JP2002030381A - Thin steel sheet and its production method - Google Patents

Thin steel sheet and its production method

Info

Publication number
JP2002030381A
JP2002030381A JP2000212963A JP2000212963A JP2002030381A JP 2002030381 A JP2002030381 A JP 2002030381A JP 2000212963 A JP2000212963 A JP 2000212963A JP 2000212963 A JP2000212963 A JP 2000212963A JP 2002030381 A JP2002030381 A JP 2002030381A
Authority
JP
Japan
Prior art keywords
less
thickness
slab
steel sheet
thin steel
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.)
Granted
Application number
JP2000212963A
Other languages
Japanese (ja)
Other versions
JP3775178B2 (en
Inventor
Akihiro Yamanaka
章裕 山中
Shigeki Nomura
茂樹 野村
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Sumitomo Metal Industries Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Sumitomo Metal Industries Ltd filed Critical Sumitomo Metal Industries Ltd
Priority to JP2000212963A priority Critical patent/JP3775178B2/en
Publication of JP2002030381A publication Critical patent/JP2002030381A/en
Application granted granted Critical
Publication of JP3775178B2 publication Critical patent/JP3775178B2/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

Links

Landscapes

  • Continuous Casting (AREA)
  • Heat Treatment Of Sheet Steel (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a thin steel sheet free from the generation of cracking at the time of press working or the like and having good workability and to provide a continuous casting method capable of obtaining the same thin steel sheet. SOLUTION: This thin steel sheet with a thickness of <=8 mm has a chemical composition on the average of the total sheet thickness of, by mass, 0.03 to 0.16% C, <=0.2% Si, <=1.4% Mn, <=0.03% P, <=0.02% S and <=0.10% sol.Al, and the balance Fe with impurity elements, and in which the ratios of the C content(C) t on the average and the Mn content(Mn) ton the average respectively in the region within 10% of the total thickness on both sides in the thickness direction from the center of the thickness to the C content (C) o on the average of the total sheet thickness and the Mn content(Mn) o on the average, i.e., (C) t/(C) o and (Mn) t/(Mn) o are respectively <=1.5.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、熱間圧延または熱
間圧延後に冷間圧延した薄鋼板に関し、さらにその薄鋼
板の製造方法に関する。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot rolled steel sheet or a cold rolled steel sheet after hot rolling, and further relates to a method for producing the thin steel sheet.

【0002】[0002]

【従来の技術】自動車の足廻り部品、ボイラーの構造部
品などは、連続鋳造された鋳片を素材として熱間圧延さ
れた薄鋼板を、またはその熱間圧延された鋼材を素材と
してさらに冷間圧延された薄鋼板を、プレス加工するこ
となどにより製造される。
2. Description of the Related Art Undercarriage parts of automobiles, structural parts of boilers, and the like are manufactured by using a continuously cast slab as a raw material for a hot-rolled thin steel plate or a hot-rolled steel material for a further cold rolling. It is manufactured by pressing a rolled thin steel plate.

【0003】ところで、連続鋳造された断面形状が長方
形の鋳片の厚さ中心部近傍には、中心偏析やV偏析と呼
ばれる内部欠陥が発生する場合がある。中心偏析は鋳片
の最終凝固部にC、S、P、Mnなどの偏析成分が濃化
して現れるもので、V偏析は鋳片の最終凝固部近傍に、
これらの偏析成分がV字状に濃化するものである。これ
ら偏析は、鋳片からの圧下比が小さい厚鋼板では、靱性
の低下の原因となり、また、厚板から曲げ加工後溶接し
て製造される大径鋼管の水素誘起割れの原因となること
が知られている。
In the vicinity of the center of the thickness of a continuously cast slab having a rectangular cross section, internal defects called center segregation or V segregation may occur. The center segregation is a segregation component such as C, S, P, and Mn that appears in the final solidified portion of the slab, and the V segregation appears near the final solidified portion of the slab.
These segregated components are concentrated in a V-shape. These segregations may cause a decrease in toughness in thick steel plates with a small reduction ratio from the slab, and may cause hydrogen-induced cracking in large diameter steel pipes manufactured by bending and welding from thick plates. Are known.

【0004】一方、薄鋼板では、従来、これら偏析はあ
まり問題となっていなかった。薄鋼板では、鋳片からの
圧下比が大きく、これら偏析が軽減されているからであ
る。しかし、近年、連続鋳造における生産性の向上の要
望が高まり、鋳造速度を速くすることが指向され、これ
ら偏析の発生程度が著しくなる傾向が顕在化してきた。
さらに、自動車の足廻り部品、ボイラーの構造部品など
では、より複雑なプレス加工が行われるようになり、さ
らに加工性の優れた薄鋼板が要望されている。鋳片のこ
れら偏析が悪化する状況下で、プレス加工が複雑になる
ことから、このような用途に用いられる薄鋼板では、プ
レス加工時の割れ発生が問題となっている。
[0004] On the other hand, in the case of thin steel sheets, these segregations have not been a serious problem. This is because in a thin steel sheet, the reduction ratio from the slab is large, and these segregations are reduced. However, in recent years, there has been an increasing demand for improvement in productivity in continuous casting, and it has been aimed to increase the casting speed, and the tendency of occurrence of these segregations has become remarkable.
Further, in the case of undercarriage parts of automobiles, structural parts of boilers, and the like, more complicated press working has been performed, and a thin steel sheet having more excellent workability has been demanded. Since the press working becomes complicated under the situation where the segregation of the cast slabs is worsened, the occurrence of cracks during the press working is a problem in the thin steel sheet used for such an application.

【0005】これらの偏析の生成機構は、次のように考
えられている。凝固が進むにつれて、凝固組織であるデ
ンドライト樹間に偏析成分が濃化する。この偏析成分の
濃化した溶鋼が、凝固時の鋳片の収縮またはバルジング
と呼ばれる鋳片のふくれなどにより、デンドライト樹間
より流出する。流出した偏析成分の濃化した溶鋼は、最
終凝固部の凝固完了点に向かって流動し、そのまま凝固
して偏析成分の濃化帯が形成される。これらの濃化帯が
中心偏析またはV字状偏析である。これら偏析の防止対
策として、たとえば特開平7−210382号公報に
は、未凝固部を含む鋳片を20mm以上バルジングさ
せ、凝固が完了する前に圧下ロール対により、バルジン
グ量相当分の厚みを圧下する方法が提案されている。デ
ンドライト樹間に残った偏析成分の濃化した溶鋼を鋳造
方向の上流側に強制的に排出することにより、中心偏析
およびV字状偏析を防止する方法である。しかし、この
方法では、未凝固部を含む鋳片を圧下するために、専用
の圧下ロール対が必要であり、設備が過大となる。
[0005] The mechanism of generation of these segregations is considered as follows. As the solidification progresses, segregated components are concentrated between dendrite trees, which are solidified structures. The molten steel in which the segregated components are concentrated flows out from between the dendrite trees due to shrinkage of the slab during solidification or swelling of the slab called bulging. The flowed-out molten steel in which the segregation component is concentrated flows toward the solidification completion point of the final solidification part, and solidifies as it is to form a concentrated zone of the segregation component. These concentrated zones are center segregation or V-shaped segregation. As a countermeasure for preventing such segregation, for example, JP-A-7-210382 discloses that a slab including an unsolidified portion is bulged by 20 mm or more, and a thickness corresponding to the bulging amount is reduced by a pair of reduction rolls before solidification is completed. A way to do that has been proposed. This is a method for preventing central segregation and V-shaped segregation by forcibly discharging molten steel, in which segregated components remaining between dendrite trees are concentrated, to the upstream side in the casting direction. However, in this method, a dedicated roll pair is required to reduce the cast slab including the unsolidified portion, and the equipment becomes excessively large.

【0006】特開平9−67619号公報には、Pを
0.05〜0.1質量%含有させることにより耐腐食性
を向上した薄鋼板において、さらに加工性を向上させる
ために、中心偏析の軽減処理を実施した鋳片を素材とし
て熱間圧延を行うに際し、仕上温度をAr3 〜(Ar3
+100℃)とし、その後の冷却速度を50℃/sと
し、巻き取り温度を300〜500℃とする方法が提案
されている。具体的な中心偏析の軽減方法は、未凝固部
を含む鋳片を軽圧下すること、未凝固溶鋼を電磁攪拌す
ること、または低温鋳造することが提案されている。し
かし、軽圧下法では、P含有率が多い場合には効果はあ
るが、通常のP含有率では、効果は少ない。また、電磁
攪拌装置を備えるには設備が過大となる。さらに、低温
鋳造の際の具体的なタンデイッシュ内の溶鋼の過熱度の
提案はないが、低温鋳造では浸漬ノズルに詰まりが発生
し、操業の継続が困難となりやすい。
Japanese Patent Application Laid-Open No. 9-67619 discloses that a steel sheet containing 0.05 to 0.1% by mass of P and having improved corrosion resistance is provided with a center segregation in order to further improve the workability. When hot rolling is performed using the slab subjected to the reduction treatment, the finishing temperature is set to Ar 3 to (Ar 3
+ 100 ° C.), a subsequent cooling rate of 50 ° C./s, and a winding temperature of 300 to 500 ° C. have been proposed. As a specific method for reducing the center segregation, it has been proposed to reduce the cast slab including the unsolidified portion by light pressure, electromagnetically stir the unsolidified molten steel, or perform low-temperature casting. However, the light reduction method has an effect when the P content is large, but has little effect with a normal P content. Further, the equipment becomes excessively large in order to provide the electromagnetic stirring device. Furthermore, although there is no specific proposal for the degree of superheat of molten steel in a tundish at the time of low-temperature casting, clogging of the immersion nozzle occurs at low-temperature casting, and continuation of operation tends to be difficult.

【0007】上述のとおり、鋳片の中心偏析およびV字
状偏析に起因して、薄鋼板のプレス加工時に割れが発生
する問題に対し、プレス加工などの際に割れが発生する
ことなく、加工性のよい薄鋼板およびその熱間圧延用素
材である中心偏析およびV字状偏析の発生のない鋳片
を、安価な設備費で安定して得ることが望まれている。
[0007] As described above, the problem of cracking during the press working of a thin steel sheet due to the center segregation and the V-shaped segregation of the cast slab is described below. It is desired to obtain a thin steel sheet having good properties and a slab free of center segregation and V-shaped segregation, which is a material for hot rolling thereof, stably at low equipment cost.

