JPH11100636A - Good workability and high strength cold rolled steel sheet having high dynamic deformation resistance and its production - Google Patents
Good workability and high strength cold rolled steel sheet having high dynamic deformation resistance and its productionInfo
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- JPH11100636A JPH11100636A JP9258928A JP25892897A JPH11100636A JP H11100636 A JPH11100636 A JP H11100636A JP 9258928 A JP9258928 A JP 9258928A JP 25892897 A JP25892897 A JP 25892897A JP H11100636 A JPH11100636 A JP H11100636A
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- steel sheet
- less
- rolled steel
- deformation resistance
- strain
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- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、自動車部材等に使
用され、衝突時の衝撃エネルギーを効率よく吸収するこ
とによって乗員の安全性確保に寄与することの出来る高
い動的変形抵抗を示す高強度冷延鋼板とその製造方法に
関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength steel having a high dynamic deformation resistance which can be used for automobile parts and the like and which can contribute to ensuring the safety of occupants by efficiently absorbing impact energy at the time of collision. The present invention relates to a cold-rolled steel sheet and a method for producing the same.
【０００２】[0002]
【従来の技術】近年、自動車衝突時の乗員保護が自動車
の最重要性能として認識され、それに対応するための高
い高速変形抵抗を示す材料への期待が高まっている。例
えば乗用車の前面衝突においては、フロントサイドメン
バと呼ばれる部材にこのような材料を適用すれば、該部
材が圧潰することで衝撃のエネルギーが吸収され、乗員
にかかる衝撃を和らげることが出来る。2. Description of the Related Art In recent years, occupant protection in the event of an automobile collision has been recognized as the most important performance of an automobile, and there has been an increasing expectation for a material exhibiting high high-speed deformation resistance in order to cope with it. For example, in a frontal collision of a passenger car, if such a material is applied to a member called a front side member, the member is crushed so that the energy of the impact is absorbed and the impact on the occupant can be reduced.
【０００３】自動車の衝突時に各部位が受ける変形の歪
み速度は１０3 （１／ｓ）程度まで達するため、材料の
衝撃吸収性能を考える場合には、この様な高歪み速度領
域での動的変形特性の解明が必要である。また同時に、
省エネルギー、ＣＯ2 排出削減を目指して自動車車体の
軽量化を同時に達成することが必須と考えられ、このた
めに有効な高強度鋼板へのニーズが高まっている。[0003] Since the strain rate of deformation applied to each part at the time of an automobile collision reaches up to about 10 3 (1 / s), when considering the shock absorbing performance of a material, dynamic deformation in such a high strain rate region is considered. It is necessary to clarify the deformation characteristics. At the same time,
It is considered essential to simultaneously reduce the weight of automobile bodies with the aim of conserving energy and reducing CO 2 emissions, and for this purpose there is a growing need for effective high-strength steel sheets.
【０００４】例えば本発明者らは、ＣＡＭＰ−ＩＳＩＪ
Ｖｏｌ．９（１９９６）Ｐ．１１１２〜１１１５に、
高強度薄鋼板の高速変形特性と衝撃エネルギー吸収能に
ついて報告し、その中で、１０3 （１／ｓ）程度の高歪
み速度領域での動的強度は、１０-3（１／ｓ）の低歪み
速度での静的強度と比較して大きく上昇すること、材料
の強化機構によって変形抵抗の歪み速度依存性が変化す
ること、この中で、ＴＲＩＰ（変態誘起塑性）型の鋼や
ＤＰ（フェライト／マルテンサイト２相）型の鋼が他の
高強度鋼板に比べて優れた成形性と衝撃吸収能を兼ね備
えていることを報告している。[0004] For example, the present inventors have proposed CAMP-ISIJ.
Vol. 9 (1996) p. 1112 to 1115,
We report the high-speed deformation characteristics and the impact energy absorption capacity of a high-strength thin steel sheet. Among them, the dynamic strength in the high strain rate region of about 10 3 (1 / s) is 10 −3 (1 / s). It greatly increases compared to the static strength at a low strain rate, and the strain rate dependence of the deformation resistance changes by the strengthening mechanism of the material. Among them, TRIP (transformation induced plasticity) type steel and DP ( It is reported that a ferrite / martensite (two phase) type steel has both excellent formability and shock absorbing ability as compared with other high strength steel sheets.
【０００５】また、残留オーステナイトを含む耐衝撃特
性に優れた高強度鋼板とその製造方法を提供するものと
して特開平７−１８３７２号公報には、衝撃吸収能を変
形速度の上昇に伴う降伏応力の上昇のみで解決できるこ
とが開示されているが、衝撃吸収能を向上させるため
に、残留オーステナイトの量以外に残留オーステナイト
の性質をどのように制御すべきかは明確にされていな
い。Japanese Patent Application Laid-Open No. 7-18372 discloses a high-strength steel sheet having excellent impact resistance including retained austenite and a method of manufacturing the same. Although it is disclosed that the problem can be solved only by raising, it is not clear how to control the properties of the retained austenite other than the amount of the retained austenite in order to improve the shock absorbing ability.
【０００６】[0006]
【発明が解決しようとする課題】このように、自動車衝
突時の衝撃エネルギーの吸収に及ぼす部材構成材料の動
的変形特性は少しづつ解明されつつあるものの、衝撃エ
ネルギー吸収能に優れた自動車部品用鋼材としてどの様
な特性に注目し、どの様な基準に従って材料選定を行う
べきかは未だ明らかにはされていない。また、自動車用
部品は、鋼材をプレス成形によって要求された部品形状
に成形され、その後、一般的には塗装焼き付けされた後
に自動車に組み込まれ、実際の衝突現象に直面する。し
かしながら、このような予変形＋焼き付け処理を行った
後の鋼材の衝突時の衝撃エネルギー吸収能の向上にどの
ような鋼材強化機構が適しているかも未だ明らかにはさ
れていない。As described above, although the dynamic deformation characteristics of the constituent materials affecting the absorption of the impact energy at the time of the collision of the automobile are gradually being elucidated, the automotive parts having excellent impact energy absorption capability are being elucidated. It has not yet been clarified what properties should be focused on and what criteria should be used for material selection as steel materials. In addition, automotive parts are formed by pressing steel into the required part shape and then, after being generally painted and baked, are assembled into the automobile and face an actual collision phenomenon. However, it has not yet been clarified what steel material strengthening mechanism is suitable for improving the impact energy absorbing ability at the time of collision of the steel material after performing such pre-deformation and baking treatment.
【０００７】[0007]
【課題を解決するための手段】本発明は、フロントサイ
ドメンバー等の衝突時の衝撃エネルギー吸収を担う部品
に成形加工されて使用される鋼材で、高い衝撃エネルギ
ー吸収能を示す高強度鋼板とその製造方法を提供するこ
とを目的としている。本発明の要旨は次のとおりであ
る。SUMMARY OF THE INVENTION The present invention relates to a high-strength steel sheet having high impact energy absorbing ability, which is a steel material formed into a part for absorbing impact energy at the time of collision such as a front side member and used. It is intended to provide a manufacturing method. The gist of the present invention is as follows.
【０００８】（１）重量％で、Ｃ：０．０４％以上０．
３％以下、ＳｉとＡｌの一方または双方を合計で０．５
％以上３．０％以下、Ｍｎ，Ｎｉ，Ｃｒ，Ｃｕ，Ｍｏの
１種または２種以上を合計で０．５％以上３．５％以下
含み、残部がＦｅ及び不可避的不純物からなり、最終的
に得られる冷延鋼板のミクロ組織がフェライトおよびベ
イナイトを含み、このいずれかを主相とし、体積分率で
３％以上の残留オーステナイトを含む第３相との複合組
織であり、残留オーステナイト中の固溶〔Ｃ〕量と鋼材
の平均Ｍｎ等量｛Ｍｎｅｑ＝Ｍｎ＋（Ｎｉ＋Ｃｒ＋Ｃｕ
＋Ｍｏ）／２｝によって決まる値（Ｍ＝６７８−４２８
×〔Ｃ〕−３３×Ｍｎｅｑ）が−１４０以上７０未満
で、その鋼材に相当歪みで０％超１０％以下の予変形を
与えた後、５×１０2 〜５×１０3 （１／ｓ）の歪み速
度範囲で変形した時の３〜１０％の相当歪み範囲におけ
る変形応力の平均値σｄｙｎ（ＭＰａ）と５×１０-4〜
５×１０-3（１／ｓ）の歪み速度範囲で変形した時の３
〜１０％の相当歪み範囲における変形応力の平均σｓｔ
（ＭＰａ）の差が５×１０-4〜５×１０-3（１／ｓ）の
歪み速度範囲で測定された静的な引張り試験における最
大応力ＴＳ（ＭＰａ）によって表現される式（σｄｙｎ
−σｓｔ）≧−０．２７２×ＴＳ＋３００を満足するこ
とを特徴とする高い動的変形抵抗を有する良加工性高強
度冷延鋼板。(1) By weight%, C: 0.04% or more.
