US20100012233A1 - Ultra high strength twip steel sheet and manufacturing method thereof - Google Patents

Ultra high strength twip steel sheet and manufacturing method thereof Download PDF

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Publication number
US20100012233A1
US20100012233A1 US12/400,077 US40007709A US2010012233A1 US 20100012233 A1 US20100012233 A1 US 20100012233A1 US 40007709 A US40007709 A US 40007709A US 2010012233 A1 US2010012233 A1 US 2010012233A1
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United States
Prior art keywords
steel sheet
twip steel
high strength
ultra high
plastic strain
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Abandoned
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US12/400,077
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English (en)
Inventor
Seung Hyun Hong
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Hyundai Motor Co
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Hyundai Motor Co
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Assigned to HYUNDAI MOTOR COMPANY reassignment HYUNDAI MOTOR COMPANY ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HONG, SEUNG HYUN
Publication of US20100012233A1 publication Critical patent/US20100012233A1/en
Abandoned legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/04—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing
    • C21D8/0421—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips to produce plates or strips for deep-drawing characterised by the working steps
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • 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

Definitions

  • the present invention relates to a twinning induced plasticity (TWIP) steel sheet in which both slip and twin serve as a deformation mechanism at the time of plastic deformation, and a method of manufacturing the same. More particularly, the invention relates to a twinning induced plasticity (TWIP) steel sheet for vehicle body components, which has a high plastic strain ratio (r value), and a method of manufacturing the same.
  • TWIP twinning induced plasticity
  • ultra high strength steel sheets which are widely used as materials for automotive body components, have a tensile strength of 590 ⁇ 780 MPa, a yield strength of 270 ⁇ 350 MPa, an elongation rate of 25 ⁇ 35% and a plastic strain ratio of 0.9 ⁇ 1.2.
  • Korean Unexamined Patent Application Publication No. 2007-0018416 (not published yet), incorporated by reference in its entirety herein, is directed to an ultra high strength TWIP steel sheet, comprising: 0.15 ⁇ 0.30 wt % of carbon, 0.01 ⁇ 0.03 wt % of silicon, 15 ⁇ 25 wt % of manganese, 1.2 ⁇ 3.0 wt % of aluminum, 0.020 wt % or less of phosphorus, 0.001 ⁇ 0.002 wt % of sulfur, and residual iron and other inevitable impurities.
  • the present invention is directed to an ultra high strength TWIP steel sheet having improved plastic strain ratio, and a method of manufacturing the same.
  • the present invention provides a technology of remarkably improving the plastic strain ratio of a TWIP steel sheet under given conditions by suitably controlling textures, that is preferred orientations, during cold rolling rather than controlling composition of the TWIP steel sheet as disclosed in Korean Unexamined Patent Application Publication No. 2007-0018416, incorporated by reference in its entirety herein.
  • an ultra high strength TWIP steel sheet according to the present invention includes 0.15 ⁇ 0.30 wt % of carbon, 0.01 ⁇ 0.03 wt % of silicon, 15 ⁇ 25 wt % of manganese, 1.2 ⁇ 3.0 wt % of aluminum, 0.020 wt % or less of phosphorus, 0.001 ⁇ 0.002 wt % of sulfur, residual iron and other inevitable impurities.
  • the ultra high strength TWIP steel sheet is suitably cold-rolled at a reduction ratio of 35 ⁇ 40% per pass under the condition of 180 ⁇ 220 Mpa of front and rear tension, so that it has an average plastic strain ratio of 1.2 or more and has an Goss orientation as a main texture component.
  • most of the materials obtained from nature or from working are polycrystalline materials in the form of crystal aggregates. Accordingly, their crystallographic orientations are not random, and appear in specific orientations. In further preferred embodiments, these materials having ordered crystal orientations are referred to as materials having preferred orientations, that is, textures.
  • an austenite matrix metal plate for example a TWIP steel sheet, preferably has a crystallographic texture including, but not limited to, copper orientation, Goss orientation, brass orientation, S orientation and cube orientation.
  • the relative volume fractions of these orientations influence the average plastic strain ratio of the austenite matrix metal plate.
