JPH0517825A - Production of cold rolled high strength steel sheet excellent in formability - Google Patents
Production of cold rolled high strength steel sheet excellent in formabilityInfo
- Publication number
- JPH0517825A JPH0517825A JP12080191A JP12080191A JPH0517825A JP H0517825 A JPH0517825 A JP H0517825A JP 12080191 A JP12080191 A JP 12080191A JP 12080191 A JP12080191 A JP 12080191A JP H0517825 A JPH0517825 A JP H0517825A
- Authority
- JP
- Japan
- Prior art keywords
- transformation point
- formability
- steel sheet
- cooling rate
- strength
- 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.)
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- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、自動車などの部材の材
料に好適な引張強さが５０kgf/mm2 以上の成形性に優れ
た高強度冷延鋼板の製造方法に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-strength cold-rolled steel sheet having a tensile strength of 50 kgf / mm 2 or more and excellent in formability, which is suitable for a material for members such as automobiles.
【０００２】[0002]
【従来の技術】近年、地球環境保護の観点から、自動車
を例にとると、省エネルギーや排ガスによる環境汚染の
減少が求められており、その対策として、材料の板厚を
削減して車体の軽量化を図る方法がとられている。材料
の板厚を削減すると、それにともない材料の強度が低下
するので、車体の強度を低下させることなく、軽量化を
図るためには、高強度の薄鋼板が是非とも必要である。
しかしながら、強度が増加するにともない延性が低下す
るため、高強度薄鋼板は成形性に劣るという欠点があ
る。2. Description of the Related Art In recent years, from the viewpoint of protecting the global environment, taking an automobile as an example, there has been a demand for energy saving and reduction of environmental pollution due to exhaust gas. The method to achieve If the plate thickness of the material is reduced, the strength of the material is reduced accordingly. Therefore, in order to reduce the weight without lowering the strength of the vehicle body, a high strength thin steel plate is absolutely necessary.
However, since the ductility decreases as the strength increases, the high-strength thin steel sheet has the drawback of being inferior in formability.
【０００３】自動車用鋼板はプレスなどの冷間成形加工
を経て使用されるのが一般であり、鋼板には優れた成形
性が求められる。高強度薄鋼板はこの成形性に難点があ
るため、成形加工の厳しい用途には不向きであり、その
用途は限られたものとなる。Steel sheets for automobiles are generally used after undergoing cold forming such as pressing, and the steel sheets are required to have excellent formability. Since the high-strength thin steel sheet has a difficulty in this formability, it is not suitable for applications where severe forming processing is required, and its applications are limited.
【０００４】このようなことから、良好な成形性を有す
る高強度の薄鋼板が望まれている。For these reasons, a high-strength thin steel sheet having good formability is desired.
【０００５】このような薄鋼板としては、Ｃｒ、Ｔｉ、
Ｖ、Ｍｏ、Ｎｂ、Ｂ等の合金元素を多量に使用して強度
と同時に延性を向上させたものがあるが、このような高
価な元素の多量使用はコスト面で不利である。特開昭53
−22812 号公報には、このような高価な元素を含有しな
い鋼から加工性に優れた高強度冷延鋼板を製造する方法
が提案されている。この方法とは、Ｃ：0.03〜0.30％、
Ｍｎ：0.7 〜3.0 ％、Ｓｉ：0.5 ％以下の鋼を熱間圧延
後、Ａ1 変態点〜Ａ3 変態点の間の温度範囲で捲き取
り、冷間圧延を施し、ついでＡ1 変態点〜Ａ3 変態点で
１５秒の焼鈍を行った後、１℃／sec 以上で冷却するも
のであり、熱間圧延後の熱延鋼板をＡ1 変態点〜Ａ3 変
態点の間の温度範囲で捲き取ることにより、ＣおよびＭ
ｎが十分に濃化されたオーステナイト相が適宜に分散
し、のちの短時間の連続焼鈍後の冷却で複合組織が形成
されることにより、強度と同時に延性も向上する。しか
し、捲き取り温度がＡ3 変態点に近くなるほど、捲き取
り後の徐冷で形成されるフェライト結晶粒が粗大化し、
引張強度が低下したり、板内異方性が大きくなって加工
性が劣化したりするため、特開昭53−22812 号公報に記
載の製造方法の場合には、捲き取り温度を高くとったと
きには所望の特性が得られないことがある。Such thin steel sheets include Cr, Ti,
