏差少的超高强度热轧钢板及其制造方法
EP3998368A4 (fr) * 2019-07-10 2023-07-05 Nippon Steel Corporation Tôle en acier hautement résistante
CN113834828A (zh) * 2020-06-08 2021-12-24 东芝三菱电机产业系统株式会社 产品品质分析支援系统
CN116145038A (zh) * 2023-02-22 2023-05-23 湖南华菱涟源钢铁有限公司 一种厚度均匀的热轧高强钢及其制备方法与应用
CN116145038B (zh) * 2023-02-22 2025-01-14 湖南华菱涟源钢铁有限公司 一种厚度均匀的热轧高强钢及其制备方法与应用

Also Published As

Publication number Publication date
CN109563601A (zh) 2019-04-02
JP2019527774A (ja) 2019-10-03
KR101797383B1 (ko) 2017-11-13

Similar Documents

Publication Publication Date Title
WO2018030790A1 (fr) Feuille d'acier laminée à chaud haute résistance ayant une faible inhomogénéité et une excellente qualité de surface, et son procédé de fabrication
WO2018117552A1 (fr) Tôle d'acier laminée à chaud, de résistance ultra-élevée, présentant une excellente aptitude au traitement par cintrage et son procédé de fabrication
WO2019009675A1 (fr) Feuille d'acier laminée à chaud à haute résistance avancée ayant une déviation de matériau réduite et une qualité de surface renforcée, et son procédé de fabrication
WO2020111640A1 (fr) Tôle d'acier électrique non orientée ayant une faible perte dans le fer et une excellente qualité de surface, et son procédé de fabrication
WO2019231023A1 (fr) Tôle d'acier plaquée d'alliage al-fe destinée à un formage à chaud, présentant d'excellentes caractéristiques de soudage twb, élément de formage à chaud et procédés de fabrication s'y rapportant
WO2017222342A1 (fr) Tôle d'acier plaqué présentant une excellente résistance et une excellente aptitude au formage, et son procédé de production
WO2016105064A1 (fr) Acier à haute résistance ayant une excellente résistance à la propagation de fissures fragiles et procédé de production s'y rapportant
WO2017105025A1 (fr) Tôle d'acier de très haute résistance présentant une excellente aptitude au traitement de conversion chimique et au traitement par pliage et son procédé de fabrication
WO2016105059A1 (fr) Acier à haute résistance ayant une excellente résistance à la propagation de fissures fragiles et procédé de production s'y rapportant
WO2023113387A1 (fr) Tôle d'acier à résistance ultra élevée ayant une excellente aptitude au pliage, et son procédé de fabrication
WO2018117497A1 (fr) Matériau d'acier pour tuyau en acier soudé, présentant un excellent allongement uniforme longitudinal, son procédé de fabrication, et tuyau en acier l'utilisant
WO2019124776A1 (fr) Tôle d'acier laminée à chaud à haute résistance ayant une excellente aptitude au pliage et une excellente ténacité à basse température et son procédé de fabrication
WO2017095190A1 (fr) Acier haute résistance présentant une excellente aptitude à arrêter les fissures de fragilité et une excellente résistance à l'initiation de fissures de fragilité d'une partie soudée et procédé pour sa production
WO2016105062A1 (fr) Acier à haute résistance ayant une excellente résistance à la propagation de fissures fragiles et son procédé de production
WO2019132317A1 (fr) Tôle d'acier électrique non orientée présentant d'excellentes propriétés magnétiques et une faible variation d'épaisseur, et son procédé de fabrication
WO2018004297A1 (fr) Plaque d'acier à haute résistance présentant d'excellentes caractéristiques de faible coefficient d'élasticité et une ténacité à basse température et son procédé de fabrication
WO2018117470A1 (fr) Tôle d'acier haute résistance ayant une excellente aptitude au soyage à basse température et son procédé de fabrication
WO2020130436A2 (fr) Acier de construction à haute résistance présentant une excellente aptitude au pliage à froid et son procédé de fabrication
WO2017111322A1 (fr) Tôle d'acier laminée à chaud, ultra-résistante, présentant une excellente ductilité et fabrication associée
WO2018117466A1 (fr) Tôle d'acier laminée à chaud pour tuyau en acier soudé par résistance électrique ayant une excellente soudabilité et son procédé de fabrication
WO2020226301A1 (fr) Feuille d'acier très haute résistance offrant une excellente ouvrabilité de cisaillement et son procédé de fabrication
WO2020111639A1 (fr) Tôle d'acier laminée à chaud à ultra-haute résistance ayant une excellente qualité de forme et une excellente aptitude au pliage, et son procédé de fabrication
WO2022065797A1 (fr) Feuille d'acier laminée à chaud épaisse de haute résistance et son procédé de fabrication
WO2019009677A1 (fr) Tôle d'acier laminée à chaud de haute résistance perfectionnée et son procédé de fabrication
WO2023018081A1 (fr) Tôle d'acier haute résistance laminée à chaud présentant une excellente aptitude au formage, et procédé de fabrication associé

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 17839808

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2019505026

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 17839808

Country of ref document: EP

Kind code of ref document: A1