EP3548641B1 - Method for manufacturing a hot-formed article, and obtained article - Google Patents

Method for manufacturing a hot-formed article, and obtained article Download PDF

Info

Publication number
EP3548641B1
EP3548641B1 EP17804538.1A EP17804538A EP3548641B1 EP 3548641 B1 EP3548641 B1 EP 3548641B1 EP 17804538 A EP17804538 A EP 17804538A EP 3548641 B1 EP3548641 B1 EP 3548641B1
Authority
EP
European Patent Office
Prior art keywords
temperature
article
steel
hot
blank
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.)
Revoked
Application number
EP17804538.1A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP3548641A1 (en
Inventor
Shangping Chen
Christiaan Theodorus LAHAYE
Radhakanta RANA
Guido Cornelis Hensen
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.)
Tata Steel Ijmuiden BV
Original Assignee
Tata Steel Ijmuiden BV
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
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=57485309&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP3548641(B1) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Tata Steel Ijmuiden BV filed Critical Tata Steel Ijmuiden BV
Publication of EP3548641A1 publication Critical patent/EP3548641A1/en
Application granted granted Critical
Publication of EP3548641B1 publication Critical patent/EP3548641B1/en
Revoked legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • 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
    • 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
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • 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
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • 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
    • 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
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of 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
    • C22C38/18—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
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
    • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
    • C23C2/06—Zinc or cadmium or alloys based thereon
    • 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
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/002—Bainite
    • 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
    • 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 invention relates to a method for hot forming a steel blank into an article having enhanced mechanical properties, such as an automotive part with improved ductility, bendability and impact toughness, and to a hot formed article obtained by said method.
  • hot forming also known as hot stamping, hot-forming, press-hardening and die-quenching
  • the basics of the hot forming technique and steel compositions adapted to be used were for the first time described in GB1490535 .
  • EP 2 660 345 discloses a hot forming process.
  • a typical steel used for the hot press forming is based on a composition system of 22MnB5, i.e. 0.22% of C, 1.2% of Mn, maximum 50 ppm of B, specified in EN10083.
  • Hot press forming of 22MnB5 steel can produce complex parts such as bumpers and pillars with ultrahigh strength, minimum springback, and reduced sheet thickness.
  • the tensile strength of boron steels is up to 1600 MPa, which is far above that of the highest-strength conventional cold stamping steels. However the ductility of total elongation is less than 6%.
  • the blank is furnace-heated and austenitized at 900-950 °C, transferred from furnace to forming tool, and stamped into the desired part geometry.
  • the blank has an ultimate tensile strength R m ⁇ 200 MPa and a total elongation A>50%.
  • the formed blank is finally die-quenched to 100-200 °C with a mean cooling rate of >30 °C/s and a homogenous martensitic microstructure is obtained, while it is constrained in the forming tool.
  • the final martensitic part typically exhibits a proof strength Rp 0.2 >1100 MPa, an ultimate tensile strength R m >1500 MPa and a total elongation A ⁇ 8%.
  • Hot stamped boron steel parts typically include anti-intrusive structural body parts such as roof pillar-, door beam- and bumper beam-reinforcements that constitute the 'safety-cell' of a car.
  • the relatively soft and ductile high-temperature austenitic microstructure during forming permits down-gauging and lightweighting while not compromising forming limits and moreover, permits part-consolidation and in turn, increased structural strength and increased process efficiency compared to cold forming as joining/welding is reduced.
  • the martensitic transformation which releases forming stresses and geometric constraint on the part during quenching, eliminates springback giving rise to geometric accuracy.
  • the ultra high strength martensitic microstructure resulting in the final part permits down-gauging (lightweighting) simultaneously while improving anti-intrusive crashworthiness compared to the use of cold formed parts.
  • the supremacy of boron steel in hot stamping applications owes to the (quench) hardenability (owing to the boron addition) and in turn ultra high strength martensitic microstructure that can be obtained from the relatively lean chemical composition.
  • hot stamped martensitic boron steel provides excellent mechanical properties for anti-intrusive crashworthiness, the limited ductility, and in turn limited toughness give rise to very poor impact-energy absorptive crashworthiness.
  • EP1939308 A1 proposed a modification of the standard hot-forming method, wherein a complete martensitic transformation is avoided during hot-forming.
  • a steel blank was heated up to its intercritical temperature between Ac1 and Ac3 and then hot-formed to a temperature below Ms so that a dual-phase microstructure consisting of martensite and proeutectoid ferrite is obtained.
  • the hot-formed article obtained by said method showed improved elongation and tensile strength.
  • dual phase steels are sensitive to damage upon forming due to the large hardness difference between ferrite and martensite.
  • the damage tolerance and formability of said hot-formed article is relatively poor due to the microstructural inhomogeneities and microcracks may occur during forming.
  • the energy absorption capability of structural components in a car body is also limited.
  • hot-stamped boron steel and the advantages of the hot stamping process cannot be exploited with impact-energy absorptive structural body parts, such as fender and longitudinal beams that constitute 'crumple zones'.
  • Such parts are typically cold formed from ferritic or multiphase steels, such as Transformation Induced Plasticity (TRIP) steels.
  • TRIP Transformation Induced Plasticity
  • the proposed heat treatment comprises the steps of: a) heating a steel blank above the austenization temperature; b) quenching: controlling the quenching temperature to be between the Ms and Mf temperature of the steel to partially transform austenite into martensite; c) partitioning: raising the temperature slightly above the Ms temperature and holding it for a short time, whereby a thin layer of austenite with high content of carbon is formed around the martensite lath by repartitioning the carbon between martensite and austenite; d) tempering: tempering the steel at a temperature to induce precipitation hardening in martensite; and e) cooling: cooling down the steel from the tempering temperature at room temperature to transform part of retained austenite into martensite, while remain a thin layer of retained austenite with high content of carbon around the martensite
