WO2024033688A1 - Acier martensitique laminé à froid et son procédé de production - Google Patents

Acier martensitique laminé à froid et son procédé de production Download PDF

Info

Publication number
WO2024033688A1
WO2024033688A1 PCT/IB2022/057528 IB2022057528W WO2024033688A1 WO 2024033688 A1 WO2024033688 A1 WO 2024033688A1 IB 2022057528 W IB2022057528 W IB 2022057528W WO 2024033688 A1 WO2024033688 A1 WO 2024033688A1
Authority
WO
WIPO (PCT)
Prior art keywords
steel sheet
temperature
anyone
rolled steel
steel
Prior art date
Application number
PCT/IB2022/057528
Other languages
English (en)
Inventor
Dongwei FAN
Ranga Nikhil Vinayak YELLAKARA
Original Assignee
Arcelormittal
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 Arcelormittal filed Critical Arcelormittal
Priority to PCT/IB2022/057528 priority Critical patent/WO2024033688A1/fr
Publication of WO2024033688A1 publication Critical patent/WO2024033688A1/fr

Links

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
    • 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
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/22—Martempering
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • 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
    • 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
    • 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
    • C22C38/02—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
    • C22C38/22—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
    • C22C38/26—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
    • 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

Definitions

  • the present invention relates to a method of manufacturing of a cold rolled martensitic steel suitable for automotive industry and particularly to Martensitic steels having tensile strength 960 MPa or more.
  • Automotive parts are required to satisfy two inconsistent necessities, viz. ease of forming and strength but in recent years a third requirement of improvement in fuel consumption is also bestowed upon automobiles in view of global environment concerns.
  • automotive parts must be made of material having high formability in order that to fit in the criteria of ease of fit in the intricate automobile assembly and at same time have to improve strength for vehicle crashworthiness and durability while reducing weight of vehicle to improve fuel efficiency.
  • EP3901299 provides a cold rolled steel sheet having excellent workability, a hot-dip galvanized steel sheet, a hot-dip galvannealed steel sheet, and manufacturing methods therefor, the cold rolled steel sheet comprising, by wt%, 0.06-0.15% of carbon (C), 1.2% or less of silicon (Si) (excluding 0), 1.7-2.7% of manganese (Mn), 0.15% or less of molybdenum (Mo) (excluding 0), 1.0% or less of chromium (Cr) (excluding 0), 0.1% or less of phosphorus (P), 0.01 % or less of sulfur (S), 0.001 -0.04% of titanium (Ti), 0.001 -0.04% of niobium (Nb), 0.01 % or less of nitrogen (N), 0.01% or less of boron (B) (excluding 0), and the balance of Fe and other inevitable impurities, wherein the amounts of silicon (Si), carbon (C), manganese (Mn), moly
  • the purpose of the present invention is to solve these problems by making available cold-rolled martensitic steel sheets that simultaneously have:
  • such steel can also have a good suitability for forming, for rolling with good weldability and coatability.
  • Another object of the present invention is also to make available a method for the manufacturing of these sheets that is compatible with conventional industrial applications while being robust towards manufacturing parameters shifts.
  • the chemical composition of the cold rolled martensitic steel comprises of the following elements:
  • Carbon is present in the steel of present invention is from 0.07% to 0.12%. Carbon is an element necessary for increasing the strength of the Steel of present invention by producing a low- temperature transformation phases such as Martensite. Carbon content less than 0.07% will not be able to impart the tensile strength to the steel of present invention. On the other hand, at a Carbon content exceeding 0.12%, the steel exhibits poor spot weldability which limits its application for the automotive parts.
  • a preferable content for the present invention may be kept from 0.08% to 0.1 1% and more preferably from 0.09% to 0.1 1 %.
  • Manganese content of the steel of present invention is from 1 .9% to 2.5%. This element promotes the Austenite formation. Manganese provides solid solution strengthening and reduces ferritic transformation rate hence assist in the formation of martensite. An amount of at least 1 .9% is required to impart strength as well as to assist the formation of Martensite. But when Manganese content is more than 2.5% it produces adverse effects such as it retards transformation of Austenite to Martensite during cooling after annealing. Manganese content of above 2.5% can get excessively segregated in the steel during solidification and homogeneity inside the material is impaired which can cause surface cracks during a hot working process.
  • the preferred limit for the presence of Manganese is from 2% to 2.4% and more preferably from 2.1 % to 2.35%.
  • Silicon content of the steel of present invention is from 0.2% to 0.6%.
  • Silicon is an element that contributes to increasing the strength by solid solution strengthening. Silicon is a constituent that can retard the precipitation of carbides during cooling after annealing, therefore, Silicon promotes formation of Martensite. But Silicon is also a ferrite former and also increases the Ac3 transformation point which will push the annealing temperature to higher temperature ranges that is why the content of Silicon is kept at a maximum of 0.6%. Silicon content above 0.6% can also temper embrittlement and in addition silicon also impairs the coatability.
  • the preferred limit for the presence of Silicon is from 0.25% to 0.5% and more preferably from 0.25% to 0.4%.
  • Chromium content of the steel of present invention is from 0.1 % to 0.5%. Chromium is an essential element that provide strength to the steel by solid solution strengthening and a minimum of 0.1 % is required to impart the strength but when used above 0.5% impairs surface finish of steel.
