WO2019088552A1 - Tôle d'acier laminée à froid à ultra-haute résistance présentant une excellente aptitude au laminage à froid et son procédé de fabrication - Google Patents

Tôle d'acier laminée à froid à ultra-haute résistance présentant une excellente aptitude au laminage à froid et son procédé de fabrication Download PDF

Info

Publication number
WO2019088552A1
WO2019088552A1 PCT/KR2018/012595 KR2018012595W WO2019088552A1 WO 2019088552 A1 WO2019088552 A1 WO 2019088552A1 KR 2018012595 W KR2018012595 W KR 2018012595W WO 2019088552 A1 WO2019088552 A1 WO 2019088552A1
Authority
WO
WIPO (PCT)
Prior art keywords
steel sheet
less
cold
rolled steel
hot
Prior art date
Application number
PCT/KR2018/012595
Other languages
English (en)
Korean (ko)
Inventor
이제웅
한상호
Original Assignee
주식회사 포스코
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 주식회사 포스코 filed Critical 주식회사 포스코
Publication of WO2019088552A1 publication Critical patent/WO2019088552A1/fr

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
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • 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
    • C21D8/0236—Cold rolling
    • 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
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • 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
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • 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
    • C21D2211/008—Martensite

Definitions

  • the present invention relates to a cold-rolled steel sheet having an ultra-high strength of at least 2000 MPa and a method for manufacturing the steel sheet.
  • AHSS Advanced High Strength Steel
  • DP Dual Phase
  • TRIP Transformation Induced Plasticity
  • Complex Phase composite structure steel
  • hot press forming As a component capable of applying structural members to secure collision safety, hot press forming (hot press forming) which ensures final strength by heat treatment at high temperature and quenching after contact with a water-cooled die after molding, Although the steel is in the spotlight, it has the problems of additional capital investment, heat treatment and process cost increase.
  • a roll forming method is a method of producing a complicated shape through multi-step roll forming.
  • an ultra-high strength material having a low elongation Is being applied to the molding of parts of an automobile.
  • Such an ultra-high strength steel material generally has a tempered martensite microstructure which is tempered with martensite and martensite.
  • the cooling rate after annealing is very important, and therefore, continuous annealing It is easy to manufacture in furnace.
  • Patent Document 1 proposes a method for producing a cold rolled steel sheet having high temper- ature and high ductility at the same time by obtaining tempered martensite transformation by microstructure after heat treatment in a continuous annealing process and also having a high plate shape. It is impossible to ignore the possibility of induction of internal dent in an annealing furnace.
  • the cooling rate is inevitably deteriorated. Therefore, in order to obtain the above-mentioned martensite microstructure, it is a top priority to secure sufficient hardenability by adjusting the alloy component.
  • the carbon content is limited to 0.2% by weight or less.
  • the content of Mn is 3.0 to 4.0% by weight and the Mn content is quite high. .
  • Patent Document 1 Japanese Laid-Open Patent Application No. 2010-090432
  • Patent Document 2 Korean Patent Application No. 2015-0098217
  • the present invention has been made in order to overcome the above-described problems of the prior art, and it is an object of the present invention to provide a continuous annealing apparatus capable of using roll cooling, mist cooling, gas cooling, And an object of the present invention is to provide an ultra-high strength cold-rolled steel sheet, a coated steel sheet and a method of manufacturing the same, which are excellent in product shape and cold rolling property, which are manufactured using a hot-dip galvanizing system.
  • the present invention provides a steel sheet comprising, by weight, 0.4 to 0.6% of C, 1.5 to 3.0% of Mn, 0.7 to 2.0% of Cr, 0.03% or less of P Mo: not more than 1.0% (excluding 0%), and B: not more than 0.005% (excluding 0%), N: not more than 0.01% %), Remaining Fe and unavoidable impurities, and satisfies the following relational expression (1)
  • the present invention relates to a cold-rolled steel sheet having excellent cold-rolling properties, comprising a steel microstructure having an area fraction of 90% or more of martensite and 10% or less of a secondary phase.
  • the present invention relates to a method for producing an ultra-high strength cold rolled steel sheet excellent in cold rolling resistance.
  • an ultra-high-strength cold-rolled steel sheet of 2000 MPa or more can be produced by using a continuous annealing process using a conventional cooling facility, and it can have a superior surface shape quality as compared with the martensitic steel produced by using water cooling.
  • ultra-high strength cold-rolled steel sheets contain a large amount of alloy components, and therefore, the hot-rolled microstructure contains a hard microstructure such as bainite and martensite, there was.
  • the present invention provides a useful effect of manufacturing a cold-rolled steel sheet having improved cold rolling property and widthwise material deviation of an ultra-high strength steel material by securing 80% or more of pearlite by hot-rolled microstructure by utilizing an open-air component system or a corresponding alloy component system have.
  • Fig. 1 is a photograph of a microstructure observed by a transmission electron microscope (TEM) after the cold rolling and continuous annealing process of Specimen No. 2-1 in this embodiment.
  • TEM transmission electron microscope