3% or less, one or both of Si and Al in total of 0.5
% Or more and 3.0% or less, one or more of Mn, Ni, Cr, Cu and Mo are contained in a total of 0.5% or more and 3.5% or less, with the balance being Fe and inevitable impurities. The microstructure of the cold-rolled steel sheet obtained as described above contains a ferrite and bainite, and is a composite structure with a third phase containing either one of the main phases and having a retained volume of 3% or more of retained austenite. [C] amount and the average Mn equivalent of steel material 鋼 Mneq = Mn + (Ni + Cr + Cu
+ Mo) / 2} (M = 678-428)
× [C] −33 × Mneq) is −140 or more and less than 70, and after giving a pre-deformation of more than 0% and 10% or less with considerable strain to the steel material, 5 × 10 2 to 5 × 10 3 (1 / s) ) And the average value of the deformation stress σdyn (MPa) in the equivalent strain range of 3 to 10% when deformed in the strain rate range of 5 × 10 −4 to 5 × 10 −4 .
3 when deformed in the strain rate range of 5 × 10 -3 (1 / s)
Average σst of deformation stress in the equivalent strain range of 〜１０10%
The equation (σdyn) represented by the maximum stress TS (MPa) in a static tensile test in which the difference in (MPa) is measured in a strain rate range of 5 × 10 −4 to 5 × 10 −3 (1 / s)
−σst) ≧ −0.272 × TS + 300. A good workability high strength cold rolled steel sheet having high dynamic deformation resistance.
【０００９】（２）Ｎｂ，Ｔｉ，Ｖの１種又は２種以上
を合計で０．３重量％以下更に含むことを特徴とする
（１）記載の高い動的変形抵抗を有する良加工性高強度
冷延鋼板。 （３）Ｐを０．２重量％以下更に含むことを特徴とする
（１）または（２）記載の高い動的変形抵抗を有する良
加工性高強度冷延鋼板。(2) High workability with high dynamic deformation resistance according to (1), further comprising one or more of Nb, Ti and V in a total of 0.3% by weight or less. Strength cold rolled steel sheet. (3) The high-workability, high-strength cold-rolled steel sheet according to (1) or (2), further comprising 0.2% by weight or less of P.
【００１０】（４）Ｂを０．０１重量％以下更に含むこ
とを特徴とする（１）〜（３）のいずれか１に記載の高
い動的変形抵抗を有する良加工性高強度冷延鋼板。 （５）０％超１０％以下の予変形を与えた後の鋼材の残
留オーステナイト体積分率が２．５％超であり、かつ、
予変形前の残留オーステナイト体積分率と予変形後の残
留オーステナイト体積分率の比が０．４以上であること
を特徴とする（１）〜（４）のいずれか１に記載の高い
動的変形抵抗を有する良加工性高強度冷延鋼板。(4) Good workability and high strength cold-rolled steel sheet having high dynamic deformation resistance according to any one of (1) to (3), further comprising B in an amount of 0.01% by weight or less. . (5) The residual austenite volume fraction of the steel material after the pre-deformation of more than 0% and 10% or less is more than 2.5%, and
The high dynamics according to any one of (1) to (4), wherein the ratio of the retained austenite volume fraction before pre-deformation to the retained austenite volume fraction after pre-deformation is 0.4 or more. Good workability high strength cold rolled steel sheet with deformation resistance.
【００１１】（６）最終的に得られた冷延鋼板のミクロ
組織中の残留オーステナイトの平均粒径と、主相である
フェライトもしくはベイナイトの平均粒径の比が０．６
以下であることを特徴とする（１）〜（５）のいずれか
１に記載の高い動的変形抵抗を有する良加工性高強度冷
延鋼板。 （７）重量％で、Ｃ：０．０４％以上０．３％以下、Ｓ
ｉとＡｌの一方または双方を合計で０．５％以上３．０
％以下、Ｍｎ，Ｎｉ，Ｃｒ，Ｃｕ，Ｍｏの１種または２
種以上を合計で０．５％以上３．５％以下含み、残部が
Ｆｅ及び不可避的不純物からなる鋳造スラブを、鋳造ま
まで熱延工程へ直送し、もしくは一旦冷却した後に再度
加熱した後、熱延して巻き取った熱延鋼板を酸洗後冷延
し、連続焼鈍工程で焼鈍して最終的な製品とする際に、
０．１×（Ａｃ3 −Ａｃ1 ）＋Ａｃ1 ℃以上Ａｃ3 ＋５
０℃以下の温度で１０秒〜３分焼鈍した後に、１〜１０
℃／秒の一次冷却速度で５５０〜７００℃の範囲の一次
冷却停止温度まで冷却し、引き続いて１０〜２００℃／
ｓｅｃの二次冷却速度で３２０℃超５００℃以下の二次
冷却停止温度まで冷却した後３２０℃超５００℃以下の
温度範囲で１５秒〜２０分保持し、室温まで冷却するこ
とを特徴とする、最終的に得られる冷延鋼板のミクロ組
織がフェライトおよびベイナイトを含み、そのいずれか
を主相とし、体積分率で３％以上の残留オーステナイト
を含む第３相との複合組織であり、残留オーステナイト
中の固溶〔Ｃ〕量と鋼材の平均Ｍｎ等量｛Ｍｎｅｑ＝Ｍ
ｎ＋（Ｎｉ＋Ｃｒ＋Ｃｕ＋Ｍｏ）／２｝によって決まる
値（Ｍ＝６７８−４２８×〔Ｃ〕−３３×Ｍｎｅｑ）が
７０以上１８０以下で、その鋼材に相当歪みで０％超１
０％以下の予変形を与えた後、５×１０2 〜５×１０3
（１／ｓ）の歪み速度範囲で変形した時の３〜１０％の
相当歪み範囲における変形応力の平均値σｄｙｎ（ＭＰ
ａ）と５×１０-4〜５×１０-3（１／ｓ）の歪み速度範
囲で変形した時の３〜１０％の相当歪み範囲における変
形応力の平均値σｓｔ（ＭＰａ）の差が５×１０-4〜５
×１０-3（１／ｓ）の歪み速度範囲で測定された静的な
引張り試験における最大応力ＴＳ（ＭＰａ）によって表
現される式（σｄｙｎ−σｓｔ）≧−０．２７２×ＴＳ
＋３００を満足することを特徴とする高い動的変形抵抗
を有する良加工性高強度冷延鋼板の製造方法。(6) The ratio of the average grain size of the retained austenite in the microstructure of the finally obtained cold-rolled steel sheet to the average grain size of the main phase of ferrite or bainite is 0.6.
The good workability high strength cold rolled steel sheet having high dynamic deformation resistance according to any one of (1) to (5), which is characterized by the following. (7) By weight%, C: 0.04% to 0.3%, S
One or both of i and Al are at least 0.5% and 3.0 in total.
% Or less, one or more of Mn, Ni, Cr, Cu, Mo
The casting slab containing 0.5% or more and 3.5% or less in total including the seed or more, and the balance is made of Fe and unavoidable impurities, is directly sent to the hot rolling process as it is cast, or after being cooled once and heated again, When hot-rolled and rolled hot-rolled steel sheet is pickled and cold-rolled, and then annealed in a continuous annealing step to obtain a final product,
0.1 × (Ac 3 −Ac 1 ) + Ac 1 ℃ or more Ac 3 +5
After annealing for 10 seconds to 3 minutes at a temperature of 0 ° C. or less, 1 to 10
At a primary cooling rate in the range of 550-700 ° C. to a primary cooling stop temperature in the range of 550-700 ° C., followed by 10-200 ° C./sec.
After cooling to a secondary cooling stop temperature of more than 320 ° C. and 500 ° C. or less at a secondary cooling rate of sec, the temperature is kept in a temperature range of more than 320 ° C. and 500 ° C. or less for 15 seconds to 20 minutes, and then cooled to room temperature. The microstructure of the finally obtained cold rolled steel sheet is a composite structure with a third phase containing ferrite and bainite, one of which is a main phase, and a retained austenite having a volume fraction of 3% or more. Amount of solid solution [C] in austenite and average Mn equivalent of steel material ｛Mneq = M
The value determined by n + (Ni + Cr + Cu + Mo) / 2} (M = 678-428 × [C] −33 × Mneq) is 70 or more and 180 or less, and the corresponding strain exceeds 0% 1
After giving a pre-deformation of 0% or less, 5 × 10 2 to 5 × 10 3
The average value of the deformation stress σdyn (MP) in the equivalent strain range of 3 to 10% when deformed in the strain rate range of (1 / s)
a) and the average value σst (MPa) of the deformation stress in the equivalent strain range of 3 to 10% when deformed in the strain rate range of 5 × 10 −4 to 5 × 10 −3 (1 / s) is 5 × 10 -4 to 5
Equation (σdyn-σst) ≧ −0.272 × TS expressed by the maximum stress TS (MPa) in a static tensile test measured in a strain rate range of × 10 −3 (1 / s).
A method for producing a high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance, characterized by satisfying +300.
【００１２】（８）Ｎｂ，Ｔｉ，Ｖの１種又は２種以上
を合計で０．３重量％以下更に含むことを特徴とする
（７）記載の高い動的変形抵抗を有する良加工性高強度
冷延鋼板の製造方法。 （９）Ｐを０．２重量％以下更に含むことを特徴とする
（７）または（８）記載の高い動的変形抵抗を有する良
加工性高強度冷延鋼板の製造方法。(8) Good workability with high dynamic deformation resistance according to (7), further comprising one or more of Nb, Ti and V in a total of 0.3% by weight or less. Manufacturing method of high strength cold rolled steel sheet. (9) The method for producing a high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance according to (7) or (8), further comprising 0.2% by weight or less of P.
