JP3219510B2 - High strength hot rolled steel sheet with excellent stretch flangeability - Google Patents
High strength hot rolled steel sheet with excellent stretch flangeabilityInfo
- Publication number
- JP3219510B2 JP3219510B2 JP35045192A JP35045192A JP3219510B2 JP 3219510 B2 JP3219510 B2 JP 3219510B2 JP 35045192 A JP35045192 A JP 35045192A JP 35045192 A JP35045192 A JP 35045192A JP 3219510 B2 JP3219510 B2 JP 3219510B2
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- steel sheet
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- stretch flangeability
- rolled steel
- strength
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Description
【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION
【０００１】[0001]
【産業上の利用分野】本発明は加工性の優れた高強度熱
延鋼板に関し、特に優れた伸びフランジ加工性を有し引
張強度が５００Ｎ／mm2級以上の高強度熱延鋼板に関す
る。The present invention relates to an excellent high-strength hot-rolled steel sheet formability, especially excellent tensile has a stretch flange formability intensities for 500 N / mm 2 or higher grade of high strength hot rolled steel sheet.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】従来、
５００Ｎ／mm2級以上の高強度熱延鋼板では加工性が要
求されてきた。特に、自動車のメンバー類やバンパー等
のプレス成形においては、特に伸びフランジ加工性が必
要とされている。2. Description of the Related Art
Workability has been required for high-strength hot-rolled steel sheets of 500 N / mm 2 class or higher. In particular, in press molding of automobile members, bumpers, and the like, stretch flangeability is particularly required.
【０００３】従来、この伸びフランジ性を向上させる方
法として、フェライト＋ベイナイト組織を有する鋼板
(特開昭５８−４２７２６号)、或いはフェライト＋ベイ
ナイト＋マルテンサイト組織を有する鋼板(特開昭５７
−７０２５７号)が知られている。また、この他にも、
フェライトに微細パーライトを分散させること(特開昭
５７−２３０２５号)、或いは微細セメンタイトを生成
させること(特開平４−８８１２５号)を意図した鋼板が
ある。Conventionally, as a method for improving the stretch flangeability, a steel sheet having a ferrite + bainite structure has been used.
(JP-A-58-42726) or a steel sheet having a ferrite + bainite + martensite structure (JP-A-57-42726).
-70257) is known. In addition,
There is a steel sheet intended to disperse fine pearlite in ferrite (JP-A-57-23025) or to produce fine cementite (JP-A-4-88125).
【０００４】しかし、これらの鋼板では、穴拡げ率(λ)
で示される伸びフランジ加工性に限界があることや、高
強度化に伴って伸びフランジ性が劣化するという欠点が
あった。このため、自動車のメンバー類の現状の加工成
形性を満足できず、高強度材の利用が難しく、薄肉化に
よる重量低減、燃費の向上が阻害されているのが現状で
ある。However, in these steel plates, the hole expansion ratio (λ)
However, there are drawbacks in that the stretch flangeability is limited and that the stretch flangeability deteriorates with increasing strength. For this reason, the current workability of members of automobiles cannot be satisfied, the use of high-strength materials is difficult, and the reduction in weight and the improvement in fuel efficiency due to thinning are currently hampered.
【０００５】本発明は、かゝる状況のもとで、高強度化
に伴う伸びフランジ加工性の劣化を防ぎ、高強度であっ
ても十分な伸びフランジ加工性を有する熱延鋼板を提供
することを目的とするものである。[0005] The present invention provides a hot-rolled steel sheet which has sufficient stretch-flange workability even under high strength, while preventing deterioration in stretch-flange workability due to high strength under such circumstances. The purpose is to do so.
【０００６】[0006]
【課題を解決するための手段】本発明者らは、前記課題
を解決するために鋭意努力した結果、ラス状組織を有
し、かつ炭化物が生成していない転位密度の高いベイニ
ティック・フェライト組織を鋼中に生成させることによ
り、高い伸びフランジ加工性を付与できることを見い出
し、ここに本発明をなしたものである。Means for Solving the Problems The inventors of the present invention have made intensive efforts to solve the above-mentioned problems, and as a result, have obtained a bainitic ferrite having a lath-like structure and having a high dislocation density in which no carbide is formed. The present inventors have found that by forming a structure in steel, high stretch flangeability can be imparted, and the present invention has been made here.