  • the present inventors have found that there are problems such as variations in material in the width direction of a hot-rolled steel sheet having an ultra-high-strength steel mainly containing bainite and martensite microstructure and high cold rolling load, In order to solve the problems that were limited to As a result, it is possible to appropriately control the alloy composition and the manufacturing method to secure a full pearlite or a corresponding large amount of pearlite microstructure after hot rolling to reduce variations in material in the width direction of the hot-rolled steel sheet, It is possible to provide a steel sheet excellent in cold rolling resistance by reducing the load, and the present invention is presented.
  • an ultrahigh strength cold rolled steel sheet excellent in the lateral direction material deviation and cold rolling property comprising 0.4 to 0.6% of C, 1.5 to 3.0% of Mn, 0.7 to 2.0% P: not more than 0.03% (excluding 0%), S: not more than 0.01% (excluding 0%), N: not more than 0.01% (excluding 0%), sol.Al: not more than 0.1% , At least 90% of at least one of the steel microstructure and at least one of the residual Fe and unavoidable impurities, satisfying the following relational expression 1: And a second phase of 10% or less.
  • Carbon (C) is an important component in the production of a steel sheet having pearlite microstructure composed of ferrite and cementite after hot rolling in the present invention. Generally, as the C content increases, a high percentage of pearlite structure can be secured. Is an indispensable element to be added. In addition, since it is the largest element that contributes to the strength increase in the martensite microstructure after cold-rolling continuous annealing, it is indispensable to obtain an ultra-high strength of 2000 MPa or more.
  • the C content is less than 0.4%, it is difficult to sufficiently secure pearlite, and it is difficult to secure the strength of martensite to obtain an ultra-high strength of 2000 MPa or more.
  • the C content is more than 0.6%, the carbide in the pearlite is excessively formed and the phase-to-phase compatibility with the precipitate is lowered, so that the hot rolling property and the room temperature ductility can be lowered, .
  • Mn in steel is one of the representative elements that inhibits ferrite formation and facilitates the formation of austenite, and is an effective element for increasing the strength of martensite.
  • Mn content is less than 1.5%, the ferrite is easily formed during the continuous cooling process during the continuous annealing process and the strength becomes low.
  • Mn content exceeds 3.0%, the bending deterioration due to the formation of manganese bands due to segregation, And the content of the alloy is limited due to an increase in the cost of the alloy iron due to the excessive amount.
  • Cr is one of the essential elements added to obtain martensite transformation during the continuous annealing process of the cooling equipment because it exhibits the property of increasing the hardenability of the steel similar to Mn.
  • Cr plays a role in lowering the carbon content required for the formation of vacancies, allowing pearlite microstructure transformation during hot working even at low carbon content. It also promotes the formation of cementite and reduces the spacing of the pearlite laminates to promote cementite spheroidization. It also has the property of further improving the corrosion resistance of the steel sheet even by adding a small amount.
  • the mechanical properties may be adversely affected and the surface scale pickling property may be deteriorated during pickling.
  • Aluminum oxide (sol.Al) is an element to be added for grain refinement and deoxidation of steel.
  • content exceeds 0.1%, there is a possibility of occurrence of defective surface of hot-dip galvanized steel sheet due to over- There is a problem that not only the size is increased but also the manufacturing cost is increased.
  • the lower limit is not particularly limited, but 0% is excluded considering the level that is unavoidably added during the manufacturing process.
  • ⁇ P 0.03% or less (excluding 0%)
  • P (P) is an element favorable in securing strength.
  • P is an element favorable in securing strength.
  • 0% is excluded considering the level that is inevitably added during the manufacturing process.
  • ⁇ S 0.01% or less (excluding 0%)
  • S Sulfur
  • S in the steel has a problem of increasing the possibility of generating fumed brittleness. Therefore, it is preferable to control the content to 0.01% or less. However, 0% is excluded considering the level that is inevitably added during the manufacturing process.
  • ⁇ N 0.01% or less (excluding 0%)
  • Nitrogen (N) is an element which is inevitably added as an impurity element in the steel, and it is preferable to control the operating conditions to 0.01% or less, which is a possible range. However, 0% is excluded considering the level that is inevitably added during the manufacturing process.
  • At least one of Mo: 1.0% or less (excluding 0%) and B: 0.005% or less (excluding 0%) is included.
  • Mo plays an important role in enhancing the hardenability of steel such as C, Mn, and Cr, and is an element having a large effect of inhibiting ferrite and bainite phase transformation when added with Cr.
  • the content is more than 1.0%, it is limited to the increase of the amount of alloy iron due to the excessive amount of alloy.
  • 0% is excluded considering the level that is inevitably added during the manufacturing process.
  • Boron (B) has an advantage of suppressing ferrite formation, and has an advantage of suppressing the formation of ferrite upon cooling after annealing.
  • B has an advantage of suppressing ferrite formation, and has an advantage of suppressing the formation of ferrite upon cooling after annealing.
