JPH02205628A - Production of accelerated cooling type thick steel plate with low yield ratio - Google Patents
Production of accelerated cooling type thick steel plate with low yield ratioInfo
- Publication number
- JPH02205628A JPH02205628A JP2616489A JP2616489A JPH02205628A JP H02205628 A JPH02205628 A JP H02205628A JP 2616489 A JP2616489 A JP 2616489A JP 2616489 A JP2616489 A JP 2616489A JP H02205628 A JPH02205628 A JP H02205628A
- Authority
- JP
- Japan
- Prior art keywords
- yield ratio
- steel plate
- ceq
- steel
- thick 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 43
- 239000010959 steel Substances 0.000 title claims abstract description 43
- 238000001816 cooling Methods 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 20
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 17
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims abstract description 3
- 229910052804 chromium Inorganic materials 0.000 claims abstract 2
- 229910052759 nickel Inorganic materials 0.000 claims abstract 2
- 229910052758 niobium Inorganic materials 0.000 claims abstract 2
- 229910052720 vanadium Inorganic materials 0.000 claims abstract 2
- 238000000034 method Methods 0.000 claims description 9
- 238000005096 rolling process Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 2
- 239000012535 impurity Substances 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims 1
- 239000000203 mixture Substances 0.000 abstract description 4
- 230000001276 controlling effect Effects 0.000 abstract description 3
- 238000005098 hot rolling Methods 0.000 abstract description 3
- 230000001105 regulatory effect Effects 0.000 abstract description 3
- 229910052802 copper Inorganic materials 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 6
- 239000000126 substance Substances 0.000 description 4
- 229910001566 austenite Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004881 precipitation hardening Methods 0.000 description 2
- 238000005728 strengthening Methods 0.000 description 2
- 238000003466 welding Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は加速冷却型厚肉鋼板の製造法に関し、更に詳し
くは、降伏比の低い板厚４０ｍｍ以上の加速冷却型５０
キロ級鋼板の製造法に関する。DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing an accelerated cooling type thick-walled steel plate, and more specifically to an accelerated cooling type 50 with a plate thickness of 40 mm or more and a low yield ratio.
Concerning the manufacturing method of kilo-class steel plate.
（従来の技術及び解決しようとする課題）従来、鉄骨建
築用の厚肉５０キロ級鋼板は、焼きならし処理により製
造されているが、Ｃｅｑ（炭素当量）が高いので、溶接
低温割れ防止のために予熱を行い、また溶接継手靭性を
確保するために入熱量を制限する等、溶接施工に際して
問題があった・
一方、鋼板の溶接性、溶接継手靭性を改善する方法とし
て、制御圧延後の冷却過程において、鋼板を水冷するこ
とによって強度を高くし、更に靭性も向上することが可
能な加速冷却法が開発され、Ｃｅｑの低い鋼板を製造す
ることが可能となってきた。(Prior art and problems to be solved) Conventionally, thick 50 kg steel plates for steel frame construction have been manufactured by normalizing treatment, but since the Ceq (carbon equivalent) is high, it is difficult to prevent welding cold cracking. There were problems during welding work, such as preheating to ensure the weld joint toughness, and limiting the amount of heat input to ensure the weld joint toughness.On the other hand, as a method to improve the weldability of steel plates and the weld joint toughness, In the cooling process, an accelerated cooling method has been developed that can increase the strength and further improve the toughness by cooling the steel plate with water, and it has become possible to manufacture a steel plate with a low Ceq.
しかしながら、低Ｃｅｑの加速冷却型厚肉５０キロ級鋼
板は、溶接性及び溶接継手靭性は良好であるものの、耐
震設計上の安全性確保のために要求される降伏比が８０
％以上と高いため、塑性変形能が低い、したがって、従
来のこのような加速冷却型鋼板は、鉄骨建築用としては
適用し難いという問題があった。However, although the weldability and weld joint toughness of low Ceq accelerated cooling type thick 50kg steel plates are good, the yield ratio required to ensure safety in seismic design is 80.
% or more, the plastic deformability is low.Therefore, such conventional accelerated cooling type steel sheets have a problem that it is difficult to apply them to steel frame construction.
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、低降伏比の加速冷却型厚肉５０キロ
級鋼板を製造する方法を提供することを目的とするもの
である。The present invention was made in order to solve the problems of the prior art described above, and an object of the present invention is to provide a method for manufacturing an accelerated cooling type thick 50 kg class steel plate with a low yield ratio. .