【0008】[0008]

【発明が解決しようとする課題】本発明は、プレス加工
などの際に割れの発生がなく、加工性のよい熱間圧延し
た薄鋼板または熱間圧延後に冷間圧延した薄鋼板を提供
することを目的とし、さらに、これら薄鋼板の製造方法
を提供することを目的とする。
SUMMARY OF THE INVENTION It is an object of the present invention to provide a hot-rolled thin steel sheet or a cold-rolled thin steel sheet which does not crack during press working and has good workability. Further, it is another object of the present invention to provide a method for producing these thin steel sheets.

【0009】[0009]

【課題を解決するための手段】本発明の要旨は、下記
(1)と(2)に示す薄鋼板、および下記(3)と
(4)に示す薄鋼板の製造方法にある。 (1)全板厚の平均の化学組成における含有率が、質量
%で、C:0.03〜0.16%、Si:0.2%以
下、Mn:1.4%以下、P:0.03%以下、S:
0.02%以下、sol.Al:0.10%以下であ
り、残部がFeおよび不純物元素からなる厚さが8mm
以下の薄鋼板であって、下記の(イ)式および(ロ)式
を満足する薄鋼板。
SUMMARY OF THE INVENTION The gist of the present invention is a method of manufacturing a thin steel sheet shown in the following (1) and (2) and a method of manufacturing a thin steel sheet shown in the following (3) and (4). (1) The content in the average chemical composition of the entire plate thickness is 0.03 to 0.16% in mass%, Si: 0.2% or less, Mn: 1.4% or less, P: 0. 0.03% or less, S:
0.02% or less, sol. Al: 0.10% or less, the balance being 8 mm in thickness composed of Fe and impurity elements
The following thin steel sheets, which satisfy the following equations (a) and (b).

【0010】 (C)t/(C)o ≦1.5 ・・・(イ) (Mn)t/(Mn)o≦1.5 ・・・(ロ) ここで、(C)t:厚さ中心から厚さ方向両側にそれぞ
れ全厚さの10%以内の領域における平均のCの含有率
(質量%) (C)o:全板厚の平均のCの含有率(質量%) (Mn)t:厚さ中心から厚さ方向両側にそれぞれ全厚
さの10%以内の領域における平均のMnの含有率(質
量%) (Mn)o:全板厚の平均のMnの含有率(質量%) (2)上記(1)に記載の薄鋼板であって、さらに質量
%で、Nb:0.2%以下、Ti:0.2%以下および
V:0.2%以下のうちの1種または2種以上を含有す
る薄鋼板。 (3)質量%で、C:0.03〜0.16%、Si:
0.2%以下、Mn:1.4%以下、P:0.03%以
下、S:0.02%以下、sol.Al:0.10%以
下を含有する鋼を溶製して、タンデッシュ内の溶鋼の過
熱度を80℃以下、鋳片断面形状が長方形で厚さ300
mm以下、鋳造速度1.2m/分〜3m/分および厚さ
中心部が凝固完了するまでの鋳片の領域において互いに
隣接する鋳片支持用ガイドロールの軸芯間距離を450
mm以下とする条件で鋳造し、次いで圧延して薄鋼板と
する薄鋼板の製造方法。 (4)質量%で、C:0.03〜0.16%、Si:
0.2%以下、Mn:1.4%以下、P:0.03%以
下、S:0.02%以下、sol.Al:0.10%以
下を含有し、さらに、Nb:0.2%以下、Ti:0.
2%以下およびV:0.2%以下のうちの1種または2
種以上を含有する鋼を溶製して、タンデッシュ内の溶鋼
の過熱度を80℃以下、鋳片断面形状が長方形で厚さ3
00mm以下、鋳造速度1.2m/分〜3m/分および
厚さ中心部が凝固完了するまでの鋳片の領域において互
いに隣接する鋳片支持用ガイドロールの軸芯間距離を4
50mm以下とする条件で鋳造し、次いで圧延して薄鋼
板とする薄鋼板の製造方法。
(C) t / (C) o ≦ 1.5 (B) (Mn) t / (Mn) o ≦ 1.5 (B) where (C) t: thickness Average C content (% by mass) in a region within 10% of the total thickness on both sides in the thickness direction from the center in the thickness direction (C) o: average C content (% by mass) of the entire plate thickness (Mn) ) T: Average Mn content (% by mass) in a region within 10% of the total thickness on both sides in the thickness direction from the center of the thickness (Mn) o: Average Mn content (% by mass) of the entire plate thickness (2) The steel sheet according to the above (1), further comprising, by mass%, one of Nb: 0.2% or less, Ti: 0.2% or less, and V: 0.2% or less. A thin steel sheet containing one or more kinds. (3) In mass%, C: 0.03 to 0.16%, Si:
0.2% or less, Mn: 1.4% or less, P: 0.03% or less, S: 0.02% or less, sol. Al: Steel containing 0.10% or less is melted, the superheat degree of the molten steel in the tundish is 80 ° C or less, the slab cross-section is rectangular, and the thickness is 300.
mm or less, the casting speed is 1.2 m / min to 3 m / min, and the distance between the axes of the slab supporting guide rolls adjacent to each other in the region of the slab until the center of the thickness is completely solidified is 450 mm.
A method for producing a thin steel sheet that is cast under the condition of not more than mm and then rolled into a thin steel sheet. (4) In mass%, C: 0.03 to 0.16%, Si:
0.2% or less, Mn: 1.4% or less, P: 0.03% or less, S: 0.02% or less, sol. Al: 0.10% or less, Nb: 0.2% or less, Ti: 0.
1% or less of 2% or less and V: 0.2% or less
A steel containing at least one seed is melted, the degree of superheat of the molten steel in the tundish is 80 ° C. or less, the cross section of the slab is rectangular and the thickness is 3
00 mm or less, the casting speed is 1.2 m / min to 3 m / min, and the distance between the axes of the guide rolls for supporting slabs adjacent to each other in the slab region until the center of the thickness is completely solidified is 4 mm.
A method for producing a thin steel sheet which is cast under conditions of 50 mm or less and then rolled to obtain a thin steel sheet.

【0011】本発明者らは、前述の課題を、下記の知見
を得て対策を採ることにより解決した。 鋳片の厚さ中心部近傍に発生する中心偏析およびV字
状偏析は、鋼の化学組成、鋳片の厚さ、鋳造速度などの
影響を受け、たとえば、偏析しやすいC、S、P、Mn
などの含有率が多い場合、鋳片が厚い場合、または鋳造
速度が速い場合に偏析の程度が高く、かつ鋳片の厚さ方
向に広がったこれら偏析帯が発生する。これら鋳片の偏
析帯は、薄鋼板において偏析帯として残存する。薄鋼板
の偏析帯の厚さは、熱間圧延の際の加熱温度、時間など
の熱間圧延条件、薄鋼板の熱処理条件などの影響を受け
るが、ほぼ鋳片から薄鋼板までの圧下比に比例して残存
しやすい。
The present inventors have solved the above-mentioned problem by obtaining the following findings and taking measures. The center segregation and the V-shaped segregation occurring near the center of the thickness of the slab are affected by the chemical composition of the steel, the thickness of the slab, the casting speed, and the like. For example, C, S, P, Mn
When the content rate is high, when the slab is thick, or when the casting speed is high, the degree of segregation is high, and these segregation zones spread in the thickness direction of the slab are generated. These segregation zones of the slab remain as segregation zones in the thin steel sheet. The thickness of the segregation zone of a thin steel sheet is affected by the hot rolling conditions such as heating temperature and time during hot rolling, and the heat treatment conditions of the thin steel sheet. It is likely to remain in proportion.

【0012】また、鋳片を熱間圧延した薄鋼板、または
熱間圧延後に冷間圧延した薄鋼板をプレス加工する際の
割れの発生のしやすさは、これら薄鋼板の全厚に対する
偏析帯の厚さの比に依存する。さらに、これらの割れの
発生のしやすさが、低炭素鋼〜中炭素鋼の薄鋼板では、
偏析線に存在するCおよびMnの偏析状況に依存する。
[0012] The ease with which cracks occur when a thin steel sheet obtained by hot rolling a cast slab or a thin steel sheet cold-rolled after hot rolling is caused by the segregation zone with respect to the total thickness of these thin steel sheets. Depends on the ratio of the thicknesses. Furthermore, the ease of occurrence of these cracks is low carbon steel to medium carbon steel thin steel sheets,
It depends on the segregation state of C and Mn existing in the segregation line.

【0013】そこで、本発明の薄鋼板では、全板厚の
平均の化学組成における含有率が、質量%で、C:0.
03〜0.16%、Si:0.2%以下、Mn:1.4
%以下、P:0.03%以下、S:0.02%以下、s
ol.Al:0.10%以下であり、残部がFeおよび
不純物元素からなる厚さ8mm以下の薄鋼板であって、
薄鋼板の全板厚の平均のCの含有率(C)oおよび全板
厚の平均のMnの含有率(Mn)oに対する、厚さ中心
から厚さ方向両側にそれぞれ全厚さの10%以内の領域
における平均のCの含有率(C)tおよび平均のMnの
含有率(Mn)tの比(C)t/(C)oおよび(M
n)t/(Mn)oが、それぞれ1.5以下とする。こ
れにより、鋳片を熱間圧延した薄鋼板、または熱間圧延
後に冷間圧延した薄鋼板をプレス加工する際に、割れの
発生を防止できる。
Accordingly, in the thin steel sheet of the present invention, the content in the average chemical composition of the entire sheet thickness is expressed by mass% and C: 0.
03-0.16%, Si: 0.2% or less, Mn: 1.4
%, P: 0.03% or less, S: 0.02% or less, s
ol. Al: 0.10% or less, the balance being a thin steel sheet having a thickness of 8 mm or less composed of Fe and an impurity element,
10% of the total thickness from the center of the thickness to both sides in the thickness direction with respect to the average C content (C) o and the average Mn content (Mn) o of the total thickness of the thin steel sheet. The ratio of the average C content (C) t and the average Mn content (Mn) t in the region within (C) t / (C) o and (M
n) t / (Mn) o is 1.5 or less, respectively. Thereby, when press-working the thin steel plate which hot rolled the slab or the cold rolled thin steel plate after hot rolling, generation | occurrence | production of a crack can be prevented.

