JP2001131691A - High strength thin steel sheet excellent in stretch formability - Google Patents
High strength thin steel sheet excellent in stretch formabilityInfo
- Publication number
- JP2001131691A JP2001131691A JP31559499A JP31559499A JP2001131691A JP 2001131691 A JP2001131691 A JP 2001131691A JP 31559499 A JP31559499 A JP 31559499A JP 31559499 A JP31559499 A JP 31559499A JP 2001131691 A JP2001131691 A JP 2001131691A
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- Japan
- Prior art keywords
- steel sheet
- thin steel
- sheet excellent
- stretch formability
- strength
- 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、張出し主体の成形
が行われるフード、フェンダー、サイドパネルなどの自
動車外板パネルに使用される高強度薄鋼板、特に引張強
さが390MPa以上500MPa未満で張出し成形性に優れた高強
度薄鋼板に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength thin steel plate used for automobile outer panels such as hoods, fenders, side panels, etc., which are mainly formed by overhanging. It relates to a high-strength thin steel sheet excellent in formability.
【０００２】[0002]
【従来の技術】近年、自動車業界では、安全性向上を目
的とした鋼板の高強度化、部品の一体化による部品点数
削減、プレス工程の省略などが積極的に推進されてお
り、自動車ボディ用鋼板に対しては、極めて高いプレス
成形性を有する高強度薄鋼板が求められている。2. Description of the Related Art In recent years, the automotive industry has been actively promoting the strengthening of steel sheets for the purpose of improving safety, reducing the number of parts by integrating parts, and omitting a pressing process. For steel sheets, high-strength thin steel sheets having extremely high press formability have been demanded.
【０００３】従来より、冷延鋼板のプレス成形性に関し
ては、主として深絞り性と張出し性の観点から検討され
ている。深絞り性に関しては、r値を高めることに主眼
が置かれ、例えば特開平5-78784号公報には、Ti添加極
低炭素鋼板にMn、Crを積極的に添加するとともにSiやP
量を制御することにより、引張強さが343〜490MPaで良
好なr値と伸びの得られることが、また、特開平8-92656
号公報には、Ar3変態点〜500℃で熱間潤滑圧延された熱
延鋼板を再結晶処理後冷間圧延・焼鈍を行うことによ
り、3.0以上の高いr値を有する極低炭素鋼板の得られる
ことが開示されている。[0003] Conventionally, the press formability of cold-rolled steel sheets has been studied mainly from the viewpoints of deep drawability and stretchability. Regarding the deep drawability, the main focus is on increasing the r value.For example, Japanese Patent Application Laid-Open No. 5-78784 discloses that while actively adding Mn and Cr to a Ti-added ultra-low carbon steel sheet,
By controlling the amount, a good r value and elongation can be obtained at a tensile strength of 343 to 490 MPa.
The publication discloses that an ultra-low carbon steel sheet having a high r value of 3.0 or more is obtained by performing cold rolling and annealing after recrystallization treatment of a hot-rolled steel sheet hot-rolled at Ar3 transformation point to 500 ° C. Is disclosed.
【０００４】一方、張出し性に関しては、例えば「薄鋼
板のプレス加工」(実教出版)には、全伸びや10%と20%の
2点から求めた高ひずみ域のn値を高めることが重要であ
ると記載されている。On the other hand, regarding the overhang property, for example, “press processing of thin steel sheet” (published by Jikkyo), the total elongation and 10% and 20%
It is stated that it is important to increase the n value in the high strain region obtained from two points.