（課題を解決するための手段）
前記問題点を解決するため１本発明者は、加速冷却型厚
肉鋼板の成分、製造条件について鋭意研究を重ねた結果
、降伏比７５％以下の低降伏比の加速冷却型厚肉５０キ
ロ級鋼板を製造し得る方法を開発し、本発明をなしたも
のである。(Means for Solving the Problems) In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive research on the composition and manufacturing conditions of accelerated cooling thick steel plates, and have developed a material with a low yield ratio of 75% or less. The present invention was achieved by developing a method for manufacturing accelerated cooling type thick-walled 50 kg steel plates.
すなわち、本発明は、Ｃ：０．０５〜０．２０％。That is, in the present invention, C: 0.05 to 0.20%.
ｓｉ：ｏ、ｏ ５〜０．６０％、Ｍｎ：０．５〜２．０
％及びＴｉ：Ｏ，ＯＯ５〜０．０３０％を含有し、かつ
。si: o, o 5-0.60%, Mn: 0.5-2.0
% and Ti:O,OO5-0.030%, and.
炭素当量（Ｃｅｑ）：０．３４〜０．４２％であり、必
要に応じて更に、Ｃｕ量０．５０％、Ｎ１≦１．０％。Carbon equivalent (Ceq): 0.34 to 0.42%, and if necessary, further Cu amount 0.50%, N1≦1.0%.
Ｃｒ≦０．５０％、Ｍｏ≦０．５０％、■≦０．１０％
及びＮｂ≦０．０３０％のうちの１種又は２種以上を含
有し、残部がＦｅ及び不可避的不純物からなる鋼を加熱
後、８００〜９００℃の温度において仕上圧延を行い、
その後、Ｃｅｑに応じた次式％式％）
を満たす冷却速度（ＣＲ）にて４００〜５５０℃の温度
まで冷却し、フェライト分率を１０〜４０％に制御する
ことを特徴とする板厚４０ｍｍ以上の低降伏比加速冷却
型５０キロ級鋼板の製造法を要旨とするものである。Cr≦0.50%, Mo≦0.50%, ■≦0.10%
and Nb≦0.030%, and the remainder is Fe and unavoidable impurities. After heating, finish rolling is performed at a temperature of 800 to 900 ° C.
Thereafter, it is cooled to a temperature of 400 to 550°C at a cooling rate (CR) that satisfies the following formula (% formula %) according to Ceq, and the ferrite fraction is controlled to 10 to 40%. The gist of the present invention is the method for manufacturing a 50 kg class steel plate with a low yield ratio accelerated cooling type as described above.
以下に本発明を更に詳細に説明する。The present invention will be explained in more detail below.
（作用）
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。(Function) First, the reason for limiting the chemical components in the present invention will be explained.
Ｃ：
Ｃは強度上昇に寄与する元素であるが、 ０．０５％未
満では強度を確保することが困難であり、また０、２０
％を超えて多量に含有すると鋼の靭性及び溶接性を劣化
させる。したがって、Ｃ量は０．０５〜０．２０％の範
囲とする。C: C is an element that contributes to increasing strength, but if it is less than 0.05%, it is difficult to ensure strength, and if it is less than 0.05%, it is difficult to maintain the strength.
If the content exceeds %, the toughness and weldability of the steel will deteriorate. Therefore, the amount of C is set in the range of 0.05 to 0.20%.
Ｓｉ：
Ｓｉは脱酸のために必須の元素であるが、０．０５％未
満では脱酸効果が少なく、また０、６０％を超えて多量
に含有すると溶接性を劣化させる。Si: Si is an essential element for deoxidation, but if it is less than 0.05%, the deoxidation effect is small, and if it is contained in a large amount exceeding 0.60%, weldability will deteriorate.
したがって、Ｓｉ量は０．０５〜０．６０％の範囲とす
る。Therefore, the amount of Si is set in the range of 0.05 to 0.60%.
Ｍｎ：
Ｍｎは鋼の強度及び靭性を確保するために必要な元素で
あるが、０．５％未満ではこのような効果は少なく、ま
た２、０％を超えて多量に含有すると溶接性を劣化させ
、かつ、靭性も劣化する。Mn: Mn is an element necessary to ensure the strength and toughness of steel, but if it is less than 0.5%, this effect is small, and if it is contained in a large amount exceeding 2.0%, it deteriorates weldability. In addition, the toughness also deteriorates.
