JPH1180879A - Stain-induced transformation type high strength steel plate excellent in dynamic deformability - Google Patents
Stain-induced transformation type high strength steel plate excellent in dynamic deformabilityInfo
- Publication number
- JPH1180879A JPH1180879A JP25893997A JP25893997A JPH1180879A JP H1180879 A JPH1180879 A JP H1180879A JP 25893997 A JP25893997 A JP 25893997A JP 25893997 A JP25893997 A JP 25893997A JP H1180879 A JPH1180879 A JP H1180879A
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- Prior art keywords
- deformation
- strength
- phase
- austenite
- deformed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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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を吸収することで安全性
確保に寄与することのできる動的変形特性に優れた加工
誘起変態型（以下ＴＲＩＰ型という）高強度鋼板に関す
るものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process-induced transformation type (hereinafter referred to as "transformation-induced transformation type") which is used for automobile members and the like and which can contribute to ensuring safety by absorbing impact energy at the time of collision. (Referred to as TRIP type).
【０００２】[0002]
【従来の技術】近年、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衝撃
吸収性能を持つ材料が要求されている。たとえば乗用車
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
ることで衝撃エネルギが吸収され、乗員にかかる衝撃を
やわらげることができる。2. Description of the Related Art In recent years, occupant protection in the event of a collision has been recognized as the most important performance of an automobile, and a material having a high shock absorption performance has been demanded in order to cope with it. For example, in the case of 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 to absorb the impact energy, so that the impact on the occupant can be reduced.
【０００３】自動車衝突時に各部位が受けるひずみ速度
は１０3 (s-1) 程度に達するため、材料の衝撃吸収性能
を考える場合、このような高速度域での動的変形特性の
解明が必要である。そして、自動車の軽量化と安全性向
上を両立させることのできる、動的変形特性に優れた高
強度鋼板が必要とされ、最近この点に関する報告が見ら
れる。Since the strain rate applied to each part during a vehicle collision reaches about 10 3 (s -1 ), it is necessary to clarify the dynamic deformation characteristics in such a high speed range when considering the shock absorbing performance of a material. It is. There is a need for a high-strength steel sheet having excellent dynamic deformation characteristics, which can achieve both reduction in the weight of a vehicle and improvement in safety. Recently, reports on this point have been made.
【０００４】例えば本発明者らは、CAMP-ISIJ Vol.9(19
96) P.1112〜1115に、高強度薄鋼板の高速変形特性と衝
撃エネルギ吸収能について報告し、その中で、１０3 (s
-1)の高ひずみ速度での動的強度は、１０-3(s-1) の低
ひずみ速度での静的強度と比較して大きく上昇するこ
と、鋼材の強度上昇によりクラッシュ時の吸収エネルギ
が向上すること、材料のひずみ速度依存性は鋼の組織に
依存すること、ＴＲＩＰ型鋼およびＤＰ型鋼（デュアル
フェーズ型鋼）は優れた成形性と高い衝撃吸収能を兼ね
備えることを述べている。また上記ＴＲＩＰ型鋼に関し
本発明者らは、WO95/29268号公報に、自動車の軽量化の
要求に応えることのできる引張強度４４０MPa 以上の深
絞り成形に適した高強度鋼板とその製造方法を提案して
いる。[0004] For example, the present inventors have proposed CAMP-ISIJ Vol.
To 96) P.1112~1115, reported on high speed deformation properties and impact energy absorption capacity of high-strength thin steel sheet, in which, 10 3 (s
Dynamic strength at high strain rate of -1), 10 -3 (s -1) of the greatly increased as compared to the static strength at a low strain rate, the absorbed energy of the crash by the intensity increase of the steel That the strain rate dependence of the material depends on the structure of the steel, and that the TRIP and DP steels (dual-phase steels) have both excellent formability and high shock absorbing ability. Regarding the TRIP type steel, the present inventors have proposed in WO95 / 29268 a high-strength steel sheet suitable for deep drawing with a tensile strength of 440 MPa or more and capable of meeting the demand for reducing the weight of automobiles, and a method for producing the same. ing.
【０００５】[0005]
【発明が解決しようとする課題】上記のように、高強度
鋼板について自動車衝突時の高ひずみ速度における動的
変形特性が解明されつつあるものの、衝撃エネルギ吸収
のための自動車部材として、鋼板のどのような特性に注
目し、どのような基準で材料選定を行えばよいかについ
ては、明らかにされていない。As described above, although the dynamic deformation characteristics of a high-strength steel plate at a high strain rate at the time of an automobile collision are being elucidated, as a vehicle member for absorbing impact energy, any of the steel plates is used as a material. It has not been clarified what kind of criteria should be used for material selection by paying attention to such characteristics.
【０００６】また上記自動車部材は、鋼板に曲げやプレ
ス等の成形を施して製造され、衝突時の衝撃は、これら
成形加工された部材に対して加えられる。しかし、この
ような成形加工後における衝撃エネルギ吸収能を解明し
た、実部材としての動的変形特性に優れた鋼板について
は、従来知られていない。さらに自動車軽量化に適した
ＴＲＩＰ型高強度鋼板に関し、衝突時の衝撃エネルギ吸
収用部材として、どのような成分および組織がよいか、
またどのような基準で材料選定を行えばよいか不明であ
った。[0006] The above-mentioned automobile members are manufactured by forming a steel plate by bending, pressing or the like, and the impact at the time of collision is applied to these formed members. However, a steel sheet excellent in dynamic deformation characteristics as an actual member, which has elucidated the impact energy absorbing ability after such forming, has not been known. Furthermore, regarding the TRIP type high-strength steel sheet suitable for reducing the weight of automobiles, what components and structures are good as members for absorbing impact energy at the time of collision,
Also, it was unclear what criteria should be used for material selection.
【０００７】本発明は、フロントサイドメンバ等の成形
加工された自動車部品に使用される高強度鋼板であっ
て、衝突時の衝撃エネルギ吸収用として、適正な特性お
よび基準に基づいて選定され、安全性確保に確実に寄与
することのできる、動的変形特性に優れたＴＲＩＰ型高
強度鋼板を提供することを目的とする。The present invention relates to a high-strength steel sheet used for molded automobile parts such as front side members and the like, which is selected on the basis of appropriate characteristics and criteria for absorbing impact energy at the time of a collision, and is used for safety. It is an object of the present invention to provide a TRIP-type high-strength steel sheet having excellent dynamic deformation characteristics, which can surely contribute to ensuring the property.
【０００８】[0008]
【課題を解決するための手段】上記目的を達成するため
の本発明の第１発明は、重量％にて、Ｃを０．０４〜
０．３０％、ＳｉとＡｌの一方または双方を合計で０．
３〜３．０％含み、残部がＦｅおよび不可避的不純物か
らなり、主相であるフェライトと、３体積％以上のオー
ステナイトを含む第２相からなる複合組織を有し、オー
ステナイト相の初期体積率Ｖ(0) と、相当ひずみにして
１０％の予変形を加えたときのオーステナイト相の体積
率Ｖ(10)の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ
相当ひずみにて０％超〜１０％以下の予変形を加えたの
ち、５×１０-4〜５×１０-3(s-1)のひずみ速度で変形
したときの準静的変形強度σs と、前記０％超〜１０％
以下の予変形を加えたのち、５×１０2 〜５×１０3 (s
-1) のひずみ速度で変形したときの動的変形強度σd と
の差（σd −σs ）が６０MPa 以上であることを特徴と
する動的変形特性に優れた加工誘起変態型高強度鋼板で
ある。According to a first aspect of the present invention for achieving the above object, the present invention provides a method for reducing C by 0.04% by weight.
0.30%, one or both of Si and Al in a total of 0.10%.
3 to 3.0%, the balance being Fe and inevitable impurities, having a composite structure of ferrite as a main phase and a second phase containing at least 3% by volume of austenite, and the initial volume fraction of the austenite phase The ratio V (10) / V (0) between V (0) and the volume ratio V (10) of the austenite phase when a predeformation of 10% is applied to the equivalent strain is 0.3 or more, and A quasi-static deformation strength σs at the time of deformation at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) after applying a predeformation of more than 0% to 10% or less by strain, Above 0% to 10%
After adding the following pre-deformation, 5 × 10 2 to 5 × 10 3 (s
A work-induced transformation type high-strength steel sheet having excellent dynamic deformation characteristics, wherein the difference (σd−σs) from the dynamic deformation strength σd when deformed at a strain rate of -1 ) is 60 MPa or more. .
