JP5003785B2 - High tensile steel plate with excellent ductility and method for producing the same - Google Patents
High tensile steel plate with excellent ductility and method for producing the same Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims description 103
- 239000010959 steel Substances 0.000 title claims description 103
- 238000004519 manufacturing process Methods 0.000 title claims description 14
- 238000000137 annealing Methods 0.000 claims description 35
- 229910001566 austenite Inorganic materials 0.000 claims description 31
- 238000001816 cooling Methods 0.000 claims description 25
- 238000010438 heat treatment Methods 0.000 claims description 11
- 229910052748 manganese Inorganic materials 0.000 claims description 11
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- 238000005097 cold rolling Methods 0.000 claims description 8
- 238000004804 winding Methods 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 7
- 239000012535 impurity Substances 0.000 claims description 6
- 229910052757 nitrogen Inorganic materials 0.000 claims description 4
- 229910052698 phosphorus Inorganic materials 0.000 claims description 4
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052759 nickel Inorganic materials 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 12
- 238000005098 hot rolling Methods 0.000 description 11
- 238000005096 rolling process Methods 0.000 description 11
- 230000007423 decrease Effects 0.000 description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- 238000001953 recrystallisation Methods 0.000 description 6
- 229910001567 cementite Inorganic materials 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 230000007547 defect Effects 0.000 description 4
- 229910000734 martensite Inorganic materials 0.000 description 4
- 239000013078 crystal Substances 0.000 description 3
- 230000001771 impaired effect Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910052802 copper Inorganic materials 0.000 description 2
- 238000001887 electron backscatter diffraction Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 229910052758 niobium Inorganic materials 0.000 description 2
- 238000005554 pickling Methods 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 230000006641 stabilisation Effects 0.000 description 2
- 238000011105 stabilization Methods 0.000 description 2
- 238000005482 strain hardening Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 230000009466 transformation Effects 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000001934 delay Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010191 image analysis Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000010422 painting Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002203 pretreatment Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000010583 slow cooling Methods 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
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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
- 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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—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
-
- 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
- C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
-
- 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
- C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
-
- 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
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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)
- Heat Treatment Of Steel (AREA)
Description
本発明は、自動車に代表される輸送機械などの産業分野で使用される高張力鋼板、特に、引張強度(TS)が700〜900MPaの延性に優れた高張力鋼板およびその製造方法に関する。 The present invention relates to a high-tensile steel plate used in the industrial field such as transportation machinery represented by automobiles, and more particularly, to a high-tensile steel plate excellent in ductility with a tensile strength (TS) of 700 to 900 MPa and a method for producing the same.
近年、地球温暖化抑制の観点から、二酸化炭素の排出量低減が喫緊の課題となり、自動車の燃費向上が従来に増して強く求められている。このため、車体材料である鋼板の高張力化により構成部品の薄肉化を図り、車体を軽量化する対策が活発に検討されている。しかし、鋼板の高張力化は不可避的にプレス成形性の低下を招くことから、高張力と良好なプレス成形性を併せ持つ鋼板の開発が推進され、これまでにフェライトとマルテンサイトからなる二相組織鋼板や変態誘起塑性を有する残留オーステナイト鋼板などの種々の複合組織鋼板が自動車部品に適用されて、一定の効果をあげてきた。 In recent years, from the viewpoint of suppressing global warming, reduction of carbon dioxide emissions has become an urgent issue, and there has been a strong demand for improving fuel efficiency of automobiles. For this reason, measures to reduce the weight of the vehicle body by reducing the thickness of the component parts by increasing the tension of the steel plate, which is the vehicle body material, are being actively studied. However, increasing the tensile strength of steel sheets inevitably causes a decrease in press formability, so the development of steel sheets having both high tension and good press formability has been promoted, and so far a two-phase structure consisting of ferrite and martensite. Various composite steel sheets such as steel sheets and retained austenitic steel sheets having transformation-induced plasticity have been applied to automobile parts, and have achieved certain effects.
最近では、近い将来に二酸化炭素の排出規制が一段と厳格化されることが決定され、車体の軽量化目標は非常に高度化している。そのため、従来はTSが540MPa以下の鋼板が使用されていた成形難度の高い部品に対しても薄肉化が必要となり、従来の鋼板と同等のプレス成形性を有するTSが700〜900MPaの高張力鋼板が強く希求されている。 Recently, it has been decided that regulations on carbon dioxide emissions will be tightened in the near future, and the goal of reducing the weight of vehicle bodies has become very sophisticated. For this reason, it is necessary to reduce the thickness of parts with high forming difficulty, where steel sheets with a TS of 540 MPa or less were used in the past, and high strength steel sheets with a TS of 700 to 900 MPa that have the same press formability as conventional steel sheets. Is strongly desired.