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、上記の
特開平5-78784号公報や特開平8-92656号公報に記載され
た深絞り性に優れた鋼板を張出し主体の成形が行われる
サイドパネルなどに適用すると、平面ひずみ張出し成形
の行われるパンチ肩部でひずみ伝播不足により破断が生
じる場合がある。こうした張出し成形における破断に関
しては、材料の高強度化とともに、従来の軟質材と同様
な全伸びやn値では評価できなくなっており、適切な対
策が取れないのが実情である。However, such side panels as described in JP-A-5-78784 and JP-A-8-92656, in which a steel sheet excellent in deep drawability is stretched and mainly formed, are used. In some cases, fracture may occur due to insufficient strain propagation at the punch shoulder where plane strain stretch forming is performed. With regard to the breakage in such stretch forming, it is impossible to evaluate with the same total elongation and n-value as the conventional soft material with the increase in the strength of the material, and in fact, no appropriate countermeasure can be taken.
【０００６】また、上記特許公報に記載の鋼板には、Cr
が多量に添加されたり、熱延鋼板で焼鈍が行われたりす
るので、コスト的にも問題がある。[0006] Further, the steel sheet described in the above patent publication contains Cr
Is added in a large amount, or annealing is performed on a hot-rolled steel sheet, so that there is a problem in cost.
【０００７】本発明はこのような課題を解決するために
なされたもので、安価に製造が可能で、張出し成形性に
優れた高強度薄鋼板を提供することを目的とする。[0007] The present invention has been made to solve such problems, and an object of the present invention is to provide a high-strength thin steel sheet which can be manufactured at low cost and has excellent stretch formability.
【０００８】[0008]
【課題を解決するための手段】上記課題は、単軸引張試
験における公称ひずみ1%と10%の2点から算出されたn値
が下記の式(1)を満足する張出し成形性に優れた高強度
薄鋼板により解決される。 n値≧-0.00029×TS(MPa)+0.313 …(1)、 ただし、TSは引張り強さを表す。The object of the present invention is to provide an overhanging formability in which the n value calculated from two points of a nominal strain of 1% and 10% in a uniaxial tensile test satisfies the following equation (1). Solved by high strength steel sheet. n value ≧ −0.00029 × TS (MPa) +0.313 (1), where TS represents tensile strength.
【０００９】本発明者らは、張出し主体の成形が行われ
るフロントフェンダーを例に取り、成形性を支配する因
子を検討した結果、以下のような知見を得た。The inventors of the present invention have taken the example of a front fender in which overmolding is performed as a main example, and have studied the factors governing the moldability. As a result, the following findings have been obtained.
【００１０】図2に、図1に示した実部品スケールのフロ
ントフェンダーモデル成形品の側壁部近傍の相当ひずみ
分布を示す。FIG. 2 shows an equivalent strain distribution in the vicinity of the side wall portion of the front fender model molded product of the actual part scale shown in FIG.
【００１１】側壁部のパンチ肩やダイ肩近傍の発生ひず
み量が大きく、パンチ底部の発生ひずみ量は0.1以下で
小さいことがわかる。It can be seen that the amount of strain generated near the punch shoulder and die shoulder on the side wall is large, and the amount of strain generated on the bottom of the punch is small at 0.1 or less.
【００１２】したがって、パンチ底に接触する鋼板に発
生するひずみ量を広範囲にわたってわずかでも増加して
やれば、側壁部のパンチ肩やダイ肩近傍へのひずみ集中
を緩和でき、この部分における破断を防止できることに
なる。そのためには、公称ひずみ1%と10%の2点から算出
されるn値が上記の式(1)を満足するようにすればよいこ
とを初めて見出した。Therefore, if the amount of strain generated in the steel sheet in contact with the bottom of the punch is slightly increased over a wide range, the concentration of strain on the side wall portion near the punch shoulder and the die shoulder can be reduced, and breakage at this portion can be prevented. Become. For this purpose, it has been found for the first time that the n value calculated from the two points of the nominal strain of 1% and 10% should satisfy the above equation (1).