【0014】本発明の薄鋼板の製造方法では、まず、
連続鋳造において、厚さ300mm以下の鋳片を1.2
〜3m/分の速度で鋳造し、その際にタンデッシュ内の
溶鋼の過熱度を80℃以下とし、かつ、厚さ中心部が凝
固完了するまでの鋳片の領域において、互いに隣接する
鋳片支持用ガイドロールの軸芯間距離を450mm以下
とする条件で鋳造する。
In the method for manufacturing a thin steel sheet according to the present invention, first,
In continuous casting, slabs with a thickness of 300 mm or less
Casting at a speed of up to 3 m / min. At this time, the superheat degree of the molten steel in the tundish is set to 80 ° C. or less, and the slab supports adjacent to each other in the slab region until the solidification of the thickness center is completed. Casting is performed under the condition that the distance between the axes of the guide rolls is 450 mm or less.

【0015】鋳片の厚さを300mm以下とし、1.2
〜3m/分の速度で鋳造すると、鋳片の厚さ中心部近傍
の凝固組織は微細な等軸晶が多く形成されるようにな
り、偏析成分が濃化した溶鋼は等軸晶の間に分散して保
持されるので、中心偏析などが発生しにくい。また、タ
ンデッシュ内の溶鋼の過熱度を80℃以下と適正にする
ので、鋳片の厚さ中心部近傍の凝固組織は微細な等軸晶
が多く形成されるようになる。
[0015] The thickness of the slab is 300 mm or less, 1.2
When casting at a speed of up to 3 m / min, the solidified structure near the center of the thickness of the slab has many fine equiaxed crystals, and the molten steel in which the segregation component is concentrated is between the equiaxed crystals. Since they are dispersed and held, center segregation and the like hardly occur. Further, since the degree of superheat of the molten steel in the tundish is appropriately set to 80 ° C. or less, the solidified structure near the center of the thickness of the slab is formed with many fine equiaxed crystals.

【0016】さらに、厚さ中心部が凝固完了するまでの
鋳片の領域において、互いに隣接する鋳片支持用ガイド
ロールの軸芯間距離を450mm以下とすると、鋳片が
バルジングすることを抑制できる。
Further, when the distance between the axes of the guide rolls for supporting slabs adjacent to each other is set to 450 mm or less in the slab area until the thickness center portion is completely solidified, bulging of the slab can be suppressed. .

【0017】図2は、ガイドロールの軸心間距離を示す
模式図である。ロールの軸心間距離7とは、鋳造方向8
に隣り合うガイドロールのロール6の軸心と軸心の距離
を意味する。厚さ中心部が凝固完了するまでの鋳片の領
域では、とくに、偏析成分の濃化した溶鋼が多く存在す
るので、鋳片のバルジングを抑制することによる中心偏
析などの発生を防止する効果は大きい。
FIG. 2 is a schematic diagram showing the distance between the center axes of the guide rolls. The distance 7 between the roll axes is the casting direction 8
Means the distance between the axes of the guide rolls 6 adjacent to each other. In the area of the slab until the center of the thickness is completely solidified, in particular, there are many molten steels with concentrated segregation components, so the effect of preventing the occurrence of center segregation etc. by suppressing bulging of the slab is large.

【0018】これら鋳片の厚さ、鋳造速度、溶鋼過熱
度、およびガイドロール対の軸芯間距離の各条件を組み
合わせて適正な範囲の条件とするので、中心偏析などの
発生のない鋳片を得ることができる。このような中心偏
析などのない鋳片を素材として熱間圧延した薄鋼板、ま
たはその熱間圧延した薄鋼板を素材として、さらに冷間
圧延した薄鋼板では、プレス加工などの際に割れは発生
しにくい。
Since the conditions of the slab thickness, casting speed, degree of superheat of molten steel, and distance between the shaft cores of the guide roll pair are combined to make the conditions within an appropriate range, the slab without generation of center segregation or the like is obtained. Can be obtained. Hot rolled thin steel sheet using such a slab without center segregation, or hot rolled thin steel sheet, and further cold rolled thin steel sheet, cracks occur during press working etc. Hard to do.

【0019】[0019]

【発明の実施の形態】本発明の薄鋼板およびその薄鋼板
の製造方法を以下に説明する。以下の%表示は質量%を
意味する。まず、化学組成を説明する。 C:0.03〜0.16% Cは、鋼の強度を確保する上で安価で有用な元素であ
り、その効果を発揮するために、その下限は0.03%
とする。多く含有させると鋼の加工性を悪化させる元素
であり、また、平衡分配係数が小さく、偏析しやすい元
素であり、その上限は0.16%とする。したがって、
Cは、0.03〜0.16%とする。
BEST MODE FOR CARRYING OUT THE INVENTION A thin steel sheet according to the present invention and a method for manufacturing the thin steel sheet will be described below. The following% indication means% by mass. First, the chemical composition will be described. C: 0.03 to 0.16% C is an inexpensive and useful element for securing the strength of steel, and its lower limit is 0.03% in order to exhibit its effect.
And If it is contained too much, it is an element that deteriorates the workability of steel, and it is an element that has a small equilibrium distribution coefficient and is easy to segregate. The upper limit is 0.16%. Therefore,
C is set to 0.03 to 0.16%.

【0020】Si:0.2%以下 Siは、通常、脱酸と鋼の強化のために添加されるが、
加工性を劣化することなく強度を高めることができる元
素であり、その効果を発揮させるためには、0.01%
以上含有させることが望ましい。ただし、多く含有させ
ると鋼材の化成処理性が悪化するので、その上限は0.
2%とする。
Si: 0.2% or less Si is usually added for deoxidation and strengthening of steel.
It is an element that can increase the strength without deteriorating the workability. In order to exhibit the effect, 0.01%
It is desirable to contain the above. However, if it is contained too much, the chemical conversion property of the steel material deteriorates.
2%.

【0021】Mn:1.4%以下 Mnは強度を増す元素として安価な元素であり、その効
果を発揮させるためには、0.2%以上含有させること
が望ましい。ただし、偏析しやすい元素であり、その上
限は1.4%とする。
Mn: 1.4% or less Mn is an inexpensive element as an element for increasing the strength, and in order to exert its effect, it is desirable to contain 0.2% or more. However, it is an element that is easily segregated, and the upper limit is 1.4%.

【0022】P:0.03%以下 Pは、不純物元素であり、多く含有させると鋼の加工性
を悪化させる元素であり、また偏析しやすい元素であ
り、その上限は0.03%とする。
P: not more than 0.03% P is an impurity element. If P is contained in a large amount, it is an element that deteriorates the workability of steel, and is an element that tends to segregate, and the upper limit is made 0.03%. .

【0023】S:0.02%以下 Sは、不純物元素であり、鋼の熱間脆性を悪化させる元
素であり、その上限は0.02%とする。
S: 0.02% or less S is an impurity element, which is an element that deteriorates the hot brittleness of steel, and its upper limit is made 0.02%.

【0024】sol.Al:0.10%以下 Alは脱酸に効果的な元素であり、その効果を発揮させ
るためには、0.005%以上含有させるのが望まし
い。ただし、多く含有させると鋳片表面に表面疵が発生
しやすく、また連続鋳造中に浸漬ノズルが詰まりやすく
なるので、その上限は0.10%とする。
Sol. Al: 0.10% or less Al is an element effective for deoxidation, and in order to exhibit its effect, it is desirable to contain 0.005% or more. However, when a large amount is contained, surface flaws are liable to be generated on the slab surface and the immersion nozzle is easily clogged during continuous casting, so the upper limit is set to 0.10%.

【0025】以下に記すTi、NbおよびVは、必要に
応じて添加する元素であり、必要に応じて1種または2
種以上添加するのがよい。
Ti, Nb and V described below are elements to be added as necessary, and one or two
It is better to add more than one species.

【0026】Ti:≦0.2% Tiは、脱酸、およびC、Nを固定するのに有効な元素
である。ただし、0.2%を超えて多く含有させるとそ
の効果が飽和するばかりでなく、鋼の加工性が悪くなる
ので、その上限は0.2%とする。
Ti: ≦ 0.2% Ti is an element effective for deoxidizing and fixing C and N. However, if the content exceeds 0.2%, not only does the effect become saturated, but also the workability of the steel deteriorates, so the upper limit is made 0.2%.

【0027】Nb:≦0.2% Nbは、C、Nを固定するのに有効な元素で、鋼の耐時
効性を向上させる。0.2%を超えると、その効果が飽
和するとともに、鋼の加工性が悪くなるので、その上限
は0.2%とする。
Nb: ≦ 0.2% Nb is an element effective for fixing C and N, and improves the aging resistance of steel. If it exceeds 0.2%, the effect is saturated and the workability of the steel deteriorates, so the upper limit is made 0.2%.

【0028】V:≦0.2% Vは、脱酸、およびC、Nを固定するのに有効な元素で
あり、0.2%を超えて多く含有させると効果が飽和す
るとともに、鋼の加工性が悪くなるので、その上限は
0.2%とする。
V: ≦ 0.2% V is an element effective for deoxidizing and fixing C and N. When the content exceeds 0.2%, the effect is saturated, and the effect of steel is reduced. Since the workability deteriorates, the upper limit is set to 0.2%.

【0029】その他の元素として、Nなど不可避的に含
まれる元素は、鋼の特性に実質的に影響を及ぼさない限
り許容される。
As other elements, elements inevitably contained such as N are permissible as long as they do not substantially affect the properties of the steel.

【0030】つぎに、薄鋼板の厚さおよび厚さ中心部の
偏析を説明する。 薄鋼板の厚さの上限は8mm
とする。通常、用いられる鋳片の厚さは、200〜30
0mmであり、薄鋼板の厚さが8mmを超えると、通常
の鋳片からの圧下比が小さくなり、薄鋼板の靱性の低下
などを招きやすい。さらに、薄鋼板の厚さの上限を8m
mとするのは、自動車の足廻り部品、ボイラーの構造部
品など、薄鋼板が対象とする製品用途からである。薄鋼
板の厚さの下限は、とくに限定しないが、製品用途から
0.7mmが望ましい。
Next, the thickness of the thin steel sheet and the segregation at the center of the thickness will be described. The upper limit of the thickness of the thin steel plate is 8mm
And Usually, the thickness of the used slab is 200-30.
If the thickness is 0 mm and the thickness of the thin steel sheet exceeds 8 mm, the reduction ratio from the normal slab becomes small, and the toughness of the thin steel sheet is likely to be reduced. Furthermore, the upper limit of the thickness of the thin steel plate is 8 m
The value of m is for product applications that target thin steel plates, such as undercarriage parts of automobiles and structural parts of boilers. Although the lower limit of the thickness of the thin steel sheet is not particularly limited, 0.7 mm is desirable from the viewpoint of product use.

