JPH02179847A - Hot rolled steel plate excellent in workability and its production - Google Patents
Hot rolled steel plate excellent in workability and its productionInfo
- Publication number
- JPH02179847A JPH02179847A JP33548988A JP33548988A JPH02179847A JP H02179847 A JPH02179847 A JP H02179847A JP 33548988 A JP33548988 A JP 33548988A JP 33548988 A JP33548988 A JP 33548988A JP H02179847 A JPH02179847 A JP H02179847A
- Authority
- JP
- Japan
- Prior art keywords
- hot
- rolled steel
- stretch flangeability
- steel plate
- rolling
- 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
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 37
- 239000010959 steel Substances 0.000 title claims abstract description 37
- 238000004519 manufacturing process Methods 0.000 title claims description 8
- 238000005098 hot rolling Methods 0.000 claims abstract description 14
- 229910001568 polygonal ferrite Inorganic materials 0.000 claims abstract description 14
- 229910001563 bainite Inorganic materials 0.000 claims abstract description 12
- 238000001816 cooling Methods 0.000 claims abstract description 8
- 229910052761 rare earth metal Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 3
- 238000005096 rolling process Methods 0.000 claims description 7
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000004804 winding Methods 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 230000001186 cumulative effect Effects 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 239000000203 mixture Substances 0.000 abstract description 6
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 238000000034 method Methods 0.000 abstract description 3
- 238000010791 quenching Methods 0.000 abstract 1
- 230000000171 quenching effect Effects 0.000 abstract 1
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 10
- 229910000859 α-Fe Inorganic materials 0.000 description 5
- 239000002245 particle Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 229910001562 pearlite Inorganic materials 0.000 description 2
- 238000001953 recrystallisation Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 229910001567 cementite Inorganic materials 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000005476 size effect Effects 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は、加工性の優れた熱延鋼板の製造に係り、より
詳しくは、優れた伸びフランジ性を有する熱延鋼板とそ
の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to the production of hot-rolled steel sheets with excellent workability, and more particularly, to a hot-rolled steel plate with excellent stretch-flangeability and a method for producing the same. .
（従来の技術及び解決しようとする課題）ホイールリム
、ディスクをはじめとする自動車周部材、或いは建設工
事足場用クランプをはじめとする建設用部材等々の部材
としては、特に良好な伸びフランジ性を有する部材が必
要とされている。(Prior art and problems to be solved) It has particularly good stretch flangeability as a member for automobile peripheral parts such as wheel rims and discs, or construction parts such as construction scaffolding clamps. parts are needed.
従来、このような伸びフランジ性の良好な鋼板としては
、フェライト＋ベイナイト鋼（特開昭５８−４２７２６
号）或いはフェライト＋ベイナイト＋マルテンサイト鋼
（特開昭５７−７０２５７号）等が一般に知られている
。Conventionally, such steel sheets with good stretch flangeability include ferrite + bainite steel (Japanese Unexamined Patent Publication No. 58-42726).
) or ferrite + bainite + martensitic steel (Japanese Unexamined Patent Application Publication No. 57-70257), etc. are generally known.
しかし、これらの鋼は、Ｓｉを比較的多量に添加するた
め、高コストとなるばかりでなく、フェライト粒径が粗
大化すると共に第２相が硬質なものとなり易く、伸びフ
ランジ性の良好な鋼を得る条件が狭いと云う問題がある
。また、Ｓｉを多量に添加すると赤い島状スケールが発
生し易く、操業上更にその対策を講じる必要が生じると
云う問題がある。However, since these steels contain a relatively large amount of Si, they are not only expensive, but also tend to have coarse ferrite grains and a hard second phase, making it difficult to make steels with good stretch flangeability. The problem is that the conditions for obtaining . Further, if a large amount of Si is added, red island-like scales are likely to occur, and there is a problem in that it is necessary to take additional countermeasures in operation.