【０００９】第２発明は、上記と同成分および同組織を
有し、前記比Ｖ(10)／Ｖ(0) が同じく０．３以上であ
り、かつ相当ひずみにて０％超〜１０％以下の予変形を
加えたのち、５×１０-4〜５×１０-3(s-1) のひずみ速
度で変形したときの準静的変形強度σs と、前記０％超
〜１０％以下の予変形を加えたのち、５×１０2 〜５×
１０3 (s-1) のひずみ速度で変形したときの動的変形強
度σd との差（σd −σs ）が （σd −σs ）≧４．１×σs 0.8 −σs （１） を満足する範囲であることを特徴とする動的変形特性に
優れた加工誘起変態型高強度鋼板である。The second invention has the same components and the same structure as described above, wherein the ratio V (10) / V (0) is also 0.3 or more, and the equivalent strain exceeds 0% to 10% After applying the following pre-deformation, the quasi-static deformation strength σs when deformed at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) and the above-mentioned 0% to 10% or less After pre-deformation, 5 × 10 2 to 5 ×
10 3 range difference between the dynamic deformation strength .sigma.d when deformed strain rate (s -1) (σd -σs) is to satisfy the (σd -σs) ≧ 4.1 × σs 0.8 -σs (1) It is a work-induced transformation type high-strength steel sheet having excellent dynamic deformation characteristics.
【００１０】第３発明は、上記と同成分および同組織を
有し、前記比Ｖ(10)／Ｖ(0) が同じく０．３以上であ
り、かつ相当ひずみにて０％超〜１０％以下の成形加工
による予変形を加えたのち、５×１０-4〜５×１０-3(s
-1) のひずみ速度で変形したときの準静的変形強度σs
と、前記０％超〜１０％以下の予変形を加えたのち、５
×１０2 〜５×１０3 (s-1) のひずみ速度で変形したと
きの動的変形強度σd との差（σd −σs ）が６０MPa
以上であることを特徴とする動的変形特性に優れた加工
誘起変態型高強度鋼板である。The third invention has the same components and the same structure as described above, wherein the ratio V (10) / V (0) is also 0.3 or more, and the equivalent strain exceeds 0% to 10%. After pre-deformation by the following forming process, 5 × 10 -4 to 5 × 10 -3 (s
-1 ) quasi-static deformation strength σs when deformed at a strain rate of
After the pre-deformation of more than 0% to 10% or less,
The difference (σd−σs) from the dynamic deformation strength σd when deformed at a strain rate of × 10 2 to 5 × 10 3 (s −1 ) is 60 MPa.
A work-induced transformation type high-strength steel sheet excellent in dynamic deformation characteristics characterized by the above.
【００１１】第４発明は、上記と同成分および同組織を
有し、前記比Ｖ(10)／Ｖ(0) が同じく０．３以上であ
り、かつ相当ひずみにて０％超〜１０％以下の成形加工
による予変形を加えたのち、５×１０-4〜５×１０-3(s
-1) のひずみ速度で変形したときの準静的変形強度σs
と、前記０％超〜１０％以下の予変形を加えたのち、５
×１０2 〜５×１０3 (s-1) のひずみ速度で変形したと
きの動的変形強度σd との差（σd −σs ）が （σd −σs ）≧４．１×σs 0.8 −σs （１） を満足する範囲であることを特徴とする動的変形特性に
優れた加工誘起変態型高強度鋼板である。A fourth invention has the same components and the same structure as described above, wherein the ratio V (10) / V (0) is also 0.3 or more, and the equivalent strain exceeds 0% to 10% After pre-deformation by the following forming process, 5 × 10 -4 to 5 × 10 -3 (s
-1 ) quasi-static deformation strength σs when deformed at a strain rate of
After the pre-deformation of more than 0% to 10% or less,
The difference (σd−σs) from the dynamic deformation strength σd when deformed at a strain rate of × 10 2 to 5 × 10 3 (s −1 ) is (σd−σs) ≧ 4.1 × σs 0.8 −σs ( 1) A high-strength steel sheet with excellent deformation characteristics, which is characterized by satisfying 1).
【００１２】第５発明は、上記と同成分および同組織を
有し、前記比Ｖ(10)／Ｖ(0) が同じく０．３以上であ
り、かつ調質圧延とテンションレベラの一方または双方
による予変形を、塑性変形量Ｔを ０．５｛Ｖ(10)／Ｖ(0) ／Ｃ−３｝＋１５≧Ｔ≧０．５｛Ｖ(10)／Ｖ(0) ／Ｃ −３｝ （２） に従って加えたのち、５×１０-4〜５×１０-3(s-1) の
ひずみ速度で変形したときの準静的変形強度σs と、前
記（２）式による予変形を加えたのち、５×１０2 〜５
×１０3 (s-1) のひずみ速度で変形したときの動的変形
強度σd との差（σd −σs ）が６０MPa 以上であるこ
とを特徴とする動的変形特性に優れた加工誘起変態型高
強度鋼板である。The fifth invention has the same composition and composition as described above, wherein the ratio V (10) / V (0) is also 0.3 or more, and one or both of temper rolling and a tension leveler. The plastic deformation amount T is set to 0.5 ｛V (10) / V (0) / C-3｝ + 15 ≧ T ≧ 0.5 ｛V (10) / V (0) / C-3｝. After adding according to (2), the quasi-static deformation strength σs when deformed at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) and the pre-deformation according to the above equation (2) are added. Afterwards, 5 × 10 2 -5
A work-induced transformation type excellent in dynamic deformation characteristics characterized in that the difference (σd−σs) from the dynamic deformation strength σd when deformed at a strain rate of × 10 3 (s −1 ) is 60 MPa or more. High strength steel plate.
【００１３】第６発明は、上記と同成分および同組織を
有し、前記比Ｖ(10)／Ｖ(0) が同じく０．３以上であ
り、かつ調質圧延とテンションレベラの一方または双方
による予変形を、塑性変形量Ｔを ０．５｛Ｖ(10)／Ｖ(0) ／Ｃ−３｝＋１５≧Ｔ≧０．５｛Ｖ(10)／Ｖ(0) ／Ｃ −３｝ （２） に従って加えたのち、５×１０-4〜５×１０-3(s-1) の
ひずみ速度で変形したときの準静的変形強度σs と、前
記（２）式による予変形を加えたのち、５×１０2 〜５
×１０3 (s-1) のひずみ速度で変形したときの動的変形
強度σd との差（σd −σs ）が （σd −σs ）≧４．１×σs 0.8 −σs （１） を満足する範囲であることを特徴とする動的変形特性に
優れた加工誘起変態型高強度鋼板である。The sixth invention has the same components and the same structure as described above, the ratio V (10) / V (0) is also 0.3 or more, and one or both of temper rolling and a tension leveler. The plastic deformation amount T is set to 0.5 ｛V (10) / V (0) / C-3｝ + 15 ≧ T ≧ 0.5 ｛V (10) / V (0) / C-3｝. After adding according to (2), the quasi-static deformation strength σs when deformed at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) and the pre-deformation according to the above equation (2) are added. Afterwards, 5 × 10 2 -5
The difference between the dynamic deformation strength .sigma.d when deformed strain rate × 10 3 (s -1) ( σd -σs) satisfies (σd -σs) ≧ 4.1 × σs 0.8 -σs (1) It is a high-strength steel plate with excellent deformation characteristics, which is characterized by being in a range.
【００１４】そして上記各発明において、重量％にて、
Ｍｎ，Ｎｉ，Ｃｕ，ＣｒおよびＭｏの少なくとも１種を
合計で０．５〜３．５％含むことが好ましい。また、重
量％にて、Ｎｂ，Ｔｉ，ＶおよびＰの少なくとも１種を
合計で０．２％以下含むことが好ましい。さらに、重量
％にて、Ｍｎ，Ｎｉ，Ｃｕ，ＣｒおよびＭｏの少なくと
も１種を合計で０．５〜３．５％と、重量％にて、Ｎ
ｂ，Ｔｉ，ＶおよびＰの少なくとも１種を合計で０．２
％以下含むことが好ましい。In each of the above inventions,
It is preferable that at least one of Mn, Ni, Cu, Cr and Mo is contained in a total amount of 0.5 to 3.5%. Further, it is preferable that at least one of Nb, Ti, V and P is contained in a total of 0.2% or less by weight. Further, at% by weight, at least one of Mn, Ni, Cu, Cr and Mo is 0.5 to 3.5% in total, and at% by weight,
at least one of b, Ti, V and P in total of 0.2
% Or less.
【００１５】[0015]
【発明の実施の形態】自動車のフロントサイドメンバ等
の衝撃吸収用部材は、鋼板に曲げ加工やプレス加工など
を施して製造される。自動車衝突時の衝撃は、これら成
形加工された部材に対して加えられるため、本発明の鋼
板は、このような成形加工に相当する予変形後の状態
で、高い衝撃吸収性能を有していることが必要である。
しかし現在までのところ、成形による変形応力の上昇と
ひずみ速度上昇による変形応力の上昇とを同時に考慮し
て、実部材としての衝撃吸収特性に優れた鋼板を得る試
みはなされていない。DESCRIPTION OF THE PREFERRED EMBODIMENTS A shock absorbing member such as a front side member of an automobile is manufactured by bending or pressing a steel plate. Since the impact at the time of automobile collision is applied to these formed members, the steel sheet of the present invention has high shock absorption performance in a state after pre-deformation corresponding to such forming. It is necessary.