【００１３】（１０）Ｂを０．０１重量％以下更に含む
ことを特徴とする（７）〜（９）のいずれか１に記載の
高い動的変形抵抗を有する良加工性高強度冷延鋼板の製
造方法。(10) A good workable high-strength cold-rolled steel sheet having high dynamic deformation resistance according to any one of (7) to (9), further comprising B in an amount of 0.01% by weight or less. Manufacturing method.
【００１４】[0014]
【発明の実施の形態】自動車のフロントサイドメンバー
等の衝突時の衝撃吸収用部材は、鋼板に曲げ加工やプレ
ス成形加工によって製造される。自動車の衝突時の衝撃
は、このようにして加工された後に一般的には塗装焼き
付けされた後に加えられる。従って、このように部材へ
の加工、処理が行われた後に高い衝撃エネルギーの吸収
能を示す鋼板が必要となる。DESCRIPTION OF THE PREFERRED EMBODIMENTS A member for absorbing a shock such as a front side member of an automobile at the time of a collision is manufactured by bending or pressing a steel plate. The impact of a car collision is applied after processing in this way, typically after paint baking. Therefore, it is necessary to provide a steel sheet having a high impact energy absorbing ability after the members are processed and processed.
【００１５】本発明者らの研究の結果、このような成形
加工された実部材において鋼板に適量の残留オーステナ
イトを含むことが優れた衝撃吸収特性を示す高強度鋼板
に適していることが判明した。すなわち、最適なミクロ
組織は、種々の置換型元素によって容易に固溶強化され
るフェライトおよびベイナイトを含み、そのいずれかを
主相として、変形中に硬質のマルテンサイトに変態する
残留オーステナイトを体積分率で３％以上含む場合に、
高い動的変形抵抗を示すことが判明した。また、初期ミ
クロ組織の第３相にマルテンサイト粒子を含む場合に
も、他の条件が満足されれば、本発明の目的とする高い
動的変形抵抗を有する良加工性高強度冷延鋼板が得られ
ることが可能になる。As a result of the research conducted by the present inventors, it has been found that the steel sheet containing an appropriate amount of retained austenite in such a molded real member is suitable for a high-strength steel sheet exhibiting excellent shock absorption characteristics. . In other words, the optimal microstructure includes ferrite and bainite, which are easily solid-solution-strengthened by various substitutional elements, and the volume of residual austenite, which transforms into hard martensite during deformation, with either one as the main phase. If the rate is 3% or more,
It was found to show high dynamic deformation resistance. In addition, even when martensite particles are contained in the third phase of the initial microstructure, if the other conditions are satisfied, a good-workability high-strength cold-rolled steel sheet having high dynamic deformation resistance as the object of the present invention is obtained. Can be obtained.
【００１６】本発明に規定する冷延鋼板の各成分の限定
理由は下記のとおりである。 Ｃ：Ｃはオーステナイトを室温で安定化させて残留させ
るために必要なオーステナイトの安定化に貢献する最も
安価な元素であるために、本発明において最も重要な元
素といえる。鋼材の平均Ｃ量は、室温で確保できる残留
オーステナイト体積分率に影響を及ぼすのみならず、製
造の加工熱処理中に未変態オーステナイト中に濃化する
ことで、残留オーステナイトの加工に対する安定性を向
上させることが出来る。しかしながら、この添加量が
０．０４重量％未満の場合には、最終的に得られる残留
オーステナイト体積分率が３％以上を確保することが出
来ないので０．０４重量％を下限とした。一方、鋼材の
平均Ｃ量が増加するに従って確保可能な残留オーステナ
イト体積分率は増加し、残留オーステナイト体積率を確
保しつつ残留オーステナイトの安定性を確保することが
可能となる。しかしながら、鋼材のＣ添加量が過大にな
ると、必要以上に鋼材の強度を上昇させ、プレス加工等
の成形性を阻害するのみならず、静的な強度上昇に比し
て動的な応力上昇が阻害されると共に、溶接性を低下さ
せることによって部品としての鋼材の利用が制限される
ようになるためＣ添加量の上限を０．３重量％とした。The reasons for limiting each component of the cold-rolled steel sheet specified in the present invention are as follows. C: C is the most important element in the present invention because it is the cheapest element that contributes to the stabilization of austenite, which is necessary for stabilizing austenite at room temperature to remain. The average C content of the steel material not only affects the retained austenite volume fraction that can be secured at room temperature, but also increases the stability of the retained austenite to processing by enriching in untransformed austenite during the thermomechanical heat treatment during production. Can be done. However, if the addition amount is less than 0.04% by weight, the finally obtained residual austenite volume fraction cannot be 3% or more, so the lower limit was made 0.04% by weight. On the other hand, the retained austenite volume fraction that can be secured increases as the average C content of the steel material increases, and it becomes possible to secure the stability of retained austenite while securing the retained austenite volume fraction. However, when the amount of C added to the steel material is excessive, the strength of the steel material is increased more than necessary, not only impairing the formability such as press working, but also increasing the dynamic stress as compared with the static strength increase. Since the use of steel as a part is restricted by lowering the weldability as well as being hindered, the upper limit of the amount of C added is set to 0.3% by weight.
【００１７】Ａｌ，Ｓｉ：ＡｌとＳｉは共にフェライト
の安定化元素であり、フェライト体積率を増加させるこ
とによって鋼材の加工性を向上させる働きがある。ま
た、Ａｌ，Ｓｉ共にセメンタイトの生成を抑制し、効果
的にオーステナイト中へのＣを濃化させることを可能と
することから、室温で適量の体積分率のオーステナイト
を残留させるためには不可避的な添加元素である。この
ようなセメンタイト生成抑制機能を持つ添加元素として
は、Ａｌ，Ｓｉ以外に、ＰやＣｕ，Ｃｒ，Ｍｏ等が挙げ
られ、このような元素を適切に添加することも同様な効
果が期待される。しかしながら、ＡｌとＳｉの一種もし
くは双方の合計が０．５重量％未満の場合には、セメン
タイト生成抑制の効果が十分でなく、オーステナイトの
安定化に最も効果的な添加されたＣの多くが炭化物の形
で浪費され、本発明に必要な残留オーステナイト体積率
を確保することが出来ないか、もしくは残留オーステナ
イトの確保に必要な製造条件が大量生産工程の条件に適
しないため下限を０．５重量％とした。また、ＡｌとＳ
ｉの一種もしくは双方の合計が３．０重量％を越える場
合には、母相であるフェライトもしくはベイナイトの硬
質化や脆化を招き、歪み速度上昇による変形抵抗の増加
を阻害するばかりでなく、鋼材の加工性の低下、靱性の
低下、さらには鋼材コストの上昇を招き、また化成処理
性等の表面処理特性が著しく劣化するために、３．０重
量％を上限値とした。Al, Si: Al and Si are both ferrite stabilizing elements, and have a function of improving the workability of steel by increasing the volume ratio of ferrite. In addition, since both Al and Si suppress the generation of cementite and enable C to be effectively enriched in austenite, it is inevitable to leave an appropriate volume fraction of austenite at room temperature. Is an additional element. As an additive element having such a cementite generation suppressing function, in addition to Al and Si, P, Cu, Cr, Mo, and the like can be cited, and a similar effect can be expected by appropriately adding such an element. . However, when the amount of one or both of Al and Si is less than 0.5% by weight, the effect of suppressing the formation of cementite is not sufficient, and most of the added C most effective for stabilizing austenite is carbide. And the lower limit is 0.5 weight because the volume ratio of retained austenite required for the present invention cannot be secured or the production conditions required for securing the retained austenite are not suitable for the conditions of the mass production process. %. Al and S
If the sum of one or both of i exceeds 3.0% by weight, hardening or embrittlement of the ferrite or bainite as a parent phase is caused, and not only increase in deformation resistance due to an increase in strain rate is prevented, The upper limit is set to 3.0% by weight because the workability and toughness of the steel material are reduced, and the cost of the steel material is increased, and the surface treatment properties such as chemical conversion property are significantly deteriorated.
【００１８】Ｍｎ，Ｎｉ，Ｃｒ，Ｃｕ，Ｍｏ：Ｍｎ，Ｎ
ｉ，Ｃｒ，Ｃｕ，Ｍｏは全てオーステナイト安定化元素
であり、室温でオーステナイトを安定化させるためには
有効な元素である。特に、溶接性の観点からＣの添加量
が制限される場合には、このようなオーステナイト安定
化元素を適量添加することによって効果的にオーステナ
イトを残留させることが可能となる。また、これらの元
素はＡｌやＳｉ程ではないがセメンタイトの生成を抑制
する効果があり、オーステナイトへのＣの濃化を助ける
働きもする。更に、これらの元素はＡｌ，Ｓｉと共にマ
トリックスであるフェライトやベイナイトを固溶強化さ
せることによって、高速での動的変形抵抗を高める働き
も持つ。しかしながら、これらの元素の１種もしくは２
種以上の添加の合計が０．５重量％未満の場合には、必
要な残留オーステナイトの確保が出来なくなるととも
に、鋼材の強度が低くなり、有効な車体軽量化が達成で
きなくなることから、下限を０．５重量％とした。一
方、これらの合計が３．５重量％を越える場合には、母
相であるフェライトもしくはベイナイトの硬質化を招
き、歪み速度上昇による変形抵抗の増加を阻害するばか
りでなく、鋼材の加工性の低下、靱性の低下、さらには
鋼材コストの上昇を招くために、上限を３．５重量％と
した。Mn, Ni, Cr, Cu, Mo: Mn, N
i, Cr, Cu, and Mo are all austenite stabilizing elements, and are effective elements for stabilizing austenite at room temperature. In particular, when the addition amount of C is limited from the viewpoint of weldability, it is possible to effectively retain austenite by adding an appropriate amount of such an austenite stabilizing element. In addition, these elements are not as effective as Al and Si, but have the effect of suppressing the generation of cementite, and also work to assist the enrichment of C in austenite. Further, these elements have a function of increasing the dynamic deformation resistance at high speed by solid-solution strengthening the matrix ferrite and bainite together with Al and Si. However, one or two of these elements
If the total of the addition of more than one kind is less than 0.5% by weight, the required residual austenite cannot be secured, and the strength of the steel material becomes low, so that effective vehicle weight reduction cannot be achieved. 0.5 wt%. On the other hand, if the sum of them exceeds 3.5% by weight, hardening of the ferrite or bainite which is the parent phase is caused, and not only the increase in deformation resistance due to the increase in strain rate is inhibited, but also the workability of the steel material is reduced. The upper limit is set at 3.5% by weight in order to cause a decrease in the toughness, a decrease in the toughness, and an increase in the cost of the steel material.
