JPH0665638A - Production method of accelerated cooling high tensile strength steel plate excellent in weldability - Google Patents
Production method of accelerated cooling high tensile strength steel plate excellent in weldabilityInfo
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- JPH0665638A JPH0665638A JP22609592A JP22609592A JPH0665638A JP H0665638 A JPH0665638 A JP H0665638A JP 22609592 A JP22609592 A JP 22609592A JP 22609592 A JP22609592 A JP 22609592A JP H0665638 A JPH0665638 A JP H0665638A
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- cooling
- weldability
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、造船、建築、タンク、
橋梁などに使用される490N/mm2級以上の溶接性の優れた
加速冷却型高張力鋼板の製造方法に関するものである。The present invention relates to shipbuilding, construction, tanks,
The present invention relates to a method for producing an accelerated cooling high-strength steel sheet having excellent weldability of 490 N / mm 2 grade or higher, which is used for bridges and the like.
【０００２】[0002]
【従来の技術】引張強さ490N/mm2級以上の加速冷却型高
張力鋼板は、造船、建築、タンク、橋梁などに使用され
ており、従来の圧延ままの鋼板に比べ加速冷却による強
度上昇の分、炭素当量が低減され溶接性は向上している
ものの、板厚、強度レベルによっては、炭素当量が高く
溶接施工時の低温割れを防止するためには、予熱を行う
必要があった。 2. Description of the Related Art Accelerated cooling type high-strength steel sheets with a tensile strength of 490 N / mm 2 or higher are used in shipbuilding, construction, tanks, bridges, etc., and their strength is increased by accelerated cooling compared to conventional as-rolled steel sheets. However, although the carbon equivalent is reduced and the weldability is improved, depending on the plate thickness and strength level, the carbon equivalent is high and preheating must be performed to prevent cold cracking during welding.
【０００３】このような背景から、加速冷却型高張力鋼
板においても炭素当量の低減による溶接性の改善が強く
求められている。しかし、炭素当量を低減すると強度確
保が困難になるという問題があった。From such a background, even in the accelerated cooling type high strength steel sheet, improvement of weldability by reduction of carbon equivalent is strongly demanded. However, there is a problem that it becomes difficult to secure strength when the carbon equivalent is reduced.
【０００４】[0004]
【発明が解決しようとする課題】本発明は、引張強さ49
0N/mm2級以上の加速冷却型高張力鋼板において、炭素当
量を低減し溶接性を向上させるとともに、所定の強度を
確保する溶接性の優れた加速冷却型高張力鋼板の製造方
法を提供することを目的とするものである。SUMMARY OF THE INVENTION The present invention has a tensile strength of 49
Provided is a method for manufacturing an accelerated cooling high-strength steel sheet excellent in weldability that secures a predetermined strength while reducing the carbon equivalent in an accelerated cooling high-strength steel sheet of 0 N / mm 2 grade or higher and improving the weldability. That is the purpose.
【０００５】[0005]
【課題を解決するための手段】本発明者らは、引張強さ
490N/mm2級以上の高強度を確保しつつ、炭素当量の低減
を達成するために鋭意研究を行った。その結果、従来型
のＡｃｃ（加速冷却：圧延終了後、すみやかにオンライ
ンで水冷を開始し、所定の冷却停止温度まで水冷を行
う）に替えてModifiedＡｃｃ（圧延終了後、所定の温度
までオンラインで空冷した後、加速冷却を開始し、所定
の冷却停止温度まで水冷を行う）とする新型加速冷却法
の適用により、従来の加速冷却法の場合よりも高い強度
を実現し得るという知見を得て本発明に至ったものであ
る。The present inventors have found that the tensile strength
We have conducted intensive research to achieve a reduction in carbon equivalent while ensuring a high strength of 490 N / mm 2 or higher. As a result, the conventional type Accelerated cooling (accelerated cooling: immediately starts water cooling after completion of rolling and performs water cooling up to a predetermined cooling stop temperature) is modified Acc (after completion of rolling, air cooling online at a predetermined temperature. After that, by applying the new accelerated cooling method, in which accelerated cooling is started and water cooling is performed up to a predetermined cooling stop temperature), it was found that higher strength can be achieved than in the case of the conventional accelerated cooling method. It was the invention.