【００１３】このような張出し成形性に優れた高強度薄
鋼板は、wt%で、C:0.0040〜0.015%、Si:0.05%以下、Mn:
0.7〜3.0%、P:0.04〜0.15%、S:0.02%以下、sol.Al:0.01
〜0.1%、N:0.004%以下、Nb:0.01〜0.2%、残部が実質的
にFeおよび不可避的不純物からなる薄鋼板によって実現
できる。[0013] Such a high-strength thin steel sheet excellent in stretch formability is, in terms of wt%, C: 0.0040 to 0.015%, Si: 0.05% or less, Mn:
0.7-3.0%, P: 0.04-0.15%, S: 0.02% or less, sol.Al: 0.01
0.1%, N: 0.004% or less, Nb: 0.01 to 0.2%, the balance being realized by a thin steel sheet substantially composed of Fe and unavoidable impurities.
【００１４】以下に、各元素量の限定理由を説明する。The reasons for limiting the amounts of the respective elements will be described below.
【００１５】C: 炭化物を形成し、素材強度およびパネ
ル成形時の低ひずみ域での加工硬化に影響をおよぼし
て、強度上昇と成形性を向上させる。0.0040wt%未満で
はその効果が得られず、0.015wt%を超えると、強度およ
び低ひずみ域での高いn値は得られるが延性低下を引き
起こすので、0.0040〜0.015wt%とする。析出物の形態お
よび分散状態を適正に制御し、より優れた成形性および
より好ましい総合特性を引き出すには、C添加量を0.005
0〜0.0080wt%、さらに望ましくは0.0050〜0.0074wt%の
範囲に規定することが好ましい。C: A carbide is formed, which affects the strength of the material and the work hardening in a low strain range at the time of panel forming, thereby increasing the strength and improving the formability. If the content is less than 0.0040 wt%, the effect cannot be obtained. If the content exceeds 0.015 wt%, a high n value in the strength and low strain range can be obtained, but the ductility decreases. Therefore, the content is set to 0.0040 to 0.015 wt%. In order to properly control the morphology and dispersion state of precipitates, and to bring out better moldability and more favorable overall characteristics, the amount of C added should be 0.005.
It is preferable to define the content in the range of 0 to 0.0080 wt%, more preferably 0.0050 to 0.0074 wt%.
【００１６】Si: 0.05wt%を超えて添加すると化成処理
性や溶融亜鉛めっきの密着性を劣化させるので、0.05wt
%以下とする。Si: If added in excess of 0.05 wt%, the chemical conversion property and the adhesion of the hot-dip galvanized coating will be degraded.
% Or less.
【００１７】Mn: 鋼中のSをMnSとして析出させスラブ
の熱間割れを防止したり、めっき密着性を劣化させるこ
となく鋼を強化する上で有効な元素である。SをMnSとし
て析出させ、強度を確保するには0.7wt%以上必要である
が、3.0wt%を超えて添加すると成形性の劣化を招くの
で、0.7〜3.0wt%とする。Mn: An element effective in precipitating S in steel as MnS to prevent hot cracking of the slab and strengthen the steel without deteriorating plating adhesion. To precipitate S as MnS and secure the strength, 0.7 wt% or more is necessary. However, if it exceeds 3.0 wt%, the formability is deteriorated.
【００１８】P: 鋼の強化に有効な元素であり、強度確
保のために0.04wt%以上必要であるが、0.15wt%を超えて
添加すると亜鉛めっきの合金化処理性の劣化を引き起こ
すので、0.04〜0.15wt%とする。P: an element effective for strengthening steel, it is necessary to secure 0.04 wt% or more for securing the strength. However, if added in excess of 0.15 wt%, the alloying property of galvanizing is deteriorated. 0.04 to 0.15 wt%.
【００１９】S: MnSとして鋼中に存在するが、0.02wt%
を超えて含まれると延性低下を招くので、0.02wt%以下
とする。S: Present in steel as MnS, but 0.02 wt%
If the content exceeds the above range, ductility is reduced.