【００１９】Ｎｂ，Ｔｉ，Ｖ：また、必要に応じて添加
するＮｂ，Ｔｉ，Ｖは、炭化物、窒化物もしくは炭窒化
物を形成することによって鋼材を高強度化することが出
来るが、その合計が０．３重量％を越えた場合には母相
であるフェライトやベイナイト粒内もしくは粒界に多量
の炭化物、窒化物もしくは炭窒化物として析出し、高速
変形時の可動転位発生源となって、高い動的変形抵抗を
得ることが出来なくなる。また、炭化物の生成は、本発
明にとって最も重要な残留オーステナイト中へのＣの濃
化を阻害し、Ｃを浪費することから上限を０．３重量％
とした。Nb, Ti, V: Nb, Ti, V added as necessary can increase the strength of steel by forming carbide, nitride or carbonitride. Exceeds 0.3% by weight, a large amount of carbides, nitrides or carbonitrides precipitates in ferrite or bainite grains which are a parent phase or in grain boundaries, and becomes a mobile dislocation generating source during high-speed deformation. High dynamic deformation resistance cannot be obtained. Also, the formation of carbides inhibits the enrichment of C in the retained austenite, which is the most important for the present invention, and wastes C, so that the upper limit is 0.3% by weight.
And
【００２０】Ｐ：更に、必要に応じて添加するＰは、鋼
材の高強度化や前述のように残留オーステナイトの確保
に有効ではあるが、０．２重量％を越えて添加された場
合には鋼材のコストの上昇を招くばかりでなく、主相で
あるフェライトやベイナイトの変形抵抗を必要以上に高
め、かつ高速変形時の変形抵抗の上昇を阻害する。更
に、耐置き割れ性の劣化や疲労特性、靱性の劣化を招く
ことから、０．２重量％をその上限とした。P: P added as necessary is effective in increasing the strength of the steel material and securing the retained austenite as described above. However, when added in excess of 0.2% by weight, Not only does the cost of the steel material rise, but also the deformation resistance of the main phase, ferrite and bainite, is unnecessarily increased, and the deformation resistance during high-speed deformation is hindered. In addition, 0.2% by weight was set as the upper limit because deterioration of storage crack resistance and deterioration of fatigue characteristics and toughness are caused.
【００２１】Ｂ：また、必要に応じて添加するＢは、粒
界の強化や鋼材の高強度化に有効ではあるが、その添加
量が０．０１重量％を越えるとその効果が飽和するばか
りでなく、必要以上に鋼板強度を上昇させ、高速変形時
の変形抵抗の上昇を阻害すると共に、部品への加工性も
低下させることから、上限を０．０１重量％とした。次
に、本発明者らの実験・検討の結果、フロントサイドメ
ンバー等の衝撃吸収用部材の成形加工に相当する予変形
の量は、部材中の部位によっては最大２０％以上に達す
る場合もあるが、相当歪みとして０％超１０％以下の部
位が大半であり、またこの範囲の予変形の効果を把握す
ることで、部材全体としての予加工後の挙動を推定する
ことが可能であることを見いだした。従って、本発明に
おいては、部材への加工時に与えられる予変形量として
相当歪みにして０％超１０％以下の変形を選択した。B: B, which is added as required, is effective for strengthening grain boundaries and increasing the strength of steel materials. However, if the added amount exceeds 0.01% by weight, the effect is only saturated. Rather, the upper limit was set to 0.01% by weight because the steel sheet strength was unnecessarily increased to prevent an increase in deformation resistance at the time of high-speed deformation and the workability to parts was also reduced. Next, as a result of experiments and studies conducted by the present inventors, the amount of pre-deformation corresponding to the forming process of the shock absorbing member such as the front side member may reach up to 20% or more depending on the part in the member. However, most of the parts have an equivalent strain of more than 0% and 10% or less, and by grasping the effect of pre-deformation in this range, it is possible to estimate the behavior of the entire member after pre-processing. Was found. Therefore, in the present invention, a deformation of more than 0% and 10% or less is selected as a substantial strain as a pre-deformation amount given at the time of processing the member.
【００２２】また、フロントサイドメンバー等の衝撃吸
収用部材は、特徴的にハット型の断面形状をしており、
このような部材の高速での衝突圧潰時の変形を本発明者
らが解析した結果、最大では４０％以上の高い歪みまで
変形が進んでいるものの、吸収エネルギー全体の約７０
％以上が、高速の応力−歪み線図の１０％以下の歪み範
囲で吸収されていることを見いだした。従って、高速で
の衝突エネルギーの吸収能の指標として、１０％以下で
の高速変形時の動的変形抵抗を採用した。特に、歪み量
として３％〜１０％の範囲が最も重要であることから、
高速引張り変形時の相当歪みで３％〜１０％の範囲の平
均応力σｄｙｎをもって衝撃エネルギー吸収能の指標と
した。The shock absorbing member such as the front side member has a characteristic hat-shaped cross section.
As a result of analyzing the deformation of such a member at the time of collision crush at high speed, the deformation has progressed up to a high strain of 40% or more at the maximum, but about 70% of the total absorbed energy.
% Was absorbed in the strain range of 10% or less of the high-speed stress-strain diagram. Therefore, the dynamic deformation resistance at the time of high-speed deformation of 10% or less was adopted as an index of the absorption capacity of the collision energy at high speed. In particular, since the range of 3% to 10% is most important as the amount of distortion,
An average stress σdyn in a range of 3% to 10% as an equivalent strain at the time of high-speed tensile deformation was used as an index of the impact energy absorbing ability.
【００２３】この高速変形時の３％〜１０％の平均応力
σｄｙｎ（ＭＰａ）は、鋼材の静的な引張り強度（５×
１０-4〜５×１０-3（１／ｓ）の歪み速度範囲で測定さ
れた静的な引張り試験における最大応力：ＴＳ（ＭＰ
ａ））の上昇に伴って大きくなることが一般的である。
従って鋼材の静的な引張り強度を増加させることは部材
の衝撃エネルギー吸収能の向上に直接寄与する。しかし
ながら、鋼材の強度が上昇すると部材への成形性が劣化
し、必要な部材形状を得ることが困難となる。従って、
同一の引張り強度（ＴＳ）で高いσｄｙｎを持つ鋼材が
望ましい。特に部材への加工時の歪みレベルが主に１０
％以下であることから、部材への成型時の形状凍結性等
の成形性の指標となる低歪み領域での応力が低いことが
成形性向上のためには重要である。従ってσｄｙｎと５
×１０-4〜５×１０-3（１／ｓ）の歪み速度範囲で変形
した時の３〜１０％の相当歪み範囲における変形応力の
平均値σｓｔ（ＭＰａ）の差が大きいほど静的には成形
性に優れ、動的には高い衝撃エネルギーの吸収能を持つ
と言える。この関係で、特に（σｄｙｎ−σｓｔ）≧−
０．２７２×ＴＳ＋３００の関係を満足する鋼材は、実
部材への成形性に優れると同時に衝撃エネルギー吸収能
が他の鋼材に比べて高く、部材の総重量を増加させるこ
となく衝撃エネルギー吸収能を向上させることができ
る。The average stress σdyn (MPa) of 3% to 10% during high-speed deformation is determined by the static tensile strength (5 ×
Maximum stress in a static tensile test measured in a strain rate range of 10 −4 to 5 × 10 −3 (1 / s): TS (MP
Generally, it increases with the increase of a)).
Therefore, increasing the static tensile strength of the steel directly contributes to the improvement of the impact energy absorbing ability of the member. However, when the strength of the steel material increases, the formability of the member deteriorates, and it becomes difficult to obtain a required member shape. Therefore,
A steel material having the same tensile strength (TS) and high σdyn is desirable. In particular, the distortion level when processing the member is mainly 10
% Or less, it is important to improve the formability that the stress in the low strain region, which is an index of the formability such as shape freezing during molding into a member, is low. Therefore, σdyn and 5
The larger the difference between the average values σst (MPa) of the deformation stresses in the equivalent strain range of 3 to 10% when the strain is deformed in the strain rate range of × 10 -4 to 5 × 10 -3 (1 / s), the more statically, Has excellent moldability and can be said to have a high ability to absorb impact energy dynamically. In this relation, in particular, (σdyn−σst) ≧ −
A steel material that satisfies the relationship of 0.272 × TS + 300 is excellent in formability to a real member and also has a higher impact energy absorption capacity than other steel materials, so that the impact energy absorption capability can be increased without increasing the total weight of the member. Can be improved.