Although some alloy elements such as V, Mo, Nb and B are used in a large amount to improve the strength and the ductility at the same time, the large amount of such an expensive element is disadvantageous in cost. JP53
No. 22812 proposes a method for producing a high-strength cold-rolled steel sheet having excellent workability from such a steel containing no expensive element. With this method, C: 0.03 to 0.30%,
After hot rolling a steel having Mn: 0.7 to 3.0% and Si: 0.5% or less, it is rolled up in a temperature range between the A 1 transformation point and the A 3 transformation point, cold rolled, and then the A 1 transformation point. After annealing for 15 seconds at the A 3 transformation point, it is cooled at 1 ° C./sec or more, and the hot-rolled steel sheet after hot rolling is in a temperature range between the A 1 transformation point and the A 3 transformation point. By winding up, C and M
The austenite phase in which n is sufficiently concentrated is appropriately dispersed, and a composite structure is formed by subsequent cooling after continuous annealing for a short time, whereby the ductility is improved at the same time as the strength. However, the closer the winding temperature is to the A 3 transformation point, the coarser the ferrite crystal grains formed by the slow cooling after winding,
In the case of the manufacturing method described in Japanese Patent Laid-Open No. 53-22812, the winding temperature is set high because the tensile strength decreases and the in-plate anisotropy increases and the workability deteriorates. Sometimes, desired characteristics may not be obtained.
【０００６】[0006]
【発明が解決しようとする課題】本発明の課題は上記の
諸問題を解消することにあり、詳しくは、Ｃｒ、Ｔｉ、
Ｖ、Ｍｏ、Ｎｂ、Ｂ等の高価な合金元素を使用すること
なく、成形性に優れ、引張強さが５０kgf/mm2 以上の高
強度冷延鋼板を製造することができる方法を提供するこ
とにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and more specifically, Cr, Ti,
To provide a method capable of producing a high-strength cold-rolled steel sheet having excellent formability and a tensile strength of 50 kgf / mm 2 or more without using expensive alloy elements such as V, Mo, Nb, and B. It is in.
【０００７】[0007]
【課題を解決するための手段】本発明者は、素材として
上記のような高価な元素を含まずＣ、ＳｉおよびＭｎの
含有量を調整した鋼を使用し、これを熱間圧延した後の
捲き取り温度を適正に調整すると、フェライト結晶粒の
粗大化が抑制され、加工性の劣化が生じないこと、およ
び冷間圧延後の焼鈍の冷却過程に２段冷却法を採用し、
一定の中間温度までは冷却速度の小さい徐冷却で、それ
以降は冷却速度の大きい急冷却で行うと、徐冷却で｛１
１１｝フェライト結晶粒の成長が促進され、急冷却で急
冷変態相が生成し、成形性と同時に強度も向上すること
を見出した。Means for Solving the Problems The present inventor uses, as a raw material, steel in which the contents of C, Si and Mn are adjusted without containing the above-mentioned expensive elements, and is used after hot rolling. If the winding temperature is properly adjusted, coarsening of ferrite crystal grains is suppressed, workability does not deteriorate, and a two-stage cooling method is adopted in the cooling process of annealing after cold rolling,
Slow cooling with a low cooling rate up to a certain intermediate temperature and rapid cooling with a high cooling rate thereafter will result in slow cooling {1
It has been found that the growth of 11} ferrite crystal grains is promoted, a quenching transformation phase is generated by quenching, and the formability and strength are improved at the same time.
【０００８】ここに本発明は「重量％で、Ｃ：0.05〜0.
