JP2001064745A - High tensile strength steel product excellent in economical efficiency and toughness - Google Patents
High tensile strength steel product excellent in economical efficiency and toughnessInfo
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- JP2001064745A JP2001064745A JP24008499A JP24008499A JP2001064745A JP 2001064745 A JP2001064745 A JP 2001064745A JP 24008499 A JP24008499 A JP 24008499A JP 24008499 A JP24008499 A JP 24008499A JP 2001064745 A JP2001064745 A JP 2001064745A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、経済性および靱性
に優れた高張力鋼材に関する。より具体的には、本発明
は、例えばアーク溶接やビーム溶接等の溶接施工により
工作される構造物の構造部材に適用するのに適した経済
性および靱性に優れた高張力鋼材に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high tensile strength steel excellent in economy and toughness. More specifically, the present invention relates to a high tensile strength steel excellent in economy and toughness suitable for being applied to a structural member of a structure machined by welding such as arc welding or beam welding.
【０００２】[0002]
【従来の技術】これまでにも、例えばラインパイプとい
った溶接構造物の構造部材として多種の鋼材が用いられ
てきた。これらの鋼材の中でも、低炭素鋼に少量の合金
元素を添加して靱性および溶接性を向上させた高張力鋼
材は、板厚の薄肉化や小径化を通して溶接工数や運搬コ
ストの削減を図ることができることから、その適用範囲
を拡げてきた。2. Description of the Related Art Various types of steel materials have been used as structural members for welding structures such as line pipes. Among these steel materials, high-strength steel materials with improved toughness and weldability by adding a small amount of alloying elements to low-carbon steel should reduce welding man-hours and transportation costs by reducing the thickness and diameter of the plates. Therefore, the scope of application has been expanded.
【０００３】しかしながら、この高張力鋼材では、炭素
量や合金元素の添加量さらには入熱のバリエーション等
が増加するに伴って、母材そのものの靱性の他に、溶接
金属や溶接熱影響部における靱性も重要視されるように
なってきた。そこで、高張力鋼材の溶接金属や溶接熱影
響部における靱性を向上させるための発明が、多数提案
されている。However, in this high-tensile steel material, as the amount of carbon, the amount of alloying element added, and the variation in heat input increase, the toughness of the base metal itself, the weld metal and the heat affected zone in the weld heat affected zone increase. Emphasis has also been placed on toughness. Thus, many inventions have been proposed for improving the toughness of a high tensile strength steel weld metal or a heat affected zone.
【０００４】例えば、特開平７−278736号公報には、
Ｃ：0.01〜0.25％（本明細書では特にことわりがない限
り「％」は「重量％」を意味するものとする。）、Si：
0.6 ％以下、Mn：0.3 〜3.0 ％、Ｎ：0.0005〜0.0100
％、Ｏ：0.0010〜0.0070％、Al：0.02％以下、さらにC
r：０〜1.5 ％、Mo：０〜1.5 ％、Cu：０〜1.5 ％、N
i：０〜3.0 ％、Nb：０〜0.5 ％、Ｖ：０〜0.5 ％の１
種以上、並びにＢ：０〜0.0020％を含み、不純物中の
Ｐ：0.03％以下およびＳ：0.01％以下、かつ鋼材中のAl
−Mn酸化物分散粒子が0.2 〜20μｍ、同じく平均密度が
１mm2 当たり４〜1000個未満、分散粒子中のAlとMnとの
関係が、（Al＋Mn）≧40モル％、およびAl／Mn＝1.0 〜
5.0 未満をともに満足する溶接熱影響部の靱性が優れた
鋼材が提案されている。すなわち、この提案にかかる発
明は、アシキュラーフェライトの生成核となるAl−Mn酸
化物分散粒子の個数を適正値に特定することによって、
鋼材の靱性向上を図っている。For example, Japanese Patent Application Laid-Open No. 7-278736 discloses that
C: 0.01 to 0.25% (herein, "%" means "% by weight" unless otherwise specified), Si:
0.6% or less, Mn: 0.3-3.0%, N: 0.0005-0.0100
%, O: 0.0010 to 0.0070%, Al: 0.02% or less, and C
r: 0 to 1.5%, Mo: 0 to 1.5%, Cu: 0 to 1.5%, N
i: 0 to 3.0%, Nb: 0 to 0.5%, V: 0 to 0.5%
Or more, B: 0 to 0.0020%, P in impurities: 0.03% or less and S: 0.01% or less, and Al in steel
-Mn oxide dispersed particles are 0.2 to 20 µm, the average density is also 4 to less than 1000 per 1 mm 2 , the relationship between Al and Mn in the dispersed particles is (Al + Mn) ≥ 40 mol%, and Al / Mn = 1.0 ~
A steel material with excellent toughness in the heat affected zone that satisfies both values less than 5.0 has been proposed. That is, the invention according to this proposal specifies an appropriate number of Al-Mn oxide dispersed particles serving as nuclei for producing acicular ferrite,
The aim is to improve the toughness of steel.