【００２４】本発明者らの実験・検討の結果、同一レベ
ルの引張り強度（ＴＳ）に対して、（σｄｙｎ−σｓ
ｔ）は部材への加工が行われる以前の鋼板中に含まれる
残留オーステナイト中の固溶炭素量〔Ｃ〕（重量％）と
鋼材の平均Ｍｎ等量｛Ｍｎｅｑ＝Ｍｎ＋（Ｎｉ＋Ｃｒ＋
Ｃｕ＋Ｍｏ）／２｝（重量％）によって変化することが
見いだされた。残留オーステナイト中の炭素濃度は、Ｘ
線解析やメスバウアー分光により実験的に求めることが
出来、例えばＭｏのＫα線を用いたＸ線解析によりフェ
ライトの（２００）面、（２１１）面及びオーステナイ
トの（２００）面、（２２０）面、（３１１）面の積分
反射強度を用いて、Journal of The Ironand Steel Ins
titute,206(1968),p.60に示された方法にて算出でき
る。本発明者らが行った実験結果から、このようにして
得られた残留オーステナイト中の固溶〔Ｃ〕と鋼材に添
加されている置換型合金元素から求められるＭｎｅｑを
用いて計算される値（Ｍ＝６７８−４２８×〔Ｃ〕−３
３×Ｍｎｅｑ）が−１４０以上７０未満の場合に、同一
の静的な引張り強度（ＴＳ）に対して大きな（σｄｙｎ
−σｓｔ）を示すことが見いだされた。このときＭが７
０以上では、残留オーステナイトが低歪み領域で硬質の
マルテンサイトに変態することから、成形性を支配する
低歪み領域での静的な応力を上昇させてしまい、形状凍
結性等の成形性を劣化させるのみならず、（σｄｙｎ−
σｓｔ）の値を小さくすることから、良好な成形性と高
い衝撃エネルギー吸収能の両立が得られないためにＭを
７０未満とした。また、Ｍが−１４０未満の場合には、
残留オーステナイトの変態が高い歪み領域に限定される
ために、良好な成形性は得られるものの（σｄｙｎ−σ
ｓｔ）を増大させる効果がなくなることからＭの下限を
−１４０とした。As a result of experiments and studies by the present inventors, for the same level of tensile strength (TS), (σdyn−σs
t) is the amount of solute carbon [C] (% by weight) in the retained austenite contained in the steel sheet before the member is processed and the average Mn equivalent of the steel material ｛Mneq = Mn + (Ni + Cr +)
(Cu + Mo) / 2% (% by weight). The carbon concentration in the retained austenite is X
It can be obtained experimentally by X-ray analysis or Mossbauer spectroscopy. For example, the (200) plane, (211) plane of ferrite and the (200) plane, (220) plane of austenite are determined by X-ray analysis using Mo's Kα ray. Journal of the Iron and Steel Ins
titute, 206 (1968), p.60. From the experimental results conducted by the present inventors, a value calculated using Mneq obtained from the solid solution [C] in the residual austenite thus obtained and the substitutional alloy element added to the steel material ( M = 678-428 × [C] -3
When (3 × Mneq) is −140 or more and less than 70, a large (σdyn) is obtained for the same static tensile strength (TS).
−σst). At this time, M is 7
Above 0, the retained austenite transforms into hard martensite in the low strain region, increasing the static stress in the low strain region that governs the formability and deteriorating formability such as shape freezing. As well as (σdyn-
Since the value of σst) is small, it is not possible to obtain both good moldability and high impact energy absorbing ability, so that M is set to less than 70. When M is less than -140,
Since the transformation of retained austenite is limited to a high strain region, good formability is obtained, but (σdyn−σ
The lower limit of M was set to -140 because the effect of increasing st) was lost.
【００２５】製造条件：熱延後冷延・焼鈍して本発明の
鋼板を製造する場合には、所定の成分に調整されたスラ
ブを、鋳造ままで熱延工程へ直送し、もしくは一旦冷却
した後再加熱して熱延を行い、その後酸洗し、冷延し、
次いで連続焼鈍することで最終製品とする。この時、熱
延仕上げ温度は鋼の化学成分によって決まるＡｒ3 変態
温度以上で行うのが一般的であるが、Ａｒ3 から１０℃
程度低温までであれば最終的な鋼板の特性を劣化させな
い。また、冷却後の巻取温度は鋼の化学成分によって決
まるベイナイト変態開始温度以上とすることで、冷延時
の荷重を必要以上に高めることが避けられるが、冷延の
全圧下率が小さい場合にはこの限りでなく、鋼のベイナ
イト変態温度以下で巻き取られても最終的な鋼板の特性
を劣化させない。また、冷延の全圧下率は、最終板厚と
冷延荷重の関係から設定されるが、４０％以上であれば
最終的な鋼板の特性を劣化させない。Manufacturing conditions: When manufacturing the steel sheet of the present invention by cold rolling and annealing after hot rolling, a slab adjusted to a predetermined component is directly sent to a hot rolling process as cast, or once cooled. After reheating and hot rolling, then pickling, cold rolling,
Then, it is made into a final product by continuous annealing. At this time, the hot rolling finishing temperature is generally carried out by determined by Ar 3 transformation temperature or more chemical components of the steel, Ar 3 from 10 ° C.
Up to a low temperature, the properties of the final steel sheet are not deteriorated. In addition, by setting the coiling temperature after cooling to be higher than the bainite transformation start temperature determined by the chemical composition of the steel, it is possible to avoid increasing the load during cold rolling more than necessary, but when the total rolling reduction of the cold rolling is small. Is not limited to this, and the properties of the final steel sheet are not deteriorated even if the steel sheet is wound below the bainite transformation temperature of the steel. Further, the total rolling reduction of the cold rolling is set from the relationship between the final sheet thickness and the cold rolling load, but if it is 40% or more, the properties of the final steel sheet are not deteriorated.
【００２６】冷延後焼鈍する際に、焼鈍温度が鋼の化学
成分によって決まる温度Ａｃ1 及びＡｃ3 温度（例えば
「鉄鋼材料学」：Ｗ．Ｃ．Ｌｅｓｌｉｅ著、幸田成康監
訳、丸善ｐ２７３，で表現される０．１×（Ａｃ3 −Ａ
ｃ1 ）＋Ａｃ1 ℃未満の場合には、焼鈍温度で得られる
オーステナイト量が少ないので、最終的な鋼板中に安定
して残留オーステナイトを残すことができないために、
０．１×（Ａｃ3 −Ａｃ1 ）＋Ａｃ1 ℃を焼鈍温度の下
限とした。また焼鈍温度がＡｃ3 ＋５０℃を越えても何
ら鋼板の特性を改善することができない一方で製造コス
トの上昇をまねくために、焼鈍温度の上限をＡｃ3 ＋５
０℃とした。この温度での焼鈍時間は鋼板の温度均一化
とオーステナイトの確保のために１０秒以上が必要であ
る。しかし、３分超では、効果が飽和するばかりでなく
コストの上昇を招くので３分を上限とした。When annealing after cold rolling, the temperatures Ac 1 and Ac 3 are determined by the chemical composition of the steel (for example, “Steel and Materials Science”: W. C. Leslie, translated by Koda Shigeyasu and translated by Maruzen p 273). 0.1 × (Ac 3 -A
When the temperature is less than c 1 ) + Ac 1 ° C., the amount of austenite obtained at the annealing temperature is small, so that the residual austenite cannot be stably left in the final steel sheet.
0.1 × (Ac 3 −Ac 1 ) + Ac 1 ° C. was set as the lower limit of the annealing temperature. Further, even if the annealing temperature exceeds Ac 3 + 50 ° C., the characteristics of the steel sheet cannot be improved at all, but in order to increase the manufacturing cost, the upper limit of the annealing temperature is set to Ac 3 +5.
0 ° C. The annealing time at this temperature needs to be 10 seconds or more in order to equalize the temperature of the steel sheet and secure austenite. However, if the time exceeds 3 minutes, not only the effect is saturated but also the cost is increased. Therefore, the upper limit is set to 3 minutes.
【００２７】その後の一次冷却はオーステナイトからフ
ェライトへの変態を促して、未変態のオーステナイト中
にＣを濃化させてオーステナイトの安定化をはかるのに
重要である。この冷却速度が１℃／秒未満にすること
は、必要な生産ライン長を長くしたり、生産速度を極め
て遅くするといった製造上のデメリットを生じるため
に、この冷却速度の下限を１℃／秒とした。一方、冷却
速度が１０℃／秒超の場合にはフェライト変態が十分に
起こらず、最終的な鋼板中の残留オーステナイト確保が
困難となるためにこれを上限とした。この一次冷却が５
５０℃未満まで行われると、冷却中にパーライトが生成
し、オーステナイト安定化元素であるＣを浪費し、最終
的に十分な量の残留オーステナイトが得られないため
に、５５０℃を下限とした。しかしながら、冷却が７０
０℃超までしか行われなかった場合にはフェライト変態
の進行が十分ではないので７００℃を上限とした。Subsequent primary cooling is important for promoting the transformation from austenite to ferrite, and for enriching C in untransformed austenite to stabilize austenite. If the cooling rate is less than 1 ° C./sec, there is a disadvantage in manufacturing that the required production line length is lengthened or the production rate is extremely slowed. Therefore, the lower limit of the cooling rate is set to 1 ° C./sec. And On the other hand, when the cooling rate is more than 10 ° C./sec, the ferrite transformation does not sufficiently occur, and it becomes difficult to secure the retained austenite in the final steel sheet. This primary cooling is 5
When the temperature is lowered to less than 50 ° C., pearlite is generated during cooling, C as an austenite stabilizing element is wasted, and a sufficient amount of residual austenite is not finally obtained. However, if the cooling is 70
When the temperature is not higher than 0 ° C., the progress of ferrite transformation is not sufficient, so 700 ° C. was set as the upper limit.