こうした状況から、これまで板金素材への適用が少なかった高Mnオーステナイト鋼の高張力鋼板への適用が検討されている。高Mnオーステナイト鋼は、室温下でもオーステナイトを主相とし、従来は非磁性鋼あるいは低温用鋼として利用されてきたが、オーステナイトの双晶誘起塑性によって著しい加工硬化と極めて高い延性を発現することから、この効果を活用した新しいタイプの高延性高張力鋼板が提案されている。例えば、特許文献1には、重量%で、C:1.0%以下、Si:0.01〜2.50%、Mn:10〜30%、sol.Al:0.001〜0.10%、P:0.05%以下、S:0.05%以下を含有し、残部が鉄および不可避不純物からなる鋼組成を有する鋼片を、1100℃以上に加熱後、粗圧延および仕上圧延の総圧下率90%以上で、かつ仕上温度800℃以上、最終板厚が1.1〜5.0mmとなるように連続熱間仕上圧延を終了し、次いで10〜100℃/sの冷却速度にて650℃以下まで冷却後、巻取る加工性に優れた自動車部品用高強度熱延鋼板の製造方法が開示されている。また、特許文献2には、質量%で、C:1.00%以下、Mn:7.00〜30.00%、Al:1.00〜10.00%、Si:2.50%超え8.00%以下、Al+Si:3.50%超え12.00%以下、B:0.00%超え0.01%未満、および任意成分として、Ni:8.00%未満、Cu:3.00%未満、N:0.60%未満、Nb:0.30%未満、Ti:0.30%未満、V:0.30%未満、P:0.01%未満を有する冷間成形性に優れた高強度軽量鋼帯または鋼板が開示されている。さらに、特許文献3には、重量%で、C:0.5〜0.7%、Mn:17〜24%、Si:3%以下、Al:0.050%以下、S:0.030%以下、P:0.08%以下、N:0.1%以下、そして任意の選択として、Cr:1%以下、Mo:0.40%以下、Ni:1%以下、Cu:5%以下、Ti:0.50%以下、Nb:0.50%以下、V:0.50%以下といった元素のうちの一つまたは複数を含み、残部がFeおよび不可避的不純物からなる組成を有し、再結晶率が75%を超え、炭化物の面積率が1.5%未満で、平均オーステナイト粒径が18μm未満であるTSが900MPa超え、TS×El(El:破断伸び)が45000MPa・%超えのFe-C-Mn系オーステナイト熱延鋼板やTSが950MPa超え、TS×Elが45000MPa・%超えのFe-C-Mn系オーステナイト冷延鋼板が開示されている。さらにまた、特許文献4には、C:0.15〜0.70wt%、Si:0.10〜3.00wt%、Mn:12〜30wt%、Ti:0.01〜0.10wt%を含有し、残部が鉄および不可避的不純物からなると共に、CおよびMnの含有量に関し60×Cwt%+Mnwt%≧36wt%を満足し、かつ非金属介在物量に関し清浄度が0.03%以下である鋼塊または鋼片を、1050〜1250℃に加熱後、仕上温度を900℃にして熱間圧延を行う局部変形能に優れた高Mn非磁性鋼の製造方法が開示されている。 Under these circumstances, application of high-Mn austenitic steel to high-tensile steel sheets, which has been rarely applied to sheet metal materials, has been studied. High-Mn austenitic steel has austenite as the main phase even at room temperature and has been used as a non-magnetic steel or a low-temperature steel in the past, but it exhibits remarkable work hardening and extremely high ductility due to twin-induced plasticity of austenite. A new type of high-ductility high-tensile steel sheet utilizing this effect has been proposed. For example, in Patent Document 1, by weight, C: 1.0% or less, Si: 0.01-2.50%, Mn: 10-30%, sol.Al: 0.001-0.10%, P: 0.05% or less, S: 0.05 A steel slab having a steel composition consisting of iron and inevitable impurities with the balance being less than or equal to 1,100 ° C. or higher, after heating to a total rolling reduction of 90% or more of rough rolling and finish rolling, and a finishing temperature of 800 ° C. Finishing continuous hot finish rolling so that the final sheet thickness is 1.1 to 5.0 mm, and then cooling to 650 ° C. or less at a cooling rate of 10 to 100 ° C./s. A method for producing a high-strength hot-rolled steel sheet is disclosed. Patent Document 2 includes mass%, C: 1.00% or less, Mn: 7.00 to 30.00%, Al: 1.00 to 10.0%, Si: 2.50% to 8.00% or less, Al + Si: 3.50% to 12.00% Below, B: more than 0.00% and less than 0.01%, and as optional components, Ni: less than 8.00%, Cu: less than 3.00%, N: less than 0.60%, Nb: less than 0.30%, Ti: less than 0.30%, V: 0.30% A high-strength lightweight steel strip or steel plate excellent in cold formability having less than P and less than 0.01% is disclosed. Furthermore, Patent Document 3 includes, by weight, C: 0.5 to 0.7%, Mn: 17 to 24%, Si: 3% or less, Al: 0.050% or less, S: 0.030% or less, P: 0.08% or less, N: 0.1% or less, and as an option, Cr: 1% or less, Mo: 0.40% or less, Ni: 1% or less, Cu: 5% or less, Ti: 0.50% or less, Nb: 0.50% or less, V: It contains one or more of elements such as 0.50% or less, the balance is composed of Fe and inevitable impurities, the recrystallization rate exceeds 75%, the area ratio of carbide is less than 1.5%, average austenite Fe-C-Mn austenitic hot-rolled steel sheets with a grain size of less than 18μm exceeding 900MPa, TS x El (El: elongation at break) exceeding 45000MPa ・%, TS exceeding 950MPa, TS x El 45000MPa ・% An excess of Fe—C—Mn austenitic cold rolled steel sheet is disclosed. Furthermore, Patent Document 4 contains C: 0.15 to 0.70 wt%, Si: 0.10 to 3.00 wt%, Mn: 12 to 30 wt%, Ti: 0.01 to 0.10 wt%, the balance being iron and inevitable impurities A steel ingot or slab satisfying 60 × Cwt% + Mnwt% ≧ 36 wt% with respect to the content of C and Mn and having a cleanness of 0.03% or less with respect to the amount of non-metallic inclusions is 1050 to 1250 ° C. Discloses a method for producing a high-Mn non-magnetic steel having excellent local deformability, in which hot rolling is performed at a finishing temperature of 900 ° C. after heating.
しかしながら、特許文献1〜4に記載された高Mnオーステナイト鋼板では、高歪域において加工硬化挙動が不安定化する、いわゆる塑性不安定現象が発生しやすいため、プレス成形時にネッキングを起こさずに突発的に破断しやすいという問題がある。 However, in the high-Mn austenitic steel sheets described in Patent Documents 1 to 4, the so-called plastic instability phenomenon that the work hardening behavior becomes unstable in a high strain region is likely to occur, so that it does not cause necking during press forming. There is a problem that it easily breaks.
本発明は、プレス成形時の突発的な破断を回避でき、700〜900MPaのTSを有する延性に優れた高張力鋼板およびその製造方法を提供することを目的とする。 An object of the present invention is to provide a high-tensile steel sheet having a high ductility having a TS of 700 to 900 MPa and a method for producing the same, which can avoid a sudden break during press forming.