【０００５】しかしながら、この提案にかかる発明は、
焼入れ性が高めであってアシキュラーフェライトを生成
せずにベイナイト以上の強度を有する鋼材には、当然の
ことながら、適用できなかった。また、この介在物制御
は、微妙なコントロールが実際の溶製では困難であるた
め、ロット毎の介在物量の変動が大きくなり、安定的な
特性を工業的規模で得ることはできなかった。However, the invention according to this proposal is:
As a matter of course, it cannot be applied to a steel material having high hardenability and having strength higher than bainite without producing acicular ferrite. Further, in this inclusion control, since delicate control is difficult in actual smelting, the amount of inclusions for each lot greatly fluctuates, and stable characteristics cannot be obtained on an industrial scale.
【０００６】一方、特開昭54−132421号公報には、炭素
当量が極めて小さく、ＢおよびTiを添加した鋼を、特定
の条件のもとで圧延することにより、溶接性および低温
靱性がともに優れたベイナイト高張力厚鋼板を製造する
方法が、また特開平９−249934号公報には、Ｃ：0.001
〜0.02％、Mn：1.0 〜3.0 ％、Ti：0.005 〜0.20％、
Ｂ：0.0003〜0.0050％、Cu：2.0 ％超3.0 ％以下および
Al：0.10％以下を含む高強度鋼材が、それぞれ提案され
ている。これらの提案にかかる発明は、いずれも、Ｃ量
を0.005 〜0.03％程度にまで低減するとともにＢを微量
添加することによって強度を確保し、これによって、ベ
イナイト組織を有する鋼材の溶接金属や溶接熱影響部に
おける靱性の向上を図っている。[0006] On the other hand, Japanese Patent Application Laid-Open No. 54-132421 discloses that a steel having an extremely small carbon equivalent and containing B and Ti is rolled under specific conditions so that both the weldability and the low-temperature toughness can be improved. A method for producing an excellent bainite high-tensile steel plate is disclosed in JP-A-9-249934.
~ 0.02%, Mn: 1.0 ~ 3.0%, Ti: 0.005 ~ 0.20%,
B: 0.0003-0.0050%, Cu: more than 2.0% and 3.0% or less and
High strength steel materials containing Al: 0.10% or less have been proposed respectively. In any of the inventions according to these proposals, the amount of C is reduced to about 0.005 to 0.03% and the strength is ensured by adding a small amount of B, whereby the welding metal or welding heat of steel having a bainite structure is obtained. The toughness of the affected area is improved.
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、特開昭
54−132421号公報や特開平９−249934号公報により提案
された発明では、靱性を確保するために添加するＢが粒
界に単体で偏析するために靱性の向上が阻害されてしま
い、高張力鋼材の靱性に対する前述した要求を満足する
ことができない。SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open
In the inventions proposed in Japanese Patent Application Laid-Open Nos. 54-132421 and 9-249934, B added to secure toughness segregates singly at the grain boundaries, so that improvement in toughness is hindered, and high tensile strength is impaired. The above-mentioned requirements for the toughness of steel cannot be satisfied.