【0031】薄鋼板の全板厚の平均のC含有率(C)o
および平均のMn含有率(Mn)oに対する厚さ中心か
ら厚さ方向両側にそれぞれ全厚さの10%以内の領域に
おける平均のC含有率(C)tおよび平均のMn含有率
(Mn)tの比(C)t/(C)oおよび(Mn)t/
(Mn)oは、それぞれ1.5以下とする。
Average C content (C) o of the total thickness of the thin steel sheet
And the average C content (C) t and the average Mn content (Mn) t in a region within 10% of the total thickness on both sides in the thickness direction from the thickness center with respect to the average Mn content (Mn) o. (C) t / (C) o and (Mn) t /
(Mn) o is 1.5 or less.

【0032】図3は、(C)o、(Mn)o、(C)t
および(Mn)tを示す模式図である。たとえば、
(C)tは、厚さ中心10から厚さ方向両側にそれぞれ
全厚さ12の10%以内の領域11、すなわち、厚さ中
心部における全厚さの20%以内の領域である偏析帯9
におけるCの平均の含有率を意味する。
FIG. 3 shows (C) o, (Mn) o, (C) t
FIG. 3 is a schematic diagram showing (Mn) t. For example,
(C) t is a region 11 within 10% of the total thickness 12 on both sides in the thickness direction from the thickness center 10, that is, a segregation zone 9 which is a region within 20% of the total thickness at the center of the thickness.
Means the average content of C in the above.

【0033】CおよびMnは、鋼の強度向上に有用な元
素であるが、一方、平衡分配係数が小さく、偏析しやす
い元素である。したがって、鋳片厚さ中心部近傍に中心
偏析およびV字状偏析が発生し、これら偏析が薄鋼板に
偏析帯として残存すると、その偏析帯にCおよびMnが
偏析している。このような偏析帯を有する薄鋼板をプレ
ス加工などを行うと、割れを生じたり、伸びフランジ性
が悪化する場合がある。これら割れなどの発生のしやす
さは、これら薄鋼板の全厚に対する偏析帯の厚さの比、
および偏析帯に存在するCおよびMnの偏析状況に依存
する。
C and Mn are elements that are useful for improving the strength of steel, but are elements that have a small equilibrium distribution coefficient and tend to segregate. Therefore, center segregation and V-shaped segregation occur near the center of the slab thickness, and when these segregation remain as segregation zones in the thin steel sheet, C and Mn segregate in the segregation zones. When a thin steel sheet having such a segregation zone is subjected to press working or the like, cracking may occur or stretch flangeability may deteriorate. The ease of occurrence of these cracks, etc. depends on the ratio of the thickness of the segregation zone to the total thickness of these thin steel sheets,
And the segregation state of C and Mn present in the segregation zone.

【0034】具体的には、薄鋼板の全厚の20%までを
偏析帯とすれば、偏析帯内のCおよびMnの偏析度、す
なわち、薄鋼板の全厚さの平均のCまたはMnの含有率
に対する偏析帯内のCまたはMnの含有率が、それぞれ
1.5を超えると、割れなどが発生しやすくなる。
Specifically, if up to 20% of the total thickness of the thin steel sheet is defined as the segregation zone, the degree of segregation of C and Mn in the segregation zone, that is, the average C or Mn of the total thickness of the thin steel sheet. If the content of C or Mn in the segregation zone with respect to the content exceeds 1.5, cracks and the like are likely to occur.

【0035】偏析帯にCおよびMnが上述のように偏析
すると、偏析帯の部分が硬化し、プレス加工などで薄鋼
板が剪断加工を受けると、その硬化した偏析帯を起点と
して、割れが発生したり、伸びフランジ性が悪化する。
とくに、Cは炭化物を形成するので、その炭化物が割れ
の起点となるばかりでなく、炭化物に沿って割れが伝播
しやすくなり、著しく伸びフランジ性を悪化させる。
When C and Mn segregate in the segregation zone as described above, the segregation zone is hardened, and when the thin steel sheet is subjected to shearing by press working or the like, cracks are generated starting from the hardened segregation zone. Or stretch flangeability deteriorates.
In particular, since C forms a carbide, not only the carbide serves as a starting point of the crack, but also the crack easily propagates along the carbide, and the stretch flangeability is remarkably deteriorated.

【0036】後述する鋳片を素材として熱間圧延して薄
鋼板を得る際に、圧延前の鋳片の加熱温度、加熱時間な
どの加熱条件、および圧延温度、巻き取り温度などの圧
延条件は、鋼に応じた通常の条件で加熱および圧延を行
うことができる。さらに、熱間圧延して得られた鋼材を
素材として、冷間圧延して薄鋼板を得る際に、酸洗条
件、冷間圧延条件、熱処理条件など、通常の方法を用い
ることができる。
When a thin steel sheet is obtained by hot rolling a slab to be described later as a raw material, heating conditions such as a heating temperature and a heating time of the slab before rolling, and rolling conditions such as a rolling temperature and a winding temperature are as follows. Heating and rolling can be performed under normal conditions according to the steel. Furthermore, when a steel sheet obtained by hot rolling is used as a material and cold rolling is performed to obtain a thin steel sheet, ordinary methods such as pickling conditions, cold rolling conditions, and heat treatment conditions can be used.

【0037】つぎに、上述する薄鋼板を得るための製造
方法を説明する。まず、鋳片を連続鋳造する際には、上
述のような偏析線を有する薄鋼板を得るために、厚さ3
00mm以下の鋳片を1.2〜3m/分の速度で鋳造
し、その際にタンデッシュ内の溶鋼の過熱度を80℃以
下とし、かつ、厚さ中心部が凝固完了するまでの鋳片の
領域において、互いに隣接する鋳片支持用ガイドロール
の軸芯間距離を450mm以下とする条件で鋳造する。
Next, a manufacturing method for obtaining the above-described thin steel sheet will be described. First, when continuously casting a slab, in order to obtain a thin steel sheet having a segregation line as described above, a thickness of 3 mm is required.
A slab of 00 mm or less is cast at a speed of 1.2 to 3 m / min. At this time, the degree of superheat of the molten steel in the tundish is set to 80 ° C. or less, and the thickness of the slab until the solidification of the center of the thickness is completed. In the region, casting is performed under the condition that the distance between the axes of the slab supporting guide rolls adjacent to each other is 450 mm or less.

【0038】鋳片の厚さが300mmを超えると、厚さ
中心部近傍に中心偏析またはV字状偏析が発生しやす
い。また、連続鋳造機が大型になる。したがって、鋳片
の厚さは300mm以下とする。
If the thickness of the slab exceeds 300 mm, center segregation or V-shaped segregation is likely to occur near the center of the thickness. In addition, the size of the continuous casting machine becomes large. Therefore, the thickness of the slab is 300 mm or less.

【0039】鋳造速度が1.2m/分未満では、鋳片厚
さ中心部に中心偏析またはV字状偏析が発生することを
抑制できるが、鋳片表層部の清浄度が悪化する。鋳片表
層部の清浄度が悪化すると、薄鋼板の表面の光沢などの
表面品質が悪化する。3m/分を超えると、鋳片表面に
割れが発生しやすく、さらに、中心偏析またはV字状偏
析が発生しやすい。
When the casting speed is less than 1.2 m / min, the occurrence of center segregation or V-shaped segregation in the center of the slab thickness can be suppressed, but the cleanliness of the slab surface layer deteriorates. When the cleanliness of the slab surface layer deteriorates, the surface quality such as the gloss of the surface of the thin steel plate deteriorates. If it exceeds 3 m / min, cracks are likely to occur on the slab surface, and furthermore, center segregation or V-shaped segregation tends to occur.

【0040】タンデッシュ内の溶鋼の過熱度が80℃を
超えると、鋳片の凝固組織が柱状晶となりやすく、中心
偏析またはV字状偏析が発生しやすい。
If the degree of superheat of the molten steel in the tundish exceeds 80 ° C., the solidified structure of the slab tends to be columnar, and center segregation or V-shaped segregation tends to occur.

【0041】溶鋼の過熱度が80℃以下では、鋳片の凝
固組織は微細な等軸晶が多く形成される。鋳片中心部近
傍が微細な等軸晶で充填されると、偏析成分が濃化した
溶鋼は等軸晶の間に分散して保持されるので、中心偏析
などが発生しにくくなる。ただし、タンデッシュ内の溶
鋼の過熱度は10℃以上が望ましい。10℃未満では、
浸漬ノズルが詰まりやすく、また鋳型内の溶鋼表面が凝
固しやすく、操業が不安定になりやすい。
When the degree of superheat of the molten steel is 80 ° C. or less, the solidified structure of the slab is formed with many fine equiaxed crystals. When the vicinity of the center of the slab is filled with fine equiaxed crystals, the molten steel in which the segregation component is concentrated is dispersed and held between the equiaxed crystals, so that center segregation and the like hardly occur. However, the degree of superheat of the molten steel in the tundish is preferably 10 ° C. or more. Below 10 ° C,
The immersion nozzle is easily clogged, the surface of the molten steel in the mold is easily solidified, and the operation tends to be unstable.

【0042】厚さ中心部が凝固完了するまでの鋳片の領
域において、互いに隣接する鋳片支持用ガイドロールの
軸芯間距離を450mm以下とするのは、厚さ中心固相
率が零を超える鋳片の領域で、隣接するガイドロールと
ガイドロールの間で鋳片がバルジングすることを抑制す
るためである。
In the area of the slab until the center of the thickness is completely solidified, the distance between the axes of the guide rolls for supporting the slab adjacent to each other is set to 450 mm or less because the thickness center solid phase ratio is set to zero. This is for suppressing bulging of the slab between adjacent guide rolls in the region of the slab that exceeds.