したがって、Ｍｎ量は０．５〜２．０％の範囲とする。Therefore, the amount of Mn is set in the range of 0.5 to 2.0%.
Ｔｉ：
Ｔｉはオーステナイト粒の粗大化を防止するために有効
であり、本発明法のように仕上げ圧延後空冷等の冷却を
行う場合には極めて有効な元素である。しかし、ｏ、ｏ
ｏｓ％未満ではこのような効果を発揮することができず
、また０、０３０％を超えて多量に含有すると溶接継手
靭性を劣化させる。したがって、Ｔｉ量は０．００５〜
０．０３０％の範囲とする。Ti: Ti is effective for preventing coarsening of austenite grains, and is an extremely effective element when cooling such as air cooling is performed after finish rolling as in the method of the present invention. However, o, o
If the content is less than os%, such an effect cannot be exhibited, and if the content exceeds 0.030%, the toughness of the welded joint will deteriorate. Therefore, the amount of Ti is 0.005~
The range is 0.030%.
以上の元素を必須成分とするが、要求される鋼の特性に
応じて、以下に説明する元素の１種又は２種以上を含有
させることができる。Although the above elements are essential components, one or more of the elements described below can be included depending on the required characteristics of the steel.
Ｃｕ：
Ｃｕは強度上昇に有効な元素であるが、０．５０％を超
えて多量に含有すると熱間加工時に表面割れが発生し、
溶接性を劣化させる。したがって、Ｃｕ量は０．５０％
以下とする。なお、含有量が０゜０１％以下ではこのよ
うな効果は期待し難いので０．０１％以上が望ましい。Cu: Cu is an effective element for increasing strength, but if it is contained in a large amount exceeding 0.50%, surface cracking will occur during hot working.
Deteriorates weldability. Therefore, the amount of Cu is 0.50%
The following shall apply. It should be noted that if the content is 0.01% or less, it is difficult to expect such an effect, so a content of 0.01% or more is desirable.
Ｎｉ：
Ｎ１は鋼の焼入れ性及び靭性向上に有効な元素であるが
、１．０％を超えて含有するとかＮる効果は飽和し、経
済的にも無駄である。したがって、Ｎｉ量は１．０％以
下とする。なお、含有量が０゜０１％以下ではこのよう
な効果は期待し難いので、０．０１％以上が望ましい。Ni: N1 is an effective element for improving the hardenability and toughness of steel, but if it is contained in an amount exceeding 1.0%, the effect of N is saturated and is economically wasteful. Therefore, the amount of Ni is set to 1.0% or less. It should be noted that if the content is less than 0.01%, it is difficult to expect such an effect, so the content is preferably 0.01% or more.
Ｃｒ：
Ｃｒは鋼の焼入れ性及び耐蝕性に有効な元素であるが、
０．５０％を超えると溶接性が劣化するので、Ｃｒ量は
０．５０％以下とする。なお、含有量が０．０５％以下
では焼入れ性が悪くなるので、０．０５％以上が望まし
い。Cr: Cr is an effective element for hardenability and corrosion resistance of steel,
If it exceeds 0.50%, weldability deteriorates, so the Cr content is set to 0.50% or less. Note that if the content is less than 0.05%, the hardenability deteriorates, so it is desirable that the content is 0.05% or more.
Ｍｏ：
Ｍｏは焼入れ性に有効な元素であるが、０．５０％を超
えると溶接性が劣化するようになる。したがって、Ｍｏ
量は０．５０％以下とする。なお、含有量が０．０８％
以下では焼入れによる強化効果は期待し難くなるので、
０．０８％以上が望ましい。Mo: Mo is an effective element for hardenability, but if it exceeds 0.50%, weldability will deteriorate. Therefore, Mo
The amount shall be 0.50% or less. In addition, the content is 0.08%
In the following conditions, it is difficult to expect the strengthening effect of quenching, so
0.08% or more is desirable.
■＝
■は析出硬化による強度上昇に有効な元素であるが、０
．１０％を超えて含有すると溶接性が劣化するので、Ｖ
量は０．１０％以下とする。なお。■= ■ is an element effective in increasing strength through precipitation hardening, but 0
．． If the content exceeds 10%, weldability deteriorates, so V
The amount shall be 0.10% or less. In addition.