【０００７】すなわち、本発明は、Ｃ：０．０３〜０．
２０％、Ｓｉ：０．２〜２．０％、Ｍｎ：２．５％以
下、Ｐ：０．０８％以下、Ｓ：０．００５％以下を含
み、必要に応じて、更にＮｂ：０．５％以下、Ｔｉ：
０．５％以下、Ｃｕ：０．５％以下、Ｎｉ：０．５％以
下、Ｍｏ：０．５％以下、Ｃｒ：０．５％以下のうちの
１種又は２種以上、或いはＣａ：２０ｐｐｍ以下を含
み、残部がＦｅ及び不可避的不純物からなる鋼であっ
て、ベイニティック・フェライトまたはこれとフェライ
トからなる組織が面積率で７０％以上であることを特徴
とする伸びフランジ加工性に優れた高強度熱延鋼板を要
旨としている。That is, according to the present invention, C: 0.03-0.
20%, Si: 0.2 to 2.0%, Mn: 2.5% or less, P: 0.08% or less, S: 0.005% or less, and Nb: 0. 5% or less, Ti:
0.5% or less, Cu: 0.5% or less, Ni: 0.5% or less, Mo: 0.5% or less, Cr: 0.5% or less, or Ca: A steel containing 20 ppm or less, with the balance being Fe and unavoidable impurities, characterized in that bainitic ferrite or a structure comprising the same and ferrite has an area ratio of 70% or more. The gist is an excellent high-strength hot-rolled steel sheet.
【０００８】[0008]
【０００９】以下に本発明を更に詳細に説明する。ま
ず、本発明における鋼の化学成分の限定理由を詳述す
る。Hereinafter, the present invention will be described in more detail. First, the reasons for limiting the chemical components of steel in the present invention will be described in detail.
【００１０】Ｃ：Ｃは強度確保のためにも、またベイニ
ティック・フェライト組織を得るために必要な元素であ
る。ベイニティック・フェライト組織を生成するために
はＣ量が０.０３％以上必要であるが、点溶接性を考慮
して上限を０.２０％とする。C: C is an element necessary for ensuring strength and for obtaining a bainitic ferrite structure. In order to form a bainitic ferrite structure, the C content is required to be 0.03% or more, but the upper limit is set to 0.20% in consideration of the spot weldability.
【００１１】Ｓi：ＳiはフェライトにおけるＣ量の固溶
限を広げ、ベイニティック・フェライト組織を得るため
には必要な元素である。Ｓiの添加によってフェライト
組織からベイニティック・フェライト組織の体積率が増
大する。この組織においては高強度化が達成でき、かつ
高強度材の局部変形時のボイド等が発生しにくく、穴拡
げ率を高めることができる。このベイニティック・フェ
ライト組織は、通常のフェライト組織に比べて転位密度
が高いが、変形能についてはベイナイト組織、微細炭化
物又はパーライト組織と違って、フェライト組織と類似
していると思われる。このベイニティック・フェライト
組織の生成のためには、Ｓi量は０.２％以上が必要であ
る。しかし、２.０％を超えて添加すると、鋼表面に生
成する酸化スケールが過度になって製造上の困難を伴う
ため、上限を２.０％と定める。Si: Si is an element necessary for widening the solid solubility limit of C content in ferrite and obtaining a bainitic ferrite structure. The addition of Si increases the volume fraction of the bainitic ferrite structure from the ferrite structure. In this structure, high strength can be achieved, and voids and the like at the time of local deformation of the high-strength material are hardly generated, and the hole expansion rate can be increased. Although this bainitic ferrite structure has a higher dislocation density than a normal ferrite structure, it is considered that the deformability is similar to the ferrite structure unlike the bainite structure, the fine carbide or the pearlite structure. In order to generate the bainitic ferrite structure, the Si content needs to be 0.2% or more. However, if it is added in excess of 2.0%, the oxide scale formed on the steel surface becomes excessive and production is difficult, so the upper limit is set to 2.0%.