  • the crystal orientation of the metal plate produced through rolling is suitably defined by a rolling plane and a rolling direction. That is, the texture of the metal plate may be defined by a crystal plane placed suitably parallel to the rolling plane and a crystal direction placed suitably parallel to the rolling direction. Accordingly, in further embodiments, the crystal plane is represented by Miller indices ⁇ hkl ⁇ , and the crystal direction is represented by ⁇ uvw>.
  • copper orientation is represented by ⁇ 112 ⁇ 111>
  • Goss orientation is represented by ⁇ 011 ⁇ 100>
  • brass orientation is represented by ⁇ 112 ⁇ 110>
  • S orientation is represented by ⁇ 123 ⁇ 634>
  • cube orientation is represented by ⁇ 001 ⁇ 100>.
  • brass orientation is preferably particularly developed as a main orientation during cold rolling.
  • plastic strain ratio at an angle of 90° with respect to a rolling direction is low, its average plastic strain ratio thereof is also low, and thus there is a problem of rupturing or cracking at the time of forming.
  • the ultra high-strength TWIP steel sheet of the present invention in addition to a brass-oriented texture, since a Goss-oriented texture in which a plastic strain ratio at an angle of 90° with respect to a rolling direction is improved is also developed, it has an average plastic strain ratio of 1.2 or more, preferably 1.5 or more, and its press formability is suitably improved.
  • a method of manufacturing the ultra high strength TWIP steel sheet according to the present invention preferably includes: cold-rolling of a hot-rolled steel sheet having an austenite matrix having the above composition at a reduction ratio of 35 ⁇ 40% per pass under the condition of 180 ⁇ 220 Mpa in front and rear tension; and annealing of the cold-rolled steel sheet at a temperature of 850 ⁇ 900° C.
  • the hot-rolled steel sheet can be suitably obtained by hot-rolling of a continuously-cast slab at a temperature of 1300 ⁇ 1100° C. and then gradually cooling the hot-rolled slab at a cooling rate of 60° C./sec or less such that a martensite phase is not formed.
  • the cold-rolling of a TWIP steel sheet was performed during 5 ⁇ 7 passes at a reduction ratio of 20 ⁇ 30% per pass while suitably applying a front and rear tension of about 120 MPa thereto.
  • the front and rear tension was less than 120 MPa. Accordingly, with the increase of the front and rear tension, rolling reduction is suitably decreased, so that it is difficult to adjust a reduction ratio per pass to 30%, thereby increasing a process time, and that, according to other further embodiments, with the increase of the front and rear tension, it is difficult to control a texture after annealing.
  • the TWIP steel sheet which is an ultrahigh tension steel sheet
  • the TWIP steel sheet has high strength, it is difficult to cold-roll the TWIP steel at a high reduction ratio.
  • the stress caused by rolling is suitably reduced, it is possible to cold-roll the TWIP steel at a high reduction ratio of about 40% per pass. Further, the number of passes can be suitably decreased.
  • vehicle or “vehicular” or other similar term as used herein is inclusive of motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum).
  • motor vehicles in general such as passenger automobiles including sports utility vehicles (SUV), buses, trucks, various commercial vehicles, watercraft including a variety of boats and ships, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g. fuels derived from resources other than petroleum).
  • SUV sports utility vehicles
  • plug-in hybrid electric vehicles e.g. fuels derived from resources other than petroleum
  • a hybrid vehicle is a vehicle that has two or more sources of power, for example both gasoline-powered and electric-powered.
  • FIG. 1 is a graph showing the orientation distribution function (ODF) of a TWIP steel sheet according to a Comparative Example
  • FIG. 2 is a graph showing the plastic strain ratio (R) to an angle relative to the rolling direction of a TWIP steel sheet according to the Comparative Example shown in FIG. 1 ;
  • FIG. 3 is a graph showing the orientation distribution function (ODF) of a TWIP steel sheet according to an Example.
  • FIG. 4 is a graph showing the plastic strain ratio (R) to an angle relative to the rolling direction of a TWIP steel sheet according to the Example shown in FIG. 3 .
  • the present invention includes an ultra high strength TWIP steel sheet having an austenite matrix, comprising 0.15 ⁇ 0.30 wt % of carbon, 0.01 ⁇ 0.03 wt % of silicon, 15 ⁇ 25 wt % of manganese, 1.2 ⁇ 3.0 wt % of aluminum, 0.020 wt % or less of phosphorus, 0.001 ⁇ 0.002 wt % of sulfur, and residual iron and other inevitable impurities, wherein the TWIP steel sheet is cold-rolled at a reduction ratio of 35 ⁇ 40% per pass under a condition of 180 ⁇ 220 Mpa in front and rear tension.
  • the sheet has an average plastic strain ratio of 1.2 or more.
