JPS63216925A - Manufacture of hot-rolled steel plate excellent in workability - Google Patents
Manufacture of hot-rolled steel plate excellent in workabilityInfo
- Publication number
- JPS63216925A JPS63216925A JP4906187A JP4906187A JPS63216925A JP S63216925 A JPS63216925 A JP S63216925A JP 4906187 A JP4906187 A JP 4906187A JP 4906187 A JP4906187 A JP 4906187A JP S63216925 A JPS63216925 A JP S63216925A
- Authority
- JP
- Japan
- Prior art keywords
- hot
- steel
- rolling
- workability
- rolled 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.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 57
- 239000010959 steel Substances 0.000 title claims abstract description 57
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 10
- 238000005098 hot rolling Methods 0.000 claims abstract description 10
- 229910052796 boron Inorganic materials 0.000 claims abstract description 7
- 239000012535 impurity Substances 0.000 claims abstract description 6
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 5
- 238000005096 rolling process Methods 0.000 abstract description 27
- 239000000203 mixture Substances 0.000 abstract description 9
- 238000001816 cooling Methods 0.000 abstract description 8
- 238000010438 heat treatment Methods 0.000 abstract description 7
- 230000009466 transformation Effects 0.000 abstract description 6
- 230000003028 elevating effect Effects 0.000 abstract 1
- 230000001105 regulatory effect Effects 0.000 abstract 1
- 239000013078 crystal Substances 0.000 description 13
- 230000000694 effects Effects 0.000 description 11
- 238000000034 method Methods 0.000 description 9
- 239000006104 solid solution Substances 0.000 description 6
- 238000007792 addition Methods 0.000 description 3
- 238000012733 comparative method Methods 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 229910000975 Carbon steel Inorganic materials 0.000 description 2
- 239000010962 carbon steel Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- ZPUCINDJVBIVPJ-LJISPDSOSA-N ***e Chemical compound O([C@H]1C[C@@H]2CC[C@@H](N2C)[C@H]1C(=O)OC)C(=O)C1=CC=CC=C1 ZPUCINDJVBIVPJ-LJISPDSOSA-N 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- -1 nitride carbides Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229910001562 pearlite Inorganic materials 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は加工性にすぐれた熱延鋼板、より詳しくは板の
全長にわたって加工性にすぐれたＦｉ厚の薄い熱延鋼板
を得るに適した製造方法に関するものである。[Detailed Description of the Invention] (Field of Industrial Application) The present invention is suitable for obtaining a hot-rolled steel plate with excellent workability, more specifically, a hot-rolled steel plate with a thin Fi thickness that has excellent workability over the entire length of the plate. This relates to a manufacturing method.
（従来の技術）
熱延鋼板は、年々高加工用としての需要が裔まり、冷延
鋼板なみに過酷な変形を受ける加工部材への用途が拡大
している。(Prior Art) Demand for hot-rolled steel sheets for high-processing applications is increasing year by year, and their use as processed parts that undergo severe deformation similar to that of cold-rolled steel sheets is expanding.
この熱延鋼板の加工性を左右する因子として、結晶の粒
径と結晶中に残存する加工歪みがあり、フェライト相（
α相）の結晶粒度はＡＳＴＭ粒度番号の８番前後で、且
つ残存歪みの除去された組織の熱延鋼板が最も加工性に
優れているものとされている。Factors that affect the workability of hot-rolled steel sheets include the grain size of the crystals and the processing strain remaining in the crystals, and the ferrite phase (
The grain size of the α phase is around 8 in the ASTM grain size number, and hot-rolled steel sheets with a structure in which residual strain has been removed are considered to have the best workability.
このような組織の熱延鋼板とするのに最も一般的な従来
からの製造方法としては、熱間圧延をＡｒｓ変態点（以
下単に＾ｒ１点と言う）以上の仕上温度（通常８７０〜
９００℃）で圧延を行う方法、或いは熱間圧延後の鋼帯
を７００℃前後の高温で巻取る方法がある。The most common conventional manufacturing method for producing hot-rolled steel sheets with such a structure is to carry out hot rolling at a finishing temperature (usually 870~
There is a method of rolling at a temperature of 900°C, or a method of winding a hot-rolled steel strip at a high temperature of around 700°C.