【００１２】Ｍn：Ｍnはベイニティック・フェライト組
織の生成に幾らかの寄与をする。しかし、過度に添加し
た場合には、ベイニティック・フェライト組織よりもベ
イナイト組織等の低温変態生成物を多く生成したり、Ｓ
i量とのバランスで残留γ組織を生成して伸びフランジ
性を低下させる。このため、添加量は２.５％以下とす
る。Mn: Mn makes some contribution to the formation of the bainitic ferrite structure. However, if added excessively, more low-temperature transformation products such as bainite structure are formed than bainitic ferrite structure, or S
A residual γ structure is generated in balance with the amount of i to reduce stretch flangeability. For this reason, the addition amount is set to 2.5% or less.
【００１３】Ｐ：Ｐは固溶強化のための元素として重要
である。高強度化のためにＰを添加しても、ベイニティ
ック・フェライト組織による伸びフランジ加工性の向上
を低下させるものではない。しかし、過度に添加すると
点溶接性などの他の性質を劣化させるため、０.０８％
以下とする。P: P is important as an element for solid solution strengthening. Even if P is added to increase the strength, it does not reduce the improvement in stretch flangeability due to the bainitic ferrite structure. However, if added excessively, other properties such as spot weldability are deteriorated.
The following is assumed.
【００１４】Ｓ：Ｓは伸びフランジ加工性を劣化させる
硫化物を生成するため、可能な限り低減する必要があ
る。しかし、本発明における他の成分添加による伸びフ
ランジ加工性の向上度合いを考慮して、その上限を０.
００５％とする。なお、後述するＣa添加によるＳの低
減は更に伸びフランジ加工性を高めるため、Ｃaの添加
があっても差し支えない。S: S forms a sulfide which degrades stretch flangeability, and therefore needs to be reduced as much as possible. However, considering the degree of improvement in stretch flangeability due to the addition of other components in the present invention, the upper limit is set to 0.1.
005%. In addition, since the reduction of S by the addition of Ca, which will be described later, further enhances the stretch flangeability, there is no problem even if Ca is added.
【００１５】本発明においては、上記成分の他、必要に
応じて、高強度化のための成分であるＮb、Ｔi、Ｃu、
Ｎi、Ｍo、Ｃrの１種又は２種以上を添加でき、或いは
Ｃa添加によるＳ量低減処理を行うことができる。In the present invention, in addition to the above-mentioned components, Nb, Ti, Cu, and Nb, which are components for increasing the strength, may be used, if necessary.
One, two or more of Ni, Mo, and Cr can be added, or an S amount reduction process can be performed by adding Ca.
【００１６】Ｎb：Ｎbは炭窒化物形成元素であり、また
結晶粒を微粒化する効果があるため、強度の向上に有効
である。結晶粒の細粒化については、このことが更に伸
びフランジ加工性を改善する。しかし、過度に添加する
と再結晶温度を高め、必要な材質を得ることができない
ため、上限を０.５％とする。Nb: Nb is a carbonitride forming element and has an effect of making crystal grains fine, so that it is effective in improving strength. For grain refinement, this further improves stretch flangeability. However, if added excessively, the recrystallization temperature is raised and the required material cannot be obtained, so the upper limit is made 0.5%.
【００１７】Ｔi：ＴiはＮbと同様の効果により、強度
の向上に有効である。しかし、Ｃ量及びＮ量とのバラン
スにおいて炭窒化物の形成する限度以上に添加すると、
固溶Ｔiが残存し特性の劣化を起こす。このため、上限
を０.５％とする。Ti: Ti is effective in improving strength by the same effect as Nb. However, if it is added in excess of the limit of carbonitride formation in the balance between the C amount and the N amount,
Solid solution Ti remains and causes deterioration of characteristics. For this reason, the upper limit is set to 0.5%.