本発明は、上記従来技術の問題点を解決するためになさ
れたものであって、伸びフランジ性の優れた熱延鋼板を
安価に提供することを目的とし、またその製造法を提供
することを目的とするものである。The present invention has been made to solve the problems of the prior art described above, and aims to provide a hot-rolled steel sheet with excellent stretch flangeability at a low cost, and also to provide a method for manufacturing the same. This is the purpose.
（課題を解決するための手段）
前記目的を達成するため、本発明者等は、Ｓｉ量を節減
する成分調整を前提とし、より安価で容易に伸びフラン
ジ性の良好な熱延鋼板を得ることができる方策について
鋭意研究を重ねた結果、本発明を完成させるに至ったの
である。(Means for Solving the Problems) In order to achieve the above object, the present inventors aimed to obtain a hot rolled steel sheet with good stretch flangeability at a lower cost and with ease, on the premise of component adjustment to reduce the amount of Si. As a result of extensive research into ways to achieve this, the present invention was completed.
すなわち、本発明は、Ｃ：０．０３〜０．１２％、Ｓｉ
：０．０１％以下−Ｍｎ：０．８〜２．０％、Ｐ：０゜
０１〜０．０３％及び”ｒｉ：ｏ、ｏｉ 〜ｏ、ｏｓ％
を含み、必要に応じて更に、Ｃａ及び希土類元素のうち
の１種又は２種以上を合計で０．００１〜０゜０２％含
み、残部が鉄及び不可避的不純物よりなる鋼であって、
平均粒径５μｍ以上２０μｍ以下のボリゴナルフェライ
トを主体とし、残部が面積率で３〜４０％の微細なベイ
ナイトからなる組織を有することを特徴とする伸びフラ
ンジ性の優れた熱延鋼板を要旨とするものである。That is, in the present invention, C: 0.03 to 0.12%, Si
: 0.01% or less - Mn: 0.8-2.0%, P: 0°01-0.03% and "ri: o, oi ~ o, os%
and, if necessary, further contains one or more of Ca and rare earth elements in a total of 0.001 to 0.02%, with the balance consisting of iron and unavoidable impurities,
The gist is a hot-rolled steel sheet with excellent stretch flangeability, characterized by having a structure consisting mainly of borigonal ferrite with an average grain size of 5 μm or more and 20 μm or less, with the remainder consisting of fine bainite with an area ratio of 3 to 40%. It is something to do.
また、該熱延鋼板の製造法の一つは、上記組成の鋼の鋼
片或いは連続鋳造された鋳片を、１１５０〜１３００℃
の温度域に加熱した後、仕上げ温度をＡで３〜９００℃
とし、且つ、Ａｒ３＋１５０’Ｃ以下での最終バスの圧
下率が１０％以上とする条件で熱間圧延を行い、その後
、平均冷却速度３０〜１５０℃／ｓｅｅで急冷し、２５
０〜５４０℃で巻取ることを特徴とするものである。In addition, one of the methods for producing the hot-rolled steel sheet is to heat a slab of steel having the above composition or a continuously cast slab at a temperature of 1150 to 1300°C.
After heating to a temperature range of A, the finishing temperature is 3 to 900℃.
Then, hot rolling is carried out under the conditions that the rolling reduction ratio of the final bath is 10% or more at Ar3+150'C or less, and then quenched at an average cooling rate of 30 to 150°C/see,
It is characterized by being wound up at a temperature of 0 to 540°C.
更に、該熱延鋼板の他の製造法は、上記組成の鋼の鋼片
或いは連続鋳造された鋳片を、１１５０〜１３００℃の
温度域に加熱した後、仕上げ温度をＡｒ３〜９００℃と
し、且つ、最終パスを含む２バス以上の圧延を３秒以内
で累積圧下率が２５％以上となる条件で熱間圧延を行い
、その後、平均冷却速度３０〜１５０℃／ｓｅｅで急冷
し、２５０〜５４０℃で巻取ることを特徴とするもので
ある。Furthermore, another method for producing the hot rolled steel sheet is to heat a slab of steel having the above composition or a continuously cast slab to a temperature range of 1150 to 1300°C, and then set the finishing temperature to Ar3 to 900°C, In addition, hot rolling is carried out under conditions such that the cumulative reduction rate is 25% or more in 2 or more buses including the final pass within 3 seconds, and then quenched at an average cooling rate of 30 to 150 °C/see, It is characterized by being wound at 540°C.