【０００８】また、0.005 〜0.03％程度のＣ含有量で所
望の強度を確保するためには、合金元素を多量に添加す
る必要がある。このため、製造コストが上昇してしま
い、特に低コスト化を強く要請されている高張力鋼材で
は、大きな問題である。Further, in order to secure a desired strength at a C content of about 0.005 to 0.03%, it is necessary to add a large amount of alloying elements. For this reason, the production cost is increased, and this is a serious problem particularly in the case of a high-tensile steel material which is strongly demanded to be reduced in cost.
【０００９】なお、0.005 〜0.03％程度のＣ含有量であ
って溶接金属や溶接熱影響部の靱性に優れた高張力鋼材
については、これまでにも多数の発明が提案されてい
る。例えば、特開昭52−131918号公報には、Ｃ含有量が
0.02〜0.10％のスラブを用いて未再結晶域圧延を行うこ
とにより高靱性を得る発明が開示されている。しかし、
これらの発明によっても、厳しい条件下で溶接された継
手部の熱影響部靱性は、例えば、衝撃吸収エネルギvE
-40(atFL) ≒10〜50 (J)しか得られない場合があり、不
十分である。A number of inventions have been proposed for high-strength steel materials having a C content of about 0.005 to 0.03% and having excellent toughness in the weld metal and the heat affected zone. For example, JP 52-131918 A discloses that the C content is
There is disclosed an invention in which high toughness is obtained by performing rolling in a non-recrystallized region using a slab of 0.02 to 0.10%. But,
According to these inventions, the heat-affected zone toughness of a joint welded under severe conditions is, for example, the impact absorption energy vE
-40 (atFL) ≒ 10 ~ 50 (J) only in some cases, not enough.
【００１０】ここに、本発明の目的は、経済性および靱
性に優れた高張力鋼材およびその製造方法、具体的に
は、例えばアーク溶接やビーム溶接等の溶接施工により
工作される構造物の構造部材に適用するのに適した経済
性および靱性に優れた高張力鋼材を提供することであ
る。Here, an object of the present invention is to provide a high-tensile steel material excellent in economy and toughness and a method of manufacturing the same, and more specifically, the structure of a structure to be machined by welding such as arc welding or beam welding. An object of the present invention is to provide a high-tensile steel material excellent in economy and toughness suitable for application to members.
【００１１】より具体的には、本発明は、母材部のF.L.
ノッチシャルピー衝撃試験の継手部の−40℃における衝
撃吸収エネルギvE-40(atFL) が100(J)超であり、例えば
圧力容器や海洋構造物等の構造部材として使用するのに
好適な経済性および靱性に優れた高張力鋼材を提供する
ことである。More specifically, the present invention relates to a method of manufacturing a base material
Impact absorption energy vE- 40 (atFL) at -40 ° C of the joint part of the notch Charpy impact test is more than 100 (J), and it is economical suitable for use as a structural member such as a pressure vessel or marine structure. Another object of the present invention is to provide a high-tensile steel material having excellent toughness.
【００１２】[0012]
【課題を解決するための手段】本発明者は、上記課題を
解決するために鋭意検討を重ねた結果、以下に列記する
新規な知見(1) 〜(6) を得ることができ、これらの知見
(1) 〜(6) に基づくことにより、極端にＣ含有量を低減
することなく、良好な溶接部靱性を得る高張力鋼材を得
られ、これにより、高張力鋼材の製造コストの上昇を充
分に抑制できることを知見して、本発明を完成した。As a result of intensive studies to solve the above-mentioned problems, the present inventor has obtained the following new findings (1) to (6). Knowledge
Based on (1) to (6), it is possible to obtain a high-strength steel material that obtains good weld toughness without extremely reducing the C content, thereby sufficiently increasing the manufacturing cost of the high-tensile steel material. The inventors have found that the present invention can be suppressed to a minimum, and completed the present invention.