10％、Ｓｉ：0.5 〜1.0 ％、Ｍｎ：1.0 〜2.0 ％を含有
し、残部がＦｅおよび不可避不純物からなる鋼を熱間圧
延後、 660〜740 ℃の温度範囲で捲き取り、冷間圧延を
施し、Ａ1 変態点〜Ａ3 変態点の温度域で30〜120 秒間
保持する焼鈍を行い、ついで下記（１）式を満足する、
中間温度（Ｔ℃）まで平均冷却速度５℃／sec 以下で冷
却し、中間温度から 200℃以下まで平均冷却速度２０℃
／sec 以上で冷却することを特徴とする成形性に優れた
高強度冷延鋼板の製造方法。In the present invention, "% by weight, C: 0.05-0.
Steel containing 10%, Si: 0.5 to 1.0%, Mn: 1.0 to 2.0%, the balance being Fe and unavoidable impurities is hot-rolled, then rolled up in a temperature range of 660 to 740 ° C, and cold-rolled. subjecting performs annealing to hold 30 to 120 seconds at a temperature range of a 1 transformation point to a 3 transformation point, then the following formula (1) is satisfied,
Cools down to an intermediate temperature (T ° C) at an average cooling rate of 5 ° C / sec or less, and from an intermediate temperature to 200 ° C or less, an average cooling rate of 20 ° C.
A method for producing a high-strength cold-rolled steel sheet excellent in formability, characterized by cooling at a speed of at least 1 sec.
【０００９】 Ａ1 変態点≦Ｔ℃≦Ａ1 変態点＋100 ・・・・・（１）A 1 transformation point ≦ T ° C. ≦ A 1 transformation point + 100 (1)
【００１０】[0010]
【作用】つぎに、本発明の方法において、素材鋼の化学
成分および製造条件を上記のとおりに数値限定した理由
を説明する。Next, the reason why the chemical composition of the raw steel and the production conditions are numerically limited as described above in the method of the present invention will be explained.
【００１１】Ａ） 素材鋼の化学成分 (a) Ｃ Ｃは強度を確保するために添加するが、その含有量が0.
05％未満では所望の強度が得られず、0.10％を超えると
成形性に劣るようになることから、その含有量を0.05〜
0.10％と定めた。A) Chemical composition of raw steel (a) C C is added to ensure strength, but its content is 0.
If it is less than 05%, the desired strength cannot be obtained, and if it exceeds 0.10%, the moldability becomes poor.
It was set at 0.10%.
【００１２】(b) Ｓｉ Ｓｉは固溶強化をとおして鋼の強度を高める作用があ
る。また、ＳｉはＣに比べ、その添加による伸びの劣化
が小さいという利点を有している。しかし、その含有量
が 0.5％未満では強度の上昇が小さく、 1.0％を超える
と脱スケール性が劣化し、鋼板表面の酸化が問題となる
ことから、その含有量を 0.5〜 1.0％と定めた。(B) Si Si has the function of increasing the strength of steel through solid solution strengthening. In addition, Si has an advantage over Si in that deterioration of elongation due to its addition is small. However, if the content is less than 0.5%, the increase in strength is small, and if it exceeds 1.0%, the descaling property deteriorates and oxidation of the steel sheet surface poses a problem, so the content was set to 0.5 to 1.0%. ..
【００１３】(c) Ｍｎ Ｍｎも強度を確保するために添加するが、その含有量が
1.0％未満では強度の上昇が小さく、 2.0％を超えると
成形性が劣化するようになることから、その含有量を
1.0〜 2.0％と定めた。(C) Mn Mn is also added to secure the strength, but its content is
If it is less than 1.0%, the increase in strength is small, and if it exceeds 2.0%, the formability deteriorates.
It was set at 1.0 to 2.0%.
【００１４】素材の鋼は、上記の成分のほか、残部のＦ
ｅおよび不可避不純物からなり、転炉、平炉、電気炉な
どで溶製され、鋼塊法または連続鋳造法によってスラブ
とされた後、熱間圧延に供される。In addition to the above components, the steel used as the raw material is the balance F
e) and unavoidable impurities, and is melted in a converter, open furnace, electric furnace, etc., made into a slab by the steel ingot method or continuous casting method, and then subjected to hot rolling.