  • B exceeds 0.005%, but rather is a problem that ferrite is formed by promoting the precipitation of Fe 23 (C, B) 6 restrict the content according.
  • 0% is excluded considering the level that is inevitably added during the manufacturing process.
  • each element symbol represents the content of each element in weight%, and is calculated as 0 if not included.
  • the above-mentioned relational expression 1 is designed in consideration of the influence of each element for producing steel having a certain area fraction or more of pearlite required in the present invention after hot working and an alloy component system for obtaining a martensite structure after cold annealing.
  • the value defined by the relational expression 1 is less than 1.6, it is difficult to secure pearlite of 80% or more by area after hot rolling, and it is difficult to secure martensite of 90 area% or more after cold rolling continuous annealing. On the other hand, if the value is more than 3.52, elongation may be lowered due to addition of a large amount of alloying elements.
  • the remainder of the present invention is iron (Fe).
  • impurities which are not intended from the raw material or the surrounding environment may be inevitably incorporated, so that it can not be excluded. These impurities are not specifically mentioned in this specification, as they are known to any person skilled in the art of manufacturing.
  • the cold-rolled steel sheet of the present invention can produce a cold-rolled steel sheet having a tensile strength of 2000 MPa or more including a martensite and a residual secondary phase of 90% or more in area fraction.
  • the secondary phase includes ferrite and bainite microstructure.
  • the steel sheet of the present invention may further have one of a zinc plating layer and a galvanized zinc plating layer formed thereon.
  • the method of manufacturing an ultra-high strength cold rolled steel sheet according to the present invention comprises the steps of: heating a steel slab having the above composition to 1100 to 1300 ⁇ ; Preparing a hot rolled steel sheet by subjecting the heated slab to finish hot rolling in a temperature range of Ar 3 + 5 ° C to Ar 3 + 95 ° C; Winding the hot rolled steel sheet at a temperature in the range of 550 to 700 ⁇ ⁇ to produce a hot rolled coil having a microstructure of 80% or more of pearlite and 20% or less of ferrite in an area fraction; Rolling the rolled hot-rolled steel sheet at a reduction ratio of 40 to 80%; And a step of subjecting the cold-rolled cold-rolled steel sheet to continuous annealing at 100 to 250 ° C to obtain an ultra-high-strength cold-rolled steel sheet having an area fraction of 90% or more of martensite and 10% or less of a second phase; .
  • the steel slab having the above-described alloy composition is heated to a temperature range of 1100 to 1300 DEG C for hot rolling.
  • the heating temperature is less than 1100 ° C, it is difficult to uniformize the structure and components of the slab, and if the heating temperature is more than 1300 ° C, problems of surface oxidation and equipment deterioration may occur.
  • the heated slab is subjected to finish hot-rolling the heated slab in a temperature range of Ar 3 + 5 ° C to Ar 3 + 95 ° C.
  • the final hot rolling temperature is lower than Ar3 + 5 deg. C, there is a possibility of an abnormal reverse rolling of ferrite and austenite, which may cause difficulty in control of mixed grain structure and plate shape in the steel surface layer, and may cause material nonuniformity.
  • the finishing hot rolling is preferably performed in a single phase of austenite which is in the range of Ar 3 + 5 ° C. to Ar 3 + 95 ° C.
  • the Ar3 temperature can be defined by the following relational expression (2).
  • the hot-rolled steel sheet is wound such that the microstructure contains 80% or more of pearlite and 20% or less of ferrite in an area fraction.
  • the microstructure of the hot-rolled coil according to the present invention contains 80% or more of pearlite and 20% or less of ferrite in an area fraction.
  • the pearlite is less than 80%, the material deviation in the width direction of the hot- It is difficult to induce the desired amount of martensite transformation after the heat treatment.
  • the cermetite in the pearlite is elongated in a lamellar form, but passes through a cold rolling and continuous annealing heat treatment process and is segmented and spheroidized. Therefore, the microstructure after the continuous annealing heat treatment contains spheroidized cementite in martensite.
  • the hot-rolled steel sheet of the present invention has a tensile strength of 1200 MPa or less and a high tensile strength, it exhibits a long elongation in the rolling direction due to the pearlite structure having elongated lamellar cementite. Which is superior to the light microstructure of bainite and martensite.
  • the winding temperature range is preferably limited to a temperature range of 550 to 700. If the coiling temperature is less than 550 ⁇ , a low-temperature transformed structure, that is, bainite or martensite is generated to cause excessive increase in the strength of the hot-rolled steel sheet, thereby causing problems such as defective shape due to excessive load during cold rolling, And it may be difficult to obtain pearlite microstructure for the purpose of the present invention.
  • the present invention may further include a step of performing batch annealing at 200 to 700 ° C after the winding step to reduce the rolling load before cold rolling as required.
  • the hot-rolled structure When the temperature is lower than 200 ° C, the hot-rolled structure is not sufficiently softened and does not significantly affect the reduction of the rolling load. If the temperature exceeds 700 ° C, pearlite decomposition may occur due to high temperature annealing.
  • the present invention is not particularly limited.