  • the invention also features a method of manufacturing an ultra high strength TWIP steel sheet having an improved average plastic strain ratio, comprising cold-rolling a hot-rolled steel sheet having an austenite matrix and comprising 15 ⁇ 25 wt % of manganese at a reduction ratio of 35 ⁇ 40% per pass under a condition of 180 ⁇ 220 Mpa in front and rear tension, and annealing the cold-rolled steel sheet.
  • the annealing is carried out at a temperature of 850 ⁇ 900° C.
  • the invention also includes a motor vehicle comprising an ultra high strength TWIP steel sheet having an austenite matrix,
  • the ultra high strength TWIP steel sheet according to preferred embodiments of the present invention is a high manganese steel sheet including 15 ⁇ 25 wt % of manganese.
  • the ultra high strength TWIP steel sheet according to the present invention may have the same composition as that of the TWIP steel sheet disclosed in Korean Unexamined Patent Application Publication No. 2007-0018416 (refer to Table 1), incorporated by reference herein.
  • the reason why the amounts of the components included in the TWIP steel sheet are limited is similar to that described in the specification of Korean Unexamined Patent Application Publication No. 2007-0018416.
  • a plurality of TWIP steel sheets having a composition shown in Table 2 below was fabricated, and in further preferred embodiments, tests for measuring the average plastic strain ratio thereof were suitably conducted.
  • the TWIP steel sheet used in the test was suitably manufactured as follows. First, the composition shown in Table 2 was melted in an electric furnace and then continuously cast to suitably obtain a slab, and then the obtained slab was hot-rolled from 1300° C. to 1100° C. In further embodiments, the hot-rolled slab was gradually cooled to a temperature of 900 ⁇ 600° C. at a cooling rate of 40° C./sec and then coiled to obtain a hot-rolled coil. In further exemplary embodiments, the obtained hot-rolled coil was cold-rolled, and then annealed at a temperature of 850° C. for 10 hours.
  • the TWIP steel sheet according to preferred embodiments of the present invention has a single phase matrix, preferably mostly including austenite although very partially including martensite or ferrite.
  • Table 3 shows the specific cold-rolling conditions and average plastic strain ratios of the TWIP steel sheets manufactured in Examples 1 to 6 and Comparative Examples 1 to 15.
  • the cold-rolling conditions are preferably that front and rear tension is 180 ⁇ 220 Mpa, and reduction ratio per pass (7 passes total) was preferably 30 ⁇ 40%.
  • the cold-rolling conditions were that front and rear tension is preferably 120 ⁇ 230 Mpa, and reduction ratio per pass (7 passes total) was 20 ⁇ 45%.
  • each of the average plastic strain ratios was obtained by calculating the plastic strain ratios suitably measured at an angle of 0°, 45° and 90° with respect to a rolling direction.
  • the average plastic strain ratios of the TWIP steel sheets in Comparative Examples 1 to 15 were about 0.83, and none of them exceeded 1.0, and the TWIP steel sheets in Comparative Examples 1 to 15 were cut and deteriorated. In other embodiments, all of the average plastic strain ratios of the TWIP steel sheets in Examples 1 to 5 were 1.5 or more, and the TWIP steel sheets in Examples 1 to 5 exhibited excellent average plastic strain ratio.
  • the reduction ratio of the TWIP steel sheet can be suitably increased only under the front and rear tension within a suitably predetermined range at the time of cold rolling. Accordingly, it is suitably determined that this fact is related to the formation of twin. That is, according to certain embodiments, it is determined that, in the case of the TWIP steel sheet which is a metal sheet having low stacking fault energy (SFE), its deformation is suitably maximized in a predetermined stress range because twin serves as a deformation mechanism, but it is deformed only by slip because the formation of twin is inhibited outside the predetermined stress range, and thus it is limited to accommodate external deformation.
  • SFE stacking fault energy
  • the texture and plastic strain ratio of the TWIP steel sheet in Example 1 are compared with those in Comparative Example 1 with reference to FIGS. 1 to 4 .
  • brass orientation was suitably developed as main orientation (refer to the orientation distribution function (ODF) graph shown in FIG. 1 ), and the average plastic strain ratio thereof was about 0.83, and the plastic strain ratios thereof at an angle of 90° with respect to a rolling direction were 0.7 or less (refer to FIG. 2 ).
  • the present invention provides an ultra high strength TWIP steel sheet having an excellent average plastic strain ratio due to the development of a Goss-oriented texture.
  • the present invention preferably provides an ultra high strength TWIP steel sheet, which can be cold-rolled at a high reduction ratio while suitably decreasing the number of passes, and which can realize press formability by improving the average plastic strain ratio 1.2 times, preferably 1.5 times.