【００１３】(1) 同じベイナイト主体の組織を生成する
場合には、Ｃ含有量はできるだけ低く抑制することが靱
性改善には有効である。すなわち、靱性改善にはベイナ
イト、特に上部ベイナイトのラス間に存在するＭＡ（島
状マルテンサイト）の生成量が影響し、このＭＡ生成量
を低減することにより、靱性が向上する。(1) When forming the same bainite-based structure, it is effective to suppress the C content as low as possible to improve the toughness. That is, the improvement in toughness is affected by the amount of bainite, particularly the amount of MA (island martensite) present between the laths of the upper bainite. By reducing this amount of MA, the toughness is improved.
【００１４】なお、「上部ベイナイト」とは、ラス状ベ
イニティックフェライトの界面に、セメンタイト若しく
はＭＡ constituent (炭素が濃縮した残留オーステナイ
トもしくはマルテンサイト、あるいは両者の混合体) 、
あるいはその両者が存在した組織であり、ベイニティッ
クフェライト内部にセメンタイトが点列状に配列する下
部ベイナイトを除く、全てのベイナイト組織を意味す
る。また、焼戻し後の組織も含む。板厚が厚く冷却速度
が小さい場合や、水冷停止温度が高く水冷停止後の空冷
時間が長い場合には、ベイニティックフェライトの合体
によってその見かけ上の形態がラス状から粒状に変化す
るが、この場合も含まれる。The term "upper bainite" refers to cementite or MA constituent (residual austenite or martensite or a mixture of both) at the interface of lath bainitic ferrite,
Alternatively, it is a structure in which both exist, and means all bainite structures except lower bainite in which cementite is arranged in a dot array inside bainitic ferrite. It also includes the structure after tempering. When the plate thickness is large and the cooling rate is small, or when the water cooling stop temperature is high and the air cooling time after the water cooling stop is long, the apparent form of the bainitic ferrite changes from lath to granular, This case is also included.
【００１５】(2) ベイナイト変態中にセメンタイトの析
出を抑制する効果を奏するSiおよびAlそれぞれの含有量
は、できるだけ低く抑制したほうが、ＭＡ生成量の抑制
を通して靱性の向上を図ることができる。特に、Al含有
量の低減はＭＡ生成量の抑制に重要なポイントであるた
め、Alは非添加とする。しかしながら、精錬時には、脱
酸のためにSiあるいはAlの添加は不可欠となるため、脱
酸のために最低限必要な量のSiの含有は許容される。(2) The content of each of Si and Al, which has the effect of suppressing the precipitation of cementite during the bainite transformation, should be suppressed as low as possible to improve the toughness through suppression of the amount of MA generated. In particular, since the reduction of the Al content is an important point in suppressing the amount of generated MA, Al is not added. However, at the time of refining, addition of Si or Al is indispensable for deoxidation, so that the minimum necessary amount of Si for deoxidation is allowed.
【００１６】(3) ＭＡは主に上部ベイナイト中に多く生
成するため、母材における上部ベイナイトの比率Ｆ
BUと、Ｃ含有量およびSi含有量との間に特定の関係を設
定することにより、ＭＡ生成量を確実に低減でき、靱性
向上を図ることができる。(3) Since MA is mainly generated in the upper bainite, the ratio of the upper bainite F
By setting a specific relationship between the BU and the C content and the Si content, it is possible to reliably reduce the amount of generated MA and to improve the toughness.
【００１７】上部ベイナイトの体積率を求めるには、走
査型電子顕微鏡による観察、または透過型電子顕微鏡に
よる観察を行う。特に走査型電子顕微鏡は局所に限らず
比較的広い領域にわたって観察できるため有用である。
走査型電子顕微鏡を用いて全金属組織中の上部ベイナイ
トの混合比率を求めるには、1000〜2000倍程度の10〜30
視野についての平均をとることが望ましい。透過型電子
顕微鏡によれば、精密な測定が可能であるが、倍率を高
くせざるを得ない。このため、10000 倍程度の50〜100
視野の平均をとることが望ましい。In order to determine the volume ratio of the upper bainite, observation with a scanning electron microscope or observation with a transmission electron microscope is performed. In particular, a scanning electron microscope is useful because it can observe not only a local area but also a relatively wide area.