  • the rolled hot-rolled steel sheet is cold-rolled at a reduction ratio of 40 to 80% to obtain a cold-rolled steel sheet.
  • the reduction rate is less than 40%, it may be difficult to secure a target thickness.
  • the cold rolling can be performed at room temperature.
  • the cold-rolled steel sheet is continuously annealed in a temperature range of Ac 3 - 5 ° C to Ac 3 + 80 ° C to obtain a tensile strength of at least 2000 MPa after cold rolling.
  • the Ac3 temperature can be defined by the following equation (3).
  • spheroidized cementite (Fe 3 C) is present in the martensite and the size is limited to a size of 50 nm or more.
  • spheroidized cementite (Fe 3 C) generated during the heat treatment from the cermetite in pearlite, there may be another type of carbide in the final structure, martensite.
  • transition carbides have a diameter limited to 50 nm or less and can be produced by a tempering heat treatment or the like and are often called transition carbides. These transition carbides are often produced at low tempering temperatures (below 300 ° C), and their chemical equivalents depend on the temperature at which they are produced, usually in the order of a few nanometers.
  • the final microstructure subjected to the annealing heat treatment is characterized by an A value of not less than 3 according to the following relational expression (4).
  • A A X / A Y
  • a X denotes the number of cementite having an aspect ratio of not less than 1.5 in 1 mm 2 area
  • a Y denotes the number of cementite having an aspect ratio within the same area of less than 1.5.
  • the annealing temperature is less than Ac3-5 deg. C, the phase transformation to austenite is small and the martensite fraction obtained after the final continuous annealing is limited.
  • Ac3 + 80 deg. C the austenite grain size becomes large, There is a fear that the tensile strength is inhibited. Therefore, continuous annealing is preferable in the temperature range of Ac3-5 deg. C to Ac3 + 80 deg.
  • the method may further include plating the cold rolled steel sheet.
  • the plating method and plating type are not particularly limited because they do not greatly affect the material properties even under normal operating conditions.
  • plating can be performed with zinc or a zinc alloy, and plating can be performed using a hot-dip coating method, an alloying hot-dip coating, an electroplating method, or the like.
  • the cold-rolled steel sheet is tempered by heat treatment.
  • This additional tempering heat treatment is limited to a temperature range of 100 to 250 DEG C and the time is not particularly limited.
  • the reason for the additional tempering heat treatment is as follows. In order to obtain a tensile strength of at least 2000 MPa, it is very important to bring the microstructure of the steel sheet into the martensite, and it is only necessary to increase the strength of the martensite itself.
  • the strength of martensite is influenced by alloy composition, packet size, block size, etc. Among them, the effect of alloying elements is very high. Among the alloying elements, carbon is the biggest contributor to the strength increase. On the other hand, carbon plays a very large role in increasing the strength of martensite, and at the same time, toughness of martensite is lowered.
  • tempering heat treatment can precipitate carbons in the martensite in the form of carbide to give toughness again. If the tempering temperature is less than 100 ⁇ ⁇ , the carbon is hardly precipitated in the form of carbide, and redistribution into martensite defects (dislocation, vacancy, etc.) only occurs and the desired toughness effect is insignificant. When the temperature exceeds 250 ° C., martensite brittleness occurs and the ductility is greatly reduced. This phenomenon is often referred to as Tempered Martensite Embrittlement (TME). Therefore, the tempering heat treatment is preferably performed in a range of 100 ° C to 250 ° C.
  • the slabs having the composition shown in the following Table 1 were heat-treated in a 1200 ° C heating furnace for 1 hour and then subjected to finish hot-rolling at 880 ° C. Then, the hot rolled material was charged into a preheated furnace at 650 ° C and held for 1 hour to simulate hot-rolled coiling by cold rolling, followed by pickling and cold rolling.
  • annealing was carried out at various annealing temperature conditions as shown in Table 2 below, followed by gradual cooling to 3O < 0 > C and 650 < 0 > C per second and cooling to 440 & After over-heat treatment for 360 seconds, it was cooled to room temperature to 3 ° C per second.
  • the hot-rolled steel sheet was annealed at 3 ° C / sec to 650 ° C / sec, cooled to 660 ° C / 560 ° C / sec and annealed at 460 ° C.
  • the microstructure after cold rolling continuous annealing contains martensite of 90% or more in an area fraction,
  • the maximum tensile strength after tempering was more than 2000 MPa and the total elongation was 3% or more.
  • the maximum tensile strength after tempering may not satisfy the maximum tensile strength of more than 2000 MPa due to insufficient martensite, It was confirmed that the tensile strength was insufficient or the toughness was not given when the tempering temperature condition was not met, so that the total elongation was less than 3%.
  • the microstructure was observed after the application of the separating etching method using a scanning electron microscope (SEM). Specifically, the size (the length of the major axis / the minor axis length) for measuring the aspect ratio of the cementite in the microstructure in the cold- was measured using a transmission electron microscope (TEM) microstructure observation photograph as shown in Fig. Fig. 1 is a photograph of a microstructure observed by a transmission electron microscope (TEM) after the cold rolling and continuous annealing process of Specimen No. 2-1 in this embodiment.
  • TEM transmission electron microscope