【００１５】Ｂ） 製造条件 (a) 熱間圧延後の捲き取り温度 高強度でしかも成形性に優れた鋼板とするためには、急
冷によって生成する急冷変態相中のＣを熱間圧延の捲き
取り段階または冷間圧延後の焼鈍段階において、オース
テナイト相中に濃化させ、フェライト相中のＣ濃度を低
下させるだけでなく、金属組織自体を微細にして板内面
異方性を小さくしてやる必要がある。B) Manufacturing conditions (a) Winding temperature after hot rolling In order to obtain a steel sheet having high strength and excellent formability, C in the quenching transformation phase generated by quenching is wound by hot rolling. In the taking step or the annealing step after cold rolling, it is necessary not only to reduce the C concentration in the ferrite phase by concentrating it in the austenite phase but also to make the metal structure itself fine and reduce the in-plane anisotropy of the plate. is there.
【００１６】上記組成の鋼を熱間圧延した後、 660〜 7
40℃の温度範囲で捲き取ることにより、ＣおよびＭｎが
十分に濃化したオーステナイト相が適宜に分散したもの
となる。熱延鋼板の段階で、このような組織にしておけ
ば冷間圧延後の焼鈍において、オーステナイト相中へＣ
およびＭｎを拡散させて濃化をはかる必要がないので、
焼鈍の冷却過程における急冷で容易に急冷変態相を生成
させることができる。After hot rolling the steel having the above composition, 660 to 7
By winding in the temperature range of 40 ° C., the austenite phase in which C and Mn are sufficiently concentrated becomes appropriately dispersed. If such a structure is provided at the stage of hot-rolled steel sheet, in annealing after cold rolling, C is introduced into the austenite phase.
Since it is not necessary to diffuse Mn and Mn for concentration,
A quenching transformation phase can be easily generated by quenching in the cooling process of annealing.
【００１７】また、このような捲き取り温度範囲内であ
れば、捲き取り後の徐冷でフェライト相が粗大化するこ
とがないので、冷間圧延後の金属組織は微細なものとな
る。Further, within such a winding temperature range, the ferrite phase does not become coarse by slow cooling after winding, so that the metal structure after cold rolling becomes fine.
【００１８】しかし、捲き取り温度が 740℃を超えると
フェライト相が粗大化し、成形性が劣化するようにな
る。一方、 660℃より低い捲き取り温度ではフェライト
相中のＣ濃度の低下が小さい。However, when the coiling temperature exceeds 740 ° C., the ferrite phase becomes coarse and the formability deteriorates. On the other hand, when the coiling temperature is lower than 660 ° C, the decrease in C concentration in the ferrite phase is small.
【００１９】 (b) 冷間圧延後の焼鈍温度および保持時間 焼鈍の目的はフェライト相中にオーステナイト相を形成
させ、フェライト相中のＣ濃度を低下させることにあ
る。そのためには、冷間圧延後の焼鈍はＡ1 変態点〜Ａ
3 変態点の温度域で30〜120 秒間保持する条件で行う必
要がある。(B) Annealing temperature and holding time after cold rolling The purpose of annealing is to form an austenite phase in the ferrite phase and reduce the C concentration in the ferrite phase. For that purpose, the annealing after cold rolling should be performed at the A 1 transformation point to A 1
It must be performed under the condition of holding for 30 to 120 seconds in the temperature range of 3 transformation points.
【００２０】焼鈍温度がＡ3 変態点より高い場合は、オ
ーステナイト相の比率が過度に高くなってｒ値が低下
し、Ａ1 変態点より低い場合は、フェライト相の再結晶
が不十分となって成形性が著しく低下する。一方、Ａ1
変態点〜Ａ3 変態点の温度域で焼鈍してもその保持時間
が30秒未満であると、フェライト相中のＣ濃度の低下が
小さく、 120秒を超えるとフェライト相中のＣ濃度の低
下以外に、オーステナイト粒の成長も進行し、いずれの
場合も良好な成形性が得られなくなる。When the annealing temperature is higher than the A 3 transformation point, the ratio of the austenite phase becomes excessively high and the r value decreases, and when it is lower than the A 1 transformation point, recrystallization of the ferrite phase becomes insufficient. And the formability is significantly reduced. On the other hand, A 1
If the holding time is less than 30 seconds even after annealing in the temperature range from transformation point to A 3 transformation point, the decrease in C concentration in the ferrite phase is small, and if it exceeds 120 seconds, the decrease in C concentration in the ferrite phase. Besides, the growth of austenite grains also progresses, and in any case, good formability cannot be obtained.