後者の高温で巻取る方法は、＾ｒ１点以下の低い仕上温
度で圧延され、歪みの′Ｔｔ積した圧延ｍ織を有する鋼
板の加工性を改善する上で有効とされているが、高温巻
取りに起因してα相の結晶粒が粗大化し、必ずしも十分
な加工性を期待することができない。更には高温巻取り
のためスケールが生じ易（なり表面品質を１貝なう等の
問題が生じる。The latter high-temperature coiling method is said to be effective in improving the workability of steel sheets that are rolled at a low finishing temperature below ^r1 point and have a rolled weave with a strain 'Tt product. Due to the removal, the crystal grains of the α phase become coarse, and sufficient workability cannot necessarily be expected. Furthermore, due to the high temperature winding, scale tends to form (which causes problems such as the surface quality becoming uneven).
このため、一般には前者のＡｒｓ点以上の仕上温度で圧
延する方法が取られている。For this reason, a method is generally used in which rolling is performed at a finishing temperature higher than the former Ars point.
しかし、冷却能の大きい、例えば厚み３．２■以下の薄
銅板においては、圧延温度が圧延中に著しく低下するた
め、通常のスラブ加熱温度（１２００℃程度）からの圧
延ではＡｒｚ点以上の仕上温度を確保することが困難で
ある。However, for thin copper plates with a large cooling capacity, for example, thickness of 3.2 mm or less, the rolling temperature drops significantly during rolling, so rolling from the normal slab heating temperature (approximately 1200°C) will result in a finish above the Arz point. Difficult to maintain temperature.
Ａｒ３点以上の仕上温度で圧延を終了しようとすれば、
加熱温度を高くしなければならず、結晶粒が粗大化した
りエネルギーコストが嵩むなどの難点がある。If you try to finish rolling at a finishing temperature of Ar3 or higher,
There are disadvantages such as the heating temperature must be increased, resulting in coarse crystal grains and increased energy costs.
ところで、このＡｒ３点は鋼の組成により変動すること
はよく知られている。By the way, it is well known that this Ar3 point varies depending on the composition of steel.
したがって、Ａｒｓ点の低い組成の鋼を用いることで、
圧延温度域が広がり圧延作業又は圧延の温度管理が容易
となることが考えられる。Therefore, by using steel with a low Ars point composition,
It is conceivable that the rolling temperature range is expanded and the rolling operation or rolling temperature control becomes easier.
このＡｒ３点を低下せしめるものとして、Ｂ（ボロン）
がよく知られている。As a substance that lowers this Ar3 point, B (boron)
is well known.
例えば、用鉄技報（１９７３，４，２２４ページ）及び
神戸製鋼所技報（Ｖｏｌ、３４． Ｎｏ３．６１ ペー
ジ）ニ、Ｂはγ相からα相への変態を防止し、変態点を
下げることが記載されているとともに、このＢを含有し
た加工性に優れた熱延鋼板が紹介されている。For example, according to the Technical Report on Steel Works (1973, p. 4, 224) and the Kobe Steel Technical Report (Vol. 34. No. 3, p. 61), B prevents the transformation from the γ phase to the α phase and lowers the transformation point. In addition to this, a hot-rolled steel sheet containing B and having excellent workability is introduced.
本発明者らの実験によってもＢがＡｒ３点を低下せしめ
ることは確認されたが、γ相からα相へ変態後のα結晶
粒が急速に粗大化して、必ずしも加工性にとって好まし
い結晶粒とならないことも観察された。Although it has been confirmed through experiments by the present inventors that B lowers the Ar3 point, the α crystal grains after the transformation from the γ phase to the α phase rapidly coarsen and do not necessarily become crystal grains favorable for workability. It was also observed.