However, to date, no attempt has been made to obtain a steel sheet having excellent shock absorption characteristics as an actual member by simultaneously considering the increase in deformation stress due to forming and the increase in deformation stress due to increase in strain rate.
【００１６】本発明者らの研究結果、このような成形加
工された実部材において優れた衝撃吸収特性を有する高
強度鋼板として、ＴＲＩＰ型鋼板が適している。すなわ
ち、主相として変形速度上昇による変形抵抗増加を担う
フェライト相と、変形中に硬質なマルテンサイト相に変
態するオーステナイト相がある場合に、静的強度に対し
て動的変形特性の優れた材料が得られることが判明し
た。しかし初期オーステナイト相が３体積％未満では、
高速変形下での加工誘起変態による変形抵抗増加への寄
与が小さく、従来材を上回る特性を得ることができない
ため、初期オーステナイト相の体積率Ｖ(0) を３体積％
以上と限定した。As a result of the present inventors' research, a TRIP steel sheet is suitable as a high-strength steel sheet having excellent impact absorption characteristics in such a molded real member. In other words, when there is a ferrite phase, which is responsible for the increase in deformation resistance due to an increase in deformation rate, and an austenite phase, which transforms into a hard martensite phase during deformation, a material with excellent dynamic deformation characteristics with respect to static strength Was obtained. However, when the initial austenite phase is less than 3% by volume,
Since the contribution of deformation induced deformation under high-speed deformation to the increase in deformation resistance is small and characteristics exceeding those of conventional materials cannot be obtained, the volume fraction V (0) of the initial austenite phase is 3% by volume.
Limited to the above.
【００１７】また、オーステナイト相の変形に対する安
定性も動的強度の高い鋼板を得るためには重要である。
残留オーステナイトの中でも比較的加工安定性に優れた
ものが存在する場合に動的変形特性に優れた鋼板が得ら
れることがわかったが、鋭意研究の結果、初期オーステ
ナイトの体積率Ｖ(0) と、相当ひずみにして１０％の予
変形を加えたときの残留オーステナイト相の体積率Ｖ(1
0)の比Ｖ(10)／Ｖ(0)が０．３以上の場合に優れた特性
を持つ鋼板が得られることが判明した。またこの安定性
は、プレス成形等の成形時に残留オーステナイトがほと
んど消費されて、衝突時の寄与が失われることを防止す
るためにも重要である。Further, stability against deformation of the austenite phase is also important for obtaining a steel sheet having high dynamic strength.
It has been found that a steel sheet with excellent dynamic deformation characteristics can be obtained when there is relatively excellent work stability among the retained austenite, but as a result of earnest studies, the volume fraction of initial austenite and V (0) , The volume fraction of the retained austenite phase V (1
It has been found that a steel sheet having excellent properties can be obtained when the ratio V (10) / V (0) of (0) is 0.3 or more. This stability is also important for preventing the remaining austenite from being consumed almost at the time of molding such as press molding and losing the contribution at the time of collision.
【００１８】成分の限定理由はつぎのとおりである。Ｃ
は他の高価な合金元素を用いることなくオーステナイト
を安定化させ、室温で残留させるために利用する本発明
で最も重要な元素である。Ｃはオーステナイトの体積分
率に影響するだけでなく、オーステナイト中にＣが濃化
することでオーステナイトの安定性が増し、加工誘起マ
ルテンサイトの変形抵抗が増大する。平均Ｃ量が０．０
４重量％未満では、最終的に得られるオーステナイト体
積分率が３％未満であり、オーステナイトの加工安定性
が低いか、加工誘起マルテンサイトの変形抵抗が比較的
小さい。平均Ｃ量が増加するにしたがって、得られる残
留オーステナイトの最大体積分率が増加し、オーステナ
イトが安定化するが、同時に溶接性が劣化する。また母
相であるフェライト相の硬質化を招き、ひずみ速度上昇
による変形抵抗増加を阻害する。したがって、Ｃ含有量
を０．０４重量％以上０．３０重量％以下とした。The reasons for limiting the components are as follows. C
Is the most important element in the present invention used for stabilizing austenite without using other expensive alloying elements and remaining at room temperature. C not only affects the volume fraction of austenite, but also increases the stability of austenite by enriching C in austenite, and increases the deformation resistance of work-induced martensite. Average C content is 0.0
If it is less than 4% by weight, the finally obtained austenite volume fraction is less than 3%, and the work stability of austenite is low or the deformation resistance of work-induced martensite is relatively small. As the average C content increases, the maximum volume fraction of the obtained retained austenite increases, and the austenite is stabilized, but at the same time, the weldability deteriorates. In addition, it hardens the ferrite phase, which is the parent phase, and hinders an increase in deformation resistance due to an increase in strain rate. Therefore, the C content is set to 0.04% by weight or more and 0.30% by weight or less.
【００１９】ＳｉとＡｌはともにフェライト安定化元素
であり、本発明の対象とするフェライトを主相とする鋼
板には有効な添加元素である。またＳｉもＡｌもセメン
タイトなどの炭化物の生成を抑制し、結果としてＣの消
費を防ぐことができる。これらの元素の添加量が単独も
しくは合計で０．３重量％未満の場合には、炭化物やマ
ルテンサイトが生成しやすく、母材が硬質化するだけで
なく、オーステナイト量が減少したり、成形初期でほと
んどが変態してしまう。Both Si and Al are ferrite stabilizing elements, and are effective addition elements for steel sheets containing ferrite as a main phase, which are the subject of the present invention. In addition, both Si and Al can suppress generation of carbides such as cementite, and as a result, consumption of C can be prevented. When the addition amount of these elements is less than 0.3% by weight alone or in total, carbides and martensite are liable to be formed, not only hardening the base material but also reducing the amount of austenite, Most of them are perverted.
【００２０】また、合計で３．０重量％を超えて添加さ
れた場合には、母相であるフェライト相の硬質化を招
き、ひずみ速度上昇による変形抵抗増加を阻害する。ま
た母相の変形抵抗が高く深絞り性向上効果が得られな
い、靭性が低下する、鋼材コストの上昇を招く、Ｓｉの
場合には化成処理性が劣化するといった問題が生じる。
したがって、ＳｉとＡｌの一方または双方を合計で０．
３重量％以上３．０重量％以下とした。Further, if the total amount exceeds 3.0% by weight, the ferrite phase as a mother phase is hardened, and the increase in deformation resistance due to an increase in strain rate is hindered. Further, there are problems that the deformation resistance of the matrix phase is high and the effect of improving the deep drawability cannot be obtained, the toughness is reduced, the cost of steel material is increased, and in the case of Si, the chemical conversion property is deteriorated.
Therefore, one or both of Si and Al are added in a total amount of 0.1.
It was set to 3% by weight or more and 3.0% by weight or less.
【００２１】必要に応じて添加するＭｎ，Ｎｉ，Ｃｕ，
Ｃｒ，Ｍｏも、ＳｉやＡｌと同様、炭化物の生成を遅ら
せる働きがあることからオーステナイトの残留に貢献す
る添加元素である。これに加えて、これらの合金元素は
オーステナイトの安定性を高めるため、Ｖ(10)／Ｖ(0)
を０．３以上とし衝撃吸収能の向上に有効である。すな
わち溶接性の観点からＣ量に制限がある場合には、これ
ら元素を添加するのが効果的である。これら元素の添加
量が合計で０．５重量％未満の場合にはその効果が十分
ではない。Mn, Ni, Cu,
Cr and Mo, like Si and Al, are elements that contribute to the retention of austenite because they have a function of delaying the generation of carbides. In addition, these alloying elements increase V (10) / V (0) to increase the stability of austenite.
Is 0.3 or more, which is effective for improving the shock absorbing ability. That is, when the amount of C is limited from the viewpoint of weldability, it is effective to add these elements. If the total amount of these elements is less than 0.5% by weight, the effect is not sufficient.
【００２２】一方これら元素の添加量が合計で３．５重
量％を超えると、母相であるフェライト相の硬質化を招
き、ひずみ速度上昇による変形抵抗増加を阻害する。ま
た母相が硬化し深絞り性に対する変態の寄与が低下する
ほか、鋼材コストの上昇を招く。したがって必要に応じ
て添加するＭｎ，Ｎｉ，Ｃｕ，Ｃｒ，Ｍｏの添加量を
０．５重量％以上３．５重量％以下とした。On the other hand, if the total amount of these elements exceeds 3.5% by weight, the ferrite phase, which is the parent phase, is hardened, which hinders an increase in deformation resistance due to an increase in strain rate. In addition, the mother phase is hardened, the contribution of transformation to the deep drawability is reduced, and the cost of steel is increased. Therefore, the addition amount of Mn, Ni, Cu, Cr, and Mo added as necessary is set to 0.5% by weight or more and 3.5% by weight or less.