【００２０】sol.Al: 鋼中のNをAlNとして析出させ固
溶Nを残さないために、0.01wt%以上必要であり、0.1wt%
を超えて添加すると固溶Alにより延性低下を招くので、
0.01〜0.1wt%とする。Sol.Al: In order to precipitate N in steel as AlN and leave no solute N, 0.01 wt% or more is required.
When added in excess of, the ductility is reduced by solid solution Al,
0.01 to 0.1 wt%.
【００２１】N: 上記sol.Al量の下限値においても、す
べてのNをAlNとして析出させるには、0.004wt%以下にす
る必要がある。N: Even at the lower limit of the sol.Al content, the content must be 0.004 wt% or less in order to precipitate all N as AlN.
【００２２】Nb:本発明で最も重要な元素であり、NbCの
形成による固溶Cの低減および適正量の固溶Nbにより低
ひずみ域でのn値を向上させ、上記式(1)が確実に満足さ
れるようになる。0.01wt%未満ではその効果が得られ
ず、0.2wt%を超えると降伏強度が上昇し低ひずみ域での
n値の低下や延性低下を招くので、0.01〜0.2wt%とす
る。低ひずみ域におけるn値をより向上させるには、Nb>
0.035wt%とすることが望ましく、さらに成形性および総
合性能を改善するには、Nb≧0.080wt%とすることが望ま
しい。また、コストを考慮した場合、Nb≦0.140wt%とす
ることが望ましい。Nb: The most important element in the present invention, the reduction of solid solution C by the formation of NbC and the improvement of n value in a low strain region by the proper amount of solid solution Nb ensure that the above equation (1) is satisfied. Will be satisfied. If it is less than 0.01 wt%, the effect cannot be obtained, and if it exceeds 0.2 wt%, the yield strength increases and the
Since the decrease in n value and the decrease in ductility are caused, the content is set to 0.01 to 0.2 wt%. To further improve the n value in the low strain range, Nb>
It is desirable to set it to 0.035 wt%, and to further improve formability and overall performance, it is desirable to set Nb ≧ 0.080 wt%. In consideration of cost, it is preferable that Nb ≦ 0.140 wt%.
【００２３】Nbにより低ひずみ域でn値が向上する理由
は必ずしも明確ではないが、電子顕微鏡を用いて緻密な
組織観察を実施したところ、以下の知見を得た。Nb、C
量が適切に制御された場合、結晶粒内に多量のNbCが析
出し、粒界近傍に析出物が非常に少ない、いわゆる析出
物枯渇帯(PFZ)が形成されており、このPFZは析出物が非
常に少ないため粒内に比べ強度が低く、低い応力レベル
で塑性変形できるので、低ひずみ域で高いn値が得られ
ると推察される。さらに、鋭意検討を進めた結果、本発
明においてこのような望ましい析出形態を得るには、Nb
/C(原子当量比)を1.7〜2.5の範囲に規制することが好ま
しいことを見出した。The reason why Nb improves the n value in a low strain region is not necessarily clear, but the following findings were obtained when a fine structure was observed using an electron microscope. Nb, C
When the amount is properly controlled, a large amount of NbC precipitates in the crystal grains, and a so-called precipitate depletion zone (PFZ) is formed near the grain boundaries with very few precipitates. It is presumed that high n-values can be obtained in the low strain region because the strength is very low compared to the intragranular state and plastic deformation can be performed at a low stress level. Furthermore, as a result of intensive studies, in order to obtain such a desirable precipitation form in the present invention, Nb
It has been found that it is preferable to control / C (atomic equivalent ratio) in the range of 1.7 to 2.5.
【００２４】なお、、本発明の高強度薄鋼板では、Nb添
加により結晶粒が細粒化されるので、溶接性や耐二次加
工脆性も改善される。Incidentally, in the high-strength thin steel sheet of the present invention, since the crystal grains are refined by adding Nb, the weldability and the resistance to secondary working embrittlement are also improved.