  • Q-P-T Quenching-Partitioning-Temping
  • TE total elongation
  • BA bending angle
  • the inventors have found that through forming the heated blank into an article as described above, complex shaped articles with enhanced mechanical properties can be obtained.
  • the articles exhibit excellent impact-energy absorptive crashworthiness and in turn, down-gauging and lightweighting opportunities based on impact-energy absorptive crashworthiness compared to the use of conventional hot-formed boron steels and cold-formed multiphase steels.
  • the steel blank In the common hot forming process, the steel blank is simply formed into the desired geometry at and then die-quenched to near-ambient temperature in which a complete transformation to martensite takes place. Thus, the final part exhibits a fully or almost fully martensitic microstructure.
  • the inventors have surprisingly found that by interrupting the die-quench and integrating a Q-P-T heat treatment in the hot-forming cycle, hot formed steel articles having a distinctive microstructure and thus improved mechanical properties can be obtained.
  • the inventors have found that by interrupting the quench temperature of the hot-forming process at a temperature T3 and/or a temperature T4 between Ms and Mf and applying a Q-P-T heat treatment, it is possible to control the phases formed, as well as the amount of each phase formed, thus the microstructure, and consequently the mechanical properties of the article.
  • Said article shows improved mechanical properties, such as enhanced tensile strength, ductility and impact toughness for impact-energy absorptive crashworthiness, while exhibiting excellent formability to enable down-gauging and moreover exhibiting excellent dimensional accuracy (minimal or no springback).
  • a heated blank is formed in a forming tool into the desired part geometry having a partially or a fully homogenous austenitic microstructure and simultaneously quenched to a(n) (interrupt) temperature T3, and preferably at a cooling velocity V2 of 25 °C/s or more.
  • T3 is too high and above Bs, and/or the cooling rate is too low, pearlite may form.
  • V2 is less than 25°C/s, there is also a risk of carbide formation resulting in degradation of the mechanical properties of the final article.
  • the cooling rate V2 is at least 50 °C/s, preferably at least 100 °C/s.
  • the cooling rate V2 is at least 150 °C/s for best results.
  • step (e) the article is brought to a temperature T4 and isothermally held at that temperature T4 for a time t4.
  • Isothermal holding time t4 is the time required for austempering, partitioning or tempering and is in the range of 10 seconds to 10 minutes. When t4 is more than 10 minutes then no further improvement of the article is achieved. If t4 is less than 10 seconds then there is not enough time for the effect to be achieved.
  • T3 is between Ms and Mf and T4 is between Bs and Ms.
  • T4 is between Bs and Ms.
  • the article must be heated up from temperature T3, which is lower than Ms, to temperature T4, which is higher than Ms.
  • T3 some martensitic transformation will take place.
  • the amount of the martensite formed is mainly controlled by the temperature T3: the lower T3, the higher the fraction of martensite. Since T4 is higher than T3, the untransformed austenite will transform to bainite and retained austenite at T4 and during following cooling.
  • the martensite will be tempered to some degree during the isothermal holding at T4.
  • T3 is between Bs and Ms and T4 is between Ms and Mf.
  • austenite will first partially transform into bainite at temperature T3.
  • the untransformed austenite will transform to martensite and retained austenite during isothermal holding at T4 and the following cooling.
  • both T3 and T4 are between Ms and Mf, and preferably T3 and T4 are the same.
  • Some martensite will form at the beginning; as the isothermal holding time increases, element partitioning between martensite and untransformed austenite may occur, the Ms point of the untransformed martensite will be decreased and some untransformed austenite may transform to bainite. At the same time, the transformed martensite might be tempered to some degree.
  • the article that is formed is held at temperature T3 during a holding time t3 of 1 to 180 seconds.
  • the length of the holding time t3 determines the amount of the microstructural elements that are first formed at temperature T3. Which microstructural elements are first formed depends on temperature T3.
  • the article is heated from temperature T3 to temperature T4 at a velocity V3 of at least 15 °C/s, preferably at least 20 °C/s, more preferably at least 30 °C/s.
  • the heating velocity V3 depends on the temperature difference between T3 and T4, and on the sheet thickness.
  • the article is cooled from temperature T3 to temperature T4 at a velocity t3 of at most 15 °C/s, preferably at most 10 °C/s, more preferably at most 8 °C/s.
  • the cooling velocity V4 depends on the temperature difference between T3 and T4, and on the sheet thickness.
  • the article is cooled from temperature T4 to room temperature at a cooling velocity V4, in the range of 0.1 - 20 °C/s, preferably in the range of 1 - 15 °C/s, more preferably in the range of 2 - 10 °C/s.
  • This cooling can be performed by natural cooling in air or by using an air blower, for instance.
  • T1 is in the range of Ac1 to Ac3+150, preferably Ac1 to Ac3+100, more preferably in the range of Ac3-50 to Ac3+50, and wherein t1 is preferably at most 12 minutes, more preferably t1 is in the range of 2-8 min, and wherein the steel blank is heated with a heating velocity V1 in the range of 10 - 25 °C/s.
  • Temperature T1 determines how much ferrite is transformed into austenite in the steel blank, which also depends on the holding time t1.
  • a heating velocity V1 above 25 °C/s can be detrimental to the properties of the blank.
  • step (e) the article undergoes fine forming.
  • a steel strip or sheet is provided as an intermediate for the subsequent steps.
  • the steel strip or sheet can be obtained by standard casting processes.
  • the steel strip or sheet is cold-rolled.
  • the steel strip or sheet is cut to a steel blank and then heated to a temperature T1 for a time period t1.
  • a preformed steel blank may also be used.
  • the preformed blank may be partially or entirely formed into the desired geometry, preferably at ambient temperature.
  • the heating apparatus may be an electric or gas powered furnace, electrical resistance heating device, infra-red induction heating device or any other heating device.
  • T1 is in the range of Ac1 to Ac3
  • the blank is austenitized at an intercritical temperature.
  • the steel has at said temperature range a ferritic austenitic microstructure. Under this conditions preferably a small amount of the ferrite is retained, wherein the ferrite fraction is preferably less than 20 vol.%.