含有量が０．０１％以下ではこのような効果は殆ど期待
できない。If the content is 0.01% or less, almost no such effect can be expected.
Ｎｂ：
Ｎｂは析出硬化及び変態強化による強度上昇及び結晶粒
の微細化による靭性の向上を図ることができ、したがっ
て、炭素当量（Ｃａｑ）を低減でき、特に、厚肉鋼板の
溶接性及び溶接継手靭性の改善に有効な元素である。し
かし、０．０３０％を超えて多量に含有すると溶接継手
靭性を劣化させるので、Ｎｂ量は０．０３０％以下とす
る。なお、０゜０Ｏ５％以下ではこのような効果を期待
し難いので、０．００５％以上が望ましい。Nb: Nb can increase strength through precipitation hardening and transformation strengthening, and improve toughness through refinement of crystal grains. Therefore, it can reduce carbon equivalent (Caq), and particularly improves the weldability of thick steel plates and welded joints. It is an effective element for improving toughness. However, if it is contained in a large amount exceeding 0.030%, the toughness of welded joints will deteriorate, so the amount of Nb is set to 0.030% or less. Note that it is difficult to expect such an effect if the content is 0°0O5% or less, so a content of 0.005% or more is desirable.
但し、以上の元素は、溶接性の指標として使用される炭
素当量（Ｃｅｑ）が０．３４〜０．４２％の範囲となる
ように含有させる必要がある。すなわち、硬化性を抑制
するためにはＣｅｑ≦０．４２％であることが必要であ
り、一方、継手部の軟化を抑制するためにはＣｅｑ≧０
．３４％が必要である。However, the above elements need to be contained so that the carbon equivalent (Ceq) used as an index of weldability is in the range of 0.34 to 0.42%. That is, in order to suppress hardenability, it is necessary that Ceq≦0.42%, and on the other hand, in order to suppress softening of the joint part, Ceq≧0.
．． 34% is required.
なお、炭素当量（Ｃｅｑ）は、次式 ０式％ にて定義される。The carbon equivalent (Ceq) is calculated using the following formula: 0 formula% Defined in
次に本発明法における圧延条件及び冷却条件について説
明する。Next, rolling conditions and cooling conditions in the method of the present invention will be explained.
上記化学成分を有する鋼については、適宜の温度に加熱
した後、熱間圧延を行うが、８００〜９００℃の温度に
おいて仕上圧延を行う必要がある。Steel having the above chemical components is hot rolled after being heated to an appropriate temperature, but it is necessary to perform finish rolling at a temperature of 800 to 900°C.
仕上温度が８００℃未満の場合は音響異方性が大きくな
り、また９００℃を超えるとオーステナイトが粗粒とな
り、焼入性が増大し、降伏比は高く、靭性も劣化するの
で好ましくない。If the finishing temperature is less than 800°C, the acoustic anisotropy will increase, and if it exceeds 900°C, the austenite will become coarse grained, hardenability will increase, yield ratio will be high, and toughness will deteriorate, which is not preferable.
熱間圧延後、冷却するが、その冷却速度は降伏比を制御
するうえで重要な製造因子であるので、Ｃｅｑに応じた
適正な範囲の冷却速度で冷却する必要がある。After hot rolling, it is cooled, and since the cooling rate is an important manufacturing factor in controlling the yield ratio, it is necessary to cool at a cooling rate within an appropriate range depending on Ceq.
すなわち、フェライト分率に及ぼす冷却速度（ＣＲ）及
び炭素当量（Ｃｅｑ）の影響について調査した結果（−
例として第１図を示す）、冷却速度は炭素当量に応じて
適正な範囲があり、その範囲は次式
％式％）
を満足する冷却速度であることが判明した。この範囲よ
り高い冷却速度では焼入性が増し、フェライト分率が１
０％未満となり、降伏比（ＹＲ＝（降伏強さｙ ｐ）／
（引張強さＴＳ））が高くなる。一方。That is, as a result of investigating the influence of cooling rate (CR) and carbon equivalent (Ceq) on ferrite fraction (-
It was found that the cooling rate has an appropriate range depending on the carbon equivalent, and that the range is a cooling rate that satisfies the following formula (%). At cooling rates higher than this range, hardenability increases and the ferrite fraction decreases to 1.