このα結晶粒の粗大化を防止し均質な組織とするために
は、熱間圧延時の仕上温度を一定の狭い温度範囲で板全
長にわたり細かく制御し、圧延後急冷するなどの処置を
施して粒度調整を行う必要がある。In order to prevent coarsening of these α grains and create a homogeneous structure, measures such as finely controlling the finishing temperature during hot rolling over the entire length of the sheet within a fixed narrow temperature range and rapidly cooling it after rolling are taken. It is necessary to adjust the particle size.
しかしながら圧延長さが数１０Ｍにも及ぶ熱延鋼板にと
っては、仮全長にわたって仕上温度及び冷却温度を細か
く制御することは極めて困難なことである。However, for hot-rolled steel sheets whose rolling length is several tens of meters, it is extremely difficult to precisely control the finishing temperature and cooling temperature over the entire length.
一方、このような処置を行うことなく、α粒を微細化さ
せ加工性を向上させる方法として、古くから結晶を細か
くする元素として知られているＮｂおよびＴｉを添加し
た鋼を用いた製造方法もある。On the other hand, as a method to refine the α grains and improve workability without performing such treatment, there is also a manufacturing method using steel containing Nb and Ti, which have long been known as elements that refine crystals. be.
例えば、日本鋼管技報（１０８４、Ｎｏ５ 、１０５
、６２ページ）には、このＮｂおよびＴ１を、結晶粒が
容易に成長しゃすい極低炭素鋼に微量添加することで、
α結晶粒度を制御し、圧延後の急冷を行うことなく加工
性に優れた熱延鋼板が得られることが紹介されている。For example, Nippon Kokan Technical Report (1084, No. 5, 105
, p. 62), by adding small amounts of Nb and T1 to ultra-low carbon steel in which crystal grains grow easily,
It is introduced that hot rolled steel sheets with excellent workability can be obtained by controlling the α grain size and without rapid cooling after rolling.
しかし、ＮｂおよびＴｉは結晶の微細化に効果はあるが
、Ａｒｓ点を低下せしめるものではな（、一般の炭素鋼
と比べＡｒ３点は変わらず、前述した如（、通常のスラ
ブ加熱温度からの圧延では、特に板厚の薄い鋼板の場合
、Ａｒ、点以上の仕上温度を確保することが極めて困難
であり、加熱温度を高くして圧延を行わねばならず、エ
ネルギーコストが高くなってしまう。However, although Nb and Ti are effective in making the crystals finer, they do not lower the Ars point (compared to general carbon steel, the Ar3 point remains unchanged, and as mentioned above (, In rolling, especially in the case of thin steel plates, it is extremely difficult to secure a finishing temperature of Ar, or higher, and rolling must be carried out at a higher heating temperature, resulting in higher energy costs.
（発明が解決しようとする問題点）
本発明の目的は、加熱温度を高（することなく、且つ圧
延及び冷却条件を細か（制御することな（、圧延及び冷
却条件が少なからず変化しても安定して加工性に優れた
熱延鋼板、特に板厚の薄い加工性に優れた熱延鋼板を製
造することを可能にする新しい方法を提供することにあ
る。(Problems to be Solved by the Invention) The object of the present invention is to avoid raising the heating temperature and finely controlling the rolling and cooling conditions (even if the rolling and cooling conditions change considerably). An object of the present invention is to provide a new method that makes it possible to stably produce a hot rolled steel plate with excellent workability, especially a thin hot rolled steel plate with excellent workability.
（問題点を解決するための手段）
本発明者らは、上述の目的を達成すべく種々検討を行っ
た結果、Ｂ ＆Ｔｉ及びＮｂとは、結晶粒を逆方向に制
御する作用を有しているが、これら元素を複合添加する
ことで、これら元素の相乗的な効果により、上記の問題
点が解決できることを確認した。(Means for Solving the Problems) As a result of various studies to achieve the above-mentioned object, the present inventors found that B & Ti and Nb have the effect of controlling crystal grains in the opposite direction. However, it has been confirmed that by adding these elements in combination, the above problems can be solved due to the synergistic effect of these elements.