  • the preferred limit for the presence of Chromium is from 0.15% to 0.4% and more preferably from 0.15% to 0.35%.
  • the content of the Aluminum is from 0.01 % to 0.1%.
  • Aluminum removes Oxygen existing in molten steel to prevent Oxygen from forming a gas phase during solidification process.
  • Aluminum also fixes Nitrogen in the steel to form Aluminum nitride to reduce the size of the grains.
  • Higher content of Aluminum, above 0.1%, increases Ac3 point to a high temperature thereby lowering the productivity.
  • the preferred limit for the presence of Aluminium is from 0.01 % to 0.09%
  • Molybdenum is an essential element that constitutes 0.2% to 0.6% of the Steel of present invention; Molybdenum plays an effective role in improving hardenability and hardness, delays the appearance of Bainite hence promote the formation of Martensite, in particular when added in an amount of at least 0.2%. However, the addition of Molybdenum excessively increases the cost of the addition of alloy elements, so that for economic reasons its content is limited to 0.6%.
  • the preferred limit for the presence of Molybdenum from 0.25% to 0.5% and more preferably from 0.25% to 0.4%.
  • Niobium is present in the Steel of present invention from 0.001 % to 0.1% and suitable for forming carbo-nitrides to impart additional strength of the Steel of present invention by precipitation hardening.
  • Niobium will also impact the size of microstructural components through its precipitation as carbo-nitrides and by retarding the recrystallization during heating process. Thus, finer microstructure formed at the end of the holding temperature and as a consequence after the complete annealing will lead to the hardening of the product.
  • Niobium content above 0.1 % is not economically interesting as a saturation effect of its influence is observed this means that additional amount of Niobium does not result in any strength improvement of the product.
  • Sulfur is not an essential element but may be contained as an impurity in steel and from point of view of the present invention the Sulfur content is preferably as low as possible but 0.09% or less from the viewpoint of manufacturing cost. Further if higher Sulfur is present in steel it combines to form Sulfides especially with Manganese and reduces its beneficial impact on the present invention.
  • Phosphorus constituent of the Steel of present invention is between 0% and 0.09%, Phosphorus reduces the spot weldability and the hot ductility, particularly due to its tendency to segregate at the grain boundaries or co-segregate with Manganese. For these reasons, its content is limited to 0.09 % and preferably lower than 0.06%.
  • Nitrogen is limited to 0.09% to avoid ageing of material and to minimize the precipitation of Aluminum nitrides during solidification which are detrimental for mechanical properties of the steel.
  • Titanium is an alloying element and may be added to the Steel of present invention from 0.001 % to 0.1 %. It forms Titanium-nitrides and protects B into solution during steelmaking. The amount of Titanium is so limited to 0.1 % to avoid the formation of coarse Titanium-nitrides detrimental for formability. In case the Titanium content below 0.001 % does not impart any effect on the steel of present invention.
  • Boron is an alloying element for the steel of present invention and can be present between 0.0005% and 0.005%. Boron can enhance hardenability of steel during cooling, which can avoid soft phase formation and promotes the formation of hard martensite in the final microstructure, when added in an amount of at least of 0.0005%.
  • Vanadium is an optional element for the steel of present invention. Vanadium is effective in enhancing the strength of steel by forming carbides or carbo-nitrides and the upper limit is 0.1% from economic points of view.
  • Nickel may be added as an optional element in an amount of 0% to 1% to increase the strength of the steel present invention and to improve its toughness. A minimum of 0.01% is preferred to get such effects. However, when its content is above 1 %, Nickel causes ductility deterioration.
  • Copper may be added as an optional element in an amount of 0% to 1 % to increase the strength of the of Steel of present invention and to improve its corrosion resistance. A minimum of 0.01% is preferred to get such effects. However, when its content is above 1 %, it can degrade the surface aspects.
  • Calcium may be added to the steel of present invention in an among between 0.001 % and 0.01 %%. Calcium is added to steel of present invention as an optional element especially during the inclusion treatment. Calcium contributes towards the refining of the Steel by binding the detrimental Sulfur content in globular form thereby retarding the harmful effect of Sulfur.
  • Sn, Pb or Sb can be added individually or in combination in the following proportions: Sn ⁇ 0.1 %, Pb ⁇ 0.1% and Sb ⁇ 0.1 %. Up to the maximum content levels indicated, these elements make it possible to refine the grain during solidification. The remainder of the composition of the steel consists of iron and inevitable impurities resulting from processing.
  • Tempered Martensite constitutes from 80% to 94% of the microstructure by area fraction. Tempered martensite is formed from the martensite which forms during the cooling after annealing and particularly in a temperature from Ms-100°C to Ms and more particularly from Ms- 70°C to Ms. Such martensite is then tempered during the holding at a tempering temperature Ttemper from 400°C to 550°C.
  • the tempered martensite of the present invention imparts ductility and strength to such steel.
  • the content of tempered martensite is from 84% to 94% and more preferably from 85% to 94%.
  • Fresh Martensite constitutes from 6% to 20% of microstructure by area fraction. Steel of present invention form fresh martensite due to the cooling after tempering holding of cold rolled steel sheet. Martensite imparts ductility and strength to the Steel of present invention. However, when fresh martensite presence is above 20% it imparts excess strength but diminishes the hole expansion ratio beyond acceptable limit for the steel of present invention. As fresh martensite contains high amount of carbon it is brittle and hard therefore preferred limit for fresh martensite for the steel of present invention is from 6% to 18% and more preferably from 6% to 15%.