【0043】厚さ中心部が凝固完了するまでの鋳片の領
域において、鋳片のバルジング量が多くなると、著しい
中心偏析またはV字状偏析が発生しやすい。これらの鋳
片の領域には偏析成分の濃化した溶鋼が多く存在するか
らである。また、ガイドロールの軸芯間距離が450m
mを超えると、厚さ中心部が凝固完了するまでの鋳片の
領域において、鋳片のバルジング量が多くなる。
If the bulging amount of the slab increases in the slab area until the thickness center portion is completely solidified, remarkable center segregation or V-shaped segregation is likely to occur. This is because there is a lot of molten steel in which the segregation component is concentrated in the area of these slabs. In addition, the distance between the center axes of the guide rolls is 450 m.
If m is exceeded, the bulging amount of the slab increases in the slab area until the thickness center portion is completely solidified.

【0044】ガイドロールの軸芯間距離を小さくしすぎ
ると、ガイドロールのロール径が小さくなりすぎ、ガイ
ドロールが溶鋼静圧などで曲がりやすくなり、かえっ
て、鋳片がバルジングしやすくなる。したがって、ガイ
ドロールの軸芯間距離は300mm以上が望ましい。
If the distance between the center axes of the guide rolls is too small, the roll diameter of the guide rolls becomes too small, and the guide rolls are easily bent by the molten steel static pressure or the like, and the slabs are more likely to bulge. Therefore, the distance between the axes of the guide rolls is desirably 300 mm or more.

【0045】このようにして得られた中心偏析などのな
い鋳片を素材として熱間圧延して薄鋼板を得る際の、鋳
片の加熱条件、圧延条件などは、通常の条件で構わな
い。また、これら熱間圧延した薄鋼板を素材として、さ
らに冷間圧延する際の、酸洗条件、圧延条件、熱処理条
件などは、通常の条件で構わない。
Heating and rolling conditions of the slab when hot-rolling a slab without center segregation or the like obtained as described above to obtain a thin steel sheet may be ordinary conditions. Further, pickling conditions, rolling conditions, heat treatment conditions, and the like in the cold rolling using the hot-rolled thin steel sheet as a material may be normal conditions.

【0046】[0046]

【実施例】垂直部長さ3m、円弧半径10m、5点曲げ
4点矯正、機長45mの垂直曲げ型連続鋳造機を用い、
厚さ230mm、幅1800mmの鋳片を鋳造する試験
を実施した。
EXAMPLE A vertical bending type continuous casting machine having a vertical part length of 3 m, an arc radius of 10 m, a five-point bending four-point straightening machine, and a machine length of 45 m was used.
A test for casting a cast piece having a thickness of 230 mm and a width of 1800 mm was performed.

【0047】用いた鋼は、C含有率が0.04〜0.1
6質量%の低炭素鋼および中炭素鋼である。鋳造速度は
1.2〜1.5m/分の範囲で変更して試験した。連続
鋳造機のガイドロールの軸心間距離は、通常、垂直部で
250mm、湾曲部で250〜400mm、水平部で4
00〜450mmであり、試験では、水平部の軸心間距
離を350〜500mmの範囲で変更して試験した。こ
の水平部はメニスカスから22〜45mの長さの範囲に
ある。また、タンディッシュ内の溶鋼の過熱度は20〜
95℃の範囲内で変化させた。二次冷却の比水量は1〜
2リットル/kg−鋼とした。
The steel used had a C content of 0.04 to 0.1.
6% by mass of low carbon steel and medium carbon steel. The casting speed was varied and tested in the range of 1.2 to 1.5 m / min. The distance between the axes of the guide rolls of the continuous casting machine is usually 250 mm in the vertical portion, 250 to 400 mm in the curved portion, and 4 mm in the horizontal portion.
In the test, the distance between the axes of the horizontal portion was changed in the range of 350 to 500 mm. This horizontal portion is in a range of 22 to 45 m from the meniscus. The degree of superheat of the molten steel in the tundish is 20 to
The temperature was varied within the range of 95 ° C. The specific water volume for secondary cooling is 1 to
2 liters / kg-steel.

【0048】上述の試験条件の範囲内では、水平部にお
いて、鋳片の中心固相率が零を超えることを、鋳片厚み
方向での1次元の非定常伝熱解析により確認している。
さらに、一部の試験では、鋳片表面温度を連続的に測定
すること、および水平部の位置にある鋳片に鋲打ち試験
を行い、鋳片の中心固相率が零を超えることを確認し
た。
Within the range of the above test conditions, it was confirmed by a one-dimensional unsteady heat transfer analysis in the slab thickness direction that the center solid fraction of the slab exceeds zero in the horizontal portion.
In addition, in some tests, the slab surface temperature was continuously measured, and a rivet test was performed on the slab at the horizontal position to confirm that the center solid fraction of the slab exceeded zero. did.

【0049】各試験で得られた鋳片を素材として熱間圧
延を行い、厚さ6mmの鋼帯を製造した。その際、鋳片
の加熱温度は1180〜1270℃の範囲とし、110
0℃前後で粗圧延を終え、引き続き930〜870℃の
温度で仕上圧延し、500〜600℃の温度でコイル形
状に巻き取った。一部の試験では、さらに、この鋼帯を
素材として酸洗後に冷間で圧延し、厚さ2mmの鋼帯と
した。この鋼帯を800℃で連続焼鈍した。
The cast slab obtained in each test was subjected to hot rolling to produce a steel strip having a thickness of 6 mm. At that time, the heating temperature of the slab is in the range of 1180 to 1270 ° C.
Rough rolling was completed at about 0 ° C., followed by finish rolling at a temperature of 930 to 870 ° C., and wound into a coil at a temperature of 500 to 600 ° C. In some tests, a steel strip having a thickness of 2 mm was obtained by using the steel strip as a raw material and cold rolling after pickling. This steel strip was continuously annealed at 800 ° C.

【0050】本試験においては実施していないが、連続
鋳造スラブを粗圧延した後、仕上圧延の前に誘導加熱ヒ
ータ等を用いて、粗バーの加熱を行ってもよい。また連
続焼鈍後に、インラインにて合金化亜鉛メッキなどを施
しても良い。
Although not performed in the present test, the rough bar may be heated using an induction heater or the like after the rough rolling of the continuous casting slab and before the finish rolling. After continuous annealing, galvanizing may be performed in-line.

【0051】熱間圧延およびその後冷間圧延して得た各
鋼帯について、幅方向中央部からサンプルを採取し、機
械的性質、化学組成、および伸びフランジ性の評価を行
うために穴拡げ試験を実施した。機械的性質は通常のJ
ISで定める方法に基づき、引張強度および伸びを調査
した。
For each steel strip obtained by hot rolling and then cold rolling, a sample was taken from the center in the width direction, and a hole expansion test was performed to evaluate the mechanical properties, chemical composition, and stretch flangeability. Was carried out. Mechanical properties are normal J
The tensile strength and elongation were investigated based on the method specified by IS.

【0052】各鋼帯の化学組成は、下記に示す方法で調
査した。まず、鋼帯の平均の化学組成は、全厚の鋼帯サ
ンプルから、直径5mmのドリル刃で切り削を採取し、
化学分析法により各元素を分析し、それぞれ各元素の平
均の含有率とした。つぎに、厚さ中心から厚さ方向両側
にそれぞれ全厚さの10%以内の領域における平均のC
およびMn含有率は、鋼帯を厚さ方向に段削りを行い、
所定の厚さ部分の切り削を採取してCおよびMnの含有
率を化学分析法により求めた。厚さ方向の断面をEPM
Aなどを用いる機器分析法によりCおよびMnを分析し
てもよい。
The chemical composition of each steel strip was investigated by the following method. First, the average chemical composition of a steel strip was obtained by cutting a steel strip sample of full thickness with a 5 mm diameter drill blade,
Each element was analyzed by a chemical analysis method, and the average content of each element was determined. Next, on both sides in the thickness direction from the thickness center, the average C
And the Mn content, the steel strip is stepped in the thickness direction,
Cuttings of a predetermined thickness portion were collected, and the contents of C and Mn were determined by a chemical analysis method. EPM cross section in thickness direction
C and Mn may be analyzed by an instrumental analysis method using A or the like.

【0053】また、穴拡げ試験は、日本鉄鋼連盟規格J
FST1001−1996に基づき実施した。図1は、
穴拡げ試験の概略を示す模式図である。図1(a)は薄
鋼板に初期の穴を開けた状態を示し、図1(b)は、そ
の初期の穴を拡げた状態を示す。穴拡げ試験では、試験
片である薄鋼板1にまず外径10mmのポンチ2による
打抜き穴3を開け、つぎに円錐のポンチ2でその穴3を
押し拡げる。穴の縁に亀裂が発生し、その後、その亀裂
が板厚方向に貫通するまで穴を押し拡げる。亀裂が板厚
方向に貫通した際の穴4の直径を求め、その直径を当初
の穴の直径10mmで除した値を下記(A)式で示す穴
拡げ率λとして、薄鋼板の伸びフランジ性、すなわち加
工性を評価する。今回の試験では、ポンチ先端角度、ダ
イス5とポンチ2の間隙等の条件は、上記規格に沿った
条件とした。 λ=(Dh-D0)/D0×100 ・・・(A) ここで、λ:穴拡げ率(%) D0 :初期の穴の直径(10mm) Dh :亀裂が板厚を貫通したときの穴の直径(mm) 各試験条件および各試験結果を表1および表2に示す。
The hole expansion test was conducted according to the Japan Iron and Steel Federation Standard J.
The test was performed based on FST1001-1996. FIG.
It is a schematic diagram which shows the outline of a hole expansion test. FIG. 1A shows a state in which an initial hole is formed in a thin steel plate, and FIG. 1B shows a state in which the initial hole is expanded. In the hole expansion test, first, a punched hole 3 made by a punch 2 having an outer diameter of 10 mm is formed in a thin steel plate 1 as a test piece, and then the hole 3 is pushed and expanded by a conical punch 2. A crack is formed at the edge of the hole, and then the hole is expanded until the crack penetrates in the thickness direction. The diameter of the hole 4 when the crack penetrated in the plate thickness direction was determined, and the value obtained by dividing the diameter by the initial hole diameter of 10 mm was defined as the hole expansion ratio λ represented by the following formula (A), and the stretch flangeability of the thin steel plate was obtained. That is, the processability is evaluated. In this test, conditions such as the tip angle of the punch and the gap between the die 5 and the punch 2 were set in accordance with the above standards. λ = (D h −D 0 ) / D 0 × 100 (A) where λ: hole expansion ratio (%) D 0 : initial hole diameter (10 mm) D h : crack has a plate thickness Table 1 and Table 2 show each test condition and each test result.