  • press hardening takes place wherein the structure of the steel part is a two-phase mixture of ferrite and austenite. After subsequent press hardening and Q-P-T heat treatment, a mixed structure of ferrite, bainite or martensite, tempered martensite and a portion of residual austenite is produced in the component.
  • T1 is above the chemistry specific Ac3 temperature to produce a fully or almost fully homogenous austenitic microstructure with uniform distribution of carbon.
  • the microstructure is a homogenous austenitic microstructure the formability is enhanced.
  • austenization time t1 may be chosen in combination with the temperature T1 and the blank thickness in order to control austenitic grain growth and associated quench hardenability of said steel.
  • the degree of quench hardenability will then influence the microstructural evolution during cooling. Therefore, t1 is at most 12 min.
  • t1 is in the range of 2-8 minutes, more preferably in the range of 2-6 minutes in view of process and energy efficiency.
  • the steel blank is transferred from the heating apparatus to a forming tool in a time period t2 (step b).
  • Time t2 is the time needed to transport the heated blank from the heating apparatus to the press forming tool and till the hot-forming apparatus is closed.
  • the blank may cool from temperature T1 to temperature T2 by the act of natural air-cooling and/or any other available cooling method.
  • the heated blank may be transferred from the heating apparatus to the forming tool by an automated robotic system or any other transfer method.
  • Time t2 may also be chosen in combination with T1, t1 and T2 in order to control the microstructural evolution of steel at the commencement of forming and quenching.
  • Time period t2 is preferably chosen such to ensure that the steel blank when placed in the hot-forming tool has a temperature T2 above the temperature Ar1 of the steel to exhibit an austenitic-ferritic microstructure and prevent the formation of pearlite.
  • shorter transport times are beneficial in view of corrosion, process efficiency and hardenability.
  • the inventors have further found that when t2 is equal or less than 10 s good results have been also achieved.
  • t2 is equal or less than 8s, more preferably equal or less than 6s.
  • the steel blank comprises, in weight % (wt%) following elements:
  • C 0.10-0.50.
  • C is an essential element for securing a high strength.
  • C is added in an amount of 0.10% or more to form required complex phase microstructures and achieve high strength and high ductility. More particularly, together with the intercritical austenization temperature, the C content determines the volume of ferrite and the carbon content of the remaining austenite, which controls the Bs and Ms points and the bainite formation kinetics. When the C content exceeds 0.50, there is a great possibility that the toughness and weldability of the steel sheet will deteriorate.
  • C amount is preferably present in the range of 0.15-0.40, more preferably in the range of 0.20-0.35.
  • Mn 0.50-4.00
  • the functions of the Mn is to stabilize the austenite and to obtain the desired multiphase microstructure.
  • the manganese content is at least 0.50 in order to provide adequate substitutional solid solution strengthening, adequate quench hardenability and adequate stabilisation of austenite at ambient temperature, while minimising segregation of Mn during casting and while maintaining sufficiently low carbon equivalent for automotive resistance spot-welding techniques. If the Mn content is less than 0.50 is difficult to attain an intended high strength of the steel by heat treating the steel in a ferrite-austenite two-phase region. When the Mn content exceeds 4%, there is the dangers that the steel sheet suffers from poor weldability and hot rolling characteristics.
  • Mn is an element that is useful in lowering the Ac3 temperature. A higher Mn content is advantageous in lowering the temperature necessary for hot press forming.
  • the Mn content is limited to the range of 1.0% to 3.0%.
  • manganese is in the range of 1.00-2.50.
  • Si ⁇ 2.0.
  • Si is an element effective for reinforcing a solid solution, and is useful for suppressing production of carbide due to decomposition of retained austenite. A certain amount of Si suppresses the precipitation of brittle cementite during bainite formation, and hence leads to an improvement in formability and toughness.
  • Si is further known to widen the intercritical temperature range of a steel. However, Si is also known that in high amount the coatability deteriorates due to the formation of oxides adherent to the steel substrate. Therefore, the Si amount is equal or less than 2.0, preferably in the range of 0.1-2.0.
  • the Si content is preferably in the range of 0.1-1.0. When steel articles having higher ductility are aimed, then the Si content is preferably in the range of 1.0-2.0.
  • Al ⁇ 2.0 Al limited to a maximum of 2.0 in order to preserve weldability and minimise 'nozzle blockage' during steelmaking and casting.
  • Al is an element useful for suppressing production of carbide due to decomposition of, particularly, retained austenite. Partial replacement of Si by same amount of Al has been shown to effectively retard carbide formation without a detrimental effect on hot-dip coatability in steels.
  • a high concentration of Al leads to higher possibility of the polygonal ferrite to be created, which is less effective than fine plate ferrite on strength.
  • Preferably Al is limited to a maximum of 1.0, more preferably Al is at most 0.5.
  • Si and Al in sufficient amount can completely resist formation of carbide.
  • a carbide free bainite i.e. bainitic ferrite
  • Si + Al Si + Al ⁇ 5 x C
  • traditional bainite consisting of bainitic ferrite + cementite
  • P is known to widen the intercritical temperature range of a steel. P is also an element useful for maintaining desired retained austenite. However, P may deteriorate the workability of the steel when it is added in an excess amount. Therefore, P cannot be added deliberately beyond its usual permissible limit in steel ⁇ 0.015 wt.%.
  • S ⁇ 0.03.
  • Sulphur needs to be minimised for minimisation of harmful non-metallic inclusions.
  • S forms a sulfide based inclusions such as MnS, which initiates crack, and deteriorates processability. Therefore, it is desirable to reduce the S amount as much as possible. Therefore the sulphur content is limited to a maximum of 0.03, preferably to a maximum of 0.01.
  • Mo and Cr are elements which improve the hardenability of the steel and facilitate the formation of bainite ferrite, and at the same time, are elements having similar effectiveness useful for stabilizing retained austenite. Therefore, Mo and Cr are very effective for the process control. Preferably Mo and Cr are each present in an amount of 0.001% or higher. However, when each of them is added excessively, the effect is saturated and the process is not economical. Therefore, the amounts of Mo is limited to a maximum of 0.5, preferably at most 0.05. Cr is limited to a maximum of 1.5, preferably 1.2. Advantageous Cr is in the range of 0.001-1.1