【０００６】このModifiedＡｃｃ法の活用により、高強
度化が可能な分だけ鋼板の炭素当量を低減することがで
きるため、加速冷却型高張力鋼板の溶接性の改善が可能
となるのである。By utilizing the Modified Acc method, the carbon equivalent of the steel sheet can be reduced to the extent that the strength can be increased, so that the weldability of the accelerated cooling type high strength steel sheet can be improved.
【０００７】その第１発明は、C:0.03〜0.20％、 Si:0.
05〜0.50％、 Mn:0.30〜2.50％、Al:0.005〜0.10％を含
有し、残部Feおよび不可避的不純物からなる鋼片を熱間
圧延し、その後下記に示すオンラインでの加速冷却処理
を施す溶接性の優れた加速冷却型高張力鋼板の製造方法
である。 加速冷却処理方法：オンライン新型加速冷却（Modified
Ａｃｃ） ただし、オンライン新型加速冷却：熱間圧延終了後、 5
00〜800 ℃の間の所定の温度まで空冷した後、オンライ
ンで冷却速度10℃/sec以上、冷却停止温度 200℃以上の
加速冷却を行うThe first invention is C: 0.03 to 0.20%, Si: 0.
A steel slab containing 05 to 0.50%, Mn: 0.30 to 2.50%, Al: 0.005 to 0.10% and the balance Fe and unavoidable impurities is hot-rolled, and then subjected to the following online accelerated cooling treatment. This is a method for producing an accelerated cooling type high strength steel sheet having excellent weldability. Accelerated cooling processing method: Online new type accelerated cooling (Modified
Acc) However, online new type accelerated cooling: 5 after hot rolling
After air cooling to a specified temperature between 00 and 800 ° C, accelerated cooling is performed online with a cooling rate of 10 ° C / sec or more and a cooling stop temperature of 200 ° C or more.
【０００８】第２発明は、C:0.03〜0.20％、 Si:0.05〜
0.50％、 Mn:0.30〜2.50％、Al:0.005〜0.10％を含有
し、残部Feおよび不可避的不純物からなる鋼片を熱間圧
延し、その後下記に示すオンラインでの加速冷却処理
と、焼もどしを施す溶接性の優れた加速冷却型高張力鋼
板の製造方法である。 加速冷却処理方法：オンライン新型加速冷却（Modified
Ａｃｃ）＋焼もどし（Ｔ） ただし、オンライン新型加速冷却：熱間圧延終了後、 5
00〜800 ℃の間の所定の温度まで空冷した後、オンライ
ンで冷却速度10℃/sec以上、冷却停止温度 200℃以上の
加速冷却を行う 焼もどし温度：400 ℃点以上Ａc1点未満The second invention is C: 0.03 to 0.20%, Si: 0.05 to
A steel slab containing 0.50%, Mn: 0.30 to 2.50%, Al: 0.005 to 0.10% and the balance Fe and unavoidable impurities is hot-rolled, and then the following online accelerated cooling treatment and tempering are performed. Is a method for producing an accelerated cooling high-strength steel sheet having excellent weldability. Accelerated cooling processing method: Online new type accelerated cooling (Modified
Acc) + tempering (T) However, online new type accelerated cooling: After hot rolling, 5
After air cooling to a specified temperature between 00 and 800 ° C, online accelerated cooling with a cooling rate of 10 ° C / sec or more and a cooling stop temperature of 200 ° C or more Tempering temperature: 400 ° C or more and less than Ac 1 point
【０００９】第３発明は、化学成分として、さらに Cu:
0.05〜1.20％、 Ni:0.05〜3.00％、Cr: 0.05〜1.20％、
Mo:0.05〜1.00％、 V:0.005〜0.08％、Nb:0.005〜0.05
％、B:0.0003〜0.0025％、Ti:0.005〜0.025 ％、Ca:0.0
01〜0.010 ％の内から選んだ１種または２種以上を含有
する請求項１または２記載の溶接性の優れた加速冷却型
高張力鋼板の製造方法である。The third aspect of the present invention further comprises Cu:
0.05 to 1.20%, Ni: 0.05 to 3.00%, Cr: 0.05 to 1.20%,
Mo: 0.05-1.00%, V: 0.005-0.08%, Nb: 0.005-0.05
%, B: 0.0003 to 0.0025%, Ti: 0.005 to 0.025%, Ca: 0.0
The method for producing an accelerated cooling high-strength steel sheet having excellent weldability according to claim 1 or 2, further comprising one or more selected from the range of 01 to 0.010%.