即ち、本発明の要旨とするところは、
重量％で、
Ｃ：０．０８％以下、Ｍｎ：０．１〜０．４％、Ｓｉ：
０．０１％未満、酸可溶性ＡＩ：０．０２〜０．０８％
、Ｎｂ又はＴｉの１種以上を総量で：０．００５〜０．
０２０％、Ｂ：０．００１５％以下、Ｎ：０．０１０％
以下で、且つＢ／８ ＞Ｎ／１４を満足し、残部Ｆｅお
よび不可避的不純物からなる鋼を、８５０℃以上の仕上
温度で熱間圧延することを特徴とする加工性にすぐれた
熱延鋼板の製造方法にある。That is, the gist of the present invention is as follows: In weight%, C: 0.08% or less, Mn: 0.1 to 0.4%, Si:
Less than 0.01%, acid soluble AI: 0.02-0.08%
, Nb or Ti in total amount: 0.005 to 0.
020%, B: 0.0015% or less, N: 0.010%
A hot-rolled steel sheet with excellent workability characterized by hot rolling a steel that satisfies B/8 > N/14 and consists of the remainder Fe and unavoidable impurities at a finishing temperature of 850°C or higher. It is in the manufacturing method.
なお、上記の８／８ ＞Ｎ／１４の式中のＢＳＮは、そ
れぞれの成分の含有量（重量％）である。Note that BSN in the above formula 8/8>N/14 is the content (% by weight) of each component.
（作用）
以下、本発明における鋼組成及び熱間圧延条件ノ限定理
由についてのべる。(Function) The reasons for limiting the steel composition and hot rolling conditions in the present invention will be described below.
まず、ｉｌＩ組成を上述のように限定した理由について
のべる。First, the reason for limiting the ilI composition as described above will be discussed.
尚、ａｍ成に関する％は、特に指定のない限り「重量％
」である。In addition, % regarding am composition is "weight%" unless otherwise specified.
”.
Ｃは加工性に大きな影響を及ぼす元素である。C is an element that has a large effect on workability.
通常炭素鋼を用いて加工性に優れた鋼板を製造するため
には、正常なα相を多く生成させることが必要であるこ
とは周知の事実である。It is a well-known fact that in order to manufacture a steel plate with excellent workability using ordinary carbon steel, it is necessary to generate a large amount of normal α phase.
Ｃ含有量が多くなるに従い、高温の安定相であるγ相か
ら冷却していくとパーライトを多く含むα相組織に変態
し、加工性にとって好ましくない相組織状態になる。As the C content increases, the γ phase, which is a stable phase at high temperatures, transforms into an α phase structure containing a large amount of pearlite when cooled, resulting in a phase structure that is unfavorable for workability.
加工性を向上させるためには、この正常なα相を体積率
で９０％以上含むα相組織とすることが好ましい、Ｃ含
有量が０．０８％を越えると正常なα相を体積率で９０
％以上含むα相組織とすることができないことから、そ
の含有量を０．０８％以下とした。In order to improve workability, it is preferable to create an α-phase structure containing 90% or more of this normal α-phase in terms of volume percentage. 90
Since it is impossible to obtain an α-phase structure containing more than % of the content, the content was set to 0.08% or less.
Ｍｎはもともと鋼中に不純物としていくらか含有されて
いる元素であるが、その積極的な効果はＭｎＳとして鋼
中に不純物として混入しているＳを固定し、加工性を向
上させることである。しかしＭｎ含有量が０．４％を越
えて多（なると鋼の強度が高くなり加工性が劣るため好
ましくない、一方、０゜１％未満では鋼中のＳを固定し
きれずにＳ単体のまま残存させてしまい加工性を損なう
ことから、その含有量を０．１〜０．４％とした。Mn is an element that is originally contained in steel to some extent as an impurity, but its positive effect is to fix S, which is mixed as an impurity in steel, as MnS and improve workability. However, if the Mn content exceeds 0.4% (it is undesirable because the strength of the steel increases and the workability deteriorates), on the other hand, if the Mn content is less than 0.1%, the S in the steel is not fully fixed and remains as a single S. The content was set to 0.1 to 0.4% because if it remained, it would impair workability.