【００２８】引き続き行われる二次冷却の急速冷却は、
冷却中にパーライト変態や鉄炭化物の析出などが起こら
ないような冷却速度として最低１０℃／秒以上が必要と
なる。但し、この冷却速度を２００℃／秒超にすること
は設備能力上困難であることから、１０〜２００℃を冷
却速度の範囲とした。この二次冷却の冷却停止温度が３
２０℃以下の場合には、得られる残留オーステナイトの
特性が好ましくなく、最終的に得ようとする（σｄｙｎ
−σｓｔ）の値を低下させる為に、３２０℃超を下限と
した。また、二次冷却停止温度が５００℃超の場合に
は、必要な量の残留オーステナイトを得ることができな
いために、５００℃を上限とした。The rapid cooling of the subsequent secondary cooling is as follows.
A cooling rate of at least 10 ° C./sec is required so that pearlite transformation and precipitation of iron carbide do not occur during cooling. However, since it is difficult to increase the cooling rate to more than 200 ° C./sec in terms of facility capacity, the cooling rate is set to 10 to 200 ° C. The cooling stop temperature of this secondary cooling is 3
If the temperature is lower than 20 ° C., the properties of the obtained retained austenite are not preferable, and the final attempt is made to obtain (σdyn).
In order to lower the value of −σst), the lower limit was set to more than 320 ° C. Further, when the secondary cooling stop temperature is higher than 500 ° C., the required amount of retained austenite cannot be obtained, so the upper limit was set at 500 ° C.
【００２９】鋼板中に残留しているオーステナイトを室
温で安定にするためには、その一部をベイナイトへ変態
させることでオーステナイト中の炭素濃度を更に高める
ことが必須である。二次冷却停止温度がベイナイト変態
処理のために保持される温度より低温である場合には、
保持温度まで加熱される。このときの加熱速度は５℃／
秒〜５０℃／秒の範囲であれば最終的な特性を劣化させ
ることはない。また逆に、二次冷却停止温度がベイナイ
ト処理温度よりも高温の場合は、ベイナイト処理温度ま
で５℃／秒〜２００℃／秒の冷却速度で強制的に冷却し
ても、あらかじめ目標温度が設定された加熱ゾーンの直
接搬送されても、鋼板の最終的な特性を劣化させない。
一方、鋼板が３２０℃以下で保持された場合には、鋼板
の静的な変形抵抗が上昇し、加工性と衝撃エネルギー吸
収能の両立を示す（σｄｙｎ−σｓｔ）の値を低下させ
るために、３２０℃超を下限とした。また５００℃超に
保持された場合には、十分な量の残留オーステナイトを
確保できないことから、保持温度の範囲を３２０℃超〜
５００℃以下とした。このとき、３２０℃超〜５００℃
以下での保持が１５秒未満ではベイナイト変態の進行が
十分でないことから最終的に必要な量の残留オーステナ
イトを得ることができず、また、２０分超ではベイナイ
ト変態の後に鉄炭化物の析出やパーライト変態が起こ
り、残留オーステナイト生成に不可欠なＣを浪費してし
まい、残留オーステナイトを得ることができなくなるた
めに保持時間を１５秒から２０分の範囲とした。ベイナ
イト変態を促進させるために行う３２０℃超〜５００℃
以下の保持は、等温での保持であっても、または、この
温度範囲であれば温度変化があっても最終的な鋼板の特
性を劣化させることはない。In order to stabilize the austenite remaining in the steel sheet at room temperature, it is essential to further increase the carbon concentration in the austenite by transforming a part of it to bainite. If the secondary cooling stop temperature is lower than the temperature maintained for the bainite transformation process,
Heat to holding temperature. The heating rate at this time is 5 ° C /
In the range of seconds to 50 ° C./second, the final characteristics are not deteriorated. Conversely, when the secondary cooling stop temperature is higher than the bainite processing temperature, the target temperature is set in advance even if the secondary cooling stop temperature is forcibly cooled to the bainite processing temperature at a cooling rate of 5 ° C./sec to 200 ° C./sec. It does not degrade the final properties of the steel sheet even if it is directly transported to the heated zone.
On the other hand, when the steel sheet is kept at 320 ° C. or lower, the static deformation resistance of the steel sheet increases, and the value of (σdyn−σst) indicating both workability and impact energy absorption capacity decreases, so that The lower limit was over 320 ° C. When the temperature is maintained at more than 500 ° C., a sufficient amount of retained austenite cannot be secured.
500 ° C. or less. At this time, over 320 ° C to 500 ° C
If the holding time is less than 15 seconds, the progress of bainite transformation is not sufficient, so that a required amount of retained austenite cannot be finally obtained. If the holding time exceeds 20 minutes, precipitation of iron carbide or pearlite occurs after bainite transformation. Transformation occurs, C which is indispensable for generation of retained austenite is wasted, and it becomes impossible to obtain retained austenite. Therefore, the holding time is set in the range of 15 seconds to 20 minutes. More than 320 ° C to 500 ° C to promote bainite transformation
The following holding is performed at an isothermal temperature or in a temperature range within this temperature range without deteriorating the properties of the final steel sheet.
【００３０】[0030]
〔実施例１〕表１に示す２５種類の鋼材を１２００℃に
加熱し、Ａｒ3 変態温度以上で熱延を完了し、冷却後各
鋼の化学成分で決まるベイナイト変態開始温度以上で巻
き取った鋼帯を酸洗後、冷延して１．０mm厚とした。そ
の後、各鋼の成分からＡｃ1＝７２３−１０．７×Ｍｎ
％−１６．９×Ｎｉ％＋２９．１×Ｓｉ％＋１６．９×
Ｃｒ，Ａｃ3 ＝９１０−２０３×（Ｃ％）1/2 −１５．
２×Ｎｉ％＋４４．７×Ｓｉ％＋１０４×Ｖ％＋３１．
５×Ｍｏ％−３０×Ｍｎ％−１１×Ｃｒ％−２０×Ｃｕ
％＋７００×Ｐ％＋４００×Ａｌ％＋４００×Ｔｉ％、
で計算されるＡｃ1 変態温度とＡｃ3 から計算される温
度（Ａｃ1 ＋Ａｃ3 ）／２に９０秒加熱し、５℃／秒で
６７０℃まで冷却した後１００℃／秒で３００℃まで冷
却し、再加熱後４００℃で５分のベイナイト変態処理を
行った後に室温まで冷却した冷延鋼板の冷延方向（Ｌ方
向）とこれに直行する方向（Ｃ方向）に単軸引張りによ
り５％の予変形を付加し、焼き付け処理を模擬するため
に１７０℃×２０分の熱処理を行った後に鋼材の動的な
特性を調査し、予変形する前の静的な特性と比較した結
果を表２に示した。鋼の成分が本発明の範囲内のものに
ついては表中の＊１の欄に示した値が正、すなわち、目
的通り（σｄｙｎ−σｓｔ）が（−０．２７２×ＴＳ＋
３００）以上であることがわかる。 〔実施例２〕表１に示した本発明の成分範囲内である鋼
Ｐ２を用いて、焼鈍条件、予変形条件及び熱処理条件、
を変化させた場合の特性を調査した結果を表３および表
４に示す。Ｐ２鋼のＡｃ1 ，Ａｃ3 変態温度は７４２，
８４８℃と計算された。熱延鋼板を酸洗後１．０mm厚ま
で冷延し、各種の焼鈍条件で焼鈍した。Example 1 Twenty-five types of steel materials shown in Table 1 were heated to 1200 ° C., hot rolling was completed at an Ar 3 transformation temperature or higher, and after cooling, wound at a bainite transformation starting temperature determined by a chemical composition of each steel. The steel strip was pickled and cold rolled to a thickness of 1.0 mm. Then, Ac 1 = 723-10.7 × Mn from the components of each steel.
%-16.9 x Ni% + 29.1 x Si% + 16.9 x
Cr, Ac 3 = 910-203 × (C%) 1/2 −15.
2 × Ni% + 44.7 × Si% + 104 × V% + 31.
5 x Mo%-30 x Mn%-11 x Cr%-20 x Cu
% + 700 × P% + 400 × Al% + 400 × Ti%
Is heated to (Ac 1 + Ac 3 ) / 2 calculated from the Ac 1 transformation temperature and Ac 3 for 90 seconds, cooled to 670 ° C. at 5 ° C./sec, and then cooled to 300 ° C. at 100 ° C./sec. After reheating, a bainite transformation treatment was performed at 400 ° C. for 5 minutes and then cooled to room temperature. 5% by uniaxial tension in a cold rolling direction (L direction) and a direction perpendicular to the cold rolling direction (C direction). After performing a heat treatment at 170 ° C for 20 minutes to simulate the baking process by adding a pre-deformation of steel, the dynamic properties of the steel were investigated, and the results were compared with the static properties before pre-deformation. 2 is shown. When the steel composition is within the range of the present invention, the value shown in the column of * 1 in the table is positive, that is, (−dyn−σst) is (−0.272 × TS +) as intended.