【0054】[0054]

【表1】 [Table 1]

【表2】 本発明例の試験No.1〜No.23では、連続鋳造の
際の鋳片厚さは230mm、鋳造速度は1.2m/分、
1.5m/分、または2.5m/分、タンディッシュ内
の溶鋼の過熱度は22〜75℃、水平部のガイドロール
の軸心間距離は350〜450mmであり、いずれも本
発明の連続鋳造方法で規定する条件の範囲内で連続鋳造
を行った。
[Table 2] Test No. of the present invention example. 1 to No. In No. 23, the slab thickness during continuous casting was 230 mm, the casting speed was 1.2 m / min,
1.5 m / min or 2.5 m / min, the degree of superheat of the molten steel in the tundish is 22 to 75 ° C., and the distance between the axial centers of the guide rolls in the horizontal portion is 350 to 450 mm. Continuous casting was performed within the range of conditions specified by the casting method.

【0055】試験No.1〜No.5では、用いた鋼
は、C含有率0.11質量%の中炭素鋼であり、その他
の元素を含めて、本発明で規定する化学組成の条件の範
囲内の鋼である。その内、試験No.1〜No.4で
は、鋳片を熱間圧延し、厚さ6mmの鋼帯とした。鋼帯
の全厚さの平均のCおよびMnの含有率に対する厚さ中
心から厚さ方向両側にそれぞれ10%以内の領域におけ
る平均のCおよびMnの含有率の比(以下、偏析帯の偏
析度と記す)は1.2〜1.5の範囲内の値であり、本
発明で規定する条件の範囲内であった。引張強度は44
〜47kgf/mm 2 、伸びは35〜38%の範囲内で
あり、良好な機械的性質であった。また、穴拡げ率は9
2〜95%で、良好な加工性を有する鋼帯であった。ま
た試験No.5では、冷間圧延した厚さ2mmの鋼帯と
した。偏析線の偏析度はCが1.5、Mnが1.2であ
り、本発明で規定する条件の範囲内であった。引張強度
は46kgf/mm2 、伸びは38%であり良好な機械
的性質であった。また、穴拡げ率は111%で、良好な
加工性を有する鋼帯であった。
Test No. 1 to No. In 5, the steel used
Is medium carbon steel with a C content of 0.11% by mass.
The range of chemical composition conditions specified in the present invention, including
The steel in the enclosure. Test No. 1 to No. At 4
For example, a slab was hot-rolled into a steel strip having a thickness of 6 mm. Steel strip
In the thickness to the average C and Mn content of the total thickness of
Within 10% each of both sides in the thickness direction from the center
Of the average C and Mn contents (hereinafter referred to as the segregation zone
Is expressed in the range of 1.2 to 1.5.
It was within the range defined by the invention. The tensile strength is 44
~ 47kgf / mm Two , Elongation within 35-38%
And good mechanical properties. The hole expansion rate is 9
It was a steel strip having good workability at 2 to 95%. Ma
Test No. In 5, the cold-rolled steel strip with a thickness of 2 mm
did. The segregation degree of the segregation line is 1.5 for C and 1.2 for Mn.
Therefore, it was within the range of the conditions specified in the present invention. Tensile strength
Is 46kgf / mmTwo Good machine with elongation of 38%
Characteristic. The hole expansion rate is 111%, which is good.
The steel strip had workability.

【0056】試験No.6〜No.9では、C含有率が
0.16質量%の中炭素鋼、また試験No.10〜N
o.13では、C含有率が0.04質量%の低炭素鋼を
用いて、それぞれ上述の試験No.1〜No.5の試験
内容に準じて、いずれも本発明の連続鋳造方法で規定す
る条件の範囲内で連続鋳造を行った。いずれも、Cおよ
びMnの偏析帯の偏析度は1.1〜1.5であり、その
ため、引張強度は46〜52kgf/mm2 、伸びは3
2〜36%で良好な機械的性質であった。さらに、穴拡
げ率は75〜117%で良好な結果が得られた。
Test No. 6-No. In Test No. 9, medium carbon steel having a C content of 0.16% by mass. 10 to N
o. In Test No. 13, each of the above-described Test Nos. 1 to No. According to the test contents of No. 5, continuous casting was performed within the range of conditions specified by the continuous casting method of the present invention. In each case, the segregation degree of the segregation zone of C and Mn is 1.1 to 1.5, so that the tensile strength is 46 to 52 kgf / mm 2 and the elongation is 3
Good mechanical properties were found at 2-36%. Further, good results were obtained with a hole expansion ratio of 75 to 117%.

【0057】試験No.14〜No.19では、C含有
率が0.11質量%の本発明で規定する化学組成の条件
の範囲内の中炭素鋼とし、さらに鋼帯の強度を向上させ
るのに望ましい元素としてTi、Nb、Vのうち1種ま
たは2種を添加した化学組成の鋼として試験した。それ
ぞれ上述の試験No.1〜No.4の試験内容に準じ
て、いずれも本発明の連続鋳造方法で規定する条件の範
囲内で連続鋳造を行った。同じC含有率の鋼を用いた試
験No.1〜No.4に比べて、引張強度が約20kg
f/mm2 程度向上し、64〜66kgf/mm2 とな
り、また、伸びは26〜27%であり、良好な機械的性
質であった。穴拡げ率は71〜75%で良好な結果が得
られた。
Test No. 14-No. In No. 19, the carbon content is 0.11 mass%, which is a medium carbon steel within the range of the chemical composition defined by the present invention, and Ti, Nb, and V are preferable elements for further improving the strength of the steel strip. One or two of these were tested as steels with a chemical composition. Each of the test Nos. 1 to No. According to the test contents of No. 4, continuous casting was performed within the range of conditions specified by the continuous casting method of the present invention. Test No. 2 using steel having the same C content. 1 to No. Approximately 20kg tensile strength compared to 4.
The f / mm 2 was improved by about 64 to 66 kgf / mm 2 , and the elongation was 26 to 27%, indicating good mechanical properties. Good results were obtained with a hole expansion ratio of 71 to 75%.

【0058】試験No.20およびNo.21では、C
含有率が0.16質量%の本発明で規定する化学組成の
条件の範囲内の中炭素鋼とし、さらにTi、Nb、Vの
うち2種を添加した化学組成の鋼として試験した。それ
ぞれ上述の試験No.6〜No.8の試験内容に準じ
て、いずれも本発明の連続鋳造方法で規定する条件の範
囲内で連続鋳造を行った。同じC含有率の鋼を用いた試
験No.6〜No.8に比べて、引張強度が約20〜2
5kgf/mm2 程度向上し、71〜75kgf/mm
2 となり、また、伸びは23〜25%であり、良好な機
械的性質であった。穴拡げ率は68〜69%で良好な結
果が得られた。
Test No. 20 and no. At 21, C
A medium-carbon steel having a content of 0.16% by mass within the range of the chemical composition specified in the present invention was tested as a steel having a chemical composition to which two types of Ti, Nb and V were added. Each of the test Nos. 6-No. According to the test contents of No. 8, continuous casting was performed within the range defined by the continuous casting method of the present invention. Test No. 2 using steel having the same C content. 6-No. 8 has a tensile strength of about 20 to 2
5kgf / mm 2 about to improve, 71~75kgf / mm
2 , and the elongation was 23 to 25%, indicating good mechanical properties. Good results were obtained with a hole expansion ratio of 68 to 69%.

【0059】試験No.22およびNo.23では、C
含有率が0.04質量%の本発明で規定する化学組成の
条件の範囲内の低炭素鋼とし、さらにTi、Nb、Vの
うち2種を添加した化学組成の鋼として試験した。それ
ぞれ上述の試験No.10〜No.12の試験内容に準
じて、いずれも本発明の連続鋳造方法で規定する条件の
範囲内で連続鋳造を行った。同じC含有率の鋼を用いた
試験No.10〜No.12に比べて、引張強度が約1
5〜20kgf/mm2 程度向上し、61〜65kgf
/mm2 となり、伸びは27〜29%であり、良好な機
械的性質であった。穴拡げ率は74〜77%で良好な結
果であった。
Test No. 22 and No. In 23, C
A low-carbon steel having a content of 0.04% by mass within the range of the chemical composition defined by the present invention was tested as a steel having a chemical composition to which two kinds of Ti, Nb and V were added. Each of the test Nos. 10-No. According to the content of the test No. 12, continuous casting was performed within the range of conditions specified by the continuous casting method of the present invention. Test No. 2 using steel having the same C content. 10-No. 12 has a tensile strength of about 1
5 to 20 kgf / mm 2 improved, 61 to 65 kgf
/ Mm 2 , and the elongation was 27 to 29%, indicating good mechanical properties. The hole expansion ratio was 74 to 77%, which was a good result.

【0060】比較例の試験No.24〜No.28で
は、連続鋳造の際の鋳片厚さは230mmで、鋳造速度
は1.5m/分とし、本発明の連続鋳造方法で規定する
条件の範囲内としたが、No.24およびNo.25で
は、水平部のガイドロールの軸心間距離を480mmと
し、本発明の連続鋳造方法で規定する条件の範囲外とし
て試験を行い、またNo.26〜No.28では、タン
ディッシュ内の溶鋼の過熱度を85℃または90℃と
し、本発明の連続鋳造方法で規定する条件の範囲外とし
て試験した。これら試験に用いた鋼は、試験No.1〜
No.5と同じ本発明で規定する化学組成の条件の範囲
内のC含有率0.11質量%の中炭素鋼とした。
Test No. of Comparative Example 24-No. In No. 28, the slab thickness at the time of continuous casting was 230 mm, the casting speed was 1.5 m / min, and within the range defined by the continuous casting method of the present invention. 24 and No. In the case of No. 25, the test was performed with the distance between the axes of the guide rolls in the horizontal portion set to 480 mm and out of the range defined by the continuous casting method of the present invention. 26-No. In No. 28, the superheat of the molten steel in the tundish was set to 85 ° C. or 90 ° C., and the test was performed outside the range defined by the continuous casting method of the present invention. The steels used in these tests were the test Nos. 1 to
No. Medium carbon steel having a C content of 0.11% by mass within the range of the chemical composition conditions defined in the present invention as in No. 5.