【００２５】このように、本発明の高強度薄鋼板は、Cr
などの特殊元素が多量には添加されておらず、また、後
述するように通常のプロセスで製造できるので、安価で
ある。Thus, the high-strength thin steel sheet of the present invention
Since a special element such as the above is not added in a large amount and can be manufactured by a normal process as described later, it is inexpensive.
【００２６】本発明の効果は、上記した元素量の限定に
より達成されるが、さらに、品質改善および耐二次加工
脆性の向上のために、Ti、Bを、Ti≦0.05wt%、B≦0.002
wt%の範囲内で添加することが可能である。The effect of the present invention can be achieved by the above-described limitation of the amount of elements. Further, in order to improve the quality and the resistance to secondary working embrittlement, Ti and B are added at Ti ≦ 0.05 wt% and B ≦ B 0.002
It can be added within the range of wt%.
【００２７】Ti:炭窒化物を形成し、熱延板の組織を微
細化することにより、成形性を改善する。しかしなが
ら、0.05wt%を超えて添加した場合、析出物が粗大化
し、十分な効果が得られない。より望ましくは、特に溶
融亜鉛めっきの表面性状の観点から、上限を0.02wt%未
満とし、必要な細粒化効果を得るために、下限を0.005w
t%とするのが好ましい。Formability is improved by forming Ti: carbonitride and making the structure of the hot-rolled sheet finer. However, if added in excess of 0.05 wt%, the precipitates become coarse and sufficient effects cannot be obtained. More desirably, particularly from the viewpoint of the surface properties of the hot-dip galvanizing, the upper limit is set to less than 0.02 wt%, and the lower limit is set to 0.005 w
It is preferably set to t%.
【００２８】B:結晶粒界を強化し、耐二次加工脆性を改
善するために添加するが、0.002wt%を超えて添加した場
合、成形性が大幅に低下するので、上限を0.002wt%とす
る。本発明鋼は、結晶粒が微細化されており、極めて優
れた耐二次加工脆性を示すので、望ましくは、成形性の
低下を極力抑えるために、B添加量を0.0001〜0.001wt%
の範囲に規制するのが好ましい。B: added to strengthen grain boundaries and improve secondary work brittleness resistance, but if added in excess of 0.002 wt%, formability is significantly reduced, so the upper limit is 0.002 wt%. And In the steel of the present invention, the crystal grains are refined and exhibit extremely excellent secondary work brittleness resistance.Therefore, in order to minimize the decrease in formability, the amount of B added is preferably 0.0001 to 0.001 wt%.
It is preferable to regulate to within the range.
【００２９】本発明である高強度薄鋼板は、そのままで
使用することができるが、表面に電気亜鉛めっきや溶融
亜鉛めっきなどの亜鉛系めっきを施しても、同様な効果
が得られる。亜鉛系めっきとしては、純亜鉛めっき、合
金化亜鉛めっき、亜鉛-Ni合金めっきなどを挙げること
ができ、めっき後に有機皮膜処理を施してもよい。The high-strength thin steel sheet of the present invention can be used as it is, but the same effect can be obtained even if the surface is subjected to zinc-based plating such as electrogalvanizing or hot-dip galvanizing. Examples of the zinc-based plating include pure zinc plating, alloyed zinc plating, and zinc-Ni alloy plating, and an organic film treatment may be performed after the plating.
【００３０】本発明である高強度薄鋼板の製造方法とし
ては、本発明の元素範囲に調整された鋼を溶製後、連続
鋳造によりスラブとなし、このスラブを再加熱後あるい
は直接熱間圧延して熱延鋼板とし、酸洗後冷間圧延して
焼鈍する通常の冷延鋼板の製造プロセスを適用できる。The method for producing a high-strength thin steel sheet according to the present invention is as follows. After smelting a steel adjusted to the elemental range of the present invention, a slab is formed by continuous casting, and the slab is reheated or directly hot-rolled. An ordinary cold-rolled steel sheet manufacturing process of hot-rolled steel sheet, cold-rolled after pickling, and then annealed can be applied.