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  • 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)
  • Metal Rolling (AREA)
US12/400,077 2008-07-18 2009-03-09 Ultra high strength twip steel sheet and manufacturing method thereof Abandoned US20100012233A1 (en)

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KR10-2008-0070011 2008-07-18
KR1020080070011A KR101020546B1 (ko) 2008-07-18 2008-07-18 초고강도 ｔｗｉｐ 강판 및 그 제조방법

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103526038A (zh) * 2013-10-22 2014-01-22 北京科技大学 一种高强度高塑性twip钢电渣重熔生产方法
CN104532137A (zh) * 2014-12-23 2015-04-22 福建工程学院 钼铬合金化的高强度高塑性高碳twip钢及其制备方法
WO2015077934A1 (zh) * 2013-11-27 2015-06-04 何丽丽 一种孪晶诱导塑性钢及其生产方法
CN106350739A (zh) * 2016-09-14 2017-01-25 钢铁研究总院 高应变速率中低碳中低合金超塑性钢及制备方法
US20180013782A1 (en) * 2014-12-26 2018-01-11 Interdigital Patent Holdings, Inc. Continuous device/uicc based authentication for lte systems
US10144982B2 (en) 2012-05-14 2018-12-04 Postech Academy-Industry Foundation Fe—Mn—C-based TWIP steel having remarkable mechanical performance at very low temperature, and preparation method thereof
CN114606430A (zh) * 2022-03-01 2022-06-10 兴机电器有限公司 一种低碳Fe-Mn-Al-Si系TWIP钢及其制备方法
CN114990438A (zh) * 2022-05-31 2022-09-02 江西宝顺昌特种合金制造有限公司 一种高锰高铝低磁奥氏体钢及其制造方法

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101585714B1 (ko) * 2013-10-21 2016-01-22 주식회사 포스코 Ｔｗｉｐ강 추출복제시료의 제조방법
EP3095889A1 (en) 2015-05-22 2016-11-23 Outokumpu Oyj Method for manufacturing a component made of austenitic steel
EP3173504A1 (en) 2015-11-09 2017-05-31 Outokumpu Oyj Method for manufacturing an austenitic steel component and use of the component

Citations (1)

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US20090010793A1 (en) * 2004-11-03 2009-01-08 Thyssenkrupp Steel Ag Method For Producing High Strength Steel Strips or Sheets With Twip Properties, Method For Producing a Component and High-Strength Steel Strip or Sheet

Family Cites Families (3)

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DE10259230B4 (de) 2002-12-17 2005-04-14 Thyssenkrupp Stahl Ag Verfahren zum Herstellen eines Stahlprodukts
KR20070018416A (ko) * 2005-08-10 2007-02-14 현대자동차주식회사 자동차 차체부품용 ｔｗｉｐ형 초고강도 강판 및 그제조방법
KR100851158B1 (ko) * 2006-12-27 2008-08-08 주식회사 포스코 충돌특성이 우수한 고망간형 고강도 강판 및 그 제조방법

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090010793A1 (en) * 2004-11-03 2009-01-08 Thyssenkrupp Steel Ag Method For Producing High Strength Steel Strips or Sheets With Twip Properties, Method For Producing a Component and High-Strength Steel Strip or Sheet

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10144982B2 (en) 2012-05-14 2018-12-04 Postech Academy-Industry Foundation Fe—Mn—C-based TWIP steel having remarkable mechanical performance at very low temperature, and preparation method thereof
CN103526038A (zh) * 2013-10-22 2014-01-22 北京科技大学 一种高强度高塑性twip钢电渣重熔生产方法
WO2015077934A1 (zh) * 2013-11-27 2015-06-04 何丽丽 一种孪晶诱导塑性钢及其生产方法
CN104532137A (zh) * 2014-12-23 2015-04-22 福建工程学院 钼铬合金化的高强度高塑性高碳twip钢及其制备方法
US20180013782A1 (en) * 2014-12-26 2018-01-11 Interdigital Patent Holdings, Inc. Continuous device/uicc based authentication for lte systems
CN106350739A (zh) * 2016-09-14 2017-01-25 钢铁研究总院 高应变速率中低碳中低合金超塑性钢及制备方法
CN114606430A (zh) * 2022-03-01 2022-06-10 兴机电器有限公司 一种低碳Fe-Mn-Al-Si系TWIP钢及其制备方法
CN114990438A (zh) * 2022-05-31 2022-09-02 江西宝顺昌特种合金制造有限公司 一种高锰高铝低磁奥氏体钢及其制造方法

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KR20100009222A (ko) 2010-01-27

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