（作用） 以下、本発明について更に詳細に説明する。(effect) The present invention will be explained in more detail below.
前述のように９本発明者等は、０．０１％以下の如く低
Ｓｉ含有鋼において、より安価で容易に伸びフランジ性
の良好な熱延鋼板を得るために鋭意検討した結果、平均
粒径５μｍ以上２０μｍ以下のポリゴナルフェライト（
ＰＦ）を主体とし、残部が面積率で３〜４０％の微細な
ベイナイト（Ｂ）からなる組織とすることにより、非常
に良好なＴＳ（引張強さ）−λ（穴拡げ率（％））バラ
ンス（伸びフランジ性）を有することを見い出した。As mentioned above, the inventors of the present invention conducted intensive studies to obtain a hot rolled steel sheet with good stretch flangeability at a lower cost and with ease in low Si content steel such as 0.01% or less, and found that the average grain size was Polygonal ferrite (5μm or more and 20μm or less)
By creating a structure consisting mainly of PF) and the remainder being fine bainite (B) with an area ratio of 3 to 40%, it has a very good TS (tensile strength) - λ (hole expansion ratio (%)). It was found that it has balance (stretch flangeability).
すなわち、第１図及び第２図は検討結果をまとめたもの
であり、まず、第１図はＴＳ−λバランスに及ぼすＰＦ
粗粒径影響を示している。同図より、ＰＦ平均粒径を５
〜２０μｍに制御することによりＴＳＸλ≧６０００の
良好な熱延鋼板を得ることができることがわかる。また
この時、残部のＢ相の面積率は第２図に示すように３〜
４０％とする必要があり、３％未満では実質上パーライ
ト或いはセメンタイトを含んだ組織となり、伸びフラン
ジ性が劣化する。一方、８面積率が４０％を超えると、
特に伸びの劣化が著しく、加工の厳しい部品に適用する
のが困難となる。In other words, Figures 1 and 2 summarize the study results. First, Figure 1 shows the effect of PF on the TS-λ balance.
It shows the coarse particle size effect. From the same figure, the PF average particle size is 5
It can be seen that by controlling the thickness to 20 μm, it is possible to obtain a good hot rolled steel sheet with TSXλ≧6000. At this time, the area ratio of the remaining B phase is 3 to 3, as shown in Figure 2.
The content should be 40%; if it is less than 3%, the structure will substantially contain pearlite or cementite, resulting in poor stretch flangeability. On the other hand, if the 8 area ratio exceeds 40%,
In particular, the deterioration in elongation is significant, making it difficult to apply to parts that require severe processing.
次に、上記のＰＦ粗粒径ベイナイト面積率を所望の範囲
に制御するための条件として、化学成分及び熱延条件に
ついて説明する。Next, chemical components and hot rolling conditions will be explained as conditions for controlling the above-mentioned PF coarse grain size bainite area ratio within a desired range.
まず、本発明における化学成分の限定理由について説明
する。First, the reasons for limiting the chemical components in the present invention will be explained.
Ｃ：
Ｃは所望のベイナイト面積率を得る上で必要な元素であ
り、その効果を発揮させるには０．０３％以上の含有が
必要である。しかし、多すぎると延性の劣化が著しく、
また溶接性も劣化するので、０．１２％を上限とする。C: C is an element necessary to obtain a desired bainite area ratio, and must be contained in an amount of 0.03% or more to exhibit its effect. However, if the amount is too high, the ductility deteriorates significantly,
Furthermore, since weldability also deteriorates, the upper limit is set at 0.12%.
Ｓｉ：
Ｓｉは、ポリゴナルフェライトの生成・成長を促進する
ため、上記の所望のＰＦ平均粒径を得るには０．０１％
以下に制限する必要がある。Si: Si promotes the formation and growth of polygonal ferrite, so to obtain the above desired PF average particle size, Si is 0.01%.