【００３１】このとき、熱間圧延条件としては、表面品
質や材質の均一性の観点からAr3変態点以上960℃以下で
仕上圧延し、酸洗時の脱スケール性や材質の安定性の観
点から680℃以下の温度で巻取ることが好ましい。ま
た、冷間圧延後連続焼鈍(CALやCGL)する場合は600℃以
上の温度で、箱焼鈍(BAF)させる場合は540℃以上の温度
で巻取ることが好ましい。なお、薄物製造時の熱延仕上
温度確保などの目的のために、熱間圧延中にバーヒータ
ーにより粗バーを加熱することもできる。At this time, the hot rolling conditions are as follows: from the viewpoint of surface quality and material uniformity, finish rolling at a temperature not lower than the Ar3 transformation point and not higher than 960 ° C., and from the viewpoint of descaling during pickling and stability of the material. It is preferable to wind at a temperature of 680 ° C. or lower. Further, it is preferable to wind at a temperature of 600 ° C. or more when performing continuous annealing (CAL or CGL) after cold rolling, and at a temperature of 540 ° C. or more when performing box annealing (BAF). The rough bar can be heated by a bar heater during hot rolling for the purpose of ensuring a hot rolling finish temperature at the time of manufacturing a thin material.
【００３２】冷間圧延の圧下率は良好な深絞り性を得る
ために50%以上が好ましく、焼鈍温度は、連続焼鈍の場
合は780〜880℃の温度域が、箱焼鈍の場合は680〜750℃
の温度域が好ましい。The rolling reduction of the cold rolling is preferably 50% or more in order to obtain a good deep drawability, and the annealing temperature is 780 to 880 ° C. for continuous annealing, and 680 to 880 ° C. for box annealing. 750 ℃
Is preferred.
【００３３】[0033]
【実施例】表1に示す鋼番1〜10の鋼を溶製後、連続鋳造
によりスラブを製造した。このスラブを1200℃に加熱
後、仕上温度880〜940℃、巻取温度540〜560℃（箱焼鈍
向け）、600〜660℃（連続焼鈍、連続焼鈍・亜鉛めっき
向け）で熱間圧延を行い熱延鋼板とし、酸洗後50〜85%
の冷間圧延を施した後、連続焼鈍（焼鈍温度800〜840
℃）、箱焼鈍（焼鈍温度680〜720℃）また、連続焼鈍・
溶融亜鉛めっき（焼鈍温度800〜840℃）のいずれかを実
施した。連続焼鈍・溶融亜鉛めっきでは，焼鈍後460℃
で溶融亜鉛めっき処理を行ない、直ちにインライン合金
化処理炉で500℃でめっき層の合金化処理を行なった。
焼鈍または焼鈍・溶融亜鉛めっき後の鋼板には圧下率0.
7%の調質圧延を行なった。これらの鋼板に対し、機械特
性およびフロントフェンダーのプレス成形を行い破断限
界クッション力を調査した。EXAMPLES After smelting steels of steel numbers 1 to 10 shown in Table 1, slabs were manufactured by continuous casting. After heating this slab to 1200 ° C, hot rolling is performed at a finishing temperature of 880 to 940 ° C, a winding temperature of 540 to 560 ° C (for box annealing), and 600 to 660 ° C (for continuous annealing, continuous annealing and galvanizing). Hot rolled steel sheet, 50-85% after pickling
After cold rolling, the steel sheet is continuously annealed (annealing temperature 800 to 840).
℃), box annealing (annealing temperature 680 ~ 720 ℃) and continuous annealing
Any of hot-dip galvanizing (annealing temperature 800 to 840 ° C) was performed. 460 ° C after annealing for continuous annealing and hot dip galvanizing
And hot-dip galvanizing treatment was performed, and immediately, an alloying treatment of the plated layer was performed at 500 ° C. in an in-line alloying treatment furnace.