【００１８】Ｃu：Ｃuは固溶強化元素である他、疲労強
度特性を向上させるために有効である。またその後の熱
処理により、ε−Ｃu析出による強度上昇の効果があ
る。これらの効果は０.５％を超えると飽和するため、
上限を０.５％とする。Cu: Cu is a solid solution strengthening element and is effective for improving fatigue strength characteristics. Further, the subsequent heat treatment has an effect of increasing the strength due to ε-Cu precipitation. Since these effects are saturated when it exceeds 0.5%,
The upper limit is set to 0.5%.
【００１９】Ｎi、Ｍo：ＮiやＭoは固溶強化元素として
有効である。しかし、多量に添加すると、延性を劣化さ
せるため、それぞれの元素の添加量の上限を０.５％と
する。Ni, Mo: Ni and Mo are effective as solid solution strengthening elements. However, if added in a large amount, the ductility is deteriorated. Therefore, the upper limit of the amount of each element added is set to 0.5%.
【００２０】Ｃr：Ｃrは炭化物を生成して鋼を高強度化
する元素として有効である。また、Ｍnなどと共に添加
すると、低温変態生成物の種類や量を調整できる。本発
明において伸びフランジ加工性は炭化物や低温変態生成
物が微量であれば劣化させることはないため、Ｃrを添
加しても差し支えない。しかし、Ｃrを多量に添加した
場合には生成した低温変態生成物が伸びフランジ加工性
を低下させるため、上限を０.５％とする。Cr: Cr is effective as an element that forms carbides to increase the strength of steel. When added together with Mn or the like, the type and amount of the low-temperature transformation product can be adjusted. In the present invention, if the amount of carbide or low-temperature transformation product is very small, the stretch flange formability does not deteriorate, so that Cr may be added. However, when a large amount of Cr is added, the generated low-temperature transformation product deteriorates stretch flangeability, so the upper limit is set to 0.5%.
【００２１】Ｃa：Ｃaは伸びフランジ加工性を劣化させ
る硫化物を低減するため、Ｃaを添加しＣaＳとしてＳを
除去する処理を施すことがある。通常、このＣa処理を
施した場合にはおよそ２０ppm程度のＣaが残存するが、
このＣaは伸びフランジ加工性を劣化させるものではな
い。Ca: In order to reduce sulfides that degrade stretch flangeability, Ca is sometimes treated with Ca added to remove S as CaS. Usually, when this Ca treatment is performed, about 20 ppm of Ca remains,
This Ca does not deteriorate the stretch flangeability.
【００２２】次に本発明における組織について説明す
る。Next, the structure of the present invention will be described.
【００２３】本発明の主要となる組織は、ベイニティッ
ク・フェライト組織である。その組織は、フェライト組
織と比較して、通常、転位密度が高くラス状の組織を有
している。しかし、ベイニティック・フェライト組織
は、ベイナイト組織がラス状の境界に炭化物を生成する
のに比べて、ベイナイトと類似したラス状組織を生成す
るものの、炭化物の生成はなく、ベイナイト組織とは異
なった組織である。The main structure of the present invention is a bainitic ferrite structure. The structure usually has a higher dislocation density and a lath-like structure as compared with the ferrite structure. However, the bainitic ferrite structure produces a lath-like structure similar to bainite, whereas the bainite structure forms a carbide at the lath-like boundary, but there is no formation of carbides, which is different from the bainite structure. Organization.
【００２４】本発明らは、このベイニティック・フェラ
イト組織が鋼中に生成した場合、特に高強度材の場合に
はフェライト・ベイナイト鋼より更に伸びフランジ加工
性を高めることになることを見い出した。The present inventors have found that when the bainitic ferrite structure is formed in the steel, particularly in the case of a high-strength material, the stretch-flange workability is further enhanced as compared with the ferritic bainite steel. .