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical 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 tôle d'acier laminée à froid à ultra-haute résistance présentant une excellente aptitude au laminage à froid, et son procédé de fabrication. La tôle d'acier laminée à froid de la présente invention comprend, en % en poids, au moins un élément parmi 0,4 à 0,6% de C, 1,5 à 3,0% de Mn, 0,7 à 2,0% de Cr, 0,03% ou moins (en excluant 0%) de P, 0,01% ou moins (en excluant 0%) de S, 0,01% ou moins (en excluant 0%) de N, 0,1% ou moins (en excluant 0%) d'Al sol., 1,0% ou moins (en excluant 0%) de Mo, et 0,005% ou moins (en excluant 0%) de B, le reste étant Fe et les impuretés inévitables; satisfait la formule relationnelle 1; et sa microstructure d'acier comprend, par fraction de surface, 90% ou plus de martensite et 10% ou moins d'une phase secondaire.
PCT/KR2018/012595 2017-11-01 2018-10-24 Tôle d'acier laminée à froid à ultra-haute résistance présentant une excellente aptitude au laminage à froid et son procédé de fabrication WO2019088552A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020170144964A KR20190049294A (ko) 2017-11-01 2017-11-01 냉간압연성이 우수한 초고강도 냉연강판 및 이의 제조방법
KR10-2017-0144964 2017-11-01