本発明者らは、上記の目的を達成するために鋭意検討を重ねた結果、以下のことを見出した。 As a result of intensive studies to achieve the above object, the present inventors have found the following.
i) プレス成形時の突発的な破断を回避するには、JIS Z2201に規定された13B号試験片を用いて測定した局部伸び(l-El)を5%以上にする必要がある。 i) In order to avoid sudden breakage during press forming, the local elongation (l-El) measured using a No. 13B test piece specified in JIS Z2201 needs to be 5% or more.
ii) l-Elを5%以上にするには、3質量%以上のNi添加と平均粒径が5μm以上の再結晶オーステナイト粒からなるミクロ組織にすることが効果的である。 ii) In order to increase l-El to 5% or more, it is effective to form a microstructure composed of Ni addition of 3% by mass or more and recrystallized austenite grains having an average particle diameter of 5 μm or more.
本発明は、このような知見に基づいてなされたものであり、質量%で、C:0.5〜1.5%、Si:0.1%以下、Mn:10〜25%、P:0.1%以下、S:0.05%以下、Al:0.1%以下、Ni:3.0〜8.0%、Mo:0.1%以下、N:0.01%以下を含み、残部がFeおよび不可避的不純物からなる成分組成を有し、平均粒径が5〜30μmの再結晶オーステナイト粒あるいはさらに面積率で1%以下のその他の組織からなるミクロ組織を有することを特徴とする延性に優れた高張力鋼板を提供する。 The present invention has been made based on such knowledge, and in mass%, C: 0.5 to 1.5%, Si: 0.1% or less, Mn: 10 to 25%, P: 0.1% or less, S: 0.05 %, Al: 0.1% or less, Ni: 3.0 to 8.0%, Mo: 0.1% or less, N: 0.01% or less, the balance is composed of Fe and inevitable impurities, the average particle size is 5 Provided is a high-tensile steel sheet having excellent ductility, characterized by having a microstructure composed of recrystallized austenite grains of ˜30 μm or other structures having an area ratio of 1% or less.
本発明の高張力鋼板は、例えば、上記の成分組成を有する鋼スラブを、1100〜1300℃の加熱温度に再加熱後、800℃以上の仕上温度で熱間圧延し、800℃以下の温度域を20℃/s以上の冷却速度で少なくとも600℃まで冷却し、600℃以下の巻取温度で巻き取ることにより製造できる。 The high-tensile steel sheet of the present invention is, for example, a steel slab having the above-described composition composition, reheated to a heating temperature of 1100 to 1300 ° C, hot-rolled at a finishing temperature of 800 ° C or higher, and a temperature range of 800 ° C or lower Is cooled to at least 600 ° C. at a cooling rate of 20 ° C./s or higher, and wound at a winding temperature of 600 ° C. or lower.
巻き取り後、さらに、スケール除去し、750〜1050℃の焼鈍温度で焼鈍し、焼鈍温度から少なくとも450℃までの温度域を10℃/s以上の冷却速度で冷却したり、また、スケール除去し、冷間圧延した後、750〜1050℃の焼鈍温度で焼鈍し、焼鈍温度から少なくとも450℃までの温度域を10℃/s以上の冷却速度で冷却することができる。 After winding, the scale is further removed and annealed at an annealing temperature of 750 to 1050 ° C. The temperature range from the annealing temperature to at least 450 ° C is cooled at a cooling rate of 10 ° C / s or more, and the scale is removed. After cold rolling, annealing is performed at an annealing temperature of 750 to 1050 ° C., and a temperature range from the annealing temperature to at least 450 ° C. can be cooled at a cooling rate of 10 ° C./s or more.
すなわち、本発明の高張力鋼板は、熱間圧延まま(以後、熱延ままと呼ぶ)の鋼板、熱延ままの鋼板を焼鈍した鋼板、熱延ままの鋼板を冷間圧延後焼鈍した鋼板のいずれかの鋼板である。 That is, the high-tensile steel sheet of the present invention is a hot-rolled steel sheet (hereinafter referred to as hot-rolled steel sheet), a hot-rolled steel sheet, a hot-rolled steel sheet, a hot-rolled steel sheet that has been cold-rolled and then annealed. Any steel plate.
本発明により、プレス成形時の突発的な破断を回避でき、700〜900MPaのTSを有する延性に優れた高張力鋼板を製造できるようになった。本発明の高張力鋼板は、優れた強度-延性バランスを有しているので、成形難度の高い部品にも適用可能であり、自動車車体の軽量化に極めて好適である。 According to the present invention, sudden breakage during press forming can be avoided, and a high-tensile steel sheet with excellent ductility having a TS of 700 to 900 MPa can be produced. Since the high-tensile steel sheet of the present invention has an excellent strength-ductility balance, it can be applied to parts with a high degree of forming difficulty, and is extremely suitable for reducing the weight of an automobile body.
本発明の延性に優れた高張力鋼板およびその製造方法について、以下に詳細に説明する。なお、成分の量を表す「%」は、特に断らない限り「質量%」を意味する。 The high-strength steel sheet excellent in ductility of the present invention and the manufacturing method thereof will be described in detail below. Note that “%” representing the amount of a component means “% by mass” unless otherwise specified.
1)成分組成
C:0.5〜1.5%
Cは、オーステナイト相の安定化に必須の元素であり、鋼の高張力化にも大きな役割を果たす。しかし、C量が0.5%未満では、オーステナイト相の安定化が不十分となり、優れた延性が得られない。一方、C量が1.5%を超えると、炭化物の析出によって延性が低下する。そのため、C量は0.5〜1.5%、好ましくは0.5〜1.0%とする。
1) Component composition
C: 0.5-1.5%
C is an essential element for stabilizing the austenite phase and plays a major role in increasing the tensile strength of steel. However, if the C content is less than 0.5%, the austenite phase is not sufficiently stabilized, and excellent ductility cannot be obtained. On the other hand, when the amount of C exceeds 1.5%, ductility decreases due to precipitation of carbides. Therefore, the C content is 0.5 to 1.5%, preferably 0.5 to 1.0%.