【００２３】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し、鋼材の
高強度化に有効である。しかし０．２重量％を超えて添
加すると、母相であるフェライト相中または粒界に多量
の炭化物、窒化物もしくは炭窒化物として析出し、高速
変形時に可動転位の放出源となり、ひずみ速度上昇によ
る変形抵抗増加を阻害する。また母相の変形抵抗が必要
以上に増し、さらに不必要にＣを浪費する。そのうえコ
ストの上昇を招く。したがって、必要に応じて添加する
Ｎｂ，Ｔｉ，Ｖは０．２重量％を上限とした。Nb, Ti, V
Forms carbides, nitrides or carbonitrides and is effective for increasing the strength of steel materials. However, if added in excess of 0.2% by weight, a large amount of carbide, nitride or carbonitride precipitates in the ferrite phase, which is the parent phase, or at the grain boundaries, and becomes a source of mobile dislocations during high-speed deformation, increasing the strain rate. Inhibit the increase in deformation resistance. Further, the deformation resistance of the mother phase is increased more than necessary, and C is unnecessarily wasted. In addition, the cost rises. Therefore, the upper limit of Nb, Ti, and V added as needed is 0.2% by weight.
【００２４】さらに必要に応じて添加するＰは、鋼材の
高強度化に効果的で安価な元素である。しかし、０．２
重量％を超えて添加された場合、鋼材のコスト上昇を招
くのみならず、フェライト相の変形抵抗が必要以上に増
す。また耐置割れ性の劣化が顕著になる。したがって
０．２重量％を上限とした。Further, P added as necessary is an inexpensive element effective for increasing the strength of steel. However, 0.2
When added in excess of weight%, not only does the cost of the steel material increase, but also the deformation resistance of the ferrite phase increases more than necessary. In addition, deterioration of the crack resistance becomes remarkable. Therefore, the upper limit was set to 0.2% by weight.
【００２５】つぎに本発明者らの実験検討の結果、実部
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２０％以上になる場合もあるが、相当ひずみに
して０％超〜１０％以下の部位が大半であり、またその
領域での挙動を見ることによってそれ以外の領域の予測
が可能であることを見出した。したがって本発明におい
て、相当ひずみにして０％超〜１０％以下の予変形を付
与することとした。Next, as a result of an experimental study by the present inventors, the amount of pre-deformation corresponding to the forming process of the actual member may be 20% or more depending on the part in the member, but the equivalent strain is 0%. It has been found that the majority of the region is more than 10% to 10% or less, and it is possible to predict the other region by observing the behavior in that region. Therefore, in the present invention, a pre-deformation of more than 0% to 10% or less in equivalent strain is provided.
【００２６】図１は、後述の実施例における表１の各鋼
種について、衝突時における成形部材の吸収エネルギＥ
abと素材強度Ｓの関係を示したものである。素材強度Ｓ
は、通常の引張り試験による引張り強さである。部材吸
収エネルギＥabは、図２に示すような成形部材の長さ方
向（矢印の方向）に、質量４００kgの重錘を速度１５m/
s で衝突させ、そのときの圧潰量１００mmまでの吸収エ
ネルギである。なお図２の成形部材は、厚さ２．０mmの
鋼板を成形したハット型部１に、同厚さ同鋼種の鋼板２
をスポット溶接により接合したものであり、ハット型部
１のコーナー半径は２mmである。３はスポット溶接部で
ある。FIG. 1 shows the absorption energy E of the formed member at the time of collision for each steel type shown in Table 1 in Examples described later.
It shows the relationship between ab and the material strength S. Material strength S
Is the tensile strength in a normal tensile test. The member absorption energy Eab is obtained by moving a weight having a mass of 400 kg in a length direction (direction of an arrow) of a formed member as shown in FIG.
It is the absorbed energy up to 100 mm crushed at that time. The molded member shown in FIG. 2 includes a hat-shaped portion 1 formed of a steel plate having a thickness of 2.0 mm and a steel plate 2 of the same thickness and the same steel type.
Are joined by spot welding, and the corner radius of the hat-shaped part 1 is 2 mm. 3 is a spot weld.
【００２７】図１から、部材吸収エネルギはＥab、素材
強度Ｓの高いものほど高くなる傾向がみられるが、ばら
つきの大きいことがわかる。そこで図１に示す各素材に
ついて、相当ひずみにして０％超〜１０％以下の予変形
を加えたのち、５×１０-4〜５×１０-3(s-1) のひずみ
速度で変形したときの準静的変形強度σs と、５×１０
2 〜５×１０3 (s-1) のひずみ速度で変形したときの動
的変形強度σd を測定した。From FIG. 1, it can be seen that the higher the Eab and the material strength S, the higher the component absorption energy, but the larger the variation. Thus, each material shown in FIG. 1 was subjected to a predeformation of more than 0% to 10% or less in terms of equivalent strain, and then deformed at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ). Quasi-static deformation strength σs and 5 × 10
The dynamic deformation strength σd at the time of deformation at a strain rate of 2 to 5 × 10 3 (s −1 ) was measured.
【００２８】その結果、（σd −σs ）によって層別す
ることができた。図１の各プロットの記号で、○印は、
０％超〜１０％以下の範囲のいずれかの予変形量で（σ
d −σs ）＜６０MPa となるもの、●印は、前記範囲の
すべての予変形量で６０MPa ≦（σd −σs ）であり、
かつ予変形量が５％のとき、６０MPa ≦（σd −σs ）
＜８０MPa であるもの、黒四角印は、前記範囲のすべて
の予変形量で６０MPa ≦（σd −σs ）であり、かつ予
変形量が５％のとき、８０MPa ≦（σd −σs ）＜１０
０MPa であるもの、黒三角印は、前記範囲のすべての予
変形量で６０MPa ≦（σd −σs ）であり、かつ予変形
量が５％のとき、１００MPa ≦（σd −σs ）であるも
の、である。As a result, stratification could be performed by (σd−σs). In the symbol of each plot in FIG.
With any pre-deformation amount in the range of more than 0% to 10% or less (σ
d−σs) <60 MPa, and the black circles indicate that 60 MPa ≦ (σd−σs) for all the pre-deformation amounts in the above range,
When the pre-deformation amount is 5%, 60 MPa ≦ (σd−σs)
<80 MPa, the black squares indicate that 60 MPa ≦ (σd−σs) for all the pre-deformation amounts in the above range, and that 80 MPa ≦ (σd−σs) <10 when the pre-deformation amount is 5%.
0MPa, black triangles indicate 60MPa ≦ (σd−σs) for all the pre-deformation amounts in the above range, and 100MPa ≦ (σd−σs) when the predeformation amount is 5%. It is.
【００２９】そして、０％超〜１０％以下の範囲のすべ
ての予変形量において６０MPa ≦（σd −σs ）である
ものは、衝突時の部材吸収エネルギＥabが、素材強度Ｓ
から予測される値以上であり、衝突時の衝撃吸収用部材
として優れた動的変形特性を有する鋼板であった。前記
予測される値は、図１の曲線で示す値であり、 Ｅab＝０．０６２Ｓ0.8 （３） で示される。したがって本発明の第１発明は、（σd −
σs ）を６０MPa 以上とした。In the case where 60 MPa ≦ (σd−σs) in all the pre-deformation amounts in the range from more than 0% to 10% or less, the material absorption energy Eab at the time of collision is reduced by the material strength S
This is a steel sheet having excellent dynamic deformation characteristics as a member for absorbing impact upon collision. The predicted value is the value shown by the curve in FIG. 1, and is expressed by Eab = 0.062S 0.8 (3). Therefore, the first invention of the present invention provides (σd −
σs) is set to 60 MPa or more.