【００１０】[0010]
【作用】以下に、本発明の製造条件について説明する。
まず、加速冷却条件の限定理由について説明する。本発
明者らは表１に示す化学成分を有する鋼板に、いく種類
かの加速冷却を施し、強度に及ぼす加速冷却法の影響に
ついて調べた。加速冷却法としては、従来の490N/mm2級
鋼板に適用されている従来型のＡｃｃ法、これを改良し
たModifiedＡｃｃ法の２種類である。加速冷却条件を図
１に示す。The manufacturing conditions of the present invention will be described below.
First, the reason for limiting the accelerated cooling conditions will be described. The present inventors performed some types of accelerated cooling on a steel sheet having the chemical composition shown in Table 1 and investigated the influence of the accelerated cooling method on the strength. There are two types of accelerated cooling methods, a conventional Acc method applied to a conventional 490 N / mm 2 grade steel sheet and a modified Acc method improved from the conventional Acc method. The accelerated cooling conditions are shown in FIG.
【００１１】ここで、Ａｃｃ法：圧延終了後、すみやか
にオンラインで水冷を開始し、所定の冷却停止温度まで
水冷を行う ModifiedＡｃｃ：圧延終了後、所定の温度までオンライ
ンで空冷した後、加速冷却を開始し、所定の冷却停止温
度まで水冷を行う なお、ModifiedＡｃｃにおける水冷開始温度は 800〜50
0 ℃の範囲で変化させ、冷却停止温度は 400℃、冷却速
度は11℃/secとした。[0011] Here, the Acc method: water cooling is immediately started after completion of rolling to perform water cooling to a predetermined cooling stop temperature. Modified Acc: After completion of rolling, air cooling is performed online to a predetermined temperature, followed by accelerated cooling. Start and perform water cooling to the specified cooling stop temperature. The water cooling start temperature in Modified Acc is 800 to 50.
The temperature was changed in the range of 0 ° C, the cooling stop temperature was 400 ° C, and the cooling rate was 11 ° C / sec.
【００１２】表１の化学成分は、従来の加速冷却型建築
用鋼板の炭素当量約0.38％に比べ、炭素当量を0.35％に
まで低減した成分系である。The chemical composition of Table 1 is a composition system in which the carbon equivalent is reduced to 0.35% as compared with the carbon equivalent of about 0.38% of the conventional accelerated cooling type steel sheet for construction.
【００１３】加速冷却後の引張試験結果を図２に示す。
図から明らかなようにModifiedＡｃｃにおいては、水冷
開始温度がいずれの場合にも、従来型のＡｃｃ法の場合
よりも高い強度が得られているが、同じ成分の鋼板に従
来型のＡｃｃ法を適用すると、490N/mm2級の強度が確保
できないことがわかる。このように、ModifiedＡｃｃ法
という新規な加速冷却法、鋼板を高強度化する上で非常
に有効である。The results of the tensile test after accelerated cooling are shown in FIG.
As is clear from the figure, in Modified Acc, higher strength is obtained than in the case of the conventional Acc method at any water cooling start temperature, but the conventional Acc method is applied to steel sheets of the same composition. Then, it can be seen that the strength of 490 N / mm 2 grade cannot be secured. As described above, the new accelerated cooling method called the Modified Acc method is very effective in increasing the strength of the steel sheet.
【００１４】この理由は、ミクロ組織の相違によるもの
と考えられる。すなわち、圧延終了後すみやかに加速冷
却を開始する従来型のＡｃｃ法では、細粒フェライトや
ベイナイトが生成するのに対して、ModifiedＡｃｃ法で
は、初期に空冷を行うため従来型のＡｃｃ法よりもフェ
ライト生成量が増加するものの、フェライトの生成とと
もに、オーステナイト中へのC の濃縮が生じ、この段階
から加速冷却を行うため、C の濃縮したオーステナイト
からはC 濃度が高くより高硬度のベイナイトが生成する
ものと考えられる。したがって、ModifiedＡｃｃ法の方
が従来型のＡｃｃ法の場合よりも高い強度が得られるの
である。The reason for this is considered to be due to the difference in microstructure. That is, in the conventional Acc method, which starts accelerated cooling promptly after the completion of rolling, fine-grained ferrite and bainite are generated, whereas in the Modified Acc method, air cooling is performed in the initial stage, so that ferrite is smaller than in the conventional Acc method. Although the amount of formation increases, along with the formation of ferrite, the concentration of C in austenite occurs, and since accelerated cooling is performed from this stage, bainite with a higher C concentration and higher hardness is formed from austenite enriched with C. It is considered to be a thing. Therefore, the Modified Acc method can obtain higher strength than the conventional Acc method.