Si:0.1%以下
Siは、鋼の脱酸のために添加できる元素である。しかし、鋼中のSi含有量として0.1%を超えるような添加は、脱酸効果の飽和や、介在物の増加による内部欠陥および表面欠陥の増加を招く。そのため、Si量は0.1%以下とする。なお、脱酸効果を十分に得るためには、Si量は0.01〜0.1%とするのが好ましい。
Si: 0.1% or less
Si is an element that can be added for deoxidation of steel. However, addition exceeding 0.1% as the Si content in the steel causes saturation of the deoxidation effect and increases in internal defects and surface defects due to an increase in inclusions. Therefore, the Si content is 0.1% or less. In order to obtain a sufficient deoxidation effect, the Si content is preferably 0.01 to 0.1%.
Mn:10〜25%
Mnは、Cと同様に、オーステナイト相の安定化に必須の元素である。しかし、Mn量が10%未満では、オーステナイト相の安定化が不十分で、優れた延性が得られない。一方、Mn量が25%を超えると、鋼の熱間加工性が低下して鋼板の製造性が損なわれる。そのため、Mn量は10〜25%、好ましくは15〜25%とする。さらに、双晶誘起塑性による延性向上効果を安定して実現させるためには、下記の(1)式を満足するようにC量とMn量を制御することが好ましい。
32≦20×[C]＋[Mn]≦36・・・(1)
ただし、[C]、[Mn]はそれぞれC、Mnの含有量を表す。
Mn: 10-25%
Like C, Mn is an essential element for stabilizing the austenite phase. However, if the Mn content is less than 10%, the austenite phase is not sufficiently stabilized, and excellent ductility cannot be obtained. On the other hand, if the amount of Mn exceeds 25%, the hot workability of the steel decreases and the manufacturability of the steel sheet is impaired. Therefore, the Mn content is 10 to 25%, preferably 15 to 25%. Furthermore, in order to stably realize the effect of improving ductility by twinning induced plasticity, it is preferable to control the amounts of C and Mn so as to satisfy the following formula (1).
32 ≦ 20 × [C] + [Mn] ≦ 36 (1)
However, [C] and [Mn] represent the contents of C and Mn, respectively.
CおよびMnは、上記したように、オーステナイト相の安定化に影響する。発明者らは、オーステナイト相の安定化と材料特性、特にTS×Elバランスとの関係を検討し、C量、Mn量が本願の範囲であり、かつ、C量とMn量が(1)式を満足すると、特にTS×Elバランスが良好となることを知見した。これは、20×[C]＋[Mn]が(1)式を下回る、すなわち32未満となると、オーステナイト相が不安定で、マルテンサイト変態しやすくなり、一方、20×[C]＋[Mn]が(1)式を上回る、すなわち36を超えると、積層欠陥エネルギーが高くなりすぎて、双晶誘起塑性が起こりづらくなるためと考えられる。 C and Mn affect the stabilization of the austenite phase as described above. The inventors examined the relationship between the stabilization of the austenite phase and the material properties, particularly the TS × El balance, and the C amount and Mn amount are within the scope of the present application, and the C amount and Mn amount are expressed by the formula (1). When satisfying the above, it was found that the TS × El balance was particularly good. This is because when 20 × [C] + [Mn] is less than the formula (1), that is, less than 32, the austenite phase is unstable and is likely to undergo martensitic transformation, while 20 × [C] + [Mn ] Exceeds (1), that is, exceeds 36, it is considered that the stacking fault energy becomes too high, and twin-induced plasticity hardly occurs.
P:0.1%以下
P量が0.1%を超えると、鋼の靱性が低下する。そのため、P量は0.1%以下、好ましくは0.05%以下とする。
P: 0.1% or less
When the P content exceeds 0.1%, the toughness of the steel decreases. Therefore, the P content is 0.1% or less, preferably 0.05% or less.
S:0.05%以下
S量が0.05%を超えると、鋼の熱間加工性が低下する。そのため、S量は0.05%以下、好ましくは0.02%以下とする。より好ましくは0.01%以下である。
S: 0.05% or less
When the amount of S exceeds 0.05%, the hot workability of the steel decreases. Therefore, the S content is 0.05% or less, preferably 0.02% or less. More preferably, it is 0.01% or less.
Al:0.1%以下
Alは、鋼の脱酸のために添加できる元素である。しかし、鋼中のAl含有量として0.1%を超えるような添加は、脱酸効果の飽和や、介在物の増加による内部欠陥および表面欠陥の増加を招く。そのため、Al量は0.1%以下とする。なお、脱酸効果を十分に得るためには、Al量は0.01〜0.1%とするのが好ましい。
Al: 0.1% or less
Al is an element that can be added for deoxidation of steel. However, the addition of more than 0.1% as the Al content in the steel causes saturation of the deoxidation effect and increases in internal defects and surface defects due to an increase in inclusions. Therefore, the Al content is 0.1% or less. In order to obtain a sufficient deoxidation effect, the Al content is preferably 0.01 to 0.1%.
Ni:3.0〜8.0%
Niは、本発明において最も重要な元素であり、鋼の積層欠陥エネルギーを増加させ、双晶誘起塑性の発現を安定化させて延性を高める作用を有する。特に、高歪域における塑性不安定化の抑制に効果的であり、高Mnオーステナイト鋼板のl-Elの向上に有効である。こうした効果を十分に得るには、Ni量は3.0%以上とする必要がある。しかし、Ni量が8.0%を超えると、その効果が飽和するとともに、製造コストの増加を招く。そのため、Ni量は3.0〜8.0%、好ましくは3.0〜6.0%とする。
Ni: 3.0-8.0%
Ni is the most important element in the present invention, and has the effects of increasing the stacking fault energy of steel, stabilizing the twin induced plasticity, and increasing the ductility. In particular, it is effective for suppressing plastic instability in a high strain region, and effective for improving l-El of a high Mn austenitic steel sheet. In order to obtain such effects sufficiently, the Ni content needs to be 3.0% or more. However, if the Ni content exceeds 8.0%, the effect is saturated and the manufacturing cost is increased. Therefore, the amount of Ni is set to 3.0 to 8.0%, preferably 3.0 to 6.0%.