【0061】その内、試験No.24〜No.27で
は、鋳片を熱間圧延し、厚さ6mmの鋼帯とした。鋼帯
のCおよびMnの偏析帯の偏析度は、1.5〜1.7の
範囲内の値であり、少なくともCまたはMnの偏析帯の
偏析度が本発明で規定する条件を外れた値であった。そ
のため、引張強度はとくに問題ないが、伸びは24〜2
9%と低く、さらに穴拡げ率は60〜68%で悪い結果
であった。
Among them, Test No. 24-No. At 27, the slab was hot rolled to form a 6 mm thick steel strip. The segregation degree of the segregation zone of C and Mn of the steel strip is a value within the range of 1.5 to 1.7, and at least the segregation degree of the segregation zone of C or Mn is out of the range specified in the present invention. Met. Therefore, the tensile strength is not particularly problematic, but the elongation is 24-2.
It was as low as 9%, and the hole expansion rate was 60-68%, which was a bad result.

【0062】また、試験No.28では、冷間圧延した
厚さ2mmの鋼帯とした。偏析帯の偏析度はCが1.
6、Mnが1.7であり、本発明で規定する条件を外れ
た値であった。そのため、引張強度はとくに問題ない
が、伸びは29%と低く、さらに穴拡げ率は58%で悪
い結果であった。
The test No. In No. 28, a cold-rolled steel strip having a thickness of 2 mm was formed. The segregation degree of the segregation zone is C = 1.
6, Mn was 1.7, which was a value outside the conditions defined in the present invention. Therefore, the tensile strength was not particularly problematic, but the elongation was as low as 29%, and the hole expansion ratio was 58%, which was a bad result.

【0063】試験No.29〜No.32では、C含有
率が0.16質量%の中炭素鋼、また試験No.33〜
No.36では、C含有率が0.04質量%の低炭素鋼
を用いて、それぞれ上述の試験No.24〜No.28
の試験内容に準じて試験を実施した。すなわち、少なく
とも水平部のガイドロールの軸心間距離、またはタンデ
ィッシュ内の溶鋼の過熱度を本発明の連続鋳造方法で規
定する条件の範囲外として試験した。いずれも鋼帯のC
およびMnの偏析帯の偏析度が1.5〜1.7の範囲内
の値であり、少なくともCまたはMnの偏析帯の偏析度
が本発明で規定する条件を外れた値であった。そのた
め、引張強度はとくに問題ないが、伸びが23〜29%
と低く、さらに穴拡げ率も熱間圧延した鋼帯で52〜7
4%と低く、また冷間圧延した鋼帯で66%または79
%と低く、悪い結果であった。
Test No. 29-No. No. 32, medium carbon steel having a C content of 0.16% by mass. 33 ~
No. In the case of Test No. 36, a low carbon steel having a C content of 0.04 mass% was used, and 24-No. 28
The test was carried out according to the test contents of the above. That is, the test was performed with at least the distance between the center axes of the guide rolls in the horizontal portion or the degree of superheat of the molten steel in the tundish being outside the range defined by the continuous casting method of the present invention. Both are steel strip C
And the segregation degree of the segregation zone of Mn was in the range of 1.5 to 1.7, and at least the segregation degree of the segregation zone of C or Mn was a value outside the conditions defined in the present invention. Therefore, the tensile strength is not particularly problematic, but the elongation is 23 to 29%.
And the hole expansion rate is 52-7 in the hot rolled steel strip.
As low as 4% and 66% or 79 for cold rolled steel strip
%, Which was a bad result.

【0064】試験No.37〜No.42では、C含有
率が0.11質量%の本発明で規定する化学組成の条件
の範囲内の中炭素鋼とし、鋼帯の強度を向上させるのに
望ましい元素としてTi、Nb、Vのうち1種または2
種を添加した化学組成の鋼として試験した。それぞれ上
述の試験No.24〜No.27の試験内容に準じて試
験を実施した。すなわち、少なくとも水平部のガイドロ
ールの軸心間距離、またはタンディッシュ内の溶鋼の過
熱度を、本発明の連続鋳造方法で規定する条件の範囲外
として試験した。いずれも鋼帯のCおよびMnの偏析帯
の偏析度が1.4〜1.6の範囲内の値であり、少なく
ともCまたはMnの偏析帯の偏析度が本発明で規定する
条件を外れた値であった。そのため、引張強度はとくに
問題ないが、伸びが20〜22%と低く、さらに穴拡げ
率も49〜72%と低く悪い結果であった。
Test No. 37-No. In No. 42, a carbon content of 0.11 mass% is defined as a medium carbon steel within the range of the chemical composition defined by the present invention, and Ti, Nb, and V are preferable elements for improving the strength of the steel strip. One or two
The steel was tested as a seeded chemical composition. Each of the test Nos. 24-No. The test was carried out according to 27 test contents. That is, at least the distance between the axial centers of the guide rolls in the horizontal portion or the degree of superheat of the molten steel in the tundish was tested outside the range defined by the continuous casting method of the present invention. In any case, the segregation degree of the segregation zone of C and Mn in the steel strip is a value in the range of 1.4 to 1.6, and at least the segregation degree of the segregation band of C or Mn is out of the condition specified in the present invention. Value. Therefore, the tensile strength was not particularly problematic, but the elongation was as low as 20 to 22%, and the hole expansion ratio was as low as 49 to 72%, which was a bad result.

【0065】試験No.43およびNo.44では、C
含有率が0.16質量%の本発明で規定する化学組成の
条件の範囲内の中炭素鋼とし、さらにTi、Nb、Vの
うち2種を添加した化学組成の鋼として試験した。それ
ぞれ上述の試験No.29〜No.31の試験内容に準
じて試験を実施した。すなわち、水平部のガイドロール
の軸心間距離、またはタンディッシュ内の溶鋼の過熱度
を、本発明の連続鋳造方法で規定する条件の範囲外とし
て試験した。いずれも鋼帯のCまたはMnの偏析帯の偏
析度が1.6または1.7の値であり、本発明で規定す
る条件を外れた値であった。そのため、引張強度はとく
に問題ないが、伸びが16〜17%と低く、さらに穴拡
げ率も48〜49%と低く悪い結果であった。
Test No. 43 and No. In 44, C
A medium-carbon steel having a content of 0.16% by mass within the range of the chemical composition specified in the present invention was tested as a steel having a chemical composition to which two types of Ti, Nb and V were added. Each of the test Nos. 29-No. The test was performed according to 31 test contents. That is, the test was performed with the distance between the axes of the guide rolls in the horizontal portion or the degree of superheat of the molten steel in the tundish being outside the range defined by the continuous casting method of the present invention. In each case, the degree of segregation of the C or Mn segregation zone of the steel strip was 1.6 or 1.7, which was out of the conditions specified in the present invention. Therefore, the tensile strength was not particularly problematic, but the elongation was as low as 16 to 17%, and the hole expansion ratio was as low as 48 to 49%.

【0066】試験No.45およびNo.46では、C
含有率が0.04質量%の本発明で規定する化学組成の
条件の範囲内の中炭素鋼とし、さらにTi、Nb、Vの
うち2種を添加した化学組成の鋼として試験した。それ
ぞれ上述の試験No.33〜No.35の試験内容に準
じて試験を実施した。すなわち、水平部のガイドロール
の軸心間距離、またはタンディッシュ内の溶鋼の過熱度
を、本発明の連続鋳造方法で規定する条件の範囲外とし
て試験した。少なくとも鋼帯のCまたはMnの偏析帯の
偏析度が1.6または1.7の値であり、本発明で規定
する条件を外れた値であった。そのため、引張強度はと
くに問題ないが、伸びが19〜21%と低く、さらに穴
拡げ率も50〜57%と低く悪い結果であった。
Test No. 45 and no. In 46, C
A medium-carbon steel having a content of 0.04% by mass within the range of the chemical composition defined by the present invention was tested as a steel having a chemical composition to which two types of Ti, Nb and V were added. Each of the test Nos. 33-No. The test was performed according to 35 test contents. That is, the test was performed with the distance between the axes of the guide rolls in the horizontal portion or the degree of superheat of the molten steel in the tundish being outside the range defined by the continuous casting method of the present invention. At least the degree of segregation of the C or Mn segregation zone of the steel strip was 1.6 or 1.7, a value out of the conditions specified in the present invention. Therefore, the tensile strength is not particularly problematic, but the elongation is as low as 19 to 21%, and the hole expansion ratio is as low as 50 to 57%, which is a bad result.

【0067】[0067]

【発明の効果】本発明の薄鋼板および連続鋳造方法の適
用により、プレス加工などの際に割れの発生がなく、加
工性のよい熱間圧延した薄鋼板または熱間圧延後に冷間
圧延した薄鋼板を得ることができる。
According to the thin steel sheet and the continuous casting method of the present invention, a hot-rolled thin steel sheet or a cold-rolled thin steel sheet which does not crack during press working and has good workability. Steel sheet can be obtained.

【図面の簡単な説明】[Brief description of the drawings]

【図1】穴拡げ試験の概略を示す模式図である。FIG. 1 is a schematic diagram showing an outline of a hole expanding test.

【図2】ガイドロールの軸心間距離を示す模式図であ
る。
FIG. 2 is a schematic diagram showing the distance between the center axes of guide rolls.

【図3】(C)o、(Mn)o、(C)tおよび(M
n)tを示す模式図である。
FIG. 3. (C) o, (Mn) o, (C) t and (M)
n) It is a schematic diagram which shows t.