Using a scanning electron microscope to determine the mixing ratio of the upper bainite in the entire metallographic structure, about 10 to 30 times 1000 to 2000 times
It is desirable to take an average for the field of view. According to the transmission electron microscope, precise measurement is possible, but the magnification must be increased. For this reason, 50 to 100, which is about 10,000 times
It is desirable to take the average of the fields of view.
【００１８】(4) Ｂは、粒界に偏析して焼入れ性を向上
させるが靱性を劣化させるため、前述した特開昭54−13
2421号公報や特開平９−249934号公報により提案された
発明とは異なり、非添加とする。(4) B segregates at the grain boundaries to improve hardenability, but deteriorates toughness.
Unlike the inventions proposed in JP-A-2421 and JP-A-9-249934, they are not added.
【００１９】(5) 添加する合金元素は経済性の観点から
Crを中心とし、Cr以外の他の合金元素は焼入れ性を調整
するために適宜添加する。(5) The alloying element to be added is economically advantageous.
Alloying elements other than Cr, mainly Cr, are appropriately added to adjust the hardenability.
【００２０】(6) 焼入れ性の指標として知られる炭素当
量Ｃeqは、例えば50〜60kgf/mm2 という充分な強度を具
備するために、0.35〜0.45％の間に調整する。(6) The carbon equivalent Ceq, which is known as an index of hardenability, is adjusted to 0.35 to 0.45% in order to have a sufficient strength of, for example, 50 to 60 kgf / mm 2 .
【００２１】ここに、本発明は、Ｃ：0.03〜0.10％、S
i：0.10〜0.40％、Mn：0.6 〜2.0 ％、Cr：0.05〜1.6
％、Nb：0.005 〜0.1 ％、Ti：0.005 〜0.1 ％を含有
し、必要に応じてCu：1.0 ％以下、Ni：2.0 ％以下、M
o：1.0 ％以下、Ｖ：0.1 ％以下、Ｗ：1.0 ％以下、REM
：0.02％以下およびCa：0.02％以下からなる群から選
ばれた１種または２種以上を含有し、AlおよびＢを実質
的に含有しないとともに下記(1) 式により規定される炭
素当量Ｃeqが0.30〜0.45％の範囲にあり、残部Feおよび
不可避的不純物からなる鋼組成を有し、Ｃ量およびSi量
が下記(2) 式を満足するとともにフェライト・ベイナイ
ト組織を呈することを特徴とする経済性および靱性に優
れた高張力鋼材である。In the present invention, C: 0.03 to 0.10%, S
i: 0.10 to 0.40%, Mn: 0.6 to 2.0%, Cr: 0.05 to 1.6
%, Nb: 0.005 to 0.1%, Ti: 0.005 to 0.1%, Cu: 1.0% or less, Ni: 2.0% or less, M as required
o: 1.0% or less, V: 0.1% or less, W: 1.0% or less, REM
: At least one selected from the group consisting of 0.02% or less and Ca: 0.02% or less, containing substantially no Al and B and having a carbon equivalent Ceq defined by the following formula (1). An economy characterized by being in the range of 0.30 to 0.45%, having a steel composition comprising the balance of Fe and unavoidable impurities, and satisfying the following formula (2) and exhibiting a ferrite bainite structure. It is a high-tensile steel material with excellent strength and toughness.
【００２２】[0022]
【数２】 (Equation 2)
【００２３】[0023]
【発明の実施の形態】以下、本発明にかかる経済性およ
び靱性に優れた高張力鋼材の実施の形態を、添付図面を
参照しながら具体的に説明する。なお、以降の実施形態
の説明では、「鋼材」が「鋼板」である場合を例にと
る。まず、本発明にかかる経済性および靱性に優れた高
張力鋼板において、組成を限定する理由を説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a high-strength steel material according to the present invention, which is excellent in economy and toughness, will be specifically described with reference to the accompanying drawings. In the following description of the embodiments, a case where the “steel material” is a “steel plate” will be taken as an example. First, the reason for limiting the composition of the high-strength steel sheet according to the present invention, which is excellent in economy and toughness, will be described.