Must be limited to the following.
Ｍｎ：
Ｍｎは低Ｃ化による強度低下の補償及びベイナイト組織
を得るための不可欠の元素である。しかし、含有量が０
．８％に満たないと所望の強度及び組織が得られず、一
方、２．０％を超えると延性が劣化するほか、製造コス
トが上昇するので好ましくない。Mn: Mn is an essential element for compensating for the decrease in strength due to lower carbon content and for obtaining a bainitic structure. However, the content is 0
．． If it is less than 8%, desired strength and structure cannot be obtained, while if it exceeds 2.0%, ductility deteriorates and manufacturing costs increase, which is not preferable.
Ｐ ：
Ｐは溶接性を劣化するので０．０３％以下とし、少ない
ほど好ましい、しかし、０．０１％未満にしても改善効
果は余りなく、却ってコスト上昇を招くので、Ｐ含有量
は０．０１〜０．０３％の範囲とする。P: Since P deteriorates weldability, the content should be 0.03% or less, and the lower the content, the better. However, even if it is less than 0.01%, there will be little improvement effect, and on the contrary, it will cause an increase in cost, so the P content should be 0.03% or less. The range is 0.01% to 0.03%.
Ｔｉ：
Ｔｉはポリゴナルフェライトの微細化に効果があると共
にベイナイト組織を得やすくする効果があり、しかも、
介在物の形態制御にも効果があり、伸びフランジ性を改
善する。しかし、０．０１％未満ではこのような効果が
なく、また０、０８％を超えて含有させると組織が微細
になりすぎ、ＴＳ−λバランスを劣化させるので好まし
くない。Ti: Ti has the effect of refining polygonal ferrite and makes it easier to obtain a bainite structure.
It is also effective in controlling the form of inclusions and improves stretch flangeability. However, if the content is less than 0.01%, no such effect is produced, and if the content exceeds 0.08%, the structure becomes too fine and the TS-λ balance is deteriorated, which is not preferable.
なお、上記元素の他に、必要に応じてＣａ及び希土類元
素（ＲＥＭ）の１種又は２種以上の合計を適量で添加す
ることができる。これらの元素は硫化物形態制御を通じ
て伸びフランジ性の改善に寄与する。しかし、含有量が
０．００１’％未満ではその効果が得られず、０．０１
％を超えるとその効果が飽和点に達し、経済的でなくな
るだけでなく、介在物量を増加するので、添加する場合
には、Ｃａ及び希土類元素の１種又は２種以上の合計を
０．００１〜０．０１％の範囲で添加する。In addition, in addition to the above elements, one or more of Ca and rare earth elements (REM) can be added in appropriate amounts as necessary. These elements contribute to improving stretch flangeability through sulfide morphology control. However, if the content is less than 0.001'%, this effect cannot be obtained;
%, the effect reaches a saturation point and not only becomes uneconomical, but also increases the amount of inclusions. Therefore, when adding Ca and rare earth elements, the total of one or more rare earth elements should be 0.001 Add in a range of 0.01%.
次に熱延条件について説明する。Next, hot rolling conditions will be explained.
上記鋼は、常法により鋼片或いは連続鋳造にて鋳片とし
、熱間圧延に先立って、１１５０℃以上の温度に加熱す
る。該加熱温度が低いと、Ｔｉが素地中に完全に固溶し
得ないため、その後のＴｉ炭窒化物等の析出が十分行わ
れず、熱延後の組織の微細化を図ることができない、一
方、加熱コストとγ粒径の粗大化防止の観点から、加熱
温度の上限は１３００℃とする。The above-mentioned steel is made into a steel billet or a slab by continuous casting using a conventional method, and is heated to a temperature of 1150° C. or higher prior to hot rolling. If the heating temperature is low, Ti cannot be completely dissolved in the base material, and the subsequent precipitation of Ti carbonitrides etc. will not occur sufficiently, making it impossible to refine the structure after hot rolling. From the viewpoint of heating cost and prevention of coarsening of the γ particle size, the upper limit of the heating temperature is set to 1300°C.