Mo:0.1%以下
Moは、鋼の再結晶を遅延させ、オーステナイト粒の微細化を通じて、鋼の高張力化に寄与する元素である。こうした効果を得るには、Mo量は0.01%以上であることが好ましい。しかし、Mo量が0.1%を超えると、TSが900MPaを超え、過度に高張力化し、延性が著しく低下する。そのため、Mo量は0.1%以下、好ましくは0.05%以下とする。
Mo: 0.1% or less
Mo is an element that delays the recrystallization of steel and contributes to increasing the tensile strength of steel through refinement of austenite grains. In order to obtain such an effect, the Mo content is preferably 0.01% or more. However, when the Mo content exceeds 0.1%, TS exceeds 900 MPa, the tension becomes excessively high, and the ductility is significantly reduced. Therefore, the Mo content is 0.1% or less, preferably 0.05% or less.
N:0.01%以下
N量が0.01%を超えると、鋼の延性が低下する。そのため、N量は0.01%以下、好ましくは0.005%以下とする。
N: 0.01% or less
If the N content exceeds 0.01%, the ductility of the steel decreases. Therefore, the N content is 0.01% or less, preferably 0.005% or less.
残部はFeおよび不可避的不純物である。 The balance is Fe and inevitable impurities.
2)ミクロ組織
本発明の高張力鋼板は、平均粒径が5〜30μmの再結晶オーステナイト粒あるいはさらに面積率で1%以下のその他の組織からなるミクロ組織を有する。オーステナイト相の双晶誘起塑性を利用して高延性化を図るには、ミクロ組織はオーステナイト単相であることが必要である。また、高歪域まで安定して双晶誘起塑性を発現させるには、オーステナイト粒は内部の歪エネルギーを十分に開放した再結晶粒であることが必要である。さらに、オーステナイト粒の平均粒径が5μm未満だと、高歪域において変形双晶が生成しにくくなり、塑性不安定現象の発生を招く。そのため、本発明の高張力鋼板では、再結晶オーステナイト粒の平均粒径は5μm以上、好ましくは10μm以上とする。一方、平均粒径が30μmを超えると、所望のTSが得にくくなる。このため、再結晶オーステナイト粒の平均粒径は30μm以下とする。
2) Microstructure The high-tensile steel sheet of the present invention has a microstructure composed of recrystallized austenite grains having an average grain size of 5 to 30 μm or other structures having an area ratio of 1% or less. In order to achieve high ductility by utilizing twin-induced plasticity of the austenite phase, the microstructure needs to be an austenite single phase. Further, in order to stably develop twin-induced plasticity up to a high strain region, it is necessary that the austenite grains are recrystallized grains whose internal strain energy is sufficiently released. Further, if the average grain size of the austenite grains is less than 5 μm, deformation twins are hardly generated in a high strain region, and a plastic instability phenomenon occurs. Therefore, in the high-tensile steel sheet of the present invention, the average grain size of the recrystallized austenite grains is 5 μm or more, preferably 10 μm or more. On the other hand, when the average particle size exceeds 30 μm, it is difficult to obtain a desired TS. For this reason, the average grain size of the recrystallized austenite grains is set to 30 μm or less.
なお、本発明のような高Mnオーステナイト鋼板では、熱間圧延後の冷却速度や焼鈍後の冷却速度により鉄炭化物やマルテンサイト相などの再結晶オーステナイト粒以外のその他の組織が生成する場合がある。高張力と優れた延性を安定して得るには、これらの生成を極力抑制することが好ましいが、組織全体に占めるこれらの面積率が1%以下程度であれば、本発明の目的が損なわれることはない。すなわち、本発明の高張力鋼板は、平均粒径が5〜30μmの再結晶オーステナイト粒からなるミクロ組織、あるいはさらに面積率で1%以下の鉄炭化物やマルテンサイト相などのその他の組織を有するものである。本発明の高張力鋼板は、再結晶オーステナイト粒の平均粒径が5〜30μmであり、該再結晶オーステナイト粒が鋼板組織全体に占める面積率が99%以上であるミクロ組織を有するものである。 In addition, in a high Mn austenitic steel sheet like the present invention, other structures other than recrystallized austenite grains such as iron carbide and martensite phase may be generated depending on the cooling rate after hot rolling and the cooling rate after annealing. . In order to stably obtain high tension and excellent ductility, it is preferable to suppress these generations as much as possible. However, if the area ratio of the entire structure is about 1% or less, the object of the present invention is impaired. There is nothing. That is, the high-tensile steel sheet of the present invention has a microstructure composed of recrystallized austenite grains having an average grain size of 5 to 30 μm, or another structure such as an iron carbide or martensite phase having an area ratio of 1% or less. It is. The high-tensile steel sheet of the present invention has a microstructure in which the average grain size of recrystallized austenite grains is 5 to 30 μm and the area ratio of the recrystallized austenite grains in the entire steel sheet structure is 99% or more.
ここで、再結晶オーステナイト粒の平均粒径は、鋼板の圧延方向平行断面の板厚1/4位置の組織を1000倍ないし5000倍の倍率で数視野SEM観察し、EBSD解析による相同定を併用して画像解析により求めた。また、再結晶粒であるかは、結晶粒形状によりアスペクト比が2未満であるかで判断し、あるいはさらにEBSD解析による粒内の歪量推定を併用して確認した。 Here, the average grain size of the recrystallized austenite grains is obtained by observing the structure of the thickness 1/4 position of the steel plate in the rolling direction parallel section at several magnifications of 1000 to 5000 times and using phase identification by EBSD analysis. And obtained by image analysis. Whether or not it is a recrystallized grain was judged by whether the aspect ratio was less than 2 depending on the crystal grain shape, or further confirmed by using the estimation of intra-grain strain by EBSD analysis.
3)製造条件
以下に、本発明鋼板の好ましい製造条件を示す。なお、本発明の高張力鋼板の製造方法は下記に限定されるものではない。
3) Production conditions The following are preferred production conditions for the steel sheet of the present invention. In addition, the manufacturing method of the high strength steel plate of this invention is not limited to the following.