【００１５】以上の理由から、本発明においては加速冷
却法として、ModifiedＡｃｃ法に限定する。なお、従来
型のＡｃｃ法においては、鋼板の残留応力の除去などを
目的として、焼もどしを行う（Ａｃｃ−Ｔ法）ことがあ
るが、同様の目的で焼もどしを行うModifiedＡｃｃ−Ｔ
法でも強度の上昇効果を利用した溶接性の改善が達成で
きるため、本発明においても、ModifiedＡｃｃ−Ｔ法も
適用可能とする。For the above reasons, in the present invention, the accelerated cooling method is limited to the Modified Acc method. In the conventional Acc method, tempering may be performed (Acc-T method) for the purpose of removing residual stress of the steel sheet, but Modified Acc-T that performs tempering for the same purpose.
Since the weldability can be improved by utilizing the strength increasing effect also by the method, the Modified Acc-T method can also be applied to the present invention.
【００１６】[0016]
【表１】 [Table 1]
【００１７】つぎに、上記の各工程における温度範囲の
限定理由について説明する。圧延終了後の加速冷却開始
温度については、フェライトの生成にともなうオーステ
ナイトへのC の濃縮を利用して高硬度のベイナイトを生
成させ、高強度化を図るためには、加速冷却開始温度を
800℃以下とする必要がある。しかしながら、加速冷却
開始温度が 500℃未満になるとフェライトの生成量が増
えすぎ、強度の低下をまねく。したがって、加速冷却開
始温度は 800〜500 ℃の範囲とする。Next, the reason for limiting the temperature range in each of the above steps will be described. Regarding the accelerated cooling start temperature after rolling, the accelerated cooling start temperature should be set in order to generate high hardness bainite by utilizing the concentration of C in austenite accompanying the formation of ferrite and to increase the strength.
It must be below 800 ℃. However, if the accelerated cooling start temperature is less than 500 ° C, the amount of ferrite produced will increase too much, leading to a decrease in strength. Therefore, the accelerated cooling start temperature should be in the range of 800-500 ℃.
【００１８】一方、加速冷却停止温度については、停止
温度が 200℃未満になると残留応力の増加による構造物
の安全性の低下、低温変態生成物の過剰による靱性の劣
化などの問題が顕著となるため、加速冷却停止温度は 2
00℃以上とする。また、加速冷却時の冷却速度について
は、所定の強度上昇効果を得るためには10℃/sec以上の
冷却速度が必要である。したがって、本発明では、圧延
終了後、 500〜800 ℃の間の所定の温度まで空冷した
後、オンラインで冷却速度10℃/sec以上、冷却停止温度
200℃以上の加速冷却を行う。On the other hand, with respect to the accelerated cooling stop temperature, when the stop temperature is less than 200 ° C., problems such as deterioration of structure safety due to increase of residual stress and deterioration of toughness due to excess low temperature transformation products become remarkable. Therefore, the accelerated cooling stop temperature is 2
The temperature should be over 00 ℃. Regarding the cooling rate during accelerated cooling, a cooling rate of 10 ° C./sec or more is required to obtain a predetermined strength increasing effect. Therefore, in the present invention, after completion of rolling, after air cooling to a predetermined temperature between 500 and 800 ° C, the cooling rate is 10 ° C / sec or more and the cooling stop temperature is online.
Perform accelerated cooling at 200 ℃ or higher.