加熱された鋼片又は鋳片は、以下の条件で熱間圧延する
。The heated steel slab or slab is hot rolled under the following conditions.
すなわち、仕上げ温度は、γの微細化を図るために９０
０℃以下とし、且つ、２相域で圧延すると加工組織が残
り、伸びフランジ性が劣化するため、 Ａｒ、以上とす
る。In other words, the finishing temperature is 90°C in order to make γ finer.
If the temperature is 0°C or lower and rolling is performed in a two-phase region, a processed structure will remain and the stretch flangeability will deteriorate, so the temperature should be Ar or higher.
圧下率は、γ→αの変態前のγを微細化、高歪化するこ
とによって、変態αの微細化を図るため、以下の■又は
■のように規定する。The rolling reduction rate is defined as shown in (1) or (2) below in order to refine the transformation α by making the γ before the transformation from γ→α finer and to increase the strain.
すなわち、■ 加工γの回復・再結晶及び再結晶後の粒
成長を抑制するにはＡｒ、＋１５０℃以下で高歪を与え
ることが重要であり、この時の圧下率を最終パスで１０
％以上とすることにより、所望の微細組織が得られる。In other words, ■ In order to suppress the recovery and recrystallization of processed γ and the grain growth after recrystallization, it is important to apply high strain to Ar at +150°C or less, and the reduction rate at this time is set to 10 in the final pass.
% or more, a desired fine structure can be obtained.
■ 或いは、短時間で連続圧延が可能な時は、上記温度
域（Ａｒ３〜９００℃）にて、最終パスを含む２バス以
上の圧延を３秒以内に、累積圧下率が２５％以上となる
ように圧延すればよい。■Alternatively, when continuous rolling is possible in a short period of time, in the above temperature range (Ar 3 to 900°C), two or more baths including the final pass are rolled within 3 seconds, with a cumulative reduction rate of 25% or more. Just roll it like this.
しかし、■又は■のいずれの態様においても、上記温度
域、圧下率のどちらかが満たされなければ、α変態前の
γ粒径が大きくなり、或いはγの残留歪が小さくなるこ
とにより、微細なαが得られない。However, in either mode (■) or (■), if either the above temperature range or rolling reduction ratio is not satisfied, the γ grain size before α transformation becomes large, or the residual strain of γ becomes small, resulting in fine grain formation. α cannot be obtained.
熱間圧延後は、以下の条件で冷却し、巻取る。After hot rolling, it is cooled and wound under the following conditions.
まず、冷却速度は、αの粗大化を防止するため３０℃／
ｓｅｃ以上とする。しかし、１５０℃／ｓｅｃを超える
とアシキュラフエライト組織となり、ＴＳ−λバランス
が劣化するので、冷却速度は３０〜ｂ
また１巻取温度は第２相をベイナイト組織にする上で重
要であり、５４０℃超えで巻取るとパーライトが出現す
る危険性があり、また２５０℃未満で巻取るとマルテン
サイトが出現する危険性があるため、巻取温度は２５０
〜５４０’Ｃの範囲とする。First, the cooling rate is set at 30℃/
sec or more. However, if it exceeds 150°C/sec, it becomes an acicular ferrite structure and the TS-λ balance deteriorates, so the cooling rate is 30~b. Also, the first winding temperature is important in making the second phase a bainite structure. If the winding temperature exceeds 540°C, there is a risk that pearlite will appear, and if the winding temperature is lower than 250°C, there is a risk that martensite will appear, so the winding temperature is 250°C.
~540'C.
次に本発明の実施例を示す。Next, examples of the present invention will be shown.
（実施例）
第１表に示す化学成分を有する鋼につき、第２表に示す
熱延条件で熱間圧延し、巻き取った。(Example) Steel having the chemical composition shown in Table 1 was hot rolled under the hot rolling conditions shown in Table 2, and then wound.