300) or more. [Example 2] Annealing conditions, pre-deformation conditions and heat treatment conditions, using steel P2 within the component range of the present invention shown in Table 1,
Tables 3 and 4 show the results of investigating the characteristics in the case where is changed. The Ac 1 and Ac 3 transformation temperature of P2 steel is 742,
848 ° C. The hot rolled steel sheet was cold rolled to a thickness of 1.0 mm after pickling, and annealed under various annealing conditions.
【００３１】Ｎｏ．１は焼鈍温度が本発明範囲外であ
り、必要量の残留オーステナイトが得られていない。ま
た、Ｎｏ．２は一次冷却の冷却停止温度が５００℃と本
発明の範囲外であるために、冷却中に出たパーライトに
より、残留オーステナイトの確保が阻害されている。ま
た、Ｎｏ．３は二次冷却の冷却速度が本発明外であるた
めに、冷却中に生成したパーライトにより、残留オース
テナイトの確保が達成されていない。またＮｏ．４は二
次冷却の冷却停止温度が低すぎたためにマルテンサイト
の生成量が多くなり、残留オーステナイトの確保が達成
できていない。また、Ｎｏ．７は二次冷却速度及びベイ
ナイト変態処理温度が高すぎて、鉄炭化物の生成により
残留オーステナイトの確保が出来ていない。更に、Ｎ
ｏ．９では、焼鈍温度を必要以上に高温としたために、
組織の粗大化がすすみ、残留オーステナイトの粒径が大
きくなり、結果として十分大きな動的変形抵抗と静的変
形抵抗の差を得ることができない。他の例はすべて本発
明の例であり、焼鈍条件が本発明の範囲内であれば、予
変形付与の形態や予変形後の加工硬化処理（ＢＨ処理：
１７０℃×２０分の熱処理）の有無に関わらず表中の＊
１の欄の値が正、すなわち、所定の変形抵抗の上昇（σ
ｄｙｎ−σｓｔ）が得らることがわかる。ここで、Ｌ方
向とは熱延と同一の方向を指し、Ｃ方向はこれと直行す
る方向を指す。No. In No. 1, the annealing temperature was out of the range of the present invention, and a required amount of retained austenite was not obtained. In addition, No. In No. 2, since the cooling stop temperature of the primary cooling was 500 ° C., which is outside the range of the present invention, securing of the retained austenite was hindered by pearlite generated during cooling. In addition, No. In No. 3, since the cooling rate of the secondary cooling was outside the present invention, the retention of retained austenite was not achieved by pearlite generated during cooling. No. In No. 4, since the cooling stop temperature of the secondary cooling was too low, the amount of generated martensite increased, and the securing of retained austenite could not be achieved. In addition, No. In No. 7, the secondary cooling rate and the bainite transformation treatment temperature were too high, so that retained austenite could not be secured due to the formation of iron carbide. Furthermore, N
o. In No. 9, since the annealing temperature was higher than necessary,
As the structure becomes coarser, the grain size of retained austenite increases, and as a result, a sufficiently large difference between dynamic deformation resistance and static deformation resistance cannot be obtained. All other examples are examples of the present invention, and if the annealing conditions are within the scope of the present invention, the form of pre-deformation imparting and the work hardening treatment after pre-deformation (BH treatment:
* In the table with or without heat treatment at 170 ° C for 20 minutes)
1 is positive, that is, the rise of the predetermined deformation resistance (σ
dyn-σst) is obtained. Here, the L direction indicates the same direction as that of hot rolling, and the C direction indicates a direction perpendicular to the direction.
【００３２】[0032]
【表１】 [Table 1]
【００３３】[0033]
【表２】 [Table 2]
【００３４】[0034]
【表３】 [Table 3]
【００３５】[0035]
【表４】 [Table 4]
【００３６】[0036]
【発明の効果】本発明により、自動車の軽量化と衝突安
全性の確保の要求に応えることのできる高い動的変形抵
抗を有する良加工性高強度冷延鋼板を確実に提供するこ
とができる。According to the present invention, it is possible to reliably provide a high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance and capable of meeting the demands for reducing the weight of an automobile and ensuring crash safety.
【図１】本発明における、衝突時の衝撃エネルギー吸収
能の指標である、５×１０2 〜５×１０3 （１／ｓ）の
歪み速度範囲で変形した時の３〜１０％の相当歪み範囲
における変形応力の平均値σｄｙｎと５×１０-4〜５×
１０-3（１／ｓ）の歪み速度範囲で変形した時の３〜１
０％の相当歪み範囲における変形応力の平均値σｓｔの
差（σｄｙｎ−σｓｔ）と静的な素材強度との関係を示
す図である。FIG. 1 is an equivalent strain of 3 to 10% when deformed in a strain rate range of 5 × 10 2 to 5 × 10 3 (1 / s), which is an index of impact energy absorption capacity at the time of collision in the present invention. Average value of deformation stress in the range σdyn and 5 × 10 -4 to 5 ×
3-1 when deformed in the strain rate range of 10 -3 (1 / s)
It is a figure which shows the relationship between the difference ((sigma) dyn- (sig) st) of the average value (sigma) st of the deformation | transformation stress in the equivalent strain range of 0%, and static material strength.
Claims (10)
以下、ＳｉとＡｌの一方または双方を合計で０．５％以
上３．０％以下、Ｍｎ，Ｎｉ，Ｃｒ，Ｃｕ，Ｍｏの１種
または２種以上を合計で０．５％以上３．５％以下含
み、残部がＦｅ及び不可避的不純物からなり、最終的に
得られる冷延鋼板のミクロ組織がフェライトおよびベイ
ナイトを含み、このいずれかを主相とし、体積分率で３
％以上の残留オーステナイトを含む第３相との複合組織
であり、残留オーステナイト中の固溶〔Ｃ〕量と鋼材の
平均Ｍｎ等量｛Ｍｎｅｑ＝Ｍｎ＋（Ｎｉ＋Ｃｒ＋Ｃｕ＋
Ｍｏ）／２｝によって決まる値（Ｍ＝６７８−４２８×
〔Ｃ〕−３３×Ｍｎｅｑ）が−１４０以上７０未満で、
その鋼材に相当歪みで０％超１０％以下の予変形を与え
た後、５×１０2 〜５×１０3 （１／ｓ）の歪み速度範
囲で変形した時の３〜１０％の相当歪み範囲における変
形応力の平均値σｄｙｎ（ＭＰａ）と５×１０-4〜５×
１０-3（１／ｓ）の歪み速度範囲で変形した時の３〜１
０％の相当歪み範囲における変形応力の平均値σｓｔ
（ＭＰａ）の差が５×１０-4〜５×１０ -3（１／ｓ）の
歪み速度範囲で測定された静的な引張り試験における最
大応力ＴＳ（ＭＰａ）によって表現される式（σｄｙｎ
−σｓｔ）≧−０．２７２×ＴＳ＋３００を満足するこ
とを特徴とする高い動的変形抵抗を有する良加工性高強
度冷延鋼板。C: 0.04% to 0.3% by weight
Hereinafter, one or both of Si and Al should be 0.5% or less in total.
3.0% or less, one of Mn, Ni, Cr, Cu, Mo
Or a total of 0.5% or more and 3.5% or less of two or more
And the remainder consists of Fe and unavoidable impurities.
The microstructure of the obtained cold rolled steel sheet is
And one of them as a main phase, with a volume fraction of 3
Composite structure with third phase containing more than 3% retained austenite
And the amount of solid solution [C] in retained austenite and steel
Average Mn equivalent ｛Mneq = Mn + (Ni + Cr + Cu +
Mo) / 2} (M = 678-428 ×
(C) −33 × Mneq) is −140 or more and less than 70,
Give the steel material a pre-deformation of more than 0% and less than 10% with equivalent strain
After 5 × 10Two~ 5 × 10Three(1 / s) strain rate range
3 to 10% equivalent deformation range when deformed
Form stress average value σdyn (MPa) and 5 × 10-Four~ 5x
10-33-1 when deformed in the strain rate range of (1 / s)
Average value σst of deformation stress in the equivalent strain range of 0%
(MPa) difference is 5 × 10-Four~ 5 × 10 -3(1 / s)
In static tensile tests measured in the strain rate range
Expression (σdyn) expressed by large stress TS (MPa)
−σst) ≧ −0.272 × TS + 300
Good workability and high strength with high dynamic deformation resistance characterized by
Degree cold rolled steel sheet.
計で０．３重量％以下更に含むことを特徴とする請求項
１記載の高い動的変形抵抗を有する良加工性高強度冷延
鋼板。2. The good workability and high strength with high dynamic deformation resistance according to claim 1, further comprising one or more of Nb, Ti and V in total of 0.3% by weight or less. Cold rolled steel sheet.
徴とする請求項１または２記載の高い動的変形抵抗を有
する良加工性高強度冷延鋼板。3. The high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance according to claim 1, further comprising 0.2% by weight or less of P.
特徴とする請求項１〜３のいずれか１項に記載の高い動
的変形抵抗を有する良加工性高強度冷延鋼板。4. The high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance according to claim 1, further comprising B in an amount of 0.01% by weight or less.