【００２５】フェライト組織は、転位も少なく、また延
性が高く、伸びフランジ加工性が良い。特に、ベイニテ
ィック・フェライト組織と共に生成した場合には、強
度、伸びフランジ加工性が共に良好である。The ferrite structure has few dislocations, high ductility, and good stretch flangeability. In particular, when formed together with a bainitic ferrite structure, both strength and stretch flangeability are good.
【００２６】なお、これらの組織に加えて、微量の炭化
物やベイナイト組織などの低温変態があっても伸びフラ
ンジ加工性を低下させるものではない。したがって、こ
のような炭化物や低温変態組織などは皆無であるのが好
ましく、最大でも３０％、より好ましくは５％以下が望
ましい。[0026] In addition to these structures, even if there is a low-temperature transformation such as a minute amount of carbide or bainite structure, it does not lower the stretch flangeability. Therefore, it is preferable that there is no such a carbide or a low-temperature transformation structure, and it is desirable that the content be at most 30%, more preferably at most 5%.
【００２７】次に本発明を実施例を示す。Next, examples of the present invention will be described.
【００２８】[0028]
【００２９】表１に実施例に用いた鋼種の各化学成分を
示す。これらの鋼は真空溶解にて溶製した。表１中の鋼
番でＮｏ．１からＮｏ．１５まではＣ−Ｍｎ系鋼種であ
り、それぞれＣ量、Ｓｉ量、Ｍｎ量、Ｐ量、Ｓ量の影響
を調べるためのものであり、Ｎｏ．１６からＮｏ．２１
までは各添加合金元素の影響を調べるためのものであ
る。更に、Ｎｏ．２２からＮｏ．２７まではＣａ処理に
よる影響を調べるためのものである。Table 1 shows the chemical components of the steel types used in the examples. These steels were melted by vacuum melting. In the steel numbers in Table 1, No. No. 1 to No. No. 15 is a C-Mn-based steel type for examining the effects of C content, Si content, Mn content, P content, and S content, respectively. No. 16 to No. 21
Up to the purpose of examining the effect of each additive alloy element. In addition, No. No. 22 to No. 22. Up to 27 is for investigating the influence of Ca treatment.
【００３０】これらの供試鋼について熱間圧延を行っ
た。ます、１２００℃の温度にて３０分保持後、熱延終
了温度を８８０℃とし、板厚３０mmから板厚２.５mmま
で圧延した。更に５０℃／sの冷却速度にて５５０℃か
ら２５０℃の温度範囲の巻取処理相当の温度まで冷却
し、その温度で１時間保持することとした。保持後は炉
冷にて常温まで冷却した。Hot rolling was performed on these test steels. First, after holding at a temperature of 1200 ° C. for 30 minutes, the hot rolling end temperature was set to 880 ° C. and rolling was performed from a thickness of 30 mm to a thickness of 2.5 mm. Further, it was cooled at a cooling rate of 50 ° C./s to a temperature corresponding to the winding process in a temperature range of 550 ° C. to 250 ° C., and kept at that temperature for 1 hour. After the holding, it was cooled to room temperature by furnace cooling.
【００３１】伸びフランジ加工性は、上記の熱間圧延を
行った後、縦横７０mの正方形の試験片の中央に１０mm
φの穴をあけ、先端角６０°の円錐ポンチでこの穴を広
げて、穴の縁にクラックが発生する限定の穴径から計算
される穴拡げ率(λ値)で評価した。After performing the above-mentioned hot rolling, the stretch flangeability was measured by adding 10 mm to the center of a square test piece of 70 m in length and width.
A hole having a diameter of φ was formed, the hole was expanded with a conical punch having a tip angle of 60 °, and the hole expansion ratio (λ value) calculated from a limited hole diameter at which a crack was generated at the edge of the hole was evaluated.