For steel sheets after annealing or annealing and hot dip galvanizing, the rolling reduction is 0.
A temper rolling of 7% was performed. For these steel plates, mechanical properties and press forming of the front fender were performed to investigate the breaking limit cushion force.
【００３４】結果を表2に示す。Table 2 shows the results.
【００３５】本発明の鋼板は、破断限界クッション力が
65TON以上と高く、優れた張出し性を示した。比較材のN
o.9、No.10は、10-20%ひずみ域のn値が0.23以上と高い
にもかかわらず1-10%のn値が小さいため、50TON以下の
低いクッション力条件で破断が発生した。The steel sheet of the present invention has a breaking limit cushioning force.
It was as high as 65 TON or more and showed excellent overhang property. Comparative material N
In o.9 and No.10, although the n value in the 10-20% strain range was as high as 0.23 or more, the n value in 1-10% was small, so the fracture occurred under low cushion force conditions of 50 TON or less. .
【００３６】本発明の鋼板では、いずれの水準において
も、縦割れ遷移温度が-65℃以下となっており、非常に
良好な耐二次加工脆性を示した。また、本発明の鋼板
は、結晶粒が微細化しており、強加工部においても肌荒
れなどの問題は全く生じなかった。さらに、溶融亜鉛め
っき後の表面品質や溶接部の加工性・疲労特性等にも優
れていることが確認された。The steel sheet of the present invention had a vertical crack transition temperature of -65 ° C. or less at any level, and exhibited very good secondary work brittleness resistance. Further, in the steel sheet of the present invention, the crystal grains were refined, and no problem such as rough skin occurred even in a strongly processed portion. Furthermore, it was confirmed that the surface quality after hot-dip galvanizing and the workability and fatigue properties of the welded portion were also excellent.
【００３７】図3に、表2中のNo.3材(本発明例)とNo.10
材(比較例)をクッション力40TONの条件で図1のフロント
フェンダモデルに成形した場合の、破断危険部近傍のひ
ずみ分布を示す。FIG. 3 shows No. 3 material (Example of the present invention) and No. 10
FIG. 3 shows a strain distribution near a fracture-prone portion when a material (comparative example) is molded into the front fender model of FIG. 1 under the condition of a cushion force of 40 TON.
【００３８】No.3材では、パンチ底部での発生ひずみ量
が大きく、側壁部のひずみ発生量が抑制されており、破
断に対して有利となっている。In the No. 3 material, the amount of strain generated at the bottom of the punch is large, and the amount of strain generated at the side wall is suppressed, which is advantageous for breaking.
【００３９】[0039]
【表1】 【table 1】
【００４０】[0040]
【表2】 [Table 2]
【００４１】[0041]
【発明の効果】本発明は以上説明したように構成されて
いるので、安価に製造が可能で、張出し成形性に優れた
高強度薄鋼板を提供できる。Since the present invention is constructed as described above, it can be manufactured at low cost and can provide a high-strength thin steel sheet excellent in stretch formability.
【００４２】また、本発明の高強度薄鋼板は、耐二次加
工脆性，表面性状、溶接性などにも優れ、大変良好な総
合性能を有する。Further, the high-strength thin steel sheet of the present invention has excellent secondary work brittleness resistance, surface properties, weldability, etc., and has very good overall performance.
【図1】実部品スケールのフロントフェンダーモデル成
形品を示す図である。FIG. 1 is a view showing a molded product of a front fender model on an actual part scale.
【図2】図1に示した成形品の側壁部近傍の相当ひずみ分
布を示す図である。2 is a view showing an equivalent strain distribution near a side wall of the molded product shown in FIG. 1.