【００２１】(c) 焼鈍後の冷却速度 焼鈍後の冷却は、フェライト｛１１１｝再結晶集合組織
を発達させるとともに急冷変態相を生成させることにあ
る。熱延鋼板の段階では、｛１１１｝フェライト結晶粒
が少ないため、良好な成形性を確保するためには冷間圧
延または焼鈍による再結晶等により｛１１１｝フェライ
ト結晶粒を増加させる必要がある。焼鈍で｛１１１｝フ
ェライト結晶粒を増加させるとともに所望の高強度を得
るに必要な急冷変態相を生成させるためには、焼鈍後の
冷却はＡ1 変態点〜（Ａ1 変態点＋100)の、中間温度ま
で平均冷却速度５℃／sec 以下の徐冷とし、中間温度か
ら200℃以下の温度まで平均冷却速度２０℃／sec 以上
の急冷とする必要がある。(C) Cooling Rate After Annealing Cooling after annealing is to develop a ferrite {111} recrystallized texture and generate a rapidly transformed phase. Since the amount of {111} ferrite crystal grains is small at the stage of hot-rolled steel sheet, it is necessary to increase the number of {111} ferrite crystal grains by cold rolling or recrystallization by annealing to secure good formability. In order to increase the {111} ferrite crystal grains by annealing and to generate a quenching transformation phase necessary for obtaining a desired high strength, the cooling after annealing is performed at A 1 transformation point to (A 1 transformation point +100), It is necessary to perform gradual cooling with an average cooling rate of 5 ° C / sec or less up to the intermediate temperature, and quenching with an average cooling rate of 20 ° C / sec or more from the intermediate temperature to a temperature of 200 ° C or less.
【００２２】第１段目のＡ1 変態点〜（Ａ1 変態点＋10
0)の、中間温度までの平均冷却速度が５℃／sec を超え
ると、徐冷却の効果が小さく、｛１１１｝の成長が低下
して成形性の向上が小さい。平均冷却速度５℃／sec 以
下の徐冷を（Ａ1 変態点＋100)より高い温度域で終える
と、冷却時間が不十分で｛１１１｝の成長が十分に得ら
ず、平均冷却速度５℃／sec 以下でＡ1 変態点より低い
温度域まで徐冷すると、次の急冷却で急冷変態相の形成
が不十分となり、所望の高強度を得ることができなくな
る。First stage A 1 transformation point to (A 1 transformation point +10
When the average cooling rate up to the intermediate temperature of 0) exceeds 5 ° C./sec, the effect of slow cooling is small, the growth of {111} is reduced, and the improvement in moldability is small. If slow cooling at an average cooling rate of 5 ° C / sec or less is finished in a temperature range higher than (A 1 transformation point +100), the cooling time is insufficient and {111} growth is not sufficiently obtained, and the average cooling rate is 5 ° C. If the material is gradually cooled to a temperature range lower than the A 1 transformation point for less than 1 sec / sec, the rapid transformation phase will not be sufficiently formed in the next quenching, and the desired high strength cannot be obtained.
【００２３】一方、第２段目の中間温度から 200℃以下
の温度までの平均冷却速度が２０℃／sec 未満である
と、本発明で使用する成分系の鋼では所望の高強度を得
るに必要な急冷変態相が十分に生成されない。On the other hand, if the average cooling rate from the intermediate temperature of the second stage to a temperature of 200 ° C. or less is less than 20 ° C./sec, the composition steel used in the present invention can obtain a desired high strength. The required quenching transformation phase is not sufficiently generated.