【符号の説明】[Explanation of symbols]

1:薄鋼板 2:ポンチ 3:穴 4:亀裂が板厚方向に貫通した際の穴 5:ダイス 6:ガイドロールのロール 7:ロール
の軸心間距離 8:鋳造方向 9:偏析帯 10:厚さ中心 11:全厚
さの10%以内の領域 12:全厚さ D0 :初期の穴の直径(10mm) Dh :亀裂が板厚を貫通したときの穴の直径(mm)
1: thin steel plate 2: punch 3: hole 4: hole when a crack penetrates in the thickness direction 5: die 6: roll of guide roll 7: distance between roll axes 8: casting direction 9: segregation zone 10: Center of thickness 11: Area within 10% of total thickness 12: Total thickness D0 : Diameter of initial hole (10 mm) Dh : Diameter of hole when crack penetrates the plate thickness (mm)

Claims (4)

【特許請求の範囲】[Claims] 【請求項1】全板厚の平均の化学組成における含有率
が、質量%で、C:0.03〜0.16%、Si:0.
2%以下、Mn:1.4%以下、P:0.03%以下、
S:0.02%以下、sol.Al:0.10%以下で
あり、残部がFeおよび不純物元素からなる厚さが8m
m以下の薄鋼板であって、下記の(イ)式および(ロ)
式を満足することを特徴とする薄鋼板。 (C)t/(C)o ≦1.5 ・・・(イ) (Mn)t/(Mn)o≦1.5 ・・・(ロ) ここで、(C)t:厚さ中心から厚さ方向両側にそれぞ
れ全厚さの10%以内の領域における平均のCの含有率
(質量%) (C)o:全板厚の平均のCの含有率(質量%) (Mn)t:厚さ中心から厚さ方向両側にそれぞれ全厚
さの10%以内の領域における平均のMnの含有率(質
量%) (Mn)o:全板厚の平均のMnの含有率(質量%)
(1) The content in the average chemical composition of the entire plate thickness is 0.03 to 0.16% in mass% and 0.03 to 0.1% in Si.
2% or less, Mn: 1.4% or less, P: 0.03% or less,
S: 0.02% or less, sol. Al: 0.10% or less, the balance being 8 m in thickness composed of Fe and impurity elements
m or less, and the following formula (a) and (b)
A thin steel sheet that satisfies the formula. (C) t / (C) o ≦ 1.5 (b) (Mn) t / (Mn) o ≦ 1.5 (b) where (C) t: from the center of thickness Average C content (% by mass) in a region within 10% of the total thickness on both sides in the thickness direction (C) o: Average C content (% by mass) of all sheet thicknesses (Mn) t: Average Mn content (% by mass) in regions within 10% of the total thickness on both sides in the thickness direction from the thickness center (Mn) o: Average Mn content (% by mass) of the entire plate thickness
【請求項2】請求項1に記載の薄鋼板であって、さらに
質量%で、Nb:0.2%以下、Ti:0.2%以下お
よびV:0.2%以下のうちの1種または2種以上を含
有することを特徴とする薄鋼板。
2. The steel sheet according to claim 1, further comprising at least one of Nb: 0.2% or less, Ti: 0.2% or less, and V: 0.2% or less. Or a thin steel sheet containing two or more kinds.
【請求項3】質量%で、C:0.03〜0.16%、S
i:0.2%以下、Mn:1.4%以下、P:0.03
%以下、S:0.02%以下、sol.Al:0.10
%以下を含有する鋼を溶製して、タンデッシュ内の溶鋼
の過熱度を80℃以下、鋳片断面形状が長方形で厚さ3
00mm以下、鋳造速度1.2m/分〜3m/分および
厚さ中心部が凝固完了するまでの鋳片の領域において互
いに隣接する鋳片支持用ガイドロールの軸芯間距離を4
50mm以下とする条件で鋳造し、次いで圧延して薄鋼
板とすることを特徴とする薄鋼板の製造方法。
3. C: 0.03 to 0.16% by mass%, S
i: 0.2% or less, Mn: 1.4% or less, P: 0.03
%, S: 0.02% or less, sol. Al: 0.10
% Of molten steel in the tundish, the degree of superheat of the molten steel in the tundish is 80 ° C. or less, the cross section of the slab is rectangular and the thickness is 3
00 mm or less, the casting speed is 1.2 m / min to 3 m / min, and the distance between the axes of the guide rolls for supporting slabs adjacent to each other in the slab region until the center of the thickness is completely solidified is 4 mm.
A method for producing a thin steel sheet, comprising casting under conditions of not more than 50 mm and then rolling to obtain a thin steel sheet.
【請求項4】質量%で、C:0.03〜0.16%、S
i:0.2%以下、Mn:1.4%以下、P:0.03
%以下、S:0.02%以下、sol.Al:0.10
%以下を含有し、さらに、Nb:0.2%以下、Ti:
0.2%以下およびV:0.2%以下のうちの1種また
は2種以上を含有する鋼を溶製して、タンデッシュ内の
溶鋼の過熱度を80℃以下、鋳片断面形状が長方形で厚
さ300mm以下、鋳造速度1.2m/分〜3m/分お
よび厚さ中心部が凝固完了するまでの鋳片の領域におい
て互いに隣接する鋳片支持用ガイドロールの軸芯間距離
を450mm以下とする条件で鋳造し、次いで圧延して
薄鋼板とすることを特徴とする薄鋼板の製造方法。
4. C: 0.03 to 0.16% by mass%, S:
i: 0.2% or less, Mn: 1.4% or less, P: 0.03
%, S: 0.02% or less, sol. Al: 0.10
% Nb: 0.2% or less, Ti:
A steel containing one or more of 0.2% or less and V: 0.2% or less is smelted, the degree of superheat of the molten steel in the tundish is 80 ° C or less, and the slab cross-sectional shape is rectangular. The thickness of the slab supporting guide rolls adjacent to each other in the region of the slab until the solidification of the center of the thickness is completed is set to 450 mm or less at a thickness of 300 mm or less at a casting speed of 1.2 m / min to 3 m / min. A method for producing a thin steel sheet, which is cast under the following conditions, and then rolled into a thin steel sheet.
JP2000212963A 2000-07-13 2000-07-13 Thin steel plate and manufacturing method thereof Expired - Fee Related JP3775178B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2000212963A JP3775178B2 (en) 2000-07-13 2000-07-13 Thin steel plate and manufacturing method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP2000212963A JP3775178B2 (en) 2000-07-13 2000-07-13 Thin steel plate and manufacturing method thereof

Publications (2)

Publication Number Publication Date
JP2002030381A true JP2002030381A (en) 2002-01-31
JP3775178B2 JP3775178B2 (en) 2006-05-17

Family

ID=18708796

Family Applications (1)

Application Number Title Priority Date Filing Date
JP2000212963A Expired - Fee Related JP3775178B2 (en) 2000-07-13 2000-07-13 Thin steel plate and manufacturing method thereof

Country Status (1)

Country Link
JP (1) JP3775178B2 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018145525A (en) * 2017-03-07 2018-09-20 Jfeスチール株式会社 Hot rolled steel sheet and production method thereof, cold rolled steel sheet and production method thereof, production method of cold rolled annealed steel sheet, and production method of hot-dip galvanized steel sheet

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018145525A (en) * 2017-03-07 2018-09-20 Jfeスチール株式会社 Hot rolled steel sheet and production method thereof, cold rolled steel sheet and production method thereof, production method of cold rolled annealed steel sheet, and production method of hot-dip galvanized steel sheet

Also Published As

Publication number Publication date
JP3775178B2 (en) 2006-05-17

Similar Documents

Publication Publication Date Title
JP4605100B2 (en) High strength hot rolled steel sheet and method for producing the same
US8646301B2 (en) Method for manufacturing high strength hot rolled steel sheet
JP4404004B2 (en) High-tensile hot-rolled steel sheet and manufacturing method thereof
US20030066580A1 (en) Method for making high-strength high-toughness martensitic stainless steel seamless pipe
CN102317491A (en) High-strength steel sheet and high-strength steel pipe having excellent hydrogen-induced cracking resistance for use in line pipe
JP5353578B2 (en) High-strength hot-rolled steel sheet excellent in hole expansibility and method for producing the same
JP7256383B2 (en) Method for manufacturing hot-rolled steel sheet
CN113453817A (en) Square steel pipe, method for producing same, and building structure
JP4840270B2 (en) Hot-rolled steel sheet and manufacturing method thereof
JP4438614B2 (en) High-strength hot-rolled steel sheet and manufacturing method thereof
JPH07286214A (en) Production of high strength thick hot coil excellent in hydrogen induced cracking resistance and dwtt property
JP4299511B2 (en) Hot-rolled steel sheet with excellent punchability
JPH0617519B2 (en) Method for producing steel plate or strip of ferritic stainless steel with good workability
JP2002030381A (en) Thin steel sheet and its production method
JP4273646B2 (en) High-strength thin steel sheet with excellent workability and manufacturing method thereof
JP3598771B2 (en) Martensitic stainless steel excellent in hot workability and sulfide stress cracking resistance, method of bulk rolling thereof, seamless steel pipe using these, and method of manufacturing the same
JPH06240355A (en) Production of high toughness thick tmcp steel plate
JPH11302739A (en) Production of ferritic stainless steel excellent in surface property and small in anisotropy
JP4319945B2 (en) High carbon steel plate with excellent hardenability and workability
RU2790840C1 (en) Method for production of hot-rolled sheets from low-alloy steel of strength class k65 for electric-welded longitudinal pipes with high strain capacity
RU2815949C1 (en) Method of producing hot-rolled sheets from low-alloy steel
JP3606199B2 (en) Manufacturing method of thin steel sheet
WO2023089950A1 (en) Thick steel sheet and manufacturing method therefor
JPH08253813A (en) Production of high chromium ferritic stainless steel plate
JP2000087141A (en) Production of thin high tensile hot rolled steel strip containing residual austenite

Legal Events

Date Code Title Description
A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20040114

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20040224

RD02 Notification of acceptance of power of attorney

Free format text: JAPANESE INTERMEDIATE CODE: A7422

Effective date: 20040405

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20051025

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20051202

TRDD Decision of grant or rejection written
A01 Written decision to grant a patent or to grant a registration (utility model)

Free format text: JAPANESE INTERMEDIATE CODE: A01

Effective date: 20060131

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20060213

R150 Certificate of patent or registration of utility model

Ref document number: 3775178

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100303

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20100303

Year of fee payment: 4

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110303

Year of fee payment: 5

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120303

Year of fee payment: 6

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130303

Year of fee payment: 7

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130303

Year of fee payment: 7

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313111

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130303

Year of fee payment: 7

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140303

Year of fee payment: 8

S533 Written request for registration of change of name

Free format text: JAPANESE INTERMEDIATE CODE: R313533

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

LAPS Cancellation because of no payment of annual fees