  • Ti ⁇ 0.1; Nb ⁇ 0.1; V ⁇ 0.2: Ti, Nb and V have the effect of forming strengthening precipitates and refining microstructure.
  • the steel should have sufficient strength level. Due to the soft phases such as proeutectoid and bainitic ferrite, the strength of the final product can be lower than standard hot formed material. To compensate for this drop in strength, microalloying elements such as Nb, Ti and V might be added individually or in combination. Said elements increase the strength by means of grain refinement and precipitation hardening. Grain refinement results in a more homogeneous microstructure improving the hot-forming behaviour, in particular when high localized strains are being introduced. Therefore the amount of Ti and Nb is each limited to a maximum of 0.1, preferably to a maximum of 0.05.
  • Advantageously Ti is at most 0.04 and/or Nb is in the range of 0.001-0.05.
  • the amount of V is limited to a maximum of 0.2 %, preferably to a maximum of 0.10.
  • Ca is an element effective for controlling a form of sulfide in the steel, and improving processability. However, It is recommended that Ca is contained at 0.0003% or more. However, when it is added excessively, the effect is saturated. Therefore, it is better to suppress an amount thereof to 0.003% or less.
  • B is an important element for increasing the hardenability of 22MnB type steel sheets and for further increasing the effect of stably guaranteeing strength after hardening.
  • B is an optional element for the relatively high carbon contented steel.
  • the B amount is preferably limited to a maximum of 0.008, preferably at most 0.005.
  • the B amount is in the range of 0.0005-0.0025 %.
  • the steel microstructural composition is a multiphase steel, preferably a complex phase (CP) like steel that exhibits the capacity for stress/strain induced transformation effect. More particularly the steel is an advanced high strength steel product suitable for hot press forming as a boron steel alternative for automotive applications.
  • CP complex phase
  • the inventors have surprisingly found that applying the present method to a CP like steel composition results in hot-formed articles exhibiting homogeneous mechanical properties.
  • the relative fraction of the existing phases in the microstructures depends essentially on the initial chemical composition of the steel and on the method conditions under which the various step are performed.
  • a CP microstructure comprising bainite, martensite, tempered martensite and/or retained austenite can be obtained, wherein the phases are homogeneously distributed in each of the regions of the part.
  • the articles obtained by the present invention show vastly improved mechanical properties comparable to those of the traditional CP steel prior to cold forming, and thus impact-energy absorptive crashworthiness can be achieved.
  • the present invention provides an improved method of introducing during hot-forming operation the desired bainitic gradient into the steel microstructure while with the standard hot-forming methods this is not possible. Further, the standard hot-forming processes can not provide sufficient amount of tempered martensite and retained austenite in the steel.
  • the bainite and tempered martensite portions in the structure of the formed steel part at the end of the Q-P-T heat treatment should be in total at least 80%, while the amount of the other phases should be less than 20%.
  • the final microstructure consists of (vol.%) (sum should be add 100).
  • the metastable retained austenite fraction ensures the balanced combination of strength and ductility properties.
  • Retained austenite enhances ductility partly through the stress / strain induced transformation effect, which manifests itself in an observed increase in uniform elongation and total elongation as the work hardening exponent increases to higher plastic strains. Above 20 vol.% the desired level of ductility and/or uniform elongation according to the present invention will not be achieved.
  • Part or the totality of the process according to the present invention may be conducted in a controlled inert atmosphere of hydrogen, nitrogen, argon or any other inert gas in order to prevent oxidation and/or decarburisation of said steel.
  • the hot-formed article obtained by the present invention has ultimate tensile strength (UTS) of at least 1000 MPa, preferably at least 1100 MPa and/or yield strength of at least 600 MPa, preferably at least 700 MPa, and/or a total elongation (TE) of at least 6% and/or a bending angle of at least 45 °, preferably 50 °C, the obtained product exhibits improved impact-energy absorptive crashworthiness.
  • UTS ultimate tensile strength
  • TE total elongation
  • the steel strip, sheet, blank, preformed blank, or article is provided with a coating.
  • a coating may be performed prior to the hot-forming process or after the hot-forming process and has the purpose of minimising oxidation of the steel when exposed to an oxidising atmosphere at high temperature and/or providing cathodic corrosion protection of the final hot formed part.
  • the steel strip, sheet, blank, preformed blank, or article is coated with a zinc based coating, aluminium-silicon based coating or an organic based coating.
  • the zinc based coating is a galvanized or galvannealed coating.
  • the coating can be applied in various ways, hot dip galvanising is preferred using a standard Gl coating bath.
  • Other Zn coatings may also be applied.
  • An example comprises a Zn alloy coating according to WO 2008102009 , in particular a zinc alloy coating layer consisting of 0.3-4.0 wt% Mg and 0.05-6.0 wt% Al and optionally at most 0.2 wt% of one or more additional elements along with unavoidable impurities and the remainder being zinc.
  • An additional element typically added in a small amount of less than 0.2 wt% could be selected from the group comprising Pb or Sb, Ti, Ca, Mn, Sn, La, Ce, Cr, Ni, Zr or Bi.
  • Pb, Sn, Bi and Sb are usually added to form spangles.
  • the total amount of additional elements in the zinc alloy is at most 0.2%.
  • These small amounts of an additional element do not alter the properties of the coating nor the bath to any significant extent for the usual applications.
  • the articles according to the present invention exhibit good adhesion to a coating layer, have good surface appearance and superior corrosion resistance after coating.
  • the horizontal axis represents the time t
  • the vertical axis represents the temperature T.
  • the hot forming of the blank into the article in the hot forming press is indicated by HF.
  • the time t and temperature T are indicated diagrammatically in the Figures, and so are the cooling and heating velocities V. No values can be derived from the Figures.
  • a steel blank is heated up to the austenitizing temperature T1 above Ac 1 at a heating rate of 15 °C/s and held at aT1 for a time period t1. Then the heated blank is transferred from the furnace to the hot forming press, during which cooling of the blank to temperature T2 by air occurs to some extend. Care is taken that the temperature T2 does not decrease below the Ar1 temperature before the blank is placed in the hot-forming press.