【００１９】焼もどし温度に関しては、靱性を向上させ
構造物の安全性を確保する上では、あまり低い温度では
好ましくないため、400 ℃以上とする。一方、Ａc1点を
超えると強度の低下を生じるため、Ａc1点未満とする。The tempering temperature is set to 400 ° C. or higher because it is not preferable at a too low temperature for improving the toughness and ensuring the safety of the structure. On the other hand, if it exceeds the Ac 1 point, the strength will be reduced, and therefore the Ac 1 point is set.
【００２０】つぎに、本発明における化学成分の限定理
由について説明する。C は高張力鋼板としての強度を確
保するために必要な元素であり、含有量が0.03％未満で
は引張強さ490N/mm2級以上の強度が得がたい。また、0.
20％を超えて添加すると耐溶接割れ性を害するので好ま
しくない。したがって、C 含有量は0.03〜0.20％の範囲
とする。Next, the reasons for limiting the chemical components in the present invention will be explained. C is an element necessary to secure the strength as a high-strength steel sheet, and if the content is less than 0.03%, it is difficult to obtain a tensile strength of 490 N / mm 2 grade or higher. Also, 0.
If it is added in excess of 20%, the weld crack resistance is impaired, which is not preferable. Therefore, the C content is set to the range of 0.03 to 0.20%.
【００２１】Siは脱酸に必要な元素であるが、含有量が
0.05％未満ではこの効果は少なく、また、0.50％を超え
て過多に添加すると、溶接性、靱性を劣化させるので好
ましくない。したがって、Si含有量は0.05〜0.50％の範
囲とする。Si is an element necessary for deoxidation, but its content is
If it is less than 0.05%, this effect is small, and if it is added in excess of 0.50%, the weldability and toughness are deteriorated, which is not preferable. Therefore, the Si content is set to the range of 0.05 to 0.50%.
【００２２】Mnは強度確保するために必要な元素である
が、含有量が0.30％未満ではこのような効果が十分に得
られず、また、2.50％を超えて過多に添加すると、溶接
性、靱性を劣化させるので好ましくない。したがって、
Mn含有量は0.30〜2.50％の範囲とする。Mn is an element necessary for ensuring strength, but if the content is less than 0.30%, such an effect cannot be sufficiently obtained, and if it is added in excess of 2.50%, weldability, It is not preferable because it deteriorates toughness. Therefore,
The Mn content is in the range of 0.30 to 2.50%.
【００２３】Alは脱酸元素であり、含有量が 0.005％未
満ではそのような効果は少なく、また、0.10％を超えて
添加すると、靱性の劣化をもたらす。したがって、Al含
有量は 0.005〜0.10％の範囲とする。Al is a deoxidizing element, and if the content is less than 0.005%, such an effect is small, and if it is added over 0.10%, toughness is deteriorated. Therefore, the Al content should be in the range of 0.005 to 0.10%.
【００２４】この他に、Cu、Ni、Cr、Mo、V 、Nb、B 、
Ti、Caなどを板厚、目標靱性レベルに応じて１種または
２種以上添加するものとする。In addition to these, Cu, Ni, Cr, Mo, V, Nb, B,
Ti, Ca, etc. are added in one kind or two or more kinds depending on the plate thickness and the target toughness level.
【００２５】Cuは固溶強化、析出強化により強度上昇に
有効な元素であるが、含有量が0.05％未満ではこのよう
な効果を十分に発揮することができず、また、1.20％を
超えて添加すると熱間加工性が劣化し鋼板表面に割れが
生じやすい。したがって、Cu含有量は0.05〜1.20％の範
囲とする。Cu is an element effective for increasing strength by solid solution strengthening and precipitation strengthening, but if the content is less than 0.05%, such effects cannot be sufficiently exhibited, and if it exceeds 1.20%. If added, hot workability deteriorates and cracks easily occur on the steel sheet surface. Therefore, the Cu content is in the range of 0.05 to 1.20%.
【００２６】Niは靱性を向上させる効果があるが、含有
量が0.05％未満ではその十分な効果が得られず、また、
3.00％を超えて添加するとスケール疵が発生しやすくな
り、またコストアップにもなる。したがって、Ni含有量
は0.05〜3.00％の範囲とする。Ni has the effect of improving toughness, but if its content is less than 0.05%, its sufficient effect cannot be obtained.
If added in excess of 3.00%, scale defects are likely to occur and the cost will increase. Therefore, the Ni content is in the range of 0.05 to 3.00%.