鋼材の残留オーステナイト体積分率が２．５％超であ
り、かつ、予変形前の残留オーステナイト体積分率と予
変形後の残留オーステナイト体積分率の比が０．４以上
であることを特徴とする請求項１〜４のいずれか１項に
記載の高い動的変形抵抗を有する良加工性高強度冷延鋼
板。5. A steel material after a predeformation of more than 0% and 10% or less has a retained austenite volume fraction of more than 2.5%, and a residual austenite volume fraction before predeformation and after predeformation. The high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance according to any one of claims 1 to 4, wherein the ratio of the retained austenite volume fraction is 0.4 or more.
中の残留オーステナイトの平均粒径と、主相であるフェ
ライトもしくはベイナイトの平均粒径の比が０．６以下
であることを特徴とする請求項１〜５のいずれか１項に
記載の高い動的変形抵抗を有する良加工性高強度冷延鋼
板。6. The ratio of the average grain size of retained austenite in the microstructure of the finally obtained cold rolled steel sheet to the average grain size of ferrite or bainite as a main phase is 0.6 or less. The high-workability high-strength cold-rolled steel sheet having high dynamic deformation resistance according to any one of claims 1 to 5.
以下、ＳｉとＡｌの一方または双方を合計で０．５％以
上３．０％以下、Ｍｎ，Ｎｉ，Ｃｒ，Ｃｕ，Ｍｏの１種
または２種以上を合計で０．５％以上３．５％以下含
み、残部がＦｅ及び不可避的不純物からなる鋳造スラブ
を、鋳造ままで熱延工程へ直送し、もしくは一旦冷却し
た後に再度加熱した後、熱延して巻き取った熱延鋼板を
酸洗後冷延し、連続焼鈍工程で焼鈍して最終的な製品と
する際に、０．１×（Ａｃ3 −Ａｃ1 ）＋Ａｃ1 ℃以上
Ａｃ3 ＋５０℃以下の温度で１０秒〜３分焼鈍した後
に、１〜１０℃／秒の一次冷却速度で５５０〜７００℃
の範囲の一次冷却停止温度まで冷却し、引き続いて１０
〜２００℃／ｓｅｃの二次冷却速度で３２０℃超５００
℃以下の二次冷却停止温度まで冷却した後３２０℃超５
００℃以下の温度範囲で１５秒〜２０分保持し、室温ま
で冷却することを特徴とする、最終的に得られる冷延鋼
板のミクロ組織がフェライトおよびベイナイトを含み、
そのいずれかを主相とし、体積分率で３％以上の残留オ
ーステナイトを含む第３相との複合組織であり、残留オ
ーステナイト中の固溶〔Ｃ〕量と鋼材の平均Ｍｎ等量
｛Ｍｎｅｑ＝Ｍｎ＋（Ｎｉ＋Ｃｒ＋Ｃｕ＋Ｍｏ）／２｝
によって決まる値（Ｍ＝６７８−４２８×〔Ｃ〕−３３
×Ｍｎｅｑ）が７０以上１８０以下で、その鋼材に相当
歪みで０％超１０％以下の予変形を与えた後、５×１０
2 〜５×１０3 （１／ｓ）の歪み速度範囲で変形した時
の３〜１０％の相当歪み範囲における変形応力の平均値
σｄｙｎ（ＭＰａ）と５×１０-4〜５×１０-3（１／
ｓ）の歪み速度範囲で変形した時の３〜１０％の相当歪
み範囲における変形応力の平均値σｓｔ（ＭＰａ）の差
が５×１０-4〜５×１０-3（１／ｓ）の歪み速度範囲で
測定された静的な引張り試験における最大応力ＴＳ（Ｍ
Ｐａ）によって表現される式（σｄｙｎ−σｓｔ）≧−
０．２７２×ＴＳ＋３００を満足する高い動的変形抵抗
を有する良加工性高強度冷延鋼板の製造方法。7. C: 0.04% to 0.3% by weight
Hereinafter, one or both of Si and Al are 0.5% or more and 3.0% or less in total, and one or two or more of Mn, Ni, Cr, Cu, and Mo are 0.5% or more and 3.5 in total. % Or less, with the balance being Fe and unavoidable impurities, the cast slab is sent directly to the hot rolling process as cast, or once cooled and heated again, then hot rolled and rolled hot rolled steel sheet is pickled. After cold-rolling and annealing in a continuous annealing step to obtain a final product, annealing at a temperature of 0.1 × (Ac 3 −Ac 1 ) + Ac 1 ° C. or higher and Ac 3 + 50 ° C. or lower for 10 seconds to 3 minutes. 550-700 ° C at a primary cooling rate of 1-10 ° C / sec
To the primary cooling stop temperature in the range of
Over 320 ° C at a secondary cooling rate of ~ 200 ° C / sec 500
After cooling to the secondary cooling stop temperature of ℃ or less, exceed 320 ℃ 5
Hold for 15 seconds to 20 minutes in a temperature range of 00 ° C. or less, and cool to room temperature, wherein the microstructure of the finally obtained cold-rolled steel sheet contains ferrite and bainite,
A composite structure with a third phase containing any one of them as a main phase and containing retained austenite in a volume fraction of 3% or more, the amount of solid solution [C] in the retained austenite and the average Mn equivalent of steel material 材 Mneq = Mn + (Ni + Cr + Cu + Mo) / 2}
(M = 678-428 × [C] -33)
× Mneq) is 70 or more and 180 or less, and after giving a predeformation of more than 0% and 10% or less with considerable strain to the steel material, 5 × 10
The average value σdyn (MPa) of the deformation stress in the equivalent strain range of 3 to 10% when deformed in the strain rate range of 2 to 5 × 10 3 (1 / s) and 5 × 10 -4 to 5 × 10 -3 (1 /
s) A strain in which the difference in the average value σst (MPa) of the deformation stress in the equivalent strain range of 3 to 10% when deformed in the strain rate range of 5) is 5 × 10 −4 to 5 × 10 −3 (1 / s). Maximum stress TS (M) in a static tensile test measured in the speed range
Pa) = (dyn−σst) ≧ −
A method for producing a high-workability, high-strength cold-rolled steel sheet having high dynamic deformation resistance satisfying 0.272 × TS + 300.
計で０．３重量％以下更に含むことを特徴とする請求項
７記載の高い動的変形抵抗を有する良加工性高強度冷延
鋼板の製造方法。8. The good workability and high strength with high dynamic deformation resistance according to claim 7, further comprising one or more of Nb, Ti and V in total of 0.3% by weight or less. Manufacturing method of cold rolled steel sheet.
徴とする請求項７または８記載の高い動的変形抵抗を有
する良加工性高強度冷延鋼板の製造方法。9. The method for producing a high-workability high-strength cold-rolled steel sheet having high dynamic deformation resistance according to claim 7, further comprising 0.2% by weight or less of P.
を特徴とする請求項７〜９のいずれか１項に記載の高い
動的変形抵抗を有する良加工性高強度冷延鋼板の製造方
法。10. The high-workability and high-strength cold-rolled steel sheet having high dynamic deformation resistance according to claim 7, further comprising B in an amount of 0.01% by weight or less. Method.
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25892897A JP3530356B2 (en) | 1997-09-24 | 1997-09-24 | Good workability high-strength cold-rolled steel sheet with high dynamic deformation resistance for impact absorption at the time of collision and method for producing the same |
| KR1019997006826A KR100334948B1 (en) | 1997-01-29 | 1998-01-23 | High-strength steel sheet highly resistant to dynamic deformation and excellent in workability and process for the production thereof |
| CA002278841A CA2278841C (en) | 1997-01-29 | 1998-01-23 | High strength steels having excellent formability and high impact energy absorption properties, and a method for producing the same |
| PCT/JP1998/000272 WO1998032889A1 (en) | 1997-01-29 | 1998-01-23 | High-strength steel sheet highly resistant to dynamic deformation and excellent in workability and process for the production thereof |
| AU55767/98A AU716203B2 (en) | 1997-01-29 | 1998-01-23 | High strength steels having excellent formability and high impact energy absorption properties, and a method for production the same |
| US09/355,435 US6544354B1 (en) | 1997-01-29 | 1998-01-23 | High-strength steel sheet highly resistant to dynamic deformation and excellent in workability and process for the production thereof |
| EP98900718.2A EP0974677B2 (en) | 1997-01-29 | 1998-01-23 | A method for producing high strength steels having excellent formability and high impact energy absorption properties |
| EP10181439A EP2312008B1 (en) | 1997-01-29 | 1998-01-23 | High-strength steels having high impact energy absorption properties. |
| CN98802157A CN1072272C (en) | 1997-01-29 | 1998-01-23 | High-strength steel sheet highly resistant to dynamic deformation and excellent in workability and process for production thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25892897A JP3530356B2 (en) | 1997-09-24 | 1997-09-24 | Good workability high-strength cold-rolled steel sheet with high dynamic deformation resistance for impact absorption at the time of collision and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11100636A true JPH11100636A (en) | 1999-04-13 |
| JP3530356B2 JP3530356B2 (en) | 2004-05-24 |
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| JP25892897A Expired - Fee Related JP3530356B2 (en) | 1997-01-29 | 1997-09-24 | Good workability high-strength cold-rolled steel sheet with high dynamic deformation resistance for impact absorption at the time of collision and method for producing the same |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006510802A (en) * | 2002-12-20 | 2006-03-30 | ユジノール（ソシエテ アノニム） | Steel composition for the production of cold rolled multiphase steel products |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3619357B2 (en) * | 1997-12-26 | 2005-02-09 | 新日本製鐵株式会社 | High strength steel sheet having high dynamic deformation resistance and manufacturing method thereof |
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