  • the blank is then hot-formed into an article and cooled down to temperature T3 at a cooling rate of >25 °C/s and the cooling is interrupted and the article is held at T3 for a time period t3. Thereafter, the three embodiments follow different routes. Finally, the formed article is cooled down to room temperature at a cooling rate V4.
  • temperatures T3, T4 and cooling or heating velocities V3 and V4, and the holding time t3 and t4 depend on the different embodiments as shown in the Figures 1 - 3 .
  • Ar1 The temperature at which transformation of austenite to ferrite is completed during cooling.
  • Ar3 The temperature at which austenite begins to transform to ferrite during cooling.
  • Ms Temperature at which, during cooling, transformation of the austenite into martensite starts.
  • Mf Temperature at which, during cooling, transformation of the austenite into martensite ends.
  • Critical phase transformation temperatures are determined by dilatometer experiments.
  • Table 1 shows the steel composition used in a method according to the present invention.
  • the tables 2, 3 and 4 give the process parameters and mechanical properties for the different steel types of Table 1, and for the process types of the three embodiments. The results are discussed below.
  • Table 1. Steel compositions (wt.%).
  • Steel blanks with dimensions of 200 mm ⁇ 110 mm ⁇ 1.5 mm have been prepared from a cold-rolled steel sheet having the composition B or C as given in Table 1.
  • the Ac3 and Ms temperatures were determined using dilatation tests.
  • the blanks were first heated at 880 °C (T1) in a box furnace for 6 min and then transported to a hot-forming apparatus.
  • the hot-forming was performed in laboratory scale by Schuler SMG company, Germany (hereafter SMG press).
  • the SMG press tools were preheated to a temperature of 450 °C or 300 °C (T3).
  • the blanks were transferred to the SMG press in 10 s and press-quenched to T3 temperature into an article.
  • the article was transferred to a muffle furnace preheated at a temperature of 350°C or 400 °C (T4) and austempering or partitioning and/or tempering heat treatment was applied (Q-P-T treatment).
  • the experimental results with respect to the yield strength (YS), ultimate tensile strength (UTS), uniform elongation (UL) total elongation (TL) and banding angle (BA), are given in Table 2 and Table 3.
  • the tensile properties were measured in the samples with the stress direction being parallel to the rolling direction.
  • the 3-point "guided bending tests" were conducted on samples with dimensions 40 mm x 3025 mm.
  • the length direction of the samples was parallel to the rolling direction of steel sheets.
  • Parallel bending tests where the bending axis is perpendicular to the rolling direction of the sheets were carried out.
  • a former and two supporting cylinders were used in order to bend the steel sheets.
  • the cylinders and the punch were mounted in a tensile testing machine.
  • the load cell is used to measure the punch force and the displacement of the crosshead gives the punch displacement.
  • the experiments were stopped at different bending angles and the bent surface of the specimen was inspected for identification of failure in order to determine the bending angle.
  • the present inventive method has been applied to a steel composition E, as shown in Table 2, similar to the known 22MnB5, but with a C content higher than from this of 22MnB5.
  • the Ac1, Ac3, and Ms temperatures were determined using dilatation tests.
  • a cold-rolled steel sheet having the composition E and a thickness of 1.5 mm has been prepared and blanks with dimensions of 600 mm ⁇ 110 mm were cut.
  • a thermal cycle according to the invention was applied to simulate the hot press forming process using a continuous annealing simulator (CASIM). The blanks were first heated to a variable soak temperature of 900 °C or 810 °C (T1) and held at said temperature for a soak time of 2 min (t1).
  • CASIM continuous annealing simulator
  • the transfer of the heated blanks from the furnace to the press forming apparatus was simulated by cooling down slowly the blanks to 750 °C (T2) and at a cooling rate of 3 °C/s.
  • the blanks are cooled down to a temperature T3 at a cooling rate of 40 °C/s (V2) and isothermal held for t3 and subsequently cooled down to room temperature at a cooling rate of 3.5°C/s (V4).
  • T3 T4.
  • the process parameters, the tensile properties and the bending angle are given in Table 2.
  • Steel compositions F, G, H, I and J according to table 1 have be used.
  • Steel blanks with dimensions of 600 mm ⁇ 110 mm ⁇ 1.5 mm or 230 mm x 110 mm x 1.5 mm have been prepared from a cold-rolled steel sheets having the composition F, G and H, I, J respectively as given in Table 1.
  • the blanks of steel F and G were heat treated in a Continuous Annealing Simulator (CASIM), those of steels H, I and J in a Hot Dip Annealing Simulator (HDAS). Whatever be the apparatus used for heat treatments, it was ensured that the thermal cycles were simulated accurately.
  • CASIM Continuous Annealing Simulator
  • HDAS Hot Dip Annealing Simulator
  • the final microstructure includes ferrite (15 vol.%), bainite/tempered martensite and retained austenite. The presence of ferrite increases the elongation but at expense of strength.
  • Certain amount of austenite transformed to martensite in steels F, G, H and I after quenching to the isothermal holding temperature (T3 T4) since this temperature is below the Ms of the respective steels. The amount of this initial martensite varied with the temperature of quenching - a lower temperature in a particular steel would form a higher amount of initial martensite.
  • the well-known Koistinen-Marburger formula can be used to estimate this initial martensite fraction. Then during the isothermal holding the martensite would temper, and at the same time carbon will partition from martensite to austenite. Carbon partitioning will be more for higher Si content in steel and vice versa. Then during final cooling to room temperature some fresh martensite will form depending on the carbon enrichment in austenite, and some amount of austenite will remain as retained austenite. For steel J, the isothermal holding temperatures (300-400 °C) were above the Ms of the steel. Therefore, during this austempering bainitic transformation took place - primarily carbide free bainite formed causing carbon enrichment in austenite. After isothermal holding, on cooling the blanks to room temperature, some martensite formed and certain amount of austenite remained untransformed due to carbon enrichment during austempering.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Articles (AREA)
  • Heat Treatment Of Steel (AREA)
EP17804538.1A 2016-11-29 2017-11-24 Method for manufacturing a hot-formed article, and obtained article Revoked EP3548641B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP16201179 2016-11-29
PCT/EP2017/080359 WO2018099819A1 (en) 2016-11-29 2017-11-24 Method for manufacturing a hot-formed article, and obtained article