  • the microstructure of the cold rolled martensitic steel sheet is free from microstructural components such as ferrite, bainite, residual austenite, pearlite and cementite.
  • the steel according to the invention can be manufactured by any suitable methods. It is however preferable to use the method according to the invention that will be detailed, as a non-limitative example.
  • Such preferred method consists in providing a semi-finished casting of steel with a chemical composition of the prime steel according to the invention.
  • the casting can be done either into ingots or continuously in form of thin slabs or thin strips, i.e. with a thickness ranging from approximately 220mm for slabs up to several tens of millimeters for thin strip.
  • a slab having the chemical composition according to the invention is manufactured by continuous casting wherein the slab optionally underwent a direct soft reduction during the continuous casting process to avoid central segregation and to ensure a ratio of local Carbon to nominal Carbon kept below 1 .10.
  • the slab provided by continuous casting process can be used directly at a high temperature after the continuous casting or may be first cooled to room temperature and then reheated for hot rolling.
  • the temperature of the slab which is subjected to hot rolling, must be at least 1000° C and must be below 1280°C.
  • the temperature of the slab In case the temperature of the slab is lower than 1000° C, excessive load is imposed on a rolling mill and, further, the temperature of the steel may decrease to a Ferrite transformation temperature during finishing rolling, whereby the steel will be rolled in a state in which transformed Ferrite contained in the structure. Therefore, the temperature of the slab must be high enough so that hot rolling should be completed in the temperature range of Ac3 to Ac3+100°C. Reheating at temperatures above 1280°C must be avoided because they are industrially expensive.
  • the sheet obtained in this manner is then cooled at a cooling rate of at least 10°C/s to the coiling temperature which must be below 675°C.
  • the cooling rate will be less than or equal to 200° C/s.
  • the hot rolled steel sheet is then coiled at a coiling temperature below 675°C to avoid ovalization and preferably between 475°C and 675°C to avoid scale formation, with an even prefererred range for such coiling temperature between 500°C and 660°C.
  • the coiled hot rolled steel sheet is then cooled down to room temperature before subjecting it to optional hot band annealing.
  • the hot rolled steel sheet may be subjected to an optional scale removal step to remove the scale formed during the hot rolling before optional hot band annealing.
  • the hot rolled sheet may then have subjected to an optional hot band annealing.
  • such hot band annealing is performed at temperatures between 400°C and 750°C, preferably for at least 12 hours and not more than 96 hours, the temperature preferably remaining below 750°C to avoid transforming partially the hot-rolled microstructure and therefore, possibly losing the microstructure homogeneity.
  • an optional scale removal step of this hot rolled steel sheet may be performed through, for example, pickling of such sheet.
  • This hot rolled steel sheet is then subjected to cold rolling to obtain a cold rolled steel sheet with a thickness reduction between 35 to 90%.
  • the cold rolled steel sheet is heated at a heating rate HR1 which is of at least 1 °C/s and preferably greater than equal to 2°C/s, to a soaking temperature Tsoak between Ac3 and Ac3+100° C and preferably between Ac3°C and Ac3+50°C, wherein Ac3 for the steel sheet is calculated by a dilatometry study conducted according to the ASTM A1033 -18 standards.
  • the cold rolled steel sheet is held at Tsoak during 10 seconds to 500 seconds to ensure a complete recrystallization and full transformation to austenite of the strongly work hardened initial structure.
  • the cold rolled steel sheet is then cooled from Tsoak, at a cooling rate CR1 from 1 °C/s to 150°C/s, to a temperature T1 which is in a range from Ms -100°C to Ms.
  • the cooling rate CR1 for such step of cooling is from 20°C/s to 120°C/s.
  • the preferred T 1 temperature for such first step is from Ms -70°C to Ms.
  • the cold rolled steel sheet is then held at T1 for a time from 5 seconds to 100 seconds and preferably from 5 seconds to 50 seconds and more preferably 5 seconds to 30 seconds.
  • Ms for the steel sheet is calculated by using the dilatometry study according to the ASTM A1033 -18 standards.
  • the cold rolled steel sheet is reheated to a tempering temperature Ttemper from 400°C to 550°C with a heating rate of at least 1 °C/s and preferably of at least 2°C/s and more preferably of at least 10°C/s during 10s and 600s.
  • the preferred temperature range for tempering is from 420°C to 500°C and the preferred duration for holding at Ttemper is from 20 s to 300 s.
  • the cold rolled martensitic steel sheet of the present invention may optionally be coated with zinc or zinc alloys, or with aluminum or aluminum alloys to improve its corrosion resistance. Then, the cold rolled steel sheet is cooled down to room temperature to obtain a cold rolled martensitic steel.
  • Table 1 Steel sheets made of steels with different compositions are gathered in Table 1 , where the steel sheets are produced according to process parameters as stipulated in Table 2, respectively. Thereafter Table 3 gathers the microstructures of the steel sheets obtained during the trials and table 4 gathers the result of evaluations of obtained properties. Table 1
  • Table 2 gathers the hot rolling and annealing process parameters implemented on cold rolled steel sheets to impart the steels of table 1 with requisite mechanical properties to become a cold rolled martensitic steel.
  • the table 2 is as follows:
  • Table 3 exemplifies the results of the tests conducted in accordance with the standards on different microscopes such as Scanning Electron Microscope for determining the microstructures of both the inventive and reference steels in terms of area fraction. The results are stipulated herein: Table 3 :