【００３０】また、通常、動的変形強度は静的変形強度
の累乗の形で表されることが知られており、静的変形強
度が高くなるにつれて、動的変形強度と静的変形強度の
差は小さくなる。しかし、材料の高強度化による軽量化
を考えた場合、動的変形強度と静的変形強度の差が小さ
くなると材料置換による衝撃吸収能の向上が大きくは期
待できず、軽量化の達成が困難となる。この点に関して
研究の結果、（σd −σs ）が上記（１）式を満足する
範囲であれば、材料置換による軽量化が達成できること
がわかり、第２発明は上記（１）式を満足する範囲とし
た。It is known that the dynamic deformation strength is usually expressed as a power of the static deformation strength. As the static deformation strength increases, the dynamic deformation strength and the static deformation strength become larger. The difference becomes smaller. However, when considering the weight reduction by increasing the strength of the material, if the difference between the dynamic deformation strength and the static deformation strength is small, the improvement in the shock absorption capacity by replacing the material cannot be expected greatly, and it is difficult to achieve the weight reduction. Becomes As a result of research on this point, it has been found that if (σd−σs) is within the range satisfying the above equation (1), weight reduction can be achieved by material replacement, and the second invention is within the range satisfying the above equation (1). And
【００３１】以下に、衝突時の衝撃吸収能が高められる
機構について考察する。ＴＲＩＰ鋼板の衝撃吸収能を高
めるには、主相であるフェライトがＳｉやＭｎ等により
固溶強化されていること、および衝突変形前のフェライ
ト相中の転位密度が高く、かつその転位がＣやＮ等の固
溶元素により固着されていること、さらに残留オーステ
ナイトが高速変形中に変形抵抗を高める働きをすること
の３要件が重要である。Hereinafter, a mechanism for enhancing the shock absorbing ability at the time of a collision will be considered. In order to increase the shock absorbing capacity of the TRIP steel sheet, the main phase ferrite is solid-solution strengthened by Si, Mn, etc., and the dislocation density in the ferrite phase before collision deformation is high, and the dislocation is C or C. It is important that the three requirements are that they are fixed by a solid solution element such as N and that the retained austenite functions to increase the deformation resistance during high-speed deformation.
【００３２】固溶強化は、固溶元素との相互作用により
転位の易動度が低下し、転位同士が絡み合うことで新た
な可動転位の増加を抑制するものであり、動的変形強度
の増大に寄与する。しかし固溶強化のみでは到達できる
動的変形強度に限界がある。また予変形により転位密度
を高めただけでは材料の延性が低下し、成形性の劣化を
来す。さらにＴＲＩＰ鋼の場合、加工時に残留オーステ
ナイトがマルテンサイトに変態することにより強度上昇
をもたらすが、衝突時の高速変形においても残留オース
テナイトがマルテンサイトに変態することで衝撃吸収能
が高められる。したがって上記３要件をともに備えるこ
とが重要である。In the solid solution strengthening, the mobility of dislocations is reduced by the interaction with a solid solution element, and the dislocations are entangled with each other to suppress the increase of new movable dislocations, and the dynamic deformation strength is increased. To contribute. However, there is a limit to the dynamic deformation strength that can be achieved only by solid solution strengthening. Further, simply increasing the dislocation density by pre-deformation lowers the ductility of the material, resulting in deterioration of formability. Further, in the case of TRIP steel, although the retained austenite is transformed into martensite during working, the strength is increased, but even during high-speed deformation at the time of collision, the retained austenite is transformed into martensite, thereby enhancing the shock absorbing ability. Therefore, it is important to satisfy all three requirements.
【００３３】そして衝撃吸収用部材には、衝突変形以前
に部材成形などの予変形が加えられている。この予変形
によって、静的な変形抵抗が上昇するほか、動的な変形
抵抗も上昇することが必要である。動的変形抵抗が上昇
しないと、従来材に比べた大きな衝撃吸収能の向上が見
込めないからである。本発明においては上記のように３
体積％以上のオーステナイトを含み、かつＶ(10)／Ｖ
(0) を０．３以上としているので、高速変形前にもオー
ステナイトが必要量残存しており、衝撃吸収能が向上す
る。The shock absorbing member is subjected to a pre-deformation such as molding before the collision deformation. This pre-deformation needs to increase not only static deformation resistance but also dynamic deformation resistance. If the dynamic deformation resistance does not increase, it is impossible to expect a great improvement in the shock absorbing capacity as compared with the conventional material. In the present invention, as described above, 3
V (10) / V containing austenite by volume% or more
Since (0) is 0.3 or more, a necessary amount of austenite remains even before high-speed deformation, and the shock absorbing ability is improved.
【００３４】つぎに、予変形は部材成形のための成形加
工であってもよく、また該成形加工以前の鋼板素材に与
えられる調質圧延やテンションレベラによる加工であっ
てもよい。この場合、調質圧延とテンションレベラの一
方または双方とすることができる。すなわち、調質圧
延、テンションレベラ、調質圧延およびテンションレベ
ラのいずれであってもよい。さらに調質圧延やテンショ
ンレベラにより加工された鋼板素材に成形加工を加えて
もよい。Next, the pre-deformation may be a forming process for forming a member, or may be a temper rolling or a tension leveler applied to a steel sheet material before the forming process. In this case, one or both of the temper rolling and the tension leveler can be used. That is, any of temper rolling, tension leveler, temper rolling and tension leveler may be used. Further, a forming process may be added to the steel sheet material processed by the temper rolling or the tension leveler.
【００３５】第３発明および第４発明は予変形を成形加
工としたものであるが、鋼板素材に上記のような加工が
施されていてもよい。また第５発明および第６発明は、
予変形を調質圧延とテンションレベラの一方または双方
で行うものであるが、さらに部材成形のための成形加工
が加えられてもよい。In the third invention and the fourth invention, the pre-deformation is formed by forming, but the above-described processing may be applied to a steel sheet material. Further, the fifth invention and the sixth invention,
Although the pre-deformation is performed by one or both of the temper rolling and the tension leveler, a forming process for forming a member may be further added.
【００３６】特に大幅な軽量化を図るために薄手の鋼板
を素材とするような場合は、部材成形前に十分な動的強
度を有していることが重要である。上記第３発明および
第４発明では、主としてプレス成形による予変形を念頭
においたものであるが、プレス成形以外の成形、例えば
ロール成形による曲げ加工で部材が成形されるときは、
曲げ加工を受けない部位はすでに十分な動的強度を有
し、曲げ部位は成形によって動的強度がより向上するか
らである。In particular, when a thin steel plate is used as a material in order to achieve a significant reduction in weight, it is important to have a sufficient dynamic strength before forming the member. In the third invention and the fourth invention, mainly pre-deformation by press molding is considered in mind, but when a member is formed by molding other than press molding, for example, bending by roll molding,
This is because a portion that is not subjected to the bending process already has a sufficient dynamic strength, and the bending portion further improves the dynamic strength by forming.
【００３７】この場合、上記と同成分および同組織を有
し、前記比Ｖ(10)／Ｖ(0) が同じく０．３以上であり、
かつ調質圧延とテンションレベラの一方または双方によ
る予変形を、塑性変形量Ｔを上記（２）式に従って加え
たのち、５×１０-4〜５×１０-3(s-1) のひずみ速度で
変形したときの準静的変形強度σs と、前記（２）式に
よる予変形を加えたのち、５×１０2 〜５×１０
3 (s-1) のひずみ速度で変形したときの動的変形強度σ
d との差（σd −σs ）が６０MPa 以上であるものを第
５発明とし、上記（１）式を満足するものを第６発明と
した。In this case, it has the same components and the same structure as above, and the ratio V (10) / V (0) is also 0.3 or more,
In addition, the strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) after pre-deformation by either or both of the temper rolling and the tension leveler and the amount of plastic deformation T added according to the above equation (2). After adding the quasi-static deformation strength σs when deformed by the equation (1) and the pre-deformation according to the equation (2), 5 × 10 2
3 Dynamic deformation strength σ when deformed at a strain rate of (s -1 )
A device having a difference (σd−σs) from d of 60 MPa or more is defined as a fifth invention, and a device satisfying the above formula (1) is defined as a sixth invention.
【００３８】第５発明および第６発明において与えられ
るべき塑性変形量Ｔには、つぎの３つ意味がある。第１
は他鋼種と同様、塑性変形による転位の導入が行われる
ということ、第２は塑性変形により残留オーステナイト
がマルテンサイト変態するということである。この変態
は、マルテンサイト周辺のフェライト相にひずみを与え
ることとなり、転位密度が増加する。第３は高速変形時
における残留オーステナイトの加工安定性を制御すると
いうことである。高速変形時の安定性を低めることで変
態が促進され、変形抵抗が上昇し、衝撃吸収能が向上す
る。The plastic deformation amount T to be given in the fifth and sixth inventions has the following three meanings. First
As in other steel types, dislocations are introduced by plastic deformation, and secondly, retained austenite undergoes martensitic transformation due to plastic deformation. This transformation gives strain to the ferrite phase around martensite, and increases the dislocation density. Third, it controls the processing stability of retained austenite during high-speed deformation. By lowering the stability during high-speed deformation, transformation is promoted, deformation resistance is increased, and shock absorbing ability is improved.