Ｓｉは加工性を向上させる上からは少ないほうが好まし
い、Ｓｔ含有量が０．０１％を越えて多くなると、鋼が
脆くなるとともに、Ｓｉは結晶粒界に偏析し熱間圧延中
あるいは熱間圧延後の巻取り中に島状スケールという特
有のスケールを発生させ、製品品質を著しく損なうこと
から、その含有量を０．０１％以下とした。In order to improve workability, it is preferable to have less Si.If the St content exceeds 0.01%, the steel becomes brittle and Si segregates at grain boundaries, causing problems during hot rolling or during hot rolling. The content was set to 0.01% or less because it generates a unique scale called island scale during subsequent winding and significantly impairs product quality.
Ａｔは、製鋼で鋳入み時の脱酸処理に用いられる元素で
あり、脱酸に関与せずに鋼中に溶は込んだＡＩ（酸可溶
ＡＩ）は、鋼中の不純物として存在するＮと結合しＡＩ
Ｎとして析出せしめる作用をもつ。At is an element used in deoxidation treatment during casting in steelmaking, and AI (acid-soluble AI) that dissolves into the steel without participating in deoxidation exists as an impurity in the steel. Combine with N and AI
It has the effect of causing precipitation as N.
０．０２％未満では、前記作用に所望の効果が得られず
、一方、０．０８％を越え多くなると綱の強度が高くな
り、加工性を損なうことから、その含有量を０．０２〜
０．０８％とした。If it is less than 0.02%, the desired effect cannot be obtained, while if it exceeds 0.08%, the strength of the rope will increase and workability will be impaired.
It was set to 0.08%.
ＮｂもしくはＴＩは１種以上含有させることが必要であ
る。Ｎｂ及びＴｉは、前述した如く結晶粒を微細化せし
める作用がある。その微細化機構は、Ｎｂ及びＴｉが鋼
中のＣ或いはＮと結合し、Ｎｂ（Ｃ，Ｎ）、Ｔｆ（Ｃ，
Ｎ）として微細に析出し結晶粒界の動きを抑制するため
である。It is necessary to contain one or more types of Nb or TI. As mentioned above, Nb and Ti have the effect of making crystal grains finer. The refinement mechanism is that Nb and Ti combine with C or N in the steel, resulting in Nb (C, N), Tf (C,
This is to suppress movement of grain boundaries by precipitating finely as N).
その含有量を総量で０．００５〜０．０２０％としたの
は、本発明者らの実験結果から得た下記の知見に足する
鋼においてＮｂ ｈ Ｔｉの合計含有量を種々変えた鋼
を、８６０℃で仕上圧延して得られた鋼板のＮｂとＴｉ
の合計含有量と降伏強度（ＹＰ）および伸び（ＥＬ）と
の関係を調べた結果を示したものである。The reason for setting the total amount of Nb h Ti to 0.005 to 0.020% is based on the following knowledge obtained from the experimental results of the present inventors. , Nb and Ti of the steel plate obtained by finish rolling at 860°C
This figure shows the results of investigating the relationship between the total content of YP, yield strength (YP), and elongation (EL).