It becomes less than 0%, and the yield ratio (YR=(yield strength y p)/
(Tensile strength TS)) increases. on the other hand.
この範囲より低い冷却速度ではフェライト分率が４０％
超えとなり、ＴＳの確保ができない。したがって、冷却
速度は前記式（１）を満足する範囲とする。If the cooling rate is lower than this range, the ferrite fraction will be 40%.
It will exceed the limit and it will not be possible to secure a TS. Therefore, the cooling rate is set within a range that satisfies the above formula (1).
また、冷却停止温度は、４００℃未満では水素欠陥によ
る超音波欠陥が生じ、また５５０℃を超えると強度上昇
を期待することができない。したがって、冷却停止温度
は４００〜５５０℃の範囲とし、この温度まで上記冷却
速度で冷却する。Further, if the cooling stop temperature is less than 400°C, ultrasonic defects will occur due to hydrogen defects, and if it exceeds 550°C, no increase in strength can be expected. Therefore, the cooling stop temperature is set in the range of 400 to 550°C, and cooling is performed to this temperature at the above cooling rate.
かくして得られる鋼板において、ミクロ組織におけるフ
ェライト分率は降伏比（ＹＲ）とよい相関があることが
判明した。すなわち、第２図に実験結果の一例として引
張強さ（ＴＳ）と降伏比（ＹＲ）の関係を示すように、
ＹＲ≦７５％の低降伏比を得るためには、このフェライ
ト分率を１０％以上にする必要がある。一方、フェライ
ト分率が４０％を超えるとＴＳ≧５０ ｋｇｆ ／ ａ
ｍ”を確保するのが困難となる。したがって、フェライ
ト分率は１０〜４０％の範囲とする。In the steel sheet thus obtained, it was found that the ferrite fraction in the microstructure had a good correlation with the yield ratio (YR). In other words, as shown in Figure 2, which shows the relationship between tensile strength (TS) and yield ratio (YR) as an example of experimental results,
In order to obtain a low yield ratio of YR≦75%, the ferrite fraction needs to be 10% or more. On the other hand, when the ferrite fraction exceeds 40%, TS≧50 kgf/a
m" is difficult to secure. Therefore, the ferrite fraction is set in the range of 10 to 40%.
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供試鋼について、加熱後
、同表に示す条件で圧延、冷却して板厚６０ｍｍの鋼板
を製造した。(Example) Test steel having the chemical components shown in Table 1 was heated, then rolled and cooled under the conditions shown in the same table to produce a steel plate with a thickness of 60 mm.
得られた鋼板について引張特性及び衝撃特性を調べた結
果を同表に併記する。また第２図にフェライト分率をＴ
ＳとＹＲの関係で示す。The results of examining the tensile properties and impact properties of the obtained steel plates are also listed in the same table. In addition, Fig. 2 shows the ferrite fraction T
It is shown by the relationship between S and YR.
第１表及び第２図より明らかなように１本発明鋼Ａ−Ｆ
は、フェライト分率が１０〜４０％の範囲にあり、低降
伏比で引張強さ５０ ｋｇｆ ／ ａ＠”級の強度と良
好な靭性が得られている。As is clear from Table 1 and Fig. 2, 1 Invention Steel A-F
The ferrite fraction is in the range of 10 to 40%, and a tensile strength of 50 kgf/a@'' grade and good toughness are obtained with a low yield ratio.
一方、比較鋼Ｇ−Ｊは、本発明範囲の成分を有するが、
比較鋼Ｇは仕上温度が高く、フェライト分率が低いため
、降伏比が高い、比較鋼Ｈは仕上温度が低く、冷却速度
も低く、フェライト分率が高いため、降伏比が高い。比
較鋼Ｉは冷却速度が高く、フェライト分率が低いため、
降伏比が高い。On the other hand, comparative steel G-J has components within the range of the present invention, but
Comparative steel G has a high finishing temperature and low ferrite fraction, so it has a high yield ratio. Comparative steel H has a low finishing temperature, a low cooling rate, and a high ferrite fraction, so it has a high yield ratio. Comparative steel I has a high cooling rate and a low ferrite fraction, so
High yield ratio.
比較鋼Ｊは冷却速度が低く、フェライト分率が低いため
、降伏比が高い。比較鋼にはＣｅｑが適切でなく、フェ
ライト分率が高いため、ＴＳが充分でない。Comparative Steel J has a low cooling rate and a low ferrite fraction, so it has a high yield ratio. Ceq is not appropriate for the comparative steel, and the ferrite fraction is high, so TS is insufficient.