Publications (2)

Publication Number Publication Date
EP3548641A1 EP3548641A1 (en) 2019-10-09
EP3548641B1 true EP3548641B1 (en) 2020-08-26

Family

ID=57485309

Family Applications (1)

Application Number Title Priority Date Filing Date
EP17804538.1A Revoked EP3548641B1 (en) 2016-11-29 2017-11-24 Method for manufacturing a hot-formed article, and obtained article

Country Status (7)

Country Link
US (1) US20210115527A1 (enExample)
EP (1) EP3548641B1 (enExample)
JP (1) JP2020501017A (enExample)
KR (1) KR102477323B1 (enExample)
CN (1) CN110023518A (enExample)
CA (1) CA3067159A1 (enExample)
WO (1) WO2018099819A1 (enExample)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020130543A1 (de) 2020-11-19 2022-05-19 Voestalpine Stahl Gmbh Stahlmaterial und Verfahren zu seiner Herstellung

Families Citing this family (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019223854A1 (de) * 2018-05-22 2019-11-28 Thyssenkrupp Steel Europe Ag Aus einem stahl geformtes blechformteil mit einer hohen zugfestigkeit und verfahren zu dessen herstellung
WO2020002285A1 (en) * 2018-06-26 2020-01-02 Tata Steel Nederland Technology B.V. Cold-rolled martensite steel with high strength and high bendability and method of producing thereof
CN109365606A (zh) * 2018-11-30 2019-02-22 宝山钢铁股份有限公司 一种耐腐蚀性优良的锌系镀层钢板或钢带的成形方法
US12286682B2 (en) 2019-04-30 2025-04-29 Tata Steel Nederland Technology B.V. High strength steel product and a process to produce a high strength steel product
DE102019208040B4 (de) * 2019-06-03 2025-05-15 Volkswagen Aktiengesellschaft Verfahren zur Herstellung eines warmumgeformten und pressgehärteten Stahlblechbauteils
ES2911661T3 (es) * 2019-06-17 2022-05-20 Tata Steel Ijmuiden Bv Tratamiento térmico de un fleje de acero laminado en frío de alta resistencia
EP3754034B1 (en) * 2019-06-17 2022-03-02 Tata Steel IJmuiden B.V. Heat treatment of cold rolled steel strip
ES2911662T5 (en) * 2019-06-17 2025-06-05 Tata Steel Ijmuiden Bv Method of heat treating a high strength cold rolled steel strip
EP3754035B2 (en) * 2019-06-17 2025-04-30 Tata Steel IJmuiden B.V. Method of heat treating a cold rolled steel strip
WO2021009543A1 (en) * 2019-07-16 2021-01-21 Arcelormittal Method for producing a steel part and steel part
CN110527908A (zh) * 2019-09-06 2019-12-03 武汉科技大学 一种中碳微纳结构贝氏体钢及其热处理方法
DE102019215053A1 (de) * 2019-09-30 2021-04-01 Thyssenkrupp Steel Europe Ag Verfahren zur Herstellung eines zumindest teilweise vergüteten Stahlblechbauteils und zumindest teilweise vergütetes Stahlblechbauteil
CN114829652B (zh) * 2020-01-09 2023-04-28 日本制铁株式会社 热压成形体
CN113265581B (zh) * 2020-02-17 2022-10-21 宝山钢铁股份有限公司 一种稳定杆用钢管及其制造方法
CN111235359A (zh) * 2020-03-11 2020-06-05 三一重机有限公司 钢材热处理方法、钢材、履带板和挖掘机
CN112853205B (zh) * 2020-12-31 2022-06-17 马鞍山钢铁股份有限公司 一种850MPa级低屈强比热轧高强复相钢及其制造方法
DE102021201845A1 (de) 2021-02-26 2022-09-01 Volkswagen Aktiengesellschaft Verfahren zur Herstellung eines warmumgeformten und pressgehärteten Stahlblechbauteils
CN113308593B (zh) * 2021-05-28 2022-08-09 四川大学 一种基于碳配分和两步等温淬火的中碳硅锰低合金钢热处理工艺
CN113528761A (zh) * 2021-06-16 2021-10-22 首钢集团有限公司 一种热成形件及其制备方法
CN113528973A (zh) * 2021-06-16 2021-10-22 首钢集团有限公司 一种高塑性热成形钢的生产方法
CN116851528A (zh) * 2022-03-28 2023-10-10 宝山钢铁股份有限公司 用于生产高冷弯性能的高强度热冲压部件的方法、热冲压部件
TWI854883B (zh) * 2023-11-06 2024-09-01 中國鋼鐵股份有限公司 中碳鋼及其製備方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007132008A1 (de) 2006-05-15 2007-11-22 Thyssenkrupp Steel Ag Verfahren zum herstellen eines mit einem korrosionsschutzsystem überzogenen stahlflachprodukts
EP1939308A1 (de) 2006-11-14 2008-07-02 ThyssenKrupp Steel AG Verfahren zum Herstellen eines Bauteils durch Wärmepresshärten und hochfestes Bauteil mit verbesserter Bruchdehnung
WO2012048841A1 (en) 2010-10-12 2012-04-19 Tata Steel Ijmuiden B.V. Method of hot forming a steel blank and the hot formed part
WO2013006108A1 (en) 2011-07-06 2013-01-10 Gestamp Hardtech Ab A method of hot-shaping and hardening a sheet steel blank
EP2546375A1 (en) 2010-03-09 2013-01-16 JFE Steel Corporation High-strength pressed member and method for producing same
EP2703513A1 (en) 2011-04-28 2014-03-05 Kabushiki Kaisha Kobe Seiko Sho Hot press molded article, fabrication method therefor, and thin steel plate for hot press molding
US20140322559A1 (en) 2011-05-18 2014-10-30 Thyssenkrupp Steel Europe Ag High-Strength Flat Steel Product and Method for Producing Same
WO2015039763A2 (en) 2013-09-19 2015-03-26 Tata Steel Ijmuiden B.V. Steel for hot forming