得られた熱延鋼板の機械的性質及びＭｉ織を第３表に示
す。Table 3 shows the mechanical properties and Mi weave of the obtained hot rolled steel sheet.
第３表より、本発明例魔１〜勲６ではＴＳＸλ≧６０ｏ
Ｏと非常に良好なＴＳ−λバランスを示し、優れた伸び
フランジ性を有していることがわかる。一方、比較例Ｎ
ａ７〜走２１ではＰＦ平均粒径又はベイナイト面積率の
少なくとも一方が本発明範囲を外れており、ＴＳＸλ＜
６０００と劣っており、強度−伸びフランジ性のバラン
スが悪い。From Table 3, in the examples 1 to 6 of the present invention, TSXλ≧60o
It can be seen that it shows a very good TS-λ balance with O and has excellent stretch flangeability. On the other hand, comparative example N
In runs a7 to run 21, at least one of the PF average grain size or the bainite area ratio is outside the range of the present invention, and TSXλ<
6000, poor balance between strength and stretch flangeability.
Ｃ以下余白】
（発明の効果）
以上詳述したように、本発明によれば、Ｓｉ含有量を０
．０１％以下にする如く成分調整し、特定の熱延条件で
製造するので、伸びフランジ性の優れた熱延鋼板を得る
ことができる。しかもＳｉ含有量が節減されるので安価
であり、容易に得ることができる等の顕著な効果がある
。Margin below C] (Effect of the invention) As detailed above, according to the present invention, the Si content can be reduced to 0.
．． Since the composition is adjusted to 0.1% or less and the hot rolling process is carried out under specific hot rolling conditions, a hot rolled steel sheet with excellent stretch flangeability can be obtained. Moreover, since the Si content is reduced, it is inexpensive and can be easily obtained, which has remarkable effects.
第１図はＴＳＸλバランスに及ぼすポリゴナルフェライ
ト（ＰＦ）平均粒径の影響を示す図、第２図はＴＳＸλ
バランスに及ぼすベイナイト面積率の影響を示す図であ
る。
特許出願人 株式会社神戸ｔＳＳ所
代理人弁理士 中 村 尚
Ｂ＠千′＊辛 く′／−ンFigure 1 shows the influence of polygonal ferrite (PF) average grain size on TSXλ balance, Figure 2 shows TSXλ balance.
FIG. 3 is a diagram showing the influence of bainite area ratio on balance. Patent applicant: Kobe tSS Co., Ltd. Patent attorney Nao Nakamura
Claims (4)
２％、Ｓｉ：０．０１％以下、Ｍｎ：０．８〜２．０％
、Ｐ：０．０１〜０．０３％及びＴｉ：０．０１〜０．
０８％を含み、残部が鉄及び不可避的不純物よりなる鋼
であって、平均粒径５μｍ以上２０μｍ以下のポリゴナ
ルフェライトを主体とし、残部が面積率で３〜４０％の
微細なベイナイトからなる組織を有することを特徴とす
る伸びフランジ性の優れた熱延鋼板。(1) In weight% (the same applies hereinafter), C: 0.03 to 0.1
2%, Si: 0.01% or less, Mn: 0.8-2.0%
, P: 0.01-0.03% and Ti: 0.01-0.
08%, with the remainder being iron and unavoidable impurities, with a structure consisting mainly of polygonal ferrite with an average grain size of 5 μm or more and 20 μm or less, and the remainder consisting of fine bainite with an area ratio of 3 to 40%. A hot rolled steel sheet with excellent stretch flangeability.
は２種以上を合計で０．００１〜０．０２％含むもので
ある請求項に１記載の熱延鋼板。(2) The hot-rolled steel sheet according to claim 1, wherein the steel further contains a total of 0.001 to 0.02% of one or more of Ca and rare earth elements.