ＮｂとＴｉの合計含有量が０．００５％未満では、前述
の窒炭化物の析出粒数が不足し、十分に粒成長を抑制で
きず結晶粒は粗大化し、降伏強度及び伸びとも低いが加
工性はあまり向上しない、一方、０．０２％を越えて多
くなると、結晶粒は殆ど成長できずに細粒のまま残留し
、降伏強度は高く、伸びが低下し、加工性は向上しない
、かかる知見に基いて、ＮｂとＴｉの含有量を１種又は
２種総量でｏ、ｏｏｓ〜０゜０２０％とした。If the total content of Nb and Ti is less than 0.005%, the number of precipitated nitride carbides described above will be insufficient, grain growth will not be sufficiently suppressed, the crystal grains will become coarse, and yield strength and elongation will be low, but workability will be poor. On the other hand, when the amount exceeds 0.02%, the crystal grains can hardly grow and remain as fine grains, yield strength is high, elongation is decreased, and workability is not improved. Based on this, the content of Nb and Ti was set to o, oos to 0°020% in either one type or the total amount of the two types.
Ｂは、前述した如＜ Ａｒｔ点を低下せしめる作用を有
する元素である。この機構は未だ定かではないが、ＢＮ
として析出した残りの鋼中に固溶しているＢがＡｒ、点
を低下せしめるというのが一般的な説である。B is an element that has the effect of lowering the Art point as described above. Although this mechanism is still unclear, BN
The general theory is that B dissolved in the remaining steel precipitated as a solid solution lowers the Ar point.
本発明では、この固溶ＢをＮ含有量に応じてＢＩ３ ＞
Ｎ／１４の式により規定する。In the present invention, this solid solution B is adjusted to BI3> according to the N content.
Defined by the formula N/14.
固溶Ｂが前弐の範囲を外れると、鋼中の固溶Ｂの量が少
ないため、前述の効果が十分得られず、Ａｒ、点の降下
が期待できない。If the solid solution B is out of the above range, the amount of solid solution B in the steel is small, so the above-mentioned effect cannot be obtained sufficiently, and a drop in the Ar point cannot be expected.
一方Ｂの総量も重要である。即ち、仮に上式を満足して
も、Ｂの含有量が０．００１５％以下より少な粒成長度
も小さくなってしまう。そのため、Ｎｂ、Ｔｉ添加によ
る細粒効果が相対的に大きくなりすぎるなど、複合添加
の効果が充分に働かず、熱延条件による特性の変動が大
きくなってしまう。On the other hand, the total amount of B is also important. That is, even if the above formula is satisfied, the degree of grain growth will also be small if the B content is less than 0.0015%. Therefore, the effect of the composite addition does not work satisfactorily, such as the fine grain effect due to the addition of Nb and Ti, which becomes relatively too large, resulting in large fluctuations in properties depending on the hot rolling conditions.
第２図はＮｂ及びＴｉ総量で０．０１０％としてＢの含
有量を種々変えた鋼を８６０℃で仕上圧延して得られた
鋼板のＢ含有量と伸び（ＥＬ）との関係を調べた結果で
ある。第２図に明らかなように、Ｎｂ及びＴｉ総量が０
．００５〜０．０２０％の範囲内でもＢ含有量が０．０
０１５％未満ではＢとＮｂ及びＴｉを複合添加している
にもかかわらず、これら複合添加による相乗効果が得ら
れず伸びは低く良好な加工性が得られない。Figure 2 shows the relationship between the B content and elongation (EL) of steel sheets obtained by finish rolling at 860°C steels with various B contents, with the total amount of Nb and Ti being 0.010%. This is the result. As is clear from Figure 2, the total amount of Nb and Ti is 0.
．． B content is 0.0 even within the range of 0.005 to 0.020%
If it is less than 0.015%, even though B, Nb, and Ti are added in combination, the synergistic effect of these combined additions cannot be obtained, and the elongation is low and good workability cannot be obtained.
従って、Ｂは０．００１５％以上の合釘が必要である。Therefore, B requires a dowel of 0.0015% or more.
Ｎは侵入型固溶元素であるために、Ｎ含有量が多くなる
と固溶強化が生じ鋼の強度が高くなり加工性にとって好
ましくないことから、その含有量を０．０１０％以下と
した。Since N is an interstitial solid solution element, when the N content increases, solid solution strengthening occurs and the strength of the steel increases, which is unfavorable for workability. Therefore, the content was set to 0.010% or less.