【００３２】各鋼種の熱延鋼板(４００℃巻取処理)の機
械的特性を調べた結果を表２に示すと共に、図１及び図
２には４００℃巻取処理を施した場合の各鋼種のλ−Ｔ
Ｓバランスを示す。なお、図中にはそれぞれの鋼板の組
織も表示した。更に、表３及び図３には、鋼番Ｎo.４、
Ｎo.７及びＮo.８について、λ値に及ぼす巻取温度の影
響を示し、それぞれの鋼の組織によるλ値の違いを示し
た。The results of examining the mechanical properties of the hot-rolled steel sheets (winding treatment at 400 ° C.) of each steel type are shown in Table 2, and FIGS. Λ-T
Shows the S balance. The structure of each steel plate is also shown in the figure. Further, in Table 3 and FIG.
Regarding No. 7 and No. 8, the effect of the winding temperature on the λ value was shown, and the difference in λ value depending on the structure of each steel was shown.
【００３３】本発明例と比較例を対比するとわかるよう
に、同じ鋼種の鋼板でも、主たる組織として、ベイニテ
ィック・フェライト組織又はフェライトとベイニティッ
ク・フェライト組織が生成した熱延鋼板は、高強度化し
ても、λ値が高い。As can be seen by comparing the present invention example and the comparative example, even with steel sheets of the same steel type, a hot rolled steel sheet having a bainitic ferrite structure or a ferrite and a bainitic ferrite structure as a main structure has a high structure. Even when the strength is increased, the λ value is high.
【００３４】図４及び図５は、それぞれＮo.４及びＮo.
８の鋼種のベイニティック・フェライト組織のＴＥＭ観
察した写真である。これらには、ラス状組織が観察され
るがその境界に炭化物の生成は認められない。FIGS. 4 and 5 show No. 4 and No., respectively.
8 is a TEM observation photograph of a bainitic ferrite structure of Steel No. 8; In these, a lath-like structure is observed, but no carbide is found at the boundary.
【００３５】[0035]
【表１】 [Table 1]
【００３６】[0036]
【表２】 [Table 2]
【００３７】[0037]
【表３】 [Table 3]
【００３８】[0038]
【発明の効果】以上詳述したように、本発明によれば、
ベイニティック・フェライト組織を鋼中に生成させたも
のであるので、高強度化に伴う伸びフランジ加工性の劣
化を防ぎ、引張強度が５００Ｎ／mm2級以上の高強度で
あっても十分な伸びフランジ加工性を有する熱延鋼板を
提供することができる。As described in detail above, according to the present invention,
Since the bainitic ferrite structure is formed in the steel, it is possible to prevent the deterioration of stretch flange workability due to the increase in strength, and it is sufficient even if the tensile strength is as high as 500 N / mm 2 class or higher. A hot-rolled steel sheet having stretch flangeability can be provided.
【図１】実施例における各鋼種の熱延鋼板のλ−ＴＳバ
ランスを示す図である。FIG. 1 is a diagram showing a λ-TS balance of a hot-rolled steel sheet of each steel type in Examples.
【図２】実施例における各鋼種の熱延鋼板のλ−ＴＳバ
ランスをしめす図である。FIG. 2 is a view showing a λ-TS balance of a hot-rolled steel sheet of each steel type in Examples.
【図３】実施例におけるＮo.４、Ｎo.７及びＮo.８の鋼
種のλ値に及ぼす巻取温度の影響を示す図である。FIG. 3 is a diagram showing the influence of the winding temperature on the λ value of steel types No. 4, No. 7, and No. 8 in the example.
【図４】Ｎo.４の鋼種のＴＥＭ観察によるベイニティッ
ク・フェライト組織(金属組織)を示す写真である。FIG. 4 is a photograph showing a bainitic ferrite structure (metal structure) of a steel type No. 4 by TEM observation.