【図3】No.3材とNo.10材をフロントフェンダモデルに成
形後の側壁部近傍の相当ひずみ分布を示す図である。FIG. 3 is a view showing an equivalent strain distribution near a side wall portion after molding No. 3 and No. 10 materials into a front fender model.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山崎 雄司 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社 (72)発明者 三塚 賢一 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社 (72)発明者 坂井 広義 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社 (72)発明者 廣瀬 俊幸 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社 (72)発明者 占部 俊明 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yuji Yamazaki 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Kenichi Mitsuka 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Japan Kokan Co., Ltd. (72) Inventor Hiroyoshi Sakai 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan Nihon Kokan Co., Ltd. (72) Inventor Toshiyuki Hirose 1-2-1, Marunouchi, Chiyoda-ku, Tokyo, Japan 72) Inventor Toshiaki Urabe 1-2-2 Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd.
Claims (5)
の2点から算出されたn値が下記の式(1)を満足する張出
し成形性に優れた高強度薄鋼板； n値≧-0.00029×TS(MPa)+0.313 …(1) ただし、TSは引張り強さを表す。[1] Nominal strain 1% and 10% in uniaxial tensile test
A high-strength steel sheet excellent in stretch formability where the n value calculated from the following two points satisfies the following formula (1): n value ≧ −0.00029 × TS (MPa) +0.313 (1) where TS is Indicates tensile strength.
下、Mn:0.7〜3.0%、P:0.04〜0.15%、S:0.02%以下、sol.
Al:0.01〜0.1%、N:0.004%以下、Nb:0.01〜0.2%、残部が
実質的にFeおよび不可避的不純物からなる請求項1に記
載の張出し成形性に優れた高強度薄鋼板。(2) In wt%, C: 0.0040 to 0.015%, Si: 0.05% or less, Mn: 0.7 to 3.0%, P: 0.04 to 0.15%, S: 0.02% or less, sol.
2. The high-strength steel sheet excellent in stretch formability according to claim 1, wherein Al: 0.01 to 0.1%, N: 0.004% or less, Nb: 0.01 to 0.2%, and the balance substantially consists of Fe and unavoidable impurities.
求項2に記載の張出し成形性に優れた高強度薄鋼板。3. The high-strength steel sheet excellent in stretch formability according to claim 2, further containing 0.05% by weight or less of Ti.
求項2または請求項3に記載の張出し成形性に優れた高強
度薄鋼板。4. The high-strength thin steel sheet excellent in stretch formability according to claim 2, further comprising B in an amount of 0.002 wt% or less.
から請求項4のいずれか1項に記載の張出し成形性に優れ
た高強度薄鋼板。5. The method according to claim 1, wherein the surface has a zinc-based plating film.
5. The high-strength thin steel sheet excellent in stretch formability according to any one of claims 1 to 4.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31559499A JP3695262B2 (en) | 1999-11-05 | 1999-11-05 | High-strength thin steel sheet with excellent stretch formability |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31559499A JP3695262B2 (en) | 1999-11-05 | 1999-11-05 | High-strength thin steel sheet with excellent stretch formability |
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| Publication Number | Publication Date |
|---|---|
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| JP3695262B2 JP3695262B2 (en) | 2005-09-14 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006328443A (en) * | 2005-05-23 | 2006-12-07 | Sumitomo Metal Ind Ltd | Cold-rolled steel sheet with high tensile strength and manufacturing method therefor |
| JP2012077384A (en) * | 2011-11-24 | 2012-04-19 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet and production method therefor |
-
1999
- 1999-11-05 JP JP31559499A patent/JP3695262B2/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006328443A (en) * | 2005-05-23 | 2006-12-07 | Sumitomo Metal Ind Ltd | Cold-rolled steel sheet with high tensile strength and manufacturing method therefor |
| JP2012077384A (en) * | 2011-11-24 | 2012-04-19 | Sumitomo Metal Ind Ltd | High tensile strength cold rolled steel sheet and production method therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3695262B2 (en) | 2005-09-14 |
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