なお、Ｂの下限含有量は、前述のようにＮ含有量で制限
されるため、Ｎ含を量が多くなるにつれＢの含有量は増
加しコスト高となる。このためＮ含有量は０．００４０
％程度に抑えるのが好ましい。In addition, since the lower limit content of B is limited by the N content as described above, as the amount of N increases, the B content increases and costs increase. Therefore, the N content is 0.0040
It is preferable to suppress it to about %.
次に、熱間圧延の仕上温度を８５０℃以上とした理由を
説明する。Next, the reason why the finishing temperature of hot rolling was set to 850° C. or higher will be explained.
本発明方法の素材とする鋼ではＢの添加効果によりＡｒ
３変態点は８５０℃以下に低下しているが、少なくとも
この温度以上の温度で仕上圧延することで全ての圧延を
安定してγ域で行うことができ、歪みの蓄積した圧延組
織が残存し加工性を損なうこがないことから、８５０℃
以上の仕上温度とした。In the steel used as the material for the method of the present invention, Ar
3 The transformation point has decreased to below 850°C, but by finishing rolling at at least this temperature or higher, all rolling can be performed stably in the γ range, and the rolled structure with accumulated strain will remain. 850℃ because it does not impair workability.
The finishing temperature was set at the above.
以下、本発明を実施例に基づき更に説明する。Hereinafter, the present invention will be further explained based on Examples.
（実施例）
真空溶解炉で第１表に示すＡ〜Ｌの成分組成の鋼を溶製
し、鍛造で厚さ３０１１１１の鋼片とし、第２表示す加
熱温度及び圧延条件で熱間圧延して厚さ６Ｉの熱延鋼板
とした。(Example) Steel having the compositions A to L shown in Table 1 was melted in a vacuum melting furnace, forged into a steel billet with a thickness of 301111, and hot rolled at the heating temperature and rolling conditions shown in Table 2. A hot-rolled steel plate with a thickness of 6I was obtained.
次いで、この鋼板より試材を採取し、その表面を研削し
て厚さ２＋ｉｍの試験片（ＪＩＳ ５号）にして引張試
験を行った。Next, a sample was taken from this steel plate, and its surface was ground to obtain a 2+im thick test piece (JIS No. 5), which was then subjected to a tensile test.
その結果を第３表に示した。The results are shown in Table 3.
第 ２ 表
第 ３ 表
第１表から第３表に示す結果から明らかなように、本発
明法で得られた鋼板はいずれの製造条件においても、比
較法で得られた鋼板よりＥＬ（伸び値）は１５％以上向
上しており、加工性に優れていることがわかる。As is clear from the results shown in Tables 1 to 3, the steel sheets obtained by the method of the present invention have a lower EL (elongation value) than the steel sheets obtained by the comparative method under any manufacturing conditions. ) has improved by 15% or more, indicating that the workability is excellent.
これに対して、Ｂ、 Ｔｉ、 Ｎｂのいずれかが本発明
の範囲よりはずれた組成の綱（■〜Ｌ）を用いて８５０
℃以上の仕上温度で圧延しても伸び値は低い（比較法１
〜４）。又組成は本発明の範囲内の鋼（＾）をもちいて
も仕上温度が８５０℃以下のものは更に伸び値は低く（
比較法５）、いずれにおいても本発明法で得られた鋼板
より加工性は劣るものである。On the other hand, 850
Even when rolled at a finishing temperature of ℃ or higher, the elongation value is low (comparative method 1
~4). Furthermore, even if steel (^) whose composition is within the range of the present invention is used, the elongation value will be even lower if the finishing temperature is 850°C or less (
Comparative method 5) In both cases, the workability is inferior to the steel plate obtained by the method of the present invention.