【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、化学成分並びに
炭素当量を調整し、圧延、冷却条件を規制し、特に冷却
速度を炭素当量に応じて適切な範囲とするので、降伏比
７５％以下の低降伏比加速冷却型５０キロ級鋼板を得る
ことができる。[Blank below] (Effects of the invention) As detailed above, according to the present invention, the chemical composition and carbon equivalent are adjusted, the rolling and cooling conditions are regulated, and in particular the cooling rate is adjusted appropriately according to the carbon equivalent. In this case, it is possible to obtain a low yield ratio accelerated cooling type 50 kg class steel plate with a yield ratio of 75% or less.
第１図はフェライト分率に及ぼす冷却速度（ＣＲ）及び
炭素当量（Ｃｅｑ）の影響を示す図、第２図はフェライ
ト分率に及ぼす引張強さ（ＴＳ）と降伏比（ＹＲ）の関
係を示す図である。
特許出願人 株式会社神戸製鋼所
代理人弁理士 中 村 尚
肩′＃」１
こり（９４）Figure 1 shows the influence of cooling rate (CR) and carbon equivalent (Ceq) on ferrite fraction, and Figure 2 shows the relationship between tensile strength (TS) and yield ratio (YR) on ferrite fraction. FIG. Patent Applicant Kobe Steel Corporation Patent Attorney Hisashi Nakamura '#'1 Stiff (94)
Claims (2)
０％、Ｓｉ：０．０５〜０．６０％、Ｍｎ：０．５〜２
．０％及びＴｉ：０．００５〜０．０３０％を含有し、
かつ、炭素当量（Ｃｅｑ）：０．３４〜０．４２％であ
り、残部がＦｅ及び不可避的不純物からなる鋼を加熱後
、８００〜９００℃の温度において仕上圧延を行い、そ
の後、Ｃｅｑに応じた次式（−１２３×Ｃｅｑ＋４８．
２）≦ＣＲ≦（−１２３×Ｃｅｑ＋５２．２）を満たす
冷却速度（ＣＲ）にて４００〜５５０℃の温度まで冷却
し、フェライト分率を１０〜４０％に制御することを特
徴とする板厚４０ｍｍ以上の低降伏比加速冷却型５０キ
ロ級鋼板の製造法。(1) In weight% (the same applies hereinafter), C: 0.05 to 0.2
0%, Si: 0.05-0.60%, Mn: 0.5-2
．． 0% and Ti: 0.005 to 0.030%,
After heating the steel, which has a carbon equivalent (Ceq) of 0.34 to 0.42%, with the balance consisting of Fe and unavoidable impurities, finish rolling is performed at a temperature of 800 to 900°C, and then, depending on the Ceq, The following formula (-123×Ceq+48.
2) Plate thickness characterized by cooling to a temperature of 400 to 550°C at a cooling rate (CR) that satisfies ≦CR≦(-123×Ceq+52.2) and controlling the ferrite fraction to 10 to 40%. A method for manufacturing 50 kg class steel plates with a diameter of 40 mm or more and a low yield ratio accelerated cooling type.
％、Ｃｒ≦０．５０％、Ｍｏ≦０．５０％、Ｖ≦０．１
０％及びＮｂ≦０．０３０％のうちの１種又は２種以上
を含有する請求項１に記載の方法。(2) The steel further includes Cu≦0.50% and Ni≦1.0
%, Cr≦0.50%, Mo≦0.50%, V≦0.1
The method according to claim 1, containing one or more of Nb 0% and Nb≦0.030%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2616489A JPH02205628A (en) | 1989-02-04 | 1989-02-04 | Production of accelerated cooling type thick steel plate with low yield ratio |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2616489A JPH02205628A (en) | 1989-02-04 | 1989-02-04 | Production of accelerated cooling type thick steel plate with low yield ratio |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02205628A true JPH02205628A (en) | 1990-08-15 |
Family
ID=12185912
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2616489A Pending JPH02205628A (en) | 1989-02-04 | 1989-02-04 | Production of accelerated cooling type thick steel plate with low yield ratio |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02205628A (en) |
-
1989
- 1989-02-04 JP JP2616489A patent/JPH02205628A/en active Pending
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