【００２４】[0024]
【実施例】転炉にて溶製した表１に示す化学成分のスラ
ブを板厚 2.9mmまで熱間圧延した後、650 〜750 ℃の温
度でコイルに捲き取り、酸洗した後、タンデム式冷間圧
延機にて板厚0.75mmまで冷間圧延を行った。次いで、連
続焼鈍炉にて650 〜880 ℃×30〜120 分保持する焼鈍を
施した後、第１段のＡ1 変態点〜（Ａ1 変態点＋100)
の、中間温度まで平均冷却速度１〜３℃／sec で、第２
段の中間温度から 200℃以下の温度まで平均冷却速度20
〜 100℃／sec で冷却した。なお、比較例３は途中で冷
却速度を変えずに、焼鈍後は平均冷却速度 100℃／sec
で 200℃以下の温度まで冷却した。比較例４は（Ａ1 変
態点＋100)より高い 840℃まで平均冷却速度３℃／sec
で徐冷し、それ以降は平均冷却速度 100℃／sec で急冷
した。[Example] A slab having the chemical composition shown in Table 1 melted in a converter was hot-rolled to a plate thickness of 2.9 mm, wound into a coil at a temperature of 650 to 750 ° C, pickled, and then tandem type. Cold rolling was performed with a cold rolling mill to a plate thickness of 0.75 mm. Next, after annealing in a continuous annealing furnace for holding at 650 to 880 ° C for 30 to 120 minutes, the first stage A 1 transformation point to (A 1 transformation point + 100)
The average cooling rate of 1 to 3 ° C / sec up to the intermediate temperature
Average cooling rate from intermediate stage temperature to below 200 ℃ 20
Cooled at ~ 100 ° C / sec. In Comparative Example 3, the average cooling rate was 100 ° C./sec after annealing without changing the cooling rate during the process.
And cooled to a temperature below 200 ° C. Comparative Example 4 has an average cooling rate of 3 ° C./sec up to 840 ° C. higher than (A 1 transformation point + 100)
After that, it was gradually cooled, and thereafter, it was rapidly cooled at an average cooling rate of 100 ° C / sec.
【００２５】比較例５はＡ1 変態点より低い 650℃まで
平均冷却速度３℃／sec で徐冷し、それ以降は平均冷却
速度 100℃／sec で急冷した。こうして得られた冷延鋼
板から試験片を切り出し、機械的性質を調べた。その結
果を表２に示す。In Comparative Example 5, 650 ° C., which is lower than the A 1 transformation point, was gradually cooled at an average cooling rate of 3 ° C./sec, and thereafter, it was rapidly cooled at an average cooling rate of 100 ° C./sec. A test piece was cut out from the cold-rolled steel sheet thus obtained, and the mechanical properties were examined. The results are shown in Table 2.
【００２６】表２から、本発明の方法により得られた冷
延鋼板 (本発明例１〜13) はいずれも引張強さが５０kg
f/mm2 以上で、しかも降伏比が低く、 1.0以上のｒ値を
有し、成形性に優れていることがわかる。これに対し
て、鋼の成分組成または製造条件のいずれかが本発明で
規定する範囲から外れている比較例１〜８は、引張強さ
が５０kgf/mm2 未満であったり、引張強さが５０kgf/mm
2 以上であっても、降伏比またはｒ値が悪く、成形性に
劣る。From Table 2, all the cold-rolled steel sheets (Invention Examples 1 to 13) obtained by the method of the present invention have a tensile strength of 50 kg.
It can be seen that the f / mm 2 or more, the yield ratio is low, the r value is 1.0 or more, and the moldability is excellent. On the other hand, in Comparative Examples 1 to 8 in which either the composition of steel or the manufacturing conditions are out of the range specified in the present invention, the tensile strength is less than 50 kgf / mm 2 , or the tensile strength is less than 50 kgf / mm 2. 50 kgf / mm
Even if it is 2 or more, the yield ratio or r value is poor and the formability is poor.
【００２７】[0027]
【表１】 [Table 1]
【００２８】[0028]
【表２】 [Table 2]
【００２９】[0029]
【発明の効果】実施例に示した如く、本発明の方法によ
れば成形性に優れた引張強さが50kgf/mm2 以上の高強度
冷延鋼板を安定して製造することができる。そして、こ
の製造方法で得られる高強度冷延鋼板には、Ｃｒ、Ｔ
ｉ、Ｖ、Ｍｏ、Ｎｂ、Ｂ等の高価な合金元素を使用して
いないので安価である。As shown in the examples, according to the method of the present invention, a high-strength cold-rolled steel sheet excellent in formability and having a tensile strength of 50 kgf / mm 2 or more can be stably manufactured. The high-strength cold-rolled steel sheet obtained by this manufacturing method contains Cr, T
It is inexpensive because no expensive alloy elements such as i, V, Mo, Nb, and B are used.