（効果）
以上説明した如く、Ｂ、Ｎｂ及びＴｉを特定量添加した
鋼を用いることにより、Ａｒａ変態点は従来の鋼に比べ
低下し、仕上温度を低くすることができ圧延温度域が広
がるから、圧延冷却温度を厳格に細かく制御する必要が
なくなる。このためスラブ加熱温度を上げることなく、
且つ圧延条件が多少変動しても安定して加工性に優れた
熱延鋼板の製造が可能となり、エネルギーコスト低減、
製品品質の向上及び製造効率が向上するなど、工業上有
用な効果かえられるものである。(Effects) As explained above, by using steel to which specific amounts of B, Nb, and Ti are added, the Ara transformation point is lower than that of conventional steel, the finishing temperature can be lowered, and the rolling temperature range is expanded. , it becomes unnecessary to strictly and finely control the rolling cooling temperature. Therefore, without increasing the slab heating temperature,
In addition, it is possible to produce hot-rolled steel sheets that are stable and have excellent workability even when rolling conditions vary slightly, reducing energy costs and
This has industrially useful effects such as improved product quality and manufacturing efficiency.
第１図は、Ｎｂ及びＴｉの合計含有量と降伏強度及び伸
びとの関係を表した図、
第２図は、Ｂ含有量と伸びとの関係を表した図である。FIG. 1 is a diagram showing the relationship between the total content of Nb and Ti and yield strength and elongation, and FIG. 2 is a diagram showing the relationship between the B content and elongation.
Claims (1)
０．０１％未満、酸可溶性Ａｌ：０．０２〜０．０８％
、Ｎｂ又はＴｉの１種以上を総量で：０．００５〜０．
０２０％、Ｂ：０．００１５％以下、Ｎ：０．０１０％
以下で、且つＢ／８＞Ｎ／１４を満足し残部Ｆｅおよび
不可避的不純物からなる鋼を、８５０℃以上の仕上温度
で熱間圧延することを特徴とする加工性にすぐれた熱延
鋼板の製造方法。[Claims] In weight %, C: 0.08% or less, Mn: 0.1 to 0.4%, Si:
Less than 0.01%, acid-soluble Al: 0.02-0.08%
, Nb or Ti in total amount: 0.005 to 0.
020%, B: 0.0015% or less, N: 0.010%
A hot-rolled steel sheet with excellent workability characterized by hot rolling a steel having the following conditions and satisfying B/8>N/14 and consisting of the remainder Fe and unavoidable impurities at a finishing temperature of 850°C or higher. Production method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4906187A JPS63216925A (en) | 1987-03-04 | 1987-03-04 | Manufacture of hot-rolled steel plate excellent in workability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4906187A JPS63216925A (en) | 1987-03-04 | 1987-03-04 | Manufacture of hot-rolled steel plate excellent in workability |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63216925A true JPS63216925A (en) | 1988-09-09 |
Family
ID=12820569
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4906187A Pending JPS63216925A (en) | 1987-03-04 | 1987-03-04 | Manufacture of hot-rolled steel plate excellent in workability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63216925A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01237007A (en) * | 1988-03-16 | 1989-09-21 | Sumitomo Metal Ind Ltd | Manufacture of hot rolled steel sheet having good mechanical descaling property |
| JPH08157952A (en) * | 1994-12-05 | 1996-06-18 | Nippon Steel Corp | Production of steel sheet excellent in formability |
| CN113337781A (en) * | 2021-06-02 | 2021-09-03 | 天津市新天钢钢铁集团有限公司 | Method for solving warping of SPHC + B hot rolled steel strip |
-
1987
- 1987-03-04 JP JP4906187A patent/JPS63216925A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01237007A (en) * | 1988-03-16 | 1989-09-21 | Sumitomo Metal Ind Ltd | Manufacture of hot rolled steel sheet having good mechanical descaling property |
| JPH08157952A (en) * | 1994-12-05 | 1996-06-18 | Nippon Steel Corp | Production of steel sheet excellent in formability |
| CN113337781A (en) * | 2021-06-02 | 2021-09-03 | 天津市新天钢钢铁集团有限公司 | Method for solving warping of SPHC + B hot rolled steel strip |
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