【００２７】Crは強度上昇に有効な元素であるが、含有
量が0.05％未満ではこのような効果は十分に発揮され
ず、また、1.20％を超えて添加すると溶接性を害する。
したがって、Cr含有量は0.05〜1.20％の範囲とする。Cr is an element effective for increasing the strength, but if the content is less than 0.05%, such an effect is not sufficiently exhibited, and if it exceeds 1.20%, the weldability is impaired.
Therefore, the Cr content is in the range of 0.05 to 1.20%.
【００２８】Moは強度上昇に有効な元素であるが、含有
量が0.05％未満では十分な効果が得られず、また、1.00
％を超えて過剰に添加すると、溶接性を劣化させ、コス
トアップにもなる。したがって、Mo含有量は0.05〜1.00
％の範囲とする。Mo is an element effective in increasing strength, but if the content is less than 0.05%, a sufficient effect cannot be obtained, and 1.00
If it is added excessively in excess of%, the weldability is deteriorated and the cost is increased. Therefore, the Mo content is 0.05 to 1.00.
The range is%.
【００２９】V は少量の添加により、結晶粒の細粒化、
強度上昇に有効な元素であり、その効果を得るために
は、 0.005％以上の添加が必要であるが、0.08％を超え
て添加すると溶接性を害する。したがって、V 含有量は
0.005〜0.08％の範囲とする。By adding a small amount of V, the crystal grains are made finer,
It is an element effective in increasing strength. To obtain that effect, 0.005% or more must be added, but if it is added in excess of 0.08%, weldability is impaired. Therefore, the V content is
The range is 0.005 to 0.08%.
【００３０】Nbは結晶粒微細化作用を有する元素であ
る。その効果を得るためには、 0.005％以上の添加が必
要であり、また、0.05％を超えて添加すると溶接性、靱
性を劣化させる傾向にある。したがって、Nb含有量は
0.005〜0.05％の範囲とする。Nb is an element having a grain refining effect. To obtain this effect, addition of 0.005% or more is necessary, and addition in excess of 0.05% tends to deteriorate weldability and toughness. Therefore, the Nb content is
The range is 0.005 to 0.05%.
【００３１】B は強度上昇に有効な元素であるが、含有
量が0.0003％未満ではその効果が得られず、また、0.00
25％を超えて添加すると靱性が劣化する。したがって、
B 含有量は0.0003〜0.0025％の範囲とする。B is an element effective for increasing strength, but if the content is less than 0.0003%, that effect cannot be obtained, and 0.00
If added over 25%, the toughness deteriorates. Therefore,
The B content is in the range of 0.0003 to 0.0025%.
【００３２】Tiは脱酸作用、溶接熱影響部の靱性向上効
果を有するが、含有量が 0.005％未満ではこれらの効果
が得られず、また、 0.025％を超えて添加すると介在物
の増加により靱性が劣化する。したがって、Ti含有量は
0.005〜0.025 ％の範囲とする。Ti has a deoxidizing action and an effect of improving the toughness of the heat-affected zone of welding, but if the content is less than 0.005%, these effects cannot be obtained, and if it exceeds 0.025%, inclusions increase. The toughness deteriorates. Therefore, the Ti content is
The range is 0.005 to 0.025%.
【００３３】Caは非金属介在物の球状化作用を有し、異
方性の低減に有効であるが、含有量が0.001 ％未満では
その十分な効果が得られず、また、0.010 ％を超えて添
加すると介在物の増加により靱性が劣化する。したがっ
て、Ca含有量は 0.001〜0.010 ％の範囲とする。Ca has a spheroidizing action of non-metallic inclusions and is effective in reducing anisotropy, but if the content is less than 0.001%, the sufficient effect cannot be obtained, and if it exceeds 0.010%. If added as an additive, the toughness deteriorates due to the increase of inclusions. Therefore, the Ca content should be in the range of 0.001 to 0.010%.
【００３４】[0034]
【実施例】以下に、本発明に係わる溶接性の優れた加速
冷却型高張力鋼板の製造方法の実施例について説明する
が、本発明は本実施例のみに限定されるものではない。EXAMPLES Examples of the method for producing an accelerated cooling type high strength steel sheet having excellent weldability according to the present invention will be described below, but the present invention is not limited to these examples.