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 martensitique comprenant les éléments suivants 0,07 % ≦ C ≦ 0,12 %; 1,9 % ≦ Mn ≦ 2,5 %; 0,2 % ≦ Si ≦ 0,6 %; 0,01 % ≦ Al ≦ 0,1 %; 0,1 % ≦ Cr ≦ 0,5 %; 0,2 % ≦ Mo ≦ 0,6 %; 0 % ≦ S ≦ 0,09 %; 0 % ≦ P ≦ 0,09 %; 0 % ≦ N ≦ 0,09 %; 0 001 % ≦ Ti ≦ 0,1 %; 0,0005 % ≦ B ≦ 0 005 %; 0 % ≦ Nb ≦ 0,1 %; 0 % ≦ V ≦ 0,1 % ; 0 % ≦ Ni ≦ 1 % ; 0 % ≦ Cu ≦ 1 % ; 0 % ≦ Sn ≦ 0,1 % ; 0 % ≦ Pb ≦ 0,1 % ; 0 % ≦ Sb ≦ 0,1 % ; 0 001 % ≦ Ca ≦ 0,01 % ; la composition restante étant composée de fer et d'impuretés inévitables provoquées par le traitement; la microstructure dudit acier étant constituée, en pourcentage de surface, de martensite revenue entre 80 % et 94 % et de martensite fraîche entre 6 % et 20 %.
PCT/IB2022/057528 2022-08-12 2022-08-12 Acier martensitique laminé à froid et son procédé de production WO2024033688A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/IB2022/057528 WO2024033688A1 (fr) 2022-08-12 2022-08-12 Acier martensitique laminé à froid et son procédé de production