鋼スラブの加熱温度:1100〜1300℃
鋼スラブの加熱温度が1300℃を超えると、熱間加工性が低下する上、加熱に要するエネルギーが増大する。一方、加熱温度が1100℃未満になると、熱間圧延時の負荷の増大を招く。そのため、鋼スラブの加熱温度は1100〜1300℃、好ましくは1150〜1250℃とする。なお、鋼スラブの加熱においては、常温まで冷却した鋼スラブを再加熱してもよいし、鋳造後の冷却途中の温度が高い鋼スラブを補助的に加熱あるいは保熱してもよい。
Steel slab heating temperature: 1100-1300 ℃
When the heating temperature of the steel slab exceeds 1300 ° C., hot workability deteriorates and energy required for heating increases. On the other hand, when the heating temperature is less than 1100 ° C., the load during hot rolling is increased. Therefore, the heating temperature of the steel slab is set to 1100 to 1300 ° C, preferably 1150 to 1250 ° C. In the heating of the steel slab, the steel slab cooled to room temperature may be reheated, or the steel slab having a high temperature during cooling after casting may be supplementarily heated or heat-retained.
熱間圧延時の仕上温度:800℃以上
熱間圧延時の仕上温度が800℃未満では、再結晶と粒成長が十分に進行せず、未再結晶粒の残存する熱延鋼板となりやすい上、その後に冷間圧延する場合に圧延負荷の増大を招く。そのため、熱間圧延時の仕上温度は800℃以上、好ましくは850℃以上とする。一方、仕上温度が1050℃を超えると、結晶粒が過度に粗大化しやすくなり、強度や延性が低下する場合がある。そのため、仕上温度は1050℃以下とすることが望ましい。なお、仕上温度を確保するために、エッヂヒーターあるいはバーヒーターなどの加熱装置を利用して、圧延中の鋼板を補助的に加熱することもできる。
Finishing temperature during hot rolling: 800 ° C or higher If the finishing temperature during hot rolling is less than 800 ° C, recrystallization and grain growth do not proceed sufficiently, and it is easy to become a hot rolled steel sheet with unrecrystallized grains remaining. Thereafter, when cold rolling is performed, the rolling load is increased. Therefore, the finishing temperature during hot rolling is 800 ° C. or higher, preferably 850 ° C. or higher. On the other hand, when the finishing temperature exceeds 1050 ° C., the crystal grains tend to be excessively coarsened, and the strength and ductility may be reduced. Therefore, the finishing temperature is desirably 1050 ° C. or lower. In order to secure the finishing temperature, the steel sheet being rolled can be supplementarily heated using a heating device such as an edge heater or a bar heater.
熱間圧延後の冷却速度:800℃以下の温度域を20℃/s以上
熱間圧延後、800℃以下の温度域を20℃/s未満の冷却速度で冷却すると、冷却中に鉄炭化物が析出して延性が低下する。そのため、熱間圧延後、800℃以下の温度域を20℃/s以上の冷却速度で少なくとも600℃まで冷却する必要がある。なお、熱間圧延後の冷却速度が100℃/sを超えると、再結晶が完了しない場合があるので、熱間圧延後の冷却速度は100℃/s以下とすることが好ましい。
Cooling rate after hot rolling: 20 ° C / s or more in the temperature range of 800 ° C or less After cooling in the temperature range of 800 ° C or less at a cooling rate of less than 20 ° C / s, iron carbide is formed during cooling. Precipitates and ductility decreases. Therefore, after hot rolling, it is necessary to cool a temperature range of 800 ° C. or lower to at least 600 ° C. at a cooling rate of 20 ° C./s or higher. Note that if the cooling rate after hot rolling exceeds 100 ° C./s, recrystallization may not be completed, and therefore the cooling rate after hot rolling is preferably 100 ° C./s or less.
なお、仕上温度が800℃を超える場合は、再結晶を促進させるために800℃までの温度域を1〜10s間放冷(空冷)することもできる。なお、この場合も、800℃以下の温度域では少なくとも600℃まで20℃/s以上の冷却速度で冷却される。 When the finishing temperature exceeds 800 ° C., the temperature range up to 800 ° C. can be allowed to cool for 1 to 10 seconds (air cooling) in order to promote recrystallization. In this case as well, in the temperature range of 800 ° C. or lower, cooling is performed at a cooling rate of 20 ° C./s or higher to at least 600 ° C.
巻取温度:600℃以下
巻取温度が600℃を超えると、巻き取り後の徐冷過程で鉄炭化物が生成し、延性の低下を招く。そのため、巻取温度は600℃以下、好ましくは550℃以下とする。
Winding temperature: 600 ° C. or less When the winding temperature exceeds 600 ° C., iron carbide is generated in the slow cooling process after winding, resulting in a decrease in ductility. Therefore, the coiling temperature is 600 ° C. or less, preferably 550 ° C. or less.
こうして製造された熱延ままの鋼板は、そのままで本発明の高張力鋼板になり得るが、熱延ままの鋼板をスケール除去後、あるいは熱延ままの鋼板をスケール除去後冷間圧延した後に、以下の焼鈍条件で焼鈍することもできる。なお、スケール除去は、酸洗など、常法に従って行えばよい。 The hot-rolled steel sheet produced in this way can be the high-tensile steel sheet of the present invention as it is, but after removing the scale of the hot-rolled steel sheet or after cold-rolling after removing the scale of the hot-rolled steel sheet, Annealing can also be performed under the following annealing conditions. The scale removal may be performed according to a conventional method such as pickling.
焼鈍条件：焼鈍温度:750〜1050℃、焼鈍温度から少なくとも450℃までの温度域の冷却速度:10℃/s以上
熱延ままの鋼板の粒成長を促進させる上で、750〜1050℃の焼鈍温度で焼鈍を行うことができる。800〜1000℃の焼鈍温度で焼鈍することがより好ましい。
Annealing conditions: Annealing temperature: 750 to 1050 ° C, Cooling rate in temperature range from annealing temperature to at least 450 ° C: 10 ° C / s or more Annealing at 750 to 1050 ° C to promote grain growth of hot rolled steel sheet Annealing can be performed at a temperature. It is more preferable to perform annealing at an annealing temperature of 800 to 1000 ° C.