Claims (1)
〜1.0 ％、Ｍｎ：1.0 〜2.0 ％を含有し、残部がＦｅお
よび不可避不純物からなる鋼を熱間圧延後、 660〜740
℃の温度範囲で捲き取り、冷間圧延を施し、Ａ1 変態点
〜Ａ3 変態点の温度域で30〜120 秒間保持する焼鈍を行
い、ついで下記（１）式を満足する中間温度（Ｔ℃）ま
で平均冷却速度５℃／sec 以下で冷却し、中間温度から
200℃以下まで平均冷却速度２０℃／sec 以上で冷却す
ることを特徴とする成形性に優れた高強度冷延鋼板の製
造方法。 Ａ1 変態点≦Ｔ℃≦Ａ1 変態点＋100 ・・・・・（１）Claims: 1. By weight%, C: 0.05 to 0.10%, Si: 0.5
~ 1.0%, Mn: 1.0 ~ 2.0%, the balance 660 ~ 740 after hot rolling steel consisting of Fe and unavoidable impurities
It is wound in the temperature range of ℃, cold-rolled, annealed for 30 to 120 seconds in the temperature range of A 1 transformation point to A 3 transformation point, and then an intermediate temperature (T ℃) at an average cooling rate of 5 ℃ / sec or less, from the intermediate temperature
A method for producing a high-strength cold-rolled steel sheet having excellent formability, which comprises cooling to 200 ° C or lower at an average cooling rate of 20 ° C / sec or higher. A 1 transformation point ≤ T ° C ≤ A 1 transformation point +100 (1)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12080191A JPH0517825A (en) | 1991-05-27 | 1991-05-27 | Production of cold rolled high strength steel sheet excellent in formability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP12080191A JPH0517825A (en) | 1991-05-27 | 1991-05-27 | Production of cold rolled high strength steel sheet excellent in formability |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0517825A true JPH0517825A (en) | 1993-01-26 |
Family
ID=14795333
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP12080191A Pending JPH0517825A (en) | 1991-05-27 | 1991-05-27 | Production of cold rolled high strength steel sheet excellent in formability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0517825A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100467712B1 (en) * | 2000-08-08 | 2005-01-24 | 주식회사 포스코 | The Manufacturing of Bake Hardening Steels with High Formability |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55131130A (en) * | 1979-03-29 | 1980-10-11 | Sumitomo Metal Ind Ltd | Production of high strength steel material having low yield ratio |
| JPS5745454A (en) * | 1980-09-02 | 1982-03-15 | Fuji Photo Film Co Ltd | Immunochemical measuring method for various minor components |
| JPS5852434A (en) * | 1981-09-21 | 1983-03-28 | Nippon Steel Corp | Production of high strength cold rolled steel plate having excellent weldability and workability |
| JPS58133321A (en) * | 1982-02-01 | 1983-08-09 | Nippon Kokan Kk <Nkk> | Preparation with low yield ratio and high strength steel plate |
-
1991
- 1991-05-27 JP JP12080191A patent/JPH0517825A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55131130A (en) * | 1979-03-29 | 1980-10-11 | Sumitomo Metal Ind Ltd | Production of high strength steel material having low yield ratio |
| JPS5745454A (en) * | 1980-09-02 | 1982-03-15 | Fuji Photo Film Co Ltd | Immunochemical measuring method for various minor components |
| JPS5852434A (en) * | 1981-09-21 | 1983-03-28 | Nippon Steel Corp | Production of high strength cold rolled steel plate having excellent weldability and workability |
| JPS58133321A (en) * | 1982-02-01 | 1983-08-09 | Nippon Kokan Kk <Nkk> | Preparation with low yield ratio and high strength steel plate |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100467712B1 (en) * | 2000-08-08 | 2005-01-24 | 주식회사 포스코 | The Manufacturing of Bake Hardening Steels with High Formability |
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