【図５】Ｎo.８の鋼種のＴＥＭ観察によるベイニティッ
ク・フェライト組織(金属組織)を示す写真である。FIG. 5 is a photograph showing a bainitic ferrite structure (metal structure) by TEM observation of a steel type No. 8;
───────────────────────────────────────────────────── フロントページの続き (72)発明者 横井利雄 兵庫県加古川市尾上町池田字池田開拓 2222番地１株式会社神戸製鋼所加古川研 究地区内 (56)参考文献 特開 平４−276024（ＪＰ，Ａ) 特開 昭57−145965（ＪＰ，Ａ) 特開 平４−325657（ＪＰ，Ａ) 特開 昭58−42725（ＪＰ，Ａ) 特開 平３−146640（ＪＰ，Ａ) 特開 昭60−184630（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) C22C 38/00 301 C22C 38/04 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshio Yokoi 2222-1, Ikeda-ku, Ikeda-cho, Onoe-cho, Kakogawa-shi, Hyogo Prefecture Within the Kakogawa Research Area, Kobe Steel, Ltd. (56) JP-A-57-145965 (JP, A) JP-A-4-325657 (JP, A) JP-A-58-42725 (JP, A) JP-A-3-146640 (JP, A) 60-184630 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) C22C 38/00 301 C22C 38/04
Claims (3)
〜０．２０％、Ｓｉ：０．２〜２．０％、Ｍｎ：２．５
％以下、Ｐ：０．０８％以下、Ｓ：０．００５％以下を
含み、残部がＦｅ及び不可避的不純物からなる鋼であっ
て、ベイニティック・フェライトまたはこれとフェライ
トからなる組織が面積率で７０％以上であることを特徴
とする伸びフランジ加工性に優れた高強度熱延鋼板。C: 0.03% by weight (hereinafter the same)
0.20%, Si: 0.2-2.0%, Mn: 2.5
% Or less, P: 0.08% or less, S: 0.005% or less, with the balance being Fe and unavoidable impurities, comprising bainitic ferrite or ferrite.
A high-strength hot-rolled steel sheet excellent in stretch flangeability, characterized in that the structure composed of g is 70% or more in area ratio .
以下、Ｃu：０.５％以下、Ｎi：０.５％以下、Ｍo：０.
５％以下、Ｃr：０.５％以下のうちの１種又は２種以上
を含む請求項１に記載の熱延鋼板。2. Nb: 0.5% or less, Ti: 0.5%
Hereinafter, Cu: 0.5% or less, Ni: 0.5% or less, Mo: 0.5% or less.
The hot-rolled steel sheet according to claim 1, wherein the hot-rolled steel sheet contains one or more of 5% or less and Cr: 0.5% or less.
又は２に記載の熱延鋼板。3. The method according to claim 1, further comprising Ca: 20 ppm or less.
Or the hot-rolled steel sheet according to 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35045192A JP3219510B2 (en) | 1992-12-02 | 1992-12-02 | High strength hot rolled steel sheet with excellent stretch flangeability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35045192A JP3219510B2 (en) | 1992-12-02 | 1992-12-02 | High strength hot rolled steel sheet with excellent stretch flangeability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06172924A JPH06172924A (en) | 1994-06-21 |
| JP3219510B2 true JP3219510B2 (en) | 2001-10-15 |
Family
ID=18410586
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP35045192A Expired - Lifetime JP3219510B2 (en) | 1992-12-02 | 1992-12-02 | High strength hot rolled steel sheet with excellent stretch flangeability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3219510B2 (en) |
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| JP4781563B2 (en) * | 2001-06-20 | 2011-09-28 | 新日本製鐵株式会社 | High strength hot-rolled steel sheet with excellent bake hardenability and method for producing the same |
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| JP5765080B2 (en) | 2010-06-25 | 2015-08-19 | Ｊｆｅスチール株式会社 | High-strength hot-rolled steel sheet excellent in stretch flangeability and manufacturing method thereof |
| JP5541263B2 (en) | 2011-11-04 | 2014-07-09 | Ｊｆｅスチール株式会社 | High-strength hot-rolled steel sheet excellent in workability and manufacturing method thereof |
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-
1992
- 1992-12-02 JP JP35045192A patent/JP3219510B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101505303B1 (en) * | 2013-06-27 | 2015-03-24 | 현대제철 주식회사 | Steel sheet and method of manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06172924A (en) | 1994-06-21 |
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