された鋳片を、１１５０〜１３００℃の温度域に加熱し
た後、仕上げ温度をＡｒ＿３〜９００℃とし、且つ、Ａ
ｒ＿３＋１５０℃以下での最終パスの圧下率が１０％以
上とする条件で熱間圧延を行い、その後、平均冷却速度
３０〜１５０℃／ｓｅｃで急冷し、２５０〜５４０℃で
巻取ることを特徴とする伸びフランジ性の優れた熱延鋼
板の製造法。(3) After heating the steel billet or continuously cast slab according to claim 1 or 2 to a temperature range of 1150 to 1300°C, the finishing temperature is set to Ar_3 to 900°C, and A
Hot rolling is carried out under the condition that the rolling reduction ratio in the final pass is 10% or more at r_3 + 150°C or lower, followed by rapid cooling at an average cooling rate of 30 to 150°C/sec, and coiling at 250 to 540°C. A method for producing hot rolled steel sheets with excellent stretch flangeability.
された鋳片を、１１５０〜１３００℃の温度域に加熱し
た後、仕上げ温度をＡｒ＿３〜９００℃とし、且つ、最
終パスを含む２パス以上の圧延を３秒以内で累積圧下率
が２５％以上となる条件で熱間圧延を行い、その後、平
均冷却速度３０〜１５０℃／ｓｅｃで急冷し、２５０〜
５４０℃で巻取ることを特徴とする伸びフランジ性の優
れた熱延鋼板の製造法。(4) After heating the steel billet or continuously cast slab according to claim 1 or 2 to a temperature range of 1150 to 1300°C, the finishing temperature is set to Ar_3 to 900°C, and the final pass is Hot rolling is carried out under conditions such that the cumulative reduction rate is 25% or more within 3 seconds, including two or more passes of rolling, and then quenched at an average cooling rate of 30 to 150 ° C / sec,
A method for producing a hot-rolled steel sheet with excellent stretch flangeability characterized by winding at 540°C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63335489A JP2555436B2 (en) | 1988-12-29 | 1988-12-29 | Hot-rolled steel sheet with excellent workability and its manufacturing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63335489A JP2555436B2 (en) | 1988-12-29 | 1988-12-29 | Hot-rolled steel sheet with excellent workability and its manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02179847A true JPH02179847A (en) | 1990-07-12 |
| JP2555436B2 JP2555436B2 (en) | 1996-11-20 |
Family
ID=18289146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63335489A Expired - Fee Related JP2555436B2 (en) | 1988-12-29 | 1988-12-29 | Hot-rolled steel sheet with excellent workability and its manufacturing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2555436B2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2431491A1 (en) * | 2009-05-12 | 2012-03-21 | JFE Steel Corporation | High-strength hot-rolled steel sheet and process for manufacture thereof |
| CN115058660A (en) * | 2022-06-17 | 2022-09-16 | 武汉钢铁有限公司 | Low-temperature magnet yoke steel for large hydroelectric generating set and production method thereof |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2001020051A1 (en) * | 1999-09-16 | 2001-03-22 | Nkk Corporation | Steel thin plate having high strength and method for production thereof |
| WO2001023624A1 (en) | 1999-09-29 | 2001-04-05 | Nkk Corporation | Sheet steel and method for producing sheet steel |
-
1988
- 1988-12-29 JP JP63335489A patent/JP2555436B2/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2431491A1 (en) * | 2009-05-12 | 2012-03-21 | JFE Steel Corporation | High-strength hot-rolled steel sheet and process for manufacture thereof |
| EP2431491A4 (en) * | 2009-05-12 | 2013-04-03 | Jfe Steel Corp | High-strength hot-rolled steel sheet and process for manufacture thereof |
| US8535458B2 (en) | 2009-05-12 | 2013-09-17 | Jfe Steel Corporation | High-strength hot-rolled steel sheet and method for manufacturing the same |
| CN115058660A (en) * | 2022-06-17 | 2022-09-16 | 武汉钢铁有限公司 | Low-temperature magnet yoke steel for large hydroelectric generating set and production method thereof |
| CN115058660B (en) * | 2022-06-17 | 2023-05-12 | 武汉钢铁有限公司 | Low Wen Cie steel for large-scale hydroelectric generating set and production method |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2555436B2 (en) | 1996-11-20 |
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