JPH07233440A - Dead soft steel having fine hot rolled structure - Google Patents
Dead soft steel having fine hot rolled structureInfo
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- JPH07233440A JPH07233440A JP17578694A JP17578694A JPH07233440A JP H07233440 A JPH07233440 A JP H07233440A JP 17578694 A JP17578694 A JP 17578694A JP 17578694 A JP17578694 A JP 17578694A JP H07233440 A JPH07233440 A JP H07233440A
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- rolled structure
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- soft steel
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車車体等の用途に
供される高成形性鋼材の冷延あるいは冷間加工素材とし
て好適な、微細熱延組織を有する極低炭素鋼に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-low carbon steel having a fine hot-rolled structure, which is suitable as a cold-rolled or cold-worked material for a highly formable steel material for use in automobile bodies and the like.
【０００２】[0002]
【従来の技術】高成形性薄鋼板として、極低炭素を基本
としたＩＦ鋼が知られている。このＩＦ鋼は、Ｃを例え
ば 0.0030%以下とするとともに、Ｔi やＮb 等を適量添
加してＣを炭化物として固定することにより、鋼中固溶
Ｃを可能な限り低減した鋼である。このような固溶Ｃの
少ない鋼では、冷間圧延−焼鈍後に (111)//ＮＤ方位の
集合組織が発達することに伴いｒ値が向上し、ｒ値で
1.5〜2 程度の優れた深絞り特性が得られる。2. Description of the Related Art As a high formability thin steel sheet, an IF steel based on extremely low carbon is known. This IF steel is a steel in which C is set to 0.0030% or less, and Ti and Nb are added in appropriate amounts to fix C as a carbide to reduce the solid solution C in the steel as much as possible. In such a steel having a small amount of solute C, the r value is improved as the texture of (111) // ND orientation is developed after cold rolling-annealing.
Excellent deep drawing characteristics of about 1.5 to 2 can be obtained.
【０００３】また近年、自動車用薄鋼板に対する要求性
能は一段と高度化しており、ｒ値に対しても 2〜3 の高
水準が要求されている。従来、ＩＦ鋼においてさらにｒ
値を向上させる方法として、Ｃ量を低減して固溶Ｃを極
力低減させる、冷間圧延率を最適化する、熱延条件を最
適化することで熱延組織を細粒化する、等の方法が提案
されている。In recent years, the performance requirements for thin steel sheets for automobiles have become more sophisticated, and a high r value of 2-3 is required. Conventionally, in IF steel,
As a method of improving the value, such as reducing the amount of C to reduce the solid solution C as much as possible, optimizing the cold rolling rate, and refining the hot rolled structure by optimizing the hot rolling conditions. A method has been proposed.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら上記の極
低炭素を基本としたＩＦ鋼について、これ以上の成形性
を向上させるためにＣ量を低減して固溶Ｃを極力低減さ
せると、Ｃ量を0.0020%以下に低減した場合、熱延組織
の粗粒化が著しく、冷延・焼鈍後において(111)// ＮＤ
方位の集合組織が発達しにくくなるという問題があり、
必ずしもｒ値の改善にはつながらないという問題点があ
る。However, in the above IF steel based on ultra-low carbon, if the C content is reduced and the solid solution C is reduced as much as possible in order to further improve the formability, the C content is reduced. Of 0.0011% or less, the coarsening of the hot-rolled structure is remarkable, and (111) // ND after cold rolling / annealing.
There is a problem that the texture of the orientation becomes difficult to develop,
There is a problem that it does not necessarily lead to improvement of the r value.
【０００５】また、冷間圧延率を最適化する方法や、熱
延条件を最適化することで熱延組織を細粒化する方法等
によるｒ値の改善は既に限界に達しており、さらにｒ値
を改善することは期待できないのが現状である。Further, the improvement of the r value by the method of optimizing the cold rolling rate or the method of refining the hot rolled structure by optimizing the hot rolling conditions has already reached the limit, and further r At present, we cannot expect to improve the value.
【０００６】本発明はこのような従来の問題に鑑みなさ
れたもので、Ｃ：0.0020% 以下の極低炭素鋼において熱
延組織の微細化を図ることを目的とする。The present invention has been made in view of such conventional problems, and an object thereof is to miniaturize a hot rolled structure in an ultra low carbon steel having a C: 0.0020% or less.