Publications (1)

Publication Number Publication Date
WO2019088552A1 true WO2019088552A1 (fr) 2019-05-09

Family

ID=66333228

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/KR2018/012595 WO2019088552A1 (fr) 2017-11-01 2018-10-24 Tôle d'acier laminée à froid à ultra-haute résistance présentant une excellente aptitude au laminage à froid et son procédé de fabrication

Country Status (2)

Country Link
KR (1) KR20190049294A (fr)
WO (1) WO2019088552A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114829661A (zh) * 2019-12-20 2022-07-29 株式会社Posco 具有优异的球化热处理特性的钢线材及其制造方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20230089785A (ko) * 2021-12-14 2023-06-21 주식회사 포스코 굽힘 특성이 우수한 초고강도 강판 및 이의 제조방법

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100711445B1 (ko) * 2005-12-19 2007-04-24 주식회사 포스코 도금밀착성 및 충격특성이 우수한 열간성형 가공용 합금화용융아연도금강판의 제조방법, 이 강판을 이용한열간성형부품의 제조방법
KR20090124263A (ko) * 2008-05-29 2009-12-03 주식회사 포스코 열처리성이 우수한 초고강도 열간성형 가공용 강판, 열처리경화형 부재 및 이들의 제조방법
KR20100116608A (ko) * 2008-01-31 2010-11-01 제이에프이 스틸 가부시키가이샤 고강도 강판 및 그 제조 방법
KR20110062899A (ko) * 2009-12-04 2011-06-10 주식회사 포스코 냉간압연성 및 도금성이 우수한 열간성형 가공용 강판 및 그 제조방법과 고강도 자동차용 구조부재 및 그 제조방법
WO2013051238A1 (fr) * 2011-10-04 2013-04-11 Ｊｆｅスチール株式会社 Tôle d'acier à haute résistance et procédé de fabrication associé

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5359168B2 (ja) 2008-10-08 2013-12-04 Ｊｆｅスチール株式会社 延性に優れる超高強度冷延鋼板およびその製造方法
JP6164113B2 (ja) 2014-02-19 2017-07-19 味の素株式会社 支持体付き樹脂シート

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100711445B1 (ko) * 2005-12-19 2007-04-24 주식회사 포스코 도금밀착성 및 충격특성이 우수한 열간성형 가공용 합금화용융아연도금강판의 제조방법, 이 강판을 이용한열간성형부품의 제조방법
KR20100116608A (ko) * 2008-01-31 2010-11-01 제이에프이 스틸 가부시키가이샤 고강도 강판 및 그 제조 방법
KR20090124263A (ko) * 2008-05-29 2009-12-03 주식회사 포스코 열처리성이 우수한 초고강도 열간성형 가공용 강판, 열처리경화형 부재 및 이들의 제조방법
KR20110062899A (ko) * 2009-12-04 2011-06-10 주식회사 포스코 냉간압연성 및 도금성이 우수한 열간성형 가공용 강판 및 그 제조방법과 고강도 자동차용 구조부재 및 그 제조방법
WO2013051238A1 (fr) * 2011-10-04 2013-04-11 Ｊｆｅスチール株式会社 Tôle d'acier à haute résistance et procédé de fabrication associé

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114829661A (zh) * 2019-12-20 2022-07-29 株式会社Posco 具有优异的球化热处理特性的钢线材及其制造方法
CN114829661B (zh) * 2019-12-20 2023-10-13 株式会社Posco 具有优异的球化热处理特性的钢线材及其制造方法