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE435527B (sv) 1973-11-06 1984-10-01 Plannja Ab Forfarande for framstellning av en detalj av herdat stal
JP4325277B2 (ja) * 2003-05-28 2009-09-02 住友金属工業株式会社 熱間成形法と熱間成形部材
WO2008102009A1 (en) 2007-02-23 2008-08-28 Corus Staal Bv Cold rolled and continuously annealed high strength steel strip and method for producing said steel
KR101253885B1 (ko) * 2010-12-27 2013-04-16 주식회사 포스코 연성이 우수한 성형 부재용 강판, 성형 부재 및 그 제조방법
JP5883351B2 (ja) * 2011-06-10 2016-03-15 株式会社神戸製鋼所 熱間プレス成形品、その製造方法および熱間プレス成形用薄鋼板
CN104936716B (zh) * 2013-01-18 2016-09-07 株式会社神户制钢所 热压成形钢构件的制造方法
WO2014136966A1 (ja) * 2013-03-08 2014-09-12 日本発條株式会社 強度部材およびその製造方法
CN105518162B (zh) * 2013-09-10 2017-06-06 株式会社神户制钢所 冲压成形品的制造方法和冲压成形品
CN104846274B (zh) * 2015-02-16 2017-07-28 重庆哈工易成形钢铁科技有限公司 热冲压成形用钢板、热冲压成形工艺及热冲压成形构件

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007132008A1 (de) 2006-05-15 2007-11-22 Thyssenkrupp Steel Ag Verfahren zum herstellen eines mit einem korrosionsschutzsystem überzogenen stahlflachprodukts
EP1939308A1 (de) 2006-11-14 2008-07-02 ThyssenKrupp Steel AG Verfahren zum Herstellen eines Bauteils durch Wärmepresshärten und hochfestes Bauteil mit verbesserter Bruchdehnung
EP2546375A1 (en) 2010-03-09 2013-01-16 JFE Steel Corporation High-strength pressed member and method for producing same
WO2012048841A1 (en) 2010-10-12 2012-04-19 Tata Steel Ijmuiden B.V. Method of hot forming a steel blank and the hot formed part
EP2703513A1 (en) 2011-04-28 2014-03-05 Kabushiki Kaisha Kobe Seiko Sho Hot press molded article, fabrication method therefor, and thin steel plate for hot press molding
US20140322559A1 (en) 2011-05-18 2014-10-30 Thyssenkrupp Steel Europe Ag High-Strength Flat Steel Product and Method for Producing Same
WO2013006108A1 (en) 2011-07-06 2013-01-10 Gestamp Hardtech Ab A method of hot-shaping and hardening a sheet steel blank
WO2015039763A2 (en) 2013-09-19 2015-03-26 Tata Steel Ijmuiden B.V. Steel for hot forming

Non-Patent Citations (11)

* Cited by examiner, † Cited by third party
Title
ABDOLLAHPOOR A, CHEN X., PEREIRA M. ASGARI A., XIAO N. ROLFE B.: "Applying a modified austenite transformation model into a thermos- mechanical model of hot-stamping", IDDRG 2013 CONFERENCE, 2013, pages 155 - 160, XP055811923
ANONYMOUS: "22MnB5 Boron alloyed quenched and tempered steel", SALZGITTER FLACHSTAHL, January 2014 (2014-01-01), pages 1 - 3, XP055811926
ANONYMOUS: "New Advanced Ultra High Strength Bainitic Steels: ductility and formability (DUCTAFORM)", EUROPEAN COMMISION, 24 May 2013 (2013-05-24), pages 1 - 130
ESA VUORINEN: "Structure and Properties of Advanced Fine Grained Steels Produced Using Novel Thermal Treatments", DOCTORAL THESIS, 2012, pages 1 - 134, XP055809211
HAN XIANHONG, YAOYAO ZHONG, KUN YANG, ZHENSHAN CUI, JUN CHEN: "Application of Hot Stamping Process by Integrating Quenching & Partitioning Heat Treatment to Improve Mechanical Properties", PROCEDIA ENGINEERING, vol. 81, no. 10, 19 October 2014 (2014-10-19), pages 1737 - 1743, XP002766082
HAN XIANHONG, YUOYAO ZHONG. KUN YANG. ZHENSHAN CUI. JUN CHEN: "Application of hot stamping process by integrating quenching & partitioning heat treatment to improve mechanical properties", PROCEDIA ENGINEERING, vol. 81, no. 10, 19 October 2014 (2014-10-19), pages 1737 - 1743, XP029078421, DOI: 10.1016/j.proeng.2014.10.223
KOISTINEN D P; MARBURGER R E: "A general equation prescribing extent of austenite-martensite transformation in pure Fe-C alloys and plain carbon steels", ACTA METALLURGICA, vol. 7, no. 1, 1 January 1959 (1959-01-01), pages 59 - 60, XP024036903, DOI: 10.1016/0001-6160(59)90170-1
LI HUIPING, BINGTAO TANG, LIANFANG HE, CHENG WANG: "Research on hot stamping for a typical part of B1500HS boron steel using experiment and numerical simulation methods", NUMIFORM 2016, vol. 80, no. 02013, 24 October 2016 (2016-10-24), pages 1 - 9, XP055809219
LIU PEIXING, YU XIANGYUN, WANG KAI, ZHU BIN, LI JIAN, YISHENG ZHANG: "A new hot stamping process with quenching and partitioning treatment", ADVANCED MATERIALS RESEARCH, vol. 1095, March 2015 (2015-03-01), pages 673 - 676, XP055811925
PETER SEBASTIAN FEUER: "Ein Ansatz zur Herstellung von pressgehärteten Karosseriekomponenten mit maßgeschneiderten mechanischen Eigenschaften: Temperierte Umformwerkzeuge. Prozessfenster, Prozesssimulation und funktionale Untersuchung", FERTIGUNGSTECHNIK- ERLANGEN, 2012, pages 1 - 226, XP055811916
SUSANNE SCHÜRZ: "Korrosionsverhalten von Zn-Al-Mg-beschichtetem Stahlband", DISSERTATION, September 2010 (2010-09-01), pages 1 - 221