【０００７】[0007]
【課題を解決するための手段】上記課題は以下の手段に
より解決される。 重量％で、Ｃ：0.0020% 以下、Ｓi ：0.02〜0.15%
、Ｍn ：0.02〜0.20% 、Sol.Ａl ：0.005 〜0.10% 、
Ｓ：0.0090〜0.030%、Ｎ：0.0050% 以下、Ｃu ：0.5%以
下（0%を含む) 、Ｎi ：0.5%以下（0%を含む) 、Ｃr ：
0.5%以下（0%を含む) 、Ｍo ：0.5%以下（0%を含む) 、
Ｖ：0.1%以下（0%を含む) を含有し、残部がＦe および
不可避的不純物からなる微細熱延組織を有する極低炭素
鋼。 に記載の成分に加え、重量％で、Ｔi ：0.005 〜
0.15% 、Ｎb ：0.005 〜0.05% のうちの一種または二種
を含有する、微細熱延組織を有する極低炭素鋼。 またはに記載の成分に加え、重量％で、Ｂ：0.
0005〜0.0030% を含有する、微細熱延組織を有する極低
炭素鋼。The above-mentioned problems can be solved by the following means. % By weight, C: 0.0020% or less, Si: 0.02 to 0.15%
, Mn: 0.02 to 0.20%, Sol.Al: 0.005 to 0.10%,
S: 0.0090 to 0.030%, N: 0.0050% or less, Cu: 0.5% or less (including 0%), Ni: 0.5% or less (including 0%), Cr:
0.5% or less (including 0%), Mo: 0.5% or less (including 0%),
V: Ultra low carbon steel containing 0.1% or less (including 0%), and the balance having a fine hot rolled structure composed of Fe and inevitable impurities. In addition to the components described in 1., Ti: 0.005-
An ultra low carbon steel having a fine hot-rolled structure, containing one or two of 0.15% and Nb: 0.005 to 0.05%. In addition to the components described in or, in% by weight, B: 0.
Ultra-low carbon steel having a fine hot-rolled structure containing 0005 to 0.0030%.
【０００８】[0008]
【作用】本発明者等はＣ：0.0020% 以下の極低炭素鋼の
熱延組織の微細化を図るにあたり、不純物元素を含めた
化学成分に注目し、その結果、特定の成分条件での下で
鋼中のＳ量を従来鋼の水準を超える所定の水準まで高め
ることにより熱延組織を微細化することができ、これを
冷延素材とした場合に極めて優れた深絞り性を有するこ
とを見い出した。本発明は、このような知見に基づいて
なされたものである。The present inventors have paid attention to the chemical composition including the impurity elements in order to refine the hot rolled structure of the ultra low carbon steel with C: 0.0020% or less. It is possible to refine the hot rolled structure by increasing the S content in the steel to a prescribed level that exceeds the level of conventional steel, and when it is used as a cold rolled material, it has extremely excellent deep drawability. I found it. The present invention has been made based on such findings.
【０００９】以下に、本発明の成分組成の限定理由につ
いて説明する。Ｃが0.0020% を超えると固溶Ｃが十分低
くならず、ｒ値の向上が期待できないため、その上限を
0.0020% とする。また、Ｃの下限は特に限定しないが、
溶製上の経済性の観点から0.0005% 程度が実質的な下限
となる。The reasons for limiting the component composition of the present invention will be described below. When C exceeds 0.0020%, the solid solution C does not become sufficiently low and improvement of the r value cannot be expected, so the upper limit is set.
It is 0.0020%. The lower limit of C is not particularly limited,
From the viewpoint of economic efficiency in melting, about 0.0005% is the practical lower limit.
【００１０】Ｓi が0.15% を超えるとＳi Ｏ2 の増加に
より延性が低下し、所望の深絞り性が得られないため、
Ｓi の上限は0.15% とする。また、Ｓi の下限は溶製上
の経済性の観点から0.02% とする。If the Si content exceeds 0.15%, the ductility decreases due to an increase in Si O 2 , and the desired deep drawability cannot be obtained.
The upper limit of Si is 0.15%. Also, the lower limit of Si is 0.02% from the viewpoint of economic efficiency in melting.