また、所望の板厚とするために熱延ままの鋼板に冷間圧延を施した鋼板を焼鈍する場合は、750〜1050℃の焼鈍温度で焼鈍を行う必要がある。これは、鋼板の組織を、平均粒径が5〜30μmの再結晶オーステナイト粒からなるミクロ組織とするためである。焼鈍温度が750℃未満では、再結晶が完了せず、十分な延性が得られない。一方、焼鈍温度が1050℃を超えると、結晶粒が過度に粗大化して、強度や延性が低下する場合がある。800〜1000℃の焼鈍温度で焼鈍することがより好ましい。なお、冷間圧延の圧下率は、所望の板厚とできる圧下率とすればよく、特に限定するものでないが、生産効率の観点から50〜70%程度とするのが望ましい。 Moreover, when annealing the steel plate which cold-rolled to the hot-rolled steel plate in order to set it as desired thickness, it is necessary to anneal at the annealing temperature of 750-1050 degreeC. This is because the microstructure of the steel sheet is a microstructure composed of recrystallized austenite grains having an average grain size of 5 to 30 μm. When the annealing temperature is less than 750 ° C., recrystallization is not completed and sufficient ductility cannot be obtained. On the other hand, when the annealing temperature exceeds 1050 ° C., the crystal grains are excessively coarsened, and the strength and ductility may be reduced. It is more preferable to perform annealing at an annealing temperature of 800 to 1000 ° C. The rolling reduction in cold rolling may be a rolling reduction that can be set to a desired thickness, and is not particularly limited, but is preferably about 50 to 70% from the viewpoint of production efficiency.
冷間圧延の有無にかかわらず、焼鈍温度から少なくとも450℃までの冷却速度が10℃/s未満では、鉄炭化物が生成して延性が低下する。そのため、焼鈍温度から少なくとも450℃までの温度域は10℃/s以上の冷却速度で冷却する必要がある。 Regardless of whether or not cold rolling is performed, if the cooling rate from the annealing temperature to at least 450 ° C. is less than 10 ° C./s, iron carbide is generated and ductility is reduced. Therefore, the temperature range from the annealing temperature to at least 450 ° C. needs to be cooled at a cooling rate of 10 ° C./s or more.
本発明の鋼を溶製するには、転炉、電炉どちらも使用可能である。こうして溶製された鋼は、造塊-分塊圧延または連続鋳造によりスラブとされる。必要に応じて、各種予備処理や二次精錬、スラブの表面手入などを実施することが好ましい。また、焼鈍については、連続焼鈍設備で実施することが、生産性の観点から好ましい。熱延ままの鋼板や焼鈍後の鋼板には、各種めっきを施しても、本発明の効果が損なわれることはない。熱延ままの鋼板、焼鈍後の鋼板あるいはめっき処理後の鋼板には、形状矯正や表面粗度の調整のための調質圧延を施すこともできる。さらに、本発明の鋼板には、塗装、被覆などの各種表面処理を施すこともできる。 To melt the steel of the present invention, both a converter and an electric furnace can be used. The steel thus melted is made into a slab by ingot-bundling rolling or continuous casting. If necessary, it is preferable to perform various pretreatments, secondary refining, surface treatment of slabs, and the like. Moreover, it is preferable from a viewpoint of productivity to implement annealing with a continuous annealing facility. The effect of the present invention is not impaired even if various types of plating are applied to a hot-rolled steel plate or a steel plate after annealing. The hot-rolled steel sheet, the steel sheet after annealing, or the steel sheet after plating treatment can be subjected to temper rolling for shape correction and surface roughness adjustment. Furthermore, the steel plate of the present invention can be subjected to various surface treatments such as painting and coating.
表1に示す成分組成の鋼A〜Kの鋼スラブを、表2に示す熱延条件にて熱間圧延して板厚3mmの熱延鋼板とし、酸洗によりスケールを除去後、一部の鋼板については、さらに、表2に示す焼鈍条件で焼鈍したり、あるいは表2に示す冷延圧下率と焼鈍条件で冷間圧延後焼鈍して、熱延まま、熱延+焼鈍、冷延+焼鈍の鋼板1〜20を作製した。 Steel slabs of steels A to K having the composition shown in Table 1 were hot-rolled under the hot rolling conditions shown in Table 2 to obtain a hot-rolled steel plate with a thickness of 3 mm, and after removing the scale by pickling, For steel sheets, further annealed under the annealing conditions shown in Table 2, or annealed after cold rolling under the cold rolling reduction and annealing conditions shown in Table 2, hot rolled, hot rolled + annealed, cold rolled + Annealed steel sheets 1 to 20 were produced.
作製した鋼板について、前記の方法によりミクロ組織を調査し、相構成、再結晶オーステナイト粒の平均粒径を求めた。なお、表3において、相構成は、再結晶オーステナイト粒以外の組織が面積率で1%超観察される場合、その他の組織の種類を示し、その他の組織が面積率で1%以下の場合、再結晶オーステナイトを表している。また、圧延方向に沿ってJIS Z 2201に規定された13B号試験片を採取し、JIS Z 2241に規定された方法に準拠して、引張試験を実施し、TS、El、l-El、TS×Elを求めた。なお、TS×Elが60GPa・%以上の場合に、延性に優れた高張力鋼板と判定した。 About the produced steel plate, the microstructure was investigated by the above-described method, and the phase composition and the average grain size of recrystallized austenite grains were obtained. In Table 3, when the structure other than the recrystallized austenite grains is observed in an area ratio of more than 1%, the structure of the phase indicates the type of other structure, and when the other structure is an area ratio of 1% or less, Recrystallized austenite. In addition, sample No. 13B specified in JIS Z 2201 was sampled along the rolling direction, and a tensile test was performed in accordance with the method specified in JIS Z 2241. TS, El, l-El, TS I asked for El. In addition, when TS × El was 60 GPa ·% or more, it was determined that the steel sheet was excellent in ductility.