【００３９】上記第１および第２のようにして導入され
た転位が、高速変形前に固溶元素により固着された状態
で存在すれば、高速変形時に大きな抵抗として作用す
る。そのため、鋼板素材のＢＨ量が５０MPa 以上あると
よく、望ましくは７０MPa 以上あればなおよい。ＢＨ量
は固溶元素の指標である。引張試験片に２％の予ひずみ
を与え、そのときの荷重を測定し、１７０℃で２０分加
熱する熱処理を行ったのち再び引張って降伏荷重を測定
し、熱処理前後の荷重差を原断面積で割ったものがＢＨ
量である。If the dislocations introduced as described above in the first and the second exist in a state of being fixed by a solid solution element before the high-speed deformation, they act as a large resistance during the high-speed deformation. Therefore, the BH amount of the steel sheet material is preferably 50 MPa or more, and more preferably 70 MPa or more. The BH amount is an index of a solid solution element. A 2% pre-strain is applied to the tensile test piece, the load at that time is measured, heat treatment is performed at 170 ° C. for 20 minutes, and then the tensile load is measured again to measure the yield load. BH divided by
Quantity.
【００４０】上記第３については、Ｖ(10)／Ｖ(0) およ
びＣ量が、与えるべき塑性変形量Ｔを決める指標とな
る。Ｖ(10)／Ｖ(0) は、高速変形前にすべてが変態して
しまうことを防ぐため下限を０．３としていた。しかし
高速変形時に変態しなければ強度上昇への寄与が期待さ
れ難い。また高速変形時により小さなひずみ域で変態す
るのであれば、衝突時に大きなひずみ域まで変形しない
部位でも多くのエネルギを吸収できるため有利である。
このような観点から残留オーステナイトの加工安定性を
制御し、安定性を低める、すなわち変態を促進すること
は重要である。In the third aspect, V (10) / V (0) and the amount of C are indices for determining the amount of plastic deformation T to be given. The lower limit of V (10) / V (0) is set to 0.3 in order to prevent all transformations before high-speed deformation. However, if it does not transform at the time of high-speed deformation, it is difficult to expect a contribution to an increase in strength. Further, if the transformation is performed in a small strain range at the time of high-speed deformation, it is advantageous because a lot of energy can be absorbed even in a portion that does not deform to a large strain range at the time of collision.
From such a viewpoint, it is important to control the processing stability of the retained austenite to reduce the stability, that is, to promote the transformation.
【００４１】このように考察すると、Ｖ(10)／Ｖ(0) の
値が大きな材料については、部材成形以前の鋼板素材に
適正な塑性変形量Ｔを与えておけばよいことがわかる。
また残留オーステナイトの安定性を決める要因としてＣ
量がある。Ｃ量、正確には残留オーステナイト中のＣ量
が多いほど加工に対する安定性が高い。From the above consideration, it can be seen that for a material having a large value of V (10) / V (0), an appropriate amount of plastic deformation T may be given to the steel sheet material before forming the member.
In addition, C is a factor that determines the stability of retained austenite.
There is quantity. The greater the C content, more precisely, the greater the C content in the retained austenite, the higher the stability to processing.
【００４２】本発明者は、鋭意研究の結果、フェライト
相と残留オーステナイト相以外のベイナイト相やマルテ
ンサイト相の状態も含めて、Ｖ(10)／Ｖ(0) ／Ｃに着目
すれば残留オーステナイトの加工安定性を制御できるこ
とが判明した。ここでＣは鋼全体のＣ含有量（重量％）
である。そして、鋼板素材に調質圧延とテンションレベ
ラの一方または双方によりあたえる塑性変形量Ｔを Ｔ≧０．５｛Ｖ(10)／Ｖ(0) ／Ｃ−３｝ とした。Ｔの上限は衝撃吸収能の点からの制限はない
が、曲げ性などの成形性の観点から ０．５｛Ｖ(10)／Ｖ(0) ／Ｃ−３｝＋１５≧Ｔ とした。As a result of intensive studies, the present inventor has focused on the residual austenite by focusing on V (10) / V (0) / C, including the state of the bainite phase and the martensite phase other than the ferrite phase and the residual austenite phase. It has been found that the processing stability can be controlled. Here, C is the C content (% by weight) of the entire steel.
It is. The amount of plastic deformation T applied to the steel sheet material by one or both of the temper rolling and the tension leveler was set to T ≧ 0.5 {V (10) / V (0) / C-3}. The upper limit of T is not limited in terms of the impact absorbing ability, but is set to 0.5 ｛V (10) / V (0) / C-3｝ + 15 ≧ T from the viewpoint of formability such as bending property.
【００４３】なお調質圧延とテンションレベラの一方ま
たは双方により塑性変形量Ｔが与えられた鋼板素材に対
して、さらに部材成形用の成形加工を加えてもよく、そ
の場合の上記塑性変形量Ｔは、上限を０．５｛Ｖ(10)／
Ｖ(0) ／Ｃ−３｝＋５とするのが望ましい。The steel sheet material to which the plastic deformation amount T is given by one or both of the temper rolling and the tension leveler may be further subjected to a forming process for forming a member. Is 0.5 上限 V (10) /
V (0) / C−3｝ +5 is desirable.
【００４４】[0044]
［実施例１］：表１に示す２４種類の鋼板について、予
変形後、塗装焼付けを想定して１７０℃２０分の処理
（ＢＨ処理）を行った場合および行わなかった場合につ
いて、σd およびσs を測定した。σd およびσs の測
定は、鋼板の圧延方向と平行な方向を軸とする引張試験
により行った。また上記と同様にして、図２に示す成形
部材を製作し、ＢＨ処理を行った場合および行わなかっ
た場合について、部材吸収エネルギを測定した。予変形
は鋼板の圧延方向と直角方向に単軸引張りにて行い、相
当ひずみ量が表２中の値となるように付加した。[Example 1]: For the 24 types of steel plates shown in Table 1, after pre-deformation, σ d and σ s were obtained with and without treatment (BH treatment) at 170 ° C for 20 minutes assuming paint baking. Was measured. The measurement of σd and σs was performed by a tensile test with an axis in a direction parallel to the rolling direction of the steel sheet. In the same manner as described above, the molded member shown in FIG. 2 was manufactured, and the member absorbed energy was measured when the BH treatment was performed and when it was not performed. The pre-deformation was performed by uniaxial tension in the direction perpendicular to the rolling direction of the steel sheet, and was added so that the equivalent strain amount became the value in Table 2.
【００４５】結果は、表２に示すとおり、成分がはずれ
た比較例のＡ鋼およびＤ鋼は（σd−σs ）が６０MPa
未満であり、かつ（１）式を満足しない。成分が本発明
の条件内であっても、Ｖ(10)／Ｖ(0) が０．３未満のN
o．８，９，１５は、（σd −σs ）が６０MPa 未満で
あり、かつ（１）式を満足しない。そして部材吸収エネ
ルギが素材強度から予測される値未満であった。それに
対して、いずれの予変形量においても（σd −σs ）が
６０MPa 以上である本発明例、および（σd −σs ）が
（１）式を満足する本発明例は、部材吸収エネルギが素
材強度から予測される値以上の優れた衝撃吸収能を示し
た。As shown in Table 2, the steels A and D of Comparative Examples having the deviated components had (σd-σs) of 60 MPa.
And does not satisfy the expression (1). V (10) / V (0) is less than 0.3 even if the components are within the conditions of the present invention.
o. 8, 9, and 15 have (σd-σs) less than 60 MPa and do not satisfy the expression (1). The member absorbed energy was less than the value predicted from the material strength. On the other hand, in any of the examples of the present invention in which (σd−σs) is equal to or greater than 60 MPa at any of the pre-deformation amounts, and in the example of the present invention in which (σd−σs) satisfies the expression (1), the material absorption energy is lower than the material strength. It exhibited excellent shock absorbing ability that was higher than the value predicted from the above.
【００４６】［実施例２］：実部材は種々の変形様式に
より成形されるため、表２の記号１１の本発明例につい
て、予変形を３種類の変形様式により行った。予変形量
はいずれも５％とし、変形様式は、鋼板の圧延方向と直
角方向（Ｃ方向）および平行方向（Ｌ方向）に単軸引張
りで行った場合、平面ひずみで行った場合、および等二
軸引張りで行った場合とした。Example 2 Since the actual member is formed by various deformation modes, the pre-deformation was performed by three types of deformation modes for the example of the present invention denoted by reference numeral 11 in Table 2. The amount of pre-deformation is 5%, and the deformation modes are uniaxial tension in the direction perpendicular to the rolling direction of the steel sheet (C direction) and parallel direction (L direction), in the case of plane strain, and so on. This was the case where the biaxial tension was applied.
【００４７】予変形後はＢＨ処理を行い、ついで鋼板の
圧延方向と平行な方向を軸とする変形によりσd および
σs を測定した。結果は表３に示すとおり、（σd −σ
s ）が６０MPa 以上で、かつ（１）式を満足する範囲で
あり、部材吸収エネルギが素材強度から予測される値以
上の優れた衝撃吸収能を示した。After the pre-deformation, a BH treatment was performed, and then σ d and σ s were measured by deformation with the axis parallel to the rolling direction of the steel sheet. As shown in Table 3, the results are (σd-σ
s) was 60 MPa or more and was within the range satisfying the expression (1), and the member absorbed energy showed an excellent impact absorbing ability not less than the value predicted from the material strength.