【００３５】供試鋼板は表２に示す化学成分を有する鋼
片を、表３に示す板厚30〜55mmの鋼板に圧延した後、表
３に示す加速冷却条件で加速冷却し、一部焼もどしを行
ったものである。これらの鋼板から試験片を採取し、母
材の引張試験を行った。その結果を加速冷却条件、焼も
どし条件とともに表３に併記する。The test steel sheets were obtained by rolling steel pieces having the chemical composition shown in Table 2 into steel sheets having a plate thickness of 30 to 55 mm shown in Table 3, followed by accelerated cooling under the accelerated cooling conditions shown in Table 3 and partial burning. It was a rehabilitation. Test pieces were sampled from these steel plates and a tensile test of the base material was performed. The results are shown in Table 3 together with the accelerated cooling conditions and the tempering conditions.
【００３６】表３から明らかなように、本発明法Ａ〜Ｉ
は、いずれも従来鋼よりも低い炭素当量の成分系で490N
/mm2級以上の引張強さを有している。As is apparent from Table 3, the present invention methods A to I
Are all 490N in the composition system with a carbon equivalent lower than that of conventional steel.
/ mm 2 It has a tensile strength of 2 grade or higher.
【００３７】これに対して、比較例Ｊ〜Ｎは加速冷却条
件がModifiedＡｃｃ法あるいはModifiedＡｃｃ−Ｔ法で
ないため、炭素当量を高くしないとModifiedＡｃｃ法ま
たはModifiedＡｃｃ−Ｔ法と同等の強度が得られない。On the other hand, in Comparative Examples J to N, the accelerated cooling conditions are not the Modified Acc method or the Modified Acc-T method, and therefore, the strength equivalent to that of the Modified Acc method or the Modified Acc-T method cannot be obtained unless the carbon equivalent is increased.
【００３８】[0038]
【表２】 [Table 2]
【００３９】[0039]
【表３】 [Table 3]
【００４０】[0040]
【発明の効果】以上説明したように、本発明の溶接性の
優れた加速冷却型高張力鋼板の製造方法は、化学成分を
制御し、熱間圧延終了後、 500〜800 ℃の間の所定の温
度まで空冷した後、オンラインで冷却速度10℃/sec以
上、冷却停止温度 200℃以上の加速冷却を行い、その後
必要に応じて焼もどしを行っているため、炭素当量を低
減することができ、このため良好な溶接性を有する490N
/mm2級以上の鋼板の製造が可能であるという優れた効果
を有するものである。As described above, the method for producing an accelerated cooling type high-strength steel sheet having excellent weldability of the present invention controls the chemical composition, and after hot rolling is completed, a predetermined temperature between 500 and 800 ° C is obtained. After air cooling to the above temperature, the cooling rate is 10 ℃ / sec or more, the accelerated cooling is performed at the cooling stop temperature of 200 ℃ or more, and the tempering is performed if necessary, so the carbon equivalent can be reduced. , Because of this it has good weldability 490N
It has an excellent effect that it is possible to manufacture a steel sheet of grade / mm 2 or higher.
【図１】加速冷却条件を示す図である。FIG. 1 is a diagram showing accelerated cooling conditions.
【図２】ModifiedＡｃｃにおける水冷開始温度と強度と
の関係を示す図である。FIG. 2 is a diagram showing a relationship between water cooling start temperature and strength in Modified Acc.
Claims (3)
n:0.30〜2.50％、Al:0.005〜0.10％を含有し、残部Feお
よび不可避的不純物からなる鋼片を熱間圧延し、その後
下記に示すオンラインでの加速冷却処理を施すことを特
徴とする溶接性の優れた加速冷却型高張力鋼板の製造方
法。 加速冷却処理方法：オンライン新型加速冷却（Modified
Ａｃｃ） ただし、オンライン新型加速冷却：熱間圧延終了後、 5
00〜800 ℃の間の所定の温度まで空冷した後、オンライ
ンで冷却速度10℃/sec以上、冷却停止温度 200℃以上の
加速冷却を行う1. C: 0.03 to 0.20%, Si: 0.05 to 0.50%, M
A steel slab containing n: 0.30 to 2.50% and Al: 0.005 to 0.10% and the balance of Fe and unavoidable impurities is hot-rolled, and then subjected to the following online accelerated cooling treatment. A method for manufacturing an accelerated cooling type high strength steel sheet having excellent weldability. Accelerated cooling processing method: Online new type accelerated cooling (Modified
Acc) However, online new type accelerated cooling: 5 after hot rolling
After air cooling to a specified temperature between 00 and 800 ° C, accelerated cooling is performed online with a cooling rate of 10 ° C / sec or more and a cooling stop temperature of 200 ° C or more.