Also Published As

Publication number Publication date
KR20190049294A (ko) 2019-05-09

Similar Documents

Publication Publication Date Title
WO2015174605A1 (fr) Feuille d'acier laminé à froid de résistance élévée présentant une excellente ductilité, feuille d'acier galvanisé zingué au feu et son procédé de fabrication
WO2018110867A1 (fr) Tôle d'acier laminée à froid à haute résistance présentant une excellente limite d'élasticité, une excellente ductilité et une excellente capacité d'expansion de trou, tôle d'acier galvanisée par immersion à chaud et procédé de production associé
WO2018117501A1 (fr) Tôle d'acier de résistance ultra-élevée présentant une excellente pliabilité et son procédé de fabrication
WO2020067752A1 (fr) Tôle d'acier laminée à froid à haute résistance ayant un rapport d'expansion de trou élevé, tôle d'acier galvanisée à chaud par trempe à haute résistance, et procédés de fabrication associés
WO2012067379A2 (fr) Procédé de fabrication d'acier dp très résistant laminé à froid/laminé à chaud ayant un niveau de résistance à la traction de 590 mpa et une excellente aptitude au façonnage, ainsi que peu d'écart en termes de propriétés de matériau de celui-ci
WO2012064129A2 (fr) Procédé pour fabriquer un acier à plasticité induite par transformation laminé à froid/laminé à chaud de haute résistance ayant une résistance à la traction d'une valeur de 590 mpa, une excellente usinabilité, et un faible écart de propriété mécanique
WO2010074370A1 (fr) Tôle d'acier étirable à haute résistance, tôle d'acier laminée à chaud, tôle d'acier laminée à froid, tôle d'acier revêtue de zinc et procédé de fabrication d'une tôle d'acier allié revêtue de zinc
WO2017188654A1 (fr) Tôle d'acier à très haute résistance et à haute ductilité ayant un excellent rapport d'élasticité et son procédé de fabrication
WO2017111524A1 (fr) Tôle d'acier à très haute résistance ayant une excellente capacité d'expansion de trou et son procédé de fabrication.
WO2017222159A1 (fr) Tôle d'acier laminée à froid de haute résistance ayant une excellente aptitude au façonnage et procédé pour la fabriquer
WO2023022445A1 (fr) Matériau d'acier pour le formage à chaud, élément formé à chaud et procédé de fabrication associé
WO2018105904A1 (fr) Plaque d'acier galvanisée à chaud ayant une excellente aptitude au durcissement à la cuisson et d'excellentes propriétés anti-vieillissement à température ambiante et procédé de fabrication associé
WO2019088552A1 (fr) Tôle d'acier laminée à froid à ultra-haute résistance présentant une excellente aptitude au laminage à froid et son procédé de fabrication
WO2017051998A1 (fr) Tôle d'acier plaquée et procédé de fabrication associé
WO2021117989A1 (fr) Tôle d'acier laminée à froid à résistance ultra-élevée et son procédé de fabrication
WO2013154254A1 (fr) Tôle d'acier laminée à chaud à teneur élevée en carbone présentant une excellente uniformité et son procédé de fabrication
WO2016093513A2 (fr) Tôle d'acier biphasé ayant une excellente formabilité et son procédé de fabrication
WO2019125018A1 (fr) Tôle d'acier laminée à froid à ultra-haute résistance et son procédé de fabrication
WO2018117500A1 (fr) Acier à haute résistance à la traction ayant une excellente aptitude au pliage et une excellente capacité d'étirage des bords et son procédé de fabrication
WO2023068763A1 (fr) Tôle d'acier écologique ayant une résistance élevée et une formabilité élevée, et procédé de fabrication y afférant
WO2024136317A1 (fr) Tôle d'acier laminée à froid et son procédé de fabrication
WO2024143768A1 (fr) Tôle d'acier laminée à froid à ultra-haute résistance et son procédé de fabrication
WO2019039774A1 (fr) Acier inoxydable ferritique ayant une ténacité à l'impact à basse température améliorée et son procédé de production
WO2023048450A1 (fr) Tôle d'acier laminée à froid à haute résistance ayant une excellente qualité de surface et une faible variation de matériau, et son procédé de fabrication
WO2024128737A1 (fr) Tôle d'acier à haute résistance ayant un rapport d'élasticité élevé, et son procédé de fabrication

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: 18873844

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18873844

Country of ref document: EP

Kind code of ref document: A1