結果を表3に示す。本発明例の鋼板はいずれも、平均粒径が5μm以上の再結晶オーステナイト粒からなるミクロ組織を有しており、TSが700〜900MPa、l-Elが5%以上、TS×Elが60GPa・%以上であり、プレス成形時の突発的な破断を回避可能な延性に優れた高張力鋼板であることがわかる。また、前記(1)式を満足する場合、特にTS×Elに優れることがわかる。 The results are shown in Table 3. Each of the steel sheets of the present invention has a microstructure composed of recrystallized austenite grains having an average grain size of 5 μm or more, TS is 700 to 900 MPa, l-El is 5% or more, TS × El is 60 GPa It can be seen that it is a high-tensile steel sheet with excellent ductility that can avoid sudden breaks during press forming. In addition, when the formula (1) is satisfied, it is found that TS × El is particularly excellent.
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| JP2010077305A JP5003785B2 (en) | 2010-03-30 | 2010-03-30 | High tensile steel plate with excellent ductility and method for producing the same |
| CN201180016733.9A CN102822371B (en) | 2010-03-30 | 2011-02-25 | Steel sheet with high tensile strength and superior ductility and method for producing same |
| PCT/JP2011/055007 WO2011122237A1 (en) | 2010-03-30 | 2011-02-25 | Steel sheet with high tensile strength and superior ductility and method for producing same |
| EP11762477.5A EP2554699B1 (en) | 2010-03-30 | 2011-02-25 | Steel sheet with high tensile strength and superior ductility and method for producing same |
| KR1020127021879A KR101287331B1 (en) | 2010-03-30 | 2011-02-25 | Steel sheet with high tensile strength and superior ductility and method for producing same |
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| US20140261918A1 (en) * | 2013-03-15 | 2014-09-18 | Exxonmobil Research And Engineering Company | Enhanced wear resistant steel and methods of making the same |
| KR101665807B1 (en) | 2014-12-23 | 2016-10-13 | 주식회사 포스코 | High manganese steel sheet having excellent hot dip aluminium coatability, and method for manufacturing the same |
| KR101665801B1 (en) | 2014-12-23 | 2016-10-13 | 주식회사 포스코 | High manganese steel sheet having excellent hot dip aluminium coatability, and method for manufacturing the same |
| KR20160078840A (en) | 2014-12-24 | 2016-07-05 | 주식회사 포스코 | High manganese steel sheet having superior yield strength and fromability, and method for manufacturing the same |
| CN104711494B (en) * | 2015-04-14 | 2017-11-28 | 钢铁研究总院 | Low-density high-ductility NiAl strengthens unimach and preparation method |
| JP6455333B2 (en) * | 2015-06-23 | 2019-01-23 | 新日鐵住金株式会社 | High Mn steel for high-pressure hydrogen gas and pipes, containers, valves and joints made of the steel |
| JP6703608B2 (en) * | 2015-12-22 | 2020-06-03 | ポスコＰｏｓｃｏ | Austenitic steel with excellent hydrogen embrittlement resistance |
| WO2017111491A1 (en) | 2015-12-24 | 2017-06-29 | 주식회사 포스코 | Austenite-based molten aluminum-plated steel sheet having excellent properties of plating and weldability, and method for manufacturing same |
| KR101747034B1 (en) | 2016-04-28 | 2017-06-14 | 주식회사 포스코 | Ultra high strength and high ductility steel sheet having excellent yield ratio, and method for manufacturing the same |
| US20170349983A1 (en) * | 2016-06-06 | 2017-12-07 | Exxonmobil Research And Engineering Company | High strength cryogenic high manganese steels and methods of making the same |
| TWI630277B (en) * | 2016-12-19 | 2018-07-21 | 杰富意鋼鐵股份有限公司 | High manganese steel plate and manufacturing method thereof |
| KR101940874B1 (en) | 2016-12-22 | 2019-01-21 | 주식회사 포스코 | High manganese steel with superior low temperature toughness and yield strength and method for manufacturing the same |
| JP2018162507A (en) * | 2017-03-27 | 2018-10-18 | 新日鐵住金株式会社 | High-strength oil well steel and oil well pipe |
| WO2019044928A1 (en) * | 2017-09-01 | 2019-03-07 | Ｊｆｅスチール株式会社 | High-mn steel and production method therefor |
| KR101977491B1 (en) | 2017-11-08 | 2019-05-10 | 주식회사 포스코 | Ultra-high strength and high-ductility steel sheet having excellent cold formability, and method for manufacturing thereof |
| KR102405388B1 (en) * | 2017-12-07 | 2022-06-03 | 제이에프이 스틸 가부시키가이샤 | High Mn steel and its manufacturing method |
| KR101999032B1 (en) | 2017-12-26 | 2019-09-27 | 주식회사 포스코 | High manganese coated steel welded structure with superior spot weldability and method for manufacturing same |
| KR102065230B1 (en) | 2017-12-26 | 2020-01-10 | 주식회사 포스코 | Zinc coated high manganese steel sheet with superior spot weldability and method for manufacturing same |
| WO2019156179A1 (en) * | 2018-02-07 | 2019-08-15 | Ｊｆｅスチール株式会社 | HIGH-Mn STEEL AND PRODUCTION METHOD THEREFOR |
| KR102492352B1 (en) | 2018-08-03 | 2023-01-27 | 제이에프이 스틸 가부시키가이샤 | High Mn steel and its manufacturing method |
| WO2021033694A1 (en) * | 2019-08-21 | 2021-02-25 | Ｊｆｅスチール株式会社 | Steel and method for manufacturing same |
| KR102462130B1 (en) * | 2020-10-26 | 2022-11-03 | 현대제철 주식회사 | Method of manufacturing ultra high strength hot rolled steel sheet having softening heat treatment and apparatus of manufacturing hot rolled steel sheet |
| CN113278894A (en) * | 2021-05-20 | 2021-08-20 | 成都先进金属材料产业技术研究院股份有限公司 | Fe-Mn-Al-S series low-density free-cutting steel and preparation method thereof |
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| JPH04259325A (en) * | 1991-02-13 | 1992-09-14 | Sumitomo Metal Ind Ltd | Production of hot rolled high strength steel sheet excellent in workability |
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| KR101287331B1 (en) | 2013-07-23 |
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| JP2011208226A (en) | 2011-10-20 |
| WO2011122237A1 (en) | 2011-10-06 |
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| KR20120113789A (en) | 2012-10-15 |
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