【００１１】Ｍn が0.20% を超えると強度が上昇し、所
望の深絞り性が得られない為、Ｍnの上限は0.20% とす
る。また、Ｍn の下限は溶製上の経済性の観点から0.02
% とする。If Mn exceeds 0.20%, the strength increases and the desired deep drawability cannot be obtained, so the upper limit of Mn is made 0.20%. Also, the lower limit of Mn is 0.02 from the viewpoint of economic efficiency in melting.
%.
【００１２】Sol.Ａl が0.10% を超えると脱酸生成物で
あるＡl2Ｏ3 が増加し、機械的特性を劣化させるため、
Sol.Ａl の上限は0.10% とする。また、Sol.Ａl の下限
は溶製上の経済性の観点から0.005%とする。When the content of Sol.Al exceeds 0.10%, the deoxidation product Al 2 O 3 increases and mechanical properties are deteriorated.
The upper limit of Sol.Al is 0.10%. Further, the lower limit of Sol.Al is 0.005% from the viewpoint of economical efficiency in melting.
【００１３】Ｓは本発明では最も重要な添加元素であ
り、Ｃ：0.0020% 以下の極低炭素鋼に適量添加すること
により熱延組織が著しく微細化する。図 1は、本発明の
成分系の鋼における熱間圧延ままの平均フェライト結晶
粒径に及ぼすＳ量の影響を示した図である。これによれ
ば、Ｓ量が0.0090% 以上においてフェライト粒径が十分
に微細化することが判る。このようなフェライト粒径の
微細化により、冷間圧延ー焼鈍後において(111)// ＮＤ
方位が発達し易くなり、ｒ値も向上する。このようにＳ
を高レベルで添加することにより熱延組織の微細化が図
られるのは、熱延プロセスにおけるオーステナイト粒の
粒成長および変態時に核発生したフェライト粒の粒成長
が固溶Ｓまたは析出した硫化物によって抑制されるため
であると考えられる。S is the most important additive element in the present invention, and the C: 0.0020% or less ultra-low carbon steel is added in an appropriate amount to remarkably refine the hot rolled structure. FIG. 1 is a diagram showing the effect of the S content on the average as-hot-rolled ferrite grain size in the steel of the component system of the present invention. According to this, it is understood that the ferrite grain size is sufficiently refined when the S amount is 0.0090% or more. Due to such a reduction in ferrite grain size, (111) // ND after cold rolling and annealing
The azimuth is easily developed and the r value is improved. Thus S
The fine graining of the hot-rolled structure is achieved by adding a high level of austenite, because the grain growth of austenite grains in the hot rolling process and the grain growth of ferrite grains nucleated during transformation are caused by solid solution S or sulfides precipitated. It is thought that this is because it is suppressed.
【００１４】以上のことから、Ｓの添加量が 0.0090%未
満では熱延組織の微細化作用が十分に得られないため、
Ｓの下限は0.0090% とする。一方、Ｓを0.030%を超えて
添加すると伸び値が著しく低下するため、その上限を0.
030%とする。Ｓを上記の範囲で添加することにより、熱
延ままの平均フェライト結晶粒径をＴi 無添加鋼で40μ
m 以下、Ｔi 添加鋼で30μm 以下とすることができる。From the above, if the amount of S added is less than 0.0090%, the effect of refining the hot-rolled structure cannot be sufficiently obtained.
The lower limit of S is 0.0090%. On the other hand, if S is added in excess of 0.030%, the elongation value will decrease significantly, so the upper limit is set to 0.
030% By adding S in the above range, the average ferrite crystal grain size as hot-rolled was 40μ in Ti-free steel.
m or less, and Ti added steel can be 30 μm or less.
【００１５】Ｎについては、過剰な固溶Ｎの存在は歪み
時効の原因となることから、その上限を0.0050% とし
た。またＣと同様、Ｎの低減により熱延組織の粗粒化が
起こるが、本鋼ではＳの効果を用いるため特にＮの下限
はもうけない。Regarding N, since the presence of an excessive amount of solid solution N causes strain aging, its upper limit was made 0.0050%. Further, similarly to C, coarsening of the hot rolled structure occurs due to the reduction of N, but since the effect of S is used in this steel, there is no particular lower limit to N.