【００４８】[0048]
【表１】 [Table 1]
【００４９】[0049]
【表２】 [Table 2]
【００５０】[0050]
【表３】 [Table 3]
【００５１】[0051]
【表４】 [Table 4]
【００５２】[0052]
【表５】 [Table 5]
【００５３】[0053]
【表６】 [Table 6]
【００５４】［実施例３］：表２のNo．５およびNo．１
１と同じ鋼、素材強度、Ｖ(0) およびＶ(10)／Ｖ(0) を
有するものについて、調質圧延の塑性変形量Ｔを変化さ
せ動的強度を測定した。図３にＴ−０．５｛Ｖ(10)／Ｖ
(0) ／Ｃ−３｝と静動比との関係を示す。静動比は（調
質圧延後の動的強度）／（調質圧延前の静的強度）であ
る。（２）式を満足する第５発明および第６発明の範囲
で塑性変形量Ｔを与えたものは、静動比が１．２以上の
優れた特性を示す。[Example 3]: No. 3 in Table 2. 5 and No. 1
With respect to steel having the same material strength, V (0) and V (10) / V (0) as in Example 1, the dynamic strength was measured by changing the amount of plastic deformation T in temper rolling. FIG. 3 shows T-0.5 ｛V (10) / V
The relationship between (0) / C-3｝ and the static-dynamic ratio is shown. The static-dynamic ratio is (dynamic strength after temper rolling) / (static strength before temper rolling). Those given the amount of plastic deformation T within the range of the fifth invention and the sixth invention satisfying the expression (2) show excellent characteristics with a static-dynamic ratio of 1.2 or more.
【００５５】[0055]
【発明の効果】本発明により、自動車の軽量化と安全性
確保の要求にともに応えることのできる、衝突時の衝撃
吸収能の優れたＴＲＩＰ型高強度鋼板を、確実に提供す
ることができる。According to the present invention, it is possible to surely provide a TRIP-type high-strength steel sheet having excellent shock absorbing ability at the time of collision, which can meet both the demands for reducing the weight of vehicles and ensuring safety.
【図１】本発明における部材吸収エネルギと素材強度の
関係を示すグラフである。FIG. 1 is a graph showing a relationship between a member absorbed energy and a material strength in the present invention.
【図２】本発明における衝撃吸収エネルギ測定用の成形
部材を示す斜視図である。FIG. 2 is a perspective view showing a molded member for measuring shock absorption energy in the present invention.
【図３】本発明例および比較例の調質圧延による静動比
の変化を示すグラフである。FIG. 3 is a graph showing a change in a static-dynamic ratio by temper rolling of the present invention example and a comparative example.
１…ハット型部 ２…鋼板 ３…スポット溶接部 1. Hat-shaped part 2. Steel plate 3. Spot welded part
───────────────────────────────────────────────────── フロントページの続き (72)発明者 佐久間 康治 千葉県君津市君津１番地 新日本製鐵株式 会社君津製鐵所内 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Koji Sakuma 1 Kimitsu, Kimitsu City, Chiba Prefecture Nippon Steel Corporation Kimitsu Works
Claims (8)
％、ＳｉとＡｌの一方または双方を合計で０．３〜３．
０％含み、残部がＦｅおよび不可避的不純物からなり、
主相であるフェライトと、３体積％以上のオーステナイ
トを含む第２相からなる複合組織を有し、オーステナイ
ト相の初期体積率Ｖ(0) と、相当ひずみにして１０％の
予変形を加えたときのオーステナイト相の体積率Ｖ(10)
の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ相当ひず
みにて０％超〜１０％以下の予変形を加えたのち、５×
１０-4〜５×１０-3(s-1) のひずみ速度で変形したとき
の準静的変形強度σs と、前記０％超〜１０％以下の予
変形を加えたのち、５×１０2 〜５×１０3 (s-1) のひ
ずみ速度で変形したときの動的変形強度σd との差（σ
d −σs ）が６０MPa 以上であることを特徴とする動的
変形特性に優れた加工誘起変態型高強度鋼板。C. 0.04 to 0.30% by weight of C
%, One or both of Si and Al in total of 0.3 to 3.
0%, the balance being Fe and unavoidable impurities,
It has a composite structure consisting of ferrite, which is the main phase, and a second phase containing at least 3% by volume of austenite, and has been subjected to an initial volume fraction V (0) of the austenite phase and a predeformation of 10% in equivalent strain. Volume fraction of austenitic phase V (10)
The ratio V (10) / V (0) is 0.3 or more, and after applying a predeformation of more than 0% to 10% or less at an equivalent strain, 5 ×
After applying the quasi-static deformation strength σs when deformed at a strain rate of 10 −4 to 5 × 10 −3 (s −1 ) and the pre-deformation of more than 0% to 10% or less, 5 × 10 2 The difference (σ) from the dynamic deformation strength σd when deformed at a strain rate of ５5 × 10 3 (s −1 )
d- [sigma] s) is 60 MPa or more, a work-induced transformation type high-strength steel sheet having excellent dynamic deformation characteristics.
％、ＳｉとＡｌの一方または双方を合計で０．３〜３．
０％含み、残部がＦｅおよび不可避的不純物からなり、
主相であるフェライトと、３体積％以上のオーステナイ
トを含む第２相からなる複合組織を有し、オーステナイ
ト相の初期体積率Ｖ(0) と、相当ひずみにして１０％の
予変形を加えたときのオーステナイト相の体積率Ｖ(10)
の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ相当ひず
みにて０％超〜１０％以下の予変形を加えたのち、５×
１０-4〜５×１０-3(s-1) のひずみ速度で変形したとき
の準静的変形強度σs と、前記０％超〜１０％以下の予
変形を加えたのち、５×１０2 〜５×１０3 (s-1) のひ
ずみ速度で変形したときの動的変形強度σd との差（σ
d −σs ）が （σd −σs ）≧４．１×σs 0.8 −σs （１） を満足する範囲であることを特徴とする動的変形特性に
優れた加工誘起変態型高強度鋼板。2. C is 0.04 to 0.30% by weight.
%, One or both of Si and Al in total of 0.3 to 3.
0%, the balance being Fe and unavoidable impurities,
It has a composite structure consisting of ferrite, which is the main phase, and a second phase containing at least 3% by volume of austenite, and has been subjected to an initial volume fraction V (0) of the austenite phase and a predeformation of 10% in equivalent strain. Volume fraction of austenitic phase V (10)
The ratio V (10) / V (0) is 0.3 or more, and after applying a predeformation of more than 0% to 10% or less at an equivalent strain, 5 ×
After applying the quasi-static deformation strength σs when deformed at a strain rate of 10 −4 to 5 × 10 −3 (s −1 ) and the pre-deformation of more than 0% to 10% or less, 5 × 10 2 The difference (σ) from the dynamic deformation strength σd when deformed at a strain rate of ５5 × 10 3 (s −1 )
d -σs) is (σd -σs) ≧ 4.1 × σs 0.8 strain-induced transformation type high-strength steel sheet having excellent dynamic deformation properties, which is a range satisfying the -σs (1).
％、ＳｉとＡｌの一方または双方を合計で０．３〜３．
０％含み、残部がＦｅおよび不可避的不純物からなり、
主相であるフェライトと、３体積％以上のオーステナイ
トを含む第２相からなる複合組織を有し、オーステナイ
ト相の初期体積率Ｖ(0) と、相当ひずみにして１０％の
予変形を加えたときのオーステナイト相の体積率Ｖ(10)
の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ相当ひず
みにて０％超〜１０％以下の成形加工による予変形を加
えたのち、５×１０-4〜５×１０-3(s-1) のひずみ速度
で変形したときの準静的変形強度σs と、前記０％超〜
１０％以下の予変形を加えたのち、５×１０2 〜５×１
０3 (s-1) のひずみ速度で変形したときの動的変形強度
σd との差（σd −σs ）が６０MPa 以上であることを
特徴とする動的変形特性に優れた加工誘起変態型高強度
鋼板。3. C is 0.04 to 0.30% by weight.
%, One or both of Si and Al in total of 0.3 to 3.
0%, the balance being Fe and unavoidable impurities,
It has a composite structure consisting of ferrite, which is the main phase, and a second phase containing at least 3% by volume of austenite, and has been subjected to an initial volume fraction V (0) of the austenite phase and a predeformation of 10% in equivalent strain. Volume fraction of austenitic phase V (10)
The ratio V (10) / V (0) is 0.3 or more, and after applying a pre-deformation by molding at an equivalent strain of more than 0% to 10% or less, 5 × 10 −4 to 5 × The quasi-static deformation strength σs when deformed at a strain rate of 10 −3 (s −1 )
After pre-deformation of 10% or less, 5 × 10 2 to 5 × 1
A difference (σd−σs) from the dynamic deformation strength σd at the time of deformation at a strain rate of 0 3 (s −1 ) of 60 MPa or more; Strength steel plate.