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102020130543A1 (de) 2020-11-19 2022-05-19 Voestalpine Stahl Gmbh Stahlmaterial und Verfahren zu seiner Herstellung

Also Published As

Publication number Publication date
US20210115527A1 (en) 2021-04-22
EP3548641A1 (en) 2019-10-09
KR102477323B1 (ko) 2022-12-13
JP2020501017A (ja) 2020-01-16
WO2018099819A1 (en) 2018-06-07
KR20190090809A (ko) 2019-08-02
CA3067159A1 (en) 2018-06-07
CN110023518A (zh) 2019-07-16

Similar Documents

Publication Publication Date Title
EP3548641B1 (en) Method for manufacturing a hot-formed article, and obtained article
EP2627790B1 (en) Method of hot forming a steel blank and the hot formed part
CN104846274B (zh) 热冲压成形用钢板、热冲压成形工艺及热冲压成形构件
EP3221476B1 (en) Method for manufacturing a high strength steel product and steel product thereby obtained
US12286682B2 (en) High strength steel product and a process to produce a high strength steel product
CA2725210C (en) Method for producing a formed steel part having a predominantly ferritic-bainitic structure
EP3164516B1 (en) Method for producing an ultra high strength coated or not coated steel sheet and obtained sheet
EP3164513B1 (en) Method for manufacturing a high-strength steel sheet and sheet obtained by the method
US20210147953A1 (en) Method for producing a high-strength steel strip with improved properties for further processing, and a steel strip of this type
EP3814536A1 (en) Cold-rolled martensite steel with high strength and high bendability and method of producing thereof
EP4114994B1 (en) High strength cold rolled and galvannealed steel sheet and manufacturing process thereof
JP7326247B2 (ja) 熱間成形された部品を製造するための鋼ストリップ、シート又はブランク、部品、及びブランクを部品に熱間成形する方法
CN114901842B (zh) 热压成型钢制品的方法及钢制品
EP3327152A1 (en) Method for hot-forming a steel blank
JP2022535352A (ja) ホットスタンプされた部品を製造するための鋼ストリップ、シート又はブランク、部品、及びブランクを部品にホットスタンプする方法
CN110945148B (zh) 用于制备热成形零件的钢带材、片材或坯料，零件，和用于将坯料热成形为零件的方法
KR20230157997A (ko) 열간-성형 부품 또는 열처리 사전성형 부품을 제조하는 방법과 강철 스트립, 시트 또는 블랭크
KR20250093772A (ko) 냉연강판 및 그 제조방법
KR20220149776A (ko) 강 물품 및 그 제조 방법

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20190701

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: GRANT OF PATENT IS INTENDED

INTG Intention to grant announced

Effective date: 20200401

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE PATENT HAS BEEN GRANTED

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REG Reference to a national code

Ref country code: DE

Ref legal event code: R096

Ref document number: 602017022501

Country of ref document: DE

REG Reference to a national code

Ref country code: AT

Ref legal event code: REF

Ref document number: 1306436

Country of ref document: AT

Kind code of ref document: T

Effective date: 20200915

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

REG Reference to a national code

Ref country code: LT

Ref legal event code: MG4D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20201228

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20201127

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: HR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: LT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: BG

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20201126

Ref country code: NO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20201126

REG Reference to a national code

Ref country code: NL

Ref legal event code: MP

Effective date: 20200826

REG Reference to a national code

Ref country code: AT

Ref legal event code: MK05

Ref document number: 1306436

Country of ref document: AT

Kind code of ref document: T

Effective date: 20200826

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: PL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: RS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: LV

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: IS

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20201226

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SM

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: DK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: CZ

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: RO

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: EE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

REG Reference to a national code

Ref country code: DE

Ref legal event code: R026

Ref document number: 602017022501

Country of ref document: DE

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

PLBI Opposition filed

Free format text: ORIGINAL CODE: 0009260

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: AL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: AT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

PLAX Notice of opposition and request to file observation + time limit sent

Free format text: ORIGINAL CODE: EPIDOSNOBS2

26 Opposition filed

Opponent name: THYSSENKRUPP STEEL EUROPE AG

Effective date: 20210519

26 Opposition filed

Opponent name: ARCELORMITTAL

Effective date: 20210525

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MC

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: SK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20201124

REG Reference to a national code

Ref country code: BE

Ref legal event code: MM

Effective date: 20201130

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20201130

Ref country code: SI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20201130

PLBB Reply of patent proprietor to notice(s) of opposition received

Free format text: ORIGINAL CODE: EPIDOSNOBS3

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20201124

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: TR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: MT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: MK

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20200826

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20201130

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20221128

Year of fee payment: 6

Ref country code: FR

Payment date: 20221123

Year of fee payment: 6

Ref country code: DE

Payment date: 20221125

Year of fee payment: 6

REG Reference to a national code

Ref country code: DE

Ref legal event code: R103

Ref document number: 602017022501

Country of ref document: DE

Ref country code: DE

Ref legal event code: R064

Ref document number: 602017022501

Country of ref document: DE

RDAF Communication despatched that patent is revoked

Free format text: ORIGINAL CODE: EPIDOSNREV1

P01 Opt-out of the competence of the unified patent court (upc) registered

Effective date: 20230517

RDAG Patent revoked

Free format text: ORIGINAL CODE: 0009271

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: PATENT REVOKED

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

27W Patent revoked

Effective date: 20230308

GBPR Gb: patent revoked under art. 102 of the ep convention designating the uk as contracting state

Effective date: 20230308