【００１６】さらに、本発明では強度上昇を抑えるた
め、Ｃu 、Ｎi 、Ｃr 、Ｍo およびＶを、それぞれＣu
：O.5%以下、Ｎi ：O.5%以下、Ｃr ：O.5%以下、Ｍo
：O.5%以下、Ｖ：O.1%以下とすることが好ましい。こ
れらの元素の含有量がそれぞれの上限を超えると強度が
上昇し、深絞り性を劣化させる。Further, in the present invention, Cu, Ni, Cr, Mo and V are respectively added to Cu in order to suppress an increase in strength.
: O.5% or less, Ni: O.5% or less, Cr: O.5% or less, Mo
: O.5% or less, V: O.1% or less. If the contents of these elements exceed the respective upper limits, the strength increases and the deep drawability deteriorates.
【００１７】Ｔi はＣおよびＮの固定のために有効な元
素であり、0.005%以上の添加によりその効果が得られる
ため下限を0.005%とする。しかし、有効Ｔi 量を大幅に
超えるような過剰な添加はコスト上のデメリットが大き
いため、その上限を0.15% とする。Ti is an element effective for fixing C and N, and its effect is obtained by adding 0.005% or more, so the lower limit is made 0.005%. However, excessive addition that greatly exceeds the effective Ti amount has a large cost demerit, so the upper limit is made 0.15%.
【００１８】Ｎb もＣの固定のために有効な元素であ
り、0.005%以上の添加によりその効果が得られるため下
限を0.005%とする。しかし、0.05% を超える添加は固溶
強化元素として強度上昇をもたらすとともに、コスト上
のデメリットも大きいため、その上限を0.05% とする。Nb is also an effective element for fixing C, and its effect is obtained by adding 0.005% or more, so the lower limit is made 0.005%. However, the addition of more than 0.05% raises the strength as a solid solution strengthening element and has a large cost demerit, so the upper limit is made 0.05%.
【００１９】Ｂは粒界におけるＣ濃度の低下に伴う粒界
の強度低下を補うのに有効な元素であり、0.0005% 以上
の添加によりその効果が得られるため下限を0.0005% と
する。しかし、0.0030% を超えて添加しても、添加量に
見合う効果が得られないため、その上限を0.0030% とす
る。B is an element effective for compensating for the decrease in the strength of the grain boundary due to the decrease in the C concentration at the grain boundary. Since the effect is obtained by adding 0.0005% or more, the lower limit is made 0.0005%. However, even if added over 0.0030%, the effect commensurate with the added amount cannot be obtained, so the upper limit is made 0.0030%.
【００２０】[0020]
【実施例】本発明の実施例を図面にもとづいて説明す
る。表１は本発明鋼板と比較鋼板の組成を示す表であ
る。Embodiments of the present invention will be described with reference to the drawings. Table 1 is a table showing compositions of the steel sheet of the present invention and the comparative steel sheet.
【００２１】[0021]
【表１】 [Table 1]
【００２２】なお、表１は溶製スラブを圧延した後の鋼
板の分析結果を示している。スラブは再加熱温度1100〜
1250℃、仕上げ温度 920〜940 ℃、巻取り温度 600〜70
0 ℃で熱間圧延し、3.0mm 厚の熱延板とした。表２はこ
れら熱延板の平均フェライト結晶粒径をインタ−セプト
法により測定した結果を示す表である。Table 1 shows the analysis results of the steel sheet after rolling the molten slab. Slab reheating temperature 1100 ~
1250 ℃, finishing temperature 920 ~ 940 ℃, winding temperature 600 ~ 70
Hot rolling was performed at 0 ° C. to obtain a hot rolled sheet having a thickness of 3.0 mm. Table 2 is a table showing the results of measuring the average ferrite crystal grain size of these hot-rolled sheets by the intercept method.
【００２３】[0023]
【表２】 [Table 2]
【００２４】表２に示すように、本発明鋼板の平均フェ
ライト結晶粒径は、Ｔi 無添加鋼で約40μm 以下、Ｔi
添加鋼で約30μm 以下となっており、比較鋼板に較べて
熱延組織が細粒化していることが判る。As shown in Table 2, the average ferrite crystal grain size of the steel sheet of the present invention is about 40 μm or less for the Ti-free steel and Ti
It is about 30 μm or less for the added steel, and it can be seen that the hot rolled microstructure is finer than that of the comparative steel sheet.
【００２５】冷延素材に適用する場合についてのみ説明
したが、他の用途の鋼材にも適用できるものである。Although only the case of applying it to a cold rolled material has been described, it can also be applied to steel materials for other purposes.