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/IB2022/057528 WO2024033688A1 (fr) 2022-08-12 2022-08-12 Acier martensitique laminé à froid et son procédé de production

Publications (1)

Publication Number Publication Date
WO2024033688A1 true WO2024033688A1 (fr) 2024-02-15

Family

ID=83280491

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2022/057528 WO2024033688A1 (fr) 2022-08-12 2022-08-12 Acier martensitique laminé à froid et son procédé de production

Country Status (1)

Country Link
WO (1) WO2024033688A1 (fr)

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101620744B1 (ko) * 2014-12-05 2016-05-13 주식회사 포스코 고항복비형 초고강도 냉연강판 및 그 제조방법
WO2020229877A1 (fr) * 2019-05-15 2020-11-19 Arcelormittal Acier martensitique laminé à froid et procédé de fabrication associé
KR20210014054A (ko) * 2019-07-29 2021-02-08 주식회사 포스코 고강도 강판 및 이의 제조방법
KR20210014055A (ko) * 2019-07-29 2021-02-08 주식회사 포스코 고강도 강판 및 이의 제조방법
EP3901299A1 (fr) 2018-12-18 2021-10-27 Posco Tôle d'acier laminée à froid ayant une excellente aptitude au façonnage, tôle d'acier galvanisée et leurs procédés de fabrication
KR20220078173A (ko) * 2020-12-03 2022-06-10 주식회사 포스코 굽힘가공성이 우수한 초고강도 냉연강판 및 그 제조방법
WO2022124609A1 (fr) * 2020-12-09 2022-06-16 주식회사 포스코 Tôle d'acier galvanisée par immersion à chaud à haute résistance présentant une ductilité élevée et une excellente formabilité, et son procédé de fabrication

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101620744B1 (ko) * 2014-12-05 2016-05-13 주식회사 포스코 고항복비형 초고강도 냉연강판 및 그 제조방법
EP3901299A1 (fr) 2018-12-18 2021-10-27 Posco Tôle d'acier laminée à froid ayant une excellente aptitude au façonnage, tôle d'acier galvanisée et leurs procédés de fabrication
WO2020229877A1 (fr) * 2019-05-15 2020-11-19 Arcelormittal Acier martensitique laminé à froid et procédé de fabrication associé
KR20210014054A (ko) * 2019-07-29 2021-02-08 주식회사 포스코 고강도 강판 및 이의 제조방법
KR20210014055A (ko) * 2019-07-29 2021-02-08 주식회사 포스코 고강도 강판 및 이의 제조방법
KR20220078173A (ko) * 2020-12-03 2022-06-10 주식회사 포스코 굽힘가공성이 우수한 초고강도 냉연강판 및 그 제조방법
WO2022124609A1 (fr) * 2020-12-09 2022-06-16 주식회사 포스코 Tôle d'acier galvanisée par immersion à chaud à haute résistance présentant une ductilité élevée et une excellente formabilité, et son procédé de fabrication

Similar Documents

Publication Publication Date Title
CA3140117C (fr) Acier martensitique lamine a froid et procede d'acier martensitique s'y rapportant
JP7547392B2 (ja) 冷間圧延マルテンサイト鋼及びその冷間圧延マルテンサイト鋼の製造方法
WO2021116741A1 (fr) Tôle d'acier laminée à froid et traitée thermiquement et procédé de fabrication de celle-ci
CA3141566C (fr) Tole d'acier laminee a froid et revetue et son procede de fabrication
CN112689684B (zh) 经冷轧和涂覆的钢板及其制造方法
EP4182488A1 (fr) Tôle d'acier laminée à froid et traitée thermiquement et procédé de fabrication de celle-ci
CN111448329A (zh) 经冷轧和涂覆的钢板及其制造方法
WO2022009032A1 (fr) Tôle d'acier laminée à froid et traitée thermiquement et procédé de fabrication de celle-ci
CA3163313C (fr) Tole d'acier laminee a froid et traitee thermiquement et procede de fabrication de celle-ci
CA3138625C (fr) Tole d'acier laminee a froid et revetue et son procede de fabrication
WO2024033688A1 (fr) Acier martensitique laminé à froid et son procédé de production
WO2023223078A1 (fr) Tôle d'acier martensitique et son procédé de fabrication
KR20240090672A (ko) 냉연 열처리 강판 및 그 제조 방법

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: 22768953

Country of ref document: EP

Kind code of ref document: A1