％、ＳｉとＡｌの一方または双方を合計で０．３〜３．
０％含み、残部がＦｅおよび不可避的不純物からなり、
主相であるフェライトと、３体積％以上のオーステナイ
トを含む第２相からなる複合組織を有し、オーステナイ
ト相の初期体積率Ｖ(0) と、相当ひずみにして１０％の
予変形を加えたときのオーステナイト相の体積率Ｖ(10)
の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ相当ひず
みにて０％超〜１０％以下の成形加工による予変形を加
えたのち、５×１０-4〜５×１０-3(s-1) のひずみ速度
で変形したときの準静的変形強度σs と、前記０％超〜
１０％以下の予変形を加えたのち、５×１０2 〜５×１
０3 (s-1) のひずみ速度で変形したときの動的変形強度
σd との差（σd −σs ）が （σd −σs ）≧４．１×σs 0.8 −σs （１） を満足する範囲であることを特徴とする動的変形特性に
優れた加工誘起変態型高強度鋼板。4. C is 0.04 to 0.30% by weight.
%, One or both of Si and Al in total of 0.3 to 3.
0%, the balance being Fe and unavoidable impurities,
It has a composite structure consisting of ferrite, which is the main phase, and a second phase containing at least 3% by volume of austenite, and has been subjected to an initial volume fraction V (0) of the austenite phase and a predeformation of 10% in equivalent strain. Volume fraction of austenitic phase V (10)
The ratio V (10) / V (0) is 0.3 or more, and after applying a pre-deformation by molding at an equivalent strain of more than 0% to 10% or less, 5 × 10 −4 to 5 × The quasi-static deformation strength σs when deformed at a strain rate of 10 −3 (s −1 )
After pre-deformation of 10% or less, 5 × 10 2 to 5 × 1
0 3 range difference between the dynamic deformation strength .sigma.d when deformed strain rate (s -1) (σd -σs) is to satisfy the (σd -σs) ≧ 4.1 × σs 0.8 -σs (1) A work-induced transformation type high-strength steel sheet having excellent dynamic deformation characteristics.
％、ＳｉとＡｌの一方または双方を合計で０．３〜３．
０％含み、残部がＦｅおよび不可避的不純物からなり、
主相であるフェライトと、３体積％以上のオーステナイ
トを含む第２相からなる複合組織を有し、オーステナイ
ト相の初期体積率Ｖ(0) と、相当ひずみにして１０％の
予変形を加えたときのオーステナイト相の体積率Ｖ(10)
の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ調質圧延
とテンションレベラの一方または双方による予変形を、
塑性変形量Ｔを ０．５｛Ｖ(10)／Ｖ(0) ／Ｃ−３｝＋１５≧Ｔ≧０．５｛Ｖ(10)／Ｖ(0) ／Ｃ −３｝ （２） に従って加えたのち、５×１０-4〜５×１０-3(s-1) の
ひずみ速度で変形したときの準静的変形強度σs と、前
記（２）式による予変形を加えたのち、５×１０2 〜５
×１０3 (s-1) のひずみ速度で変形したときの動的変形
強度σd との差（σd −σs ）が６０MPa 以上であるこ
とを特徴とする動的変形特性に優れた加工誘起変態型高
強度鋼板。5. C is 0.04 to 0.30% by weight.
%, One or both of Si and Al in total of 0.3 to 3.
0%, the balance being Fe and unavoidable impurities,
It has a composite structure consisting of ferrite, which is the main phase, and a second phase containing at least 3% by volume of austenite, and has been subjected to an initial volume fraction V (0) of the austenite phase and a predeformation of 10% in equivalent strain. Volume fraction of austenitic phase V (10)
The ratio V (10) / V (0) is 0.3 or more, and the pre-deformation by one or both of the temper rolling and the tension leveler is
The plastic deformation amount T is added according to the following equation: 0.5 ｛V (10) / V (0) / C-3｝ + 15 ≧ T ≧ 0.5 ｛V (10) / V (0) / C-3｝ (2) Thereafter, the quasi-static deformation strength σs when deformed at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) and the pre-deformation by the above equation (2) are added, and then 5 × 10 2 to 5
A work-induced transformation type excellent in dynamic deformation characteristics characterized in that the difference (σd−σs) from the dynamic deformation strength σd when deformed at a strain rate of × 10 3 (s −1 ) is 60 MPa or more. High strength steel plate.
％、ＳｉとＡｌの一方または双方を合計で０．３〜３．
０％含み、残部がＦｅおよび不可避的不純物からなり、
主相であるフェライトと、３体積％以上のオーステナイ
トを含む第２相からなる複合組織を有し、オーステナイ
ト相の初期体積率Ｖ(0) と、相当ひずみにして１０％の
予変形を加えたときのオーステナイト相の体積率Ｖ(10)
の比Ｖ(10)／Ｖ(0) が０．３以上であり、かつ調質圧延
とテンションレベラの一方または双方による予変形を、
塑性変形量Ｔを ０．５｛Ｖ(10)／Ｖ(0) ／Ｃ−３｝＋１５≧Ｔ≧０．５｛Ｖ(10)／Ｖ(0) ／Ｃ −３｝ （２） に従って加えたのち、５×１０-4〜５×１０-3(s-1) の
ひずみ速度で変形したときの準静的変形強度σs と、前
記（２）式による予変形を加えたのち、５×１０2 〜５
×１０3 (s-1) のひずみ速度で変形したときの動的変形
強度σd との差（σd −σs ）が （σd −σs ）≧４．１×σs 0.8 −σs （１） を満足する範囲であることを特徴とする動的変形特性に
優れた加工誘起変態型高強度鋼板。6. C is 0.04 to 0.30% by weight.
%, One or both of Si and Al in total of 0.3 to 3.
0%, the balance being Fe and unavoidable impurities,
It has a composite structure consisting of ferrite, which is the main phase, and a second phase containing at least 3% by volume of austenite, and has been subjected to an initial volume fraction V (0) of the austenite phase and a predeformation of 10% in equivalent strain. Volume fraction of austenitic phase V (10)
The ratio V (10) / V (0) is 0.3 or more, and the pre-deformation by one or both of the temper rolling and the tension leveler is
The plastic deformation amount T is added according to the following equation: 0.5 ｛V (10) / V (0) / C-3｝ + 15 ≧ T ≧ 0.5 ｛V (10) / V (0) / C-3｝ (2) Thereafter, the quasi-static deformation strength σs when deformed at a strain rate of 5 × 10 −4 to 5 × 10 −3 (s −1 ) and the pre-deformation by the above equation (2) are added, and then 5 × 10 2 to 5
The difference between the dynamic deformation strength .sigma.d when deformed strain rate × 10 3 (s -1) ( σd -σs) satisfies (σd -σs) ≧ 4.1 × σs 0.8 -σs (1) A work-induced transformation type high-strength steel sheet having excellent dynamic deformation characteristics, characterized by being within the range.
よびＭｏの少なくとも１種を合計で０．５〜３．５％含
む請求項１〜６記載の動的変形特性に優れた加工誘起変
態型高強度鋼板。7. The process excellent in dynamic deformation characteristics according to claim 1, wherein at least one of Mn, Ni, Cu, Cr and Mo is contained by 0.5 to 3.5% by weight in total. Induction transformation type high strength steel sheet.
少なくとも１種を合計で０．２％以下含む請求項１〜７
記載の動的変形特性に優れた加工誘起変態型高強度鋼
板。8. The method according to claim 1, wherein at least one of Nb, Ti, V and P is contained in a total of not more than 0.2% by weight.
A work-induced transformation type high-strength steel sheet having excellent dynamic deformation characteristics as described.
Priority Applications (9)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25893997A JP3958842B2 (en) | 1997-07-15 | 1997-09-24 | Work-induced transformation-type high-strength steel sheet for absorbing automobile collision energy with excellent dynamic deformation characteristics |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| EP10181439A EP2312008B1 (en) | 1997-01-29 | 1998-01-23 | High-strength steels having high impact energy absorption properties. |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9-190298 | 1997-07-15 | ||
| JP19029897 | 1997-07-15 | ||
| JP25893997A JP3958842B2 (en) | 1997-07-15 | 1997-09-24 | Work-induced transformation-type high-strength steel sheet for absorbing automobile collision energy with excellent dynamic deformation characteristics |
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| Publication Number | Publication Date |
|---|---|
| JPH1180879A true JPH1180879A (en) | 1999-03-26 |
| JP3958842B2 JP3958842B2 (en) | 2007-08-15 |
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| Application Number | Title | Priority Date | Filing Date |
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| WO2000032831A1 (en) * | 1998-11-30 | 2000-06-08 | Nippon Steel Corporation | Ferrite sheet steel excellent in strain rate dependency and automobile using it |
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