【００２６】[0026]
【発明の効果】以上のように、本発明によればＣ：0.00
20% 以下の極低炭素鋼において、特定の成分条件の下で
従来鋼よりも高レベルでＳを添加することにより、熱延
組織を十分に微細化することができ、このため冷延ー焼
鈍後の(111)// ＮＤ方向の集合組織が十分に発達し、自
動車車体等に好適な深絞り性に優れた極低炭素鋼の製造
を可能ならしめるものである。As described above, according to the present invention, C: 0.00
In ultra-low carbon steel of 20% or less, by adding S at a higher level than that of conventional steel under specific composition conditions, the hot rolled structure can be sufficiently refined, and therefore cold rolling-annealing The later texture in the (111) // ND direction is sufficiently developed, and it becomes possible to manufacture an ultra-low carbon steel excellent in deep drawability suitable for automobile bodies and the like.
【図１】鋼中のＳ含有量と熱延板の平均フェライト結晶
粒径との関係を示す図。FIG. 1 is a diagram showing a relationship between an S content in steel and an average ferrite crystal grain size of a hot rolled sheet.
Claims (3)
02〜0.15% 、Ｍn ：0.02〜0.20% 、Sol.Ａl ：0.005 〜
0.10% 、Ｓ：0.0090〜0.030%、Ｎ：0.0050%以下、Ｃu
：0.5%以下（0%を含む) 、Ｎi ：0.5%以下（0%を含む)
、Ｃr ：0.5%以下（0%を含む) 、Ｍo ：0.5%以下（0%
を含む) 、Ｖ：0.1%以下（0%を含む) を含有し、残部が
Ｆe および不可避的不純物からなる微細熱延組織を有す
る極低炭素鋼。1. By weight%, C: 0.0020% or less, Si: 0.0.
02-0.15%, Mn: 0.02-0.20%, Sol.Al: 0.005-
0.10%, S: 0.0090 to 0.030%, N: 0.0050% or less, Cu
: 0.5% or less (including 0%), Ni: 0.5% or less (including 0%)
, Cr: 0.5% or less (including 0%), Mo: 0.5% or less (0%
, V: 0.1% or less (including 0%), and the balance is an ultra-low carbon steel having a fine hot-rolled structure composed of Fe and unavoidable impurities.
で、Ｔi ：0.005 〜0.15% 、Ｎb ：0.005 〜0.05% のう
ちの一種または二種を含有する、微細熱延組織を有する
極低炭素鋼。2. In addition to the components of claim 1, weight%
And an ultra low carbon steel having a fine hot-rolled structure, containing one or two of Ti: 0.005 to 0.15% and Nb: 0.005 to 0.05%.
加え、重量％で、Ｂ：0.0005〜0.0030% を含有する、微
細熱延組織を有する極低炭素鋼。3. An ultra-low carbon steel having a fine hot-rolled structure, which contains B: 0.0005 to 0.0030% by weight in addition to the components described in claim 1 or 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17578694A JPH07233440A (en) | 1993-12-28 | 1994-07-27 | Dead soft steel having fine hot rolled structure |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP5-350438 | 1993-12-28 | ||
| JP35043893 | 1993-12-28 | ||
| JP17578694A JPH07233440A (en) | 1993-12-28 | 1994-07-27 | Dead soft steel having fine hot rolled structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07233440A true JPH07233440A (en) | 1995-09-05 |
Family
ID=26496942
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP17578694A Withdrawn JPH07233440A (en) | 1993-12-28 | 1994-07-27 | Dead soft steel having fine hot rolled structure |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07233440A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000068444A1 (en) * | 1999-05-08 | 2000-11-16 | Thyssen Krupp Stahl Ag | Steel for producing components of picture tubes and method for producing the sheet steel, from which the picture tubes are made |
-
1994
- 1994-07-27 JP JP17578694A patent/JPH07233440A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2000068444A1 (en) * | 1999-05-08 | 2000-11-16 | Thyssen Krupp Stahl Ag | Steel for producing components of picture tubes and method for producing the sheet steel, from which the picture tubes are made |
| US6645317B1 (en) | 1999-05-08 | 2003-11-11 | Thyssen Krupp Stahl Ag | Metal components for picture tubes |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20011002 |