n:0.30〜2.50％、Al:0.005〜0.10％を含有し、残部Feお
よび不可避的不純物からなる鋼片を熱間圧延し、その後
下記に示すオンラインでの加速冷却処理と、焼もどしを
施すことを特徴とする溶接性の優れた加速冷却型高張力
鋼板の製造方法。 加速冷却処理方法：オンライン新型加速冷却（Modified
Ａｃｃ）＋焼もどし（Ｔ） ただし、オンライン新型加速冷却：熱間圧延終了後、 5
00〜800 ℃の間の所定の温度まで空冷した後、オンライ
ンで冷却速度10℃/sec以上、冷却停止温度 200℃以上の
加速冷却を行う 焼もどし温度：400 ℃点以上Ａc1点未満2. C: 0.03 to 0.20%, Si: 0.05 to 0.50%, M
Hot rolling a steel slab containing n: 0.30 to 2.50%, Al: 0.005 to 0.10% and the balance Fe and unavoidable impurities, and then performing the following online accelerated cooling treatment and tempering A method for producing an accelerated cooling high-strength steel sheet having excellent weldability, which is characterized by: Accelerated cooling processing method: Online new type accelerated cooling (Modified
Acc) + tempering (T) However, online new type accelerated cooling: After hot rolling, 5
After air cooling to a specified temperature between 00 and 800 ° C, online accelerated cooling with a cooling rate of 10 ° C / sec or more and a cooling stop temperature of 200 ° C or more Tempering temperature: 400 ° C or more and less than Ac 1 point
％、 Ni:0.05〜3.00％、Cr: 0.05〜1.20％、 Mo:0.05〜
1.00％、 V:0.005〜0.08％、Nb:0.005〜0.05％、B:0.00
03〜0.0025％、Ti:0.005〜0.025 ％、Ca:0.001〜0.010
％の内から選んだ１種または２種以上を含有する請求項
１または２記載の溶接性の優れた加速冷却型高張力鋼板
の製造方法。3. The chemical composition further contains Cu: 0.05 to 1.20.
%, Ni: 0.05 to 3.00%, Cr: 0.05 to 1.20%, Mo: 0.05 to
1.00%, V: 0.005-0.08%, Nb: 0.005-0.05%, B: 0.00
03-0.0025%, Ti: 0.005-0.025%, Ca: 0.001-0.010
The method for producing an accelerated cooling high-strength steel sheet having excellent weldability according to claim 1 or 2, which contains one or more selected from the group.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22609592A JPH0665638A (en) | 1992-08-25 | 1992-08-25 | Production method of accelerated cooling high tensile strength steel plate excellent in weldability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22609592A JPH0665638A (en) | 1992-08-25 | 1992-08-25 | Production method of accelerated cooling high tensile strength steel plate excellent in weldability |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0665638A true JPH0665638A (en) | 1994-03-08 |
Family
ID=16839749
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22609592A Pending JPH0665638A (en) | 1992-08-25 | 1992-08-25 | Production method of accelerated cooling high tensile strength steel plate excellent in weldability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0665638A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6659243B2 (en) | 2001-08-02 | 2003-12-09 | Showa Corporation | Shaft seat part structure of hydraulic shock absorber and assembling method thereof |
| WO2023148087A1 (en) * | 2022-02-03 | 2023-08-10 | Tata Steel Ijmuiden B.V. | Method of manufacturing a low-carbon steel strip having improved formability |
-
1992
- 1992-08-25 JP JP22609592A patent/JPH0665638A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6659243B2 (en) | 2001-08-02 | 2003-12-09 | Showa Corporation | Shaft seat part structure of hydraulic shock absorber and assembling method thereof |
| WO2023148087A1 (en) * | 2022-02-03 | 2023-08-10 | Tata Steel Ijmuiden B.V. | Method of manufacturing a low-carbon steel strip having improved formability |
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