【００２４】(Ｃ：0.03〜0.10％)Ｃは、強度向上に最も
有効であるとともに安価な元素であるが、Ｃ含有量が0.
03％未満であるとＣ以外の他の元素の含有量を増加して
強度不足を補う必要が生じ、結果的に経済性が損なわれ
る。一方、Ｃ含有量が0.10％を超えるとＭＡ量が増加し
て、継手部の靱性を著しく阻害する。そこで、本発明で
は、Ｃ含有量は0.03％以上0.10％以下と限定する。同様
の観点から、Ｃ含有量の上限は0.08％、下限は0.03％で
あることがそれぞれ望ましい。(C: 0.03 to 0.10%) C is the most effective and inexpensive element for improving the strength, but has a C content of 0.3%.
If it is less than 03%, it is necessary to increase the content of elements other than C to compensate for the lack of strength, and as a result, economic efficiency is impaired. On the other hand, if the C content exceeds 0.10%, the amount of MA increases, and the toughness of the joint is significantly impaired. Therefore, in the present invention, the C content is limited to 0.03% or more and 0.10% or less. From the same viewpoint, it is preferable that the upper limit of the C content is 0.08% and the lower limit is 0.03%.
【００２５】(Si：0.10〜0.40％)Siは、ＭＡを生成させ
る効果を有するため極力低めにコントロールする必要が
あるが、精錬の際の脱酸に必要であるため、少なくとも
0.10％以上含有する。しかし、Si含有量が0.40％を超え
ると、ＭＡの生成を通して靱性が著しく劣化する。そこ
で、本発明では、Si含有量は0.10％以上0.40％以下と限
定する。同様の観点から、Si含有量の上限は0.25％、下
限は0.10％であることがそれぞれ望ましい。(Si: 0.10 to 0.40%) Since Si has the effect of producing MA, it is necessary to control it as low as possible. However, since it is necessary for deoxidation during refining, at least
Contains 0.10% or more. However, if the Si content exceeds 0.40%, the toughness is significantly degraded through the formation of MA. Therefore, in the present invention, the Si content is limited to 0.10% or more and 0.40% or less. From the same viewpoint, it is preferable that the upper limit of the Si content is 0.25% and the lower limit is 0.10%.
【００２６】(Mn：0.6 〜2.0 ％)Mnは、強度確保のため
に0.6 ％以上含有する。しかし、Mn含有量が2.0 ％を超
えると、靱性およびアレスト性を著しく劣化させる。そ
こで、本発明では、Mn含有量は0.6 ％以上2.0 ％以下と
限定する。同様の観点から、Mn含有量の上限は1.4 ％、
下限は0.7 ％であることがそれぞれ望ましい。(Mn: 0.6 to 2.0%) Mn is contained in an amount of 0.6% or more to ensure strength. However, if the Mn content exceeds 2.0%, the toughness and arrestability are significantly deteriorated. Therefore, in the present invention, the Mn content is limited to 0.6% or more and 2.0% or less. From the same viewpoint, the upper limit of the Mn content is 1.4%,
Preferably, the lower limit is 0.7%.
【００２７】(Cr：0.05〜1.6 ％)Crは、焼入れ性を高め
る働きを発揮し、安価なため強度確保を目的として添加
される。Cr含有量が0.05％以上であると強度上昇に効果
がある。一方、Cr含有量が1.6 ％を超えると、靱性およ
び溶接性の劣化を招く。そこで、本発明では、Cr含有量
は0.05％以上1.6 ％以下と限定する。同様の観点から、
Cr含有量の上限は0.9 ％、下限は0.2 ％であることがそ
れぞれ望ましい。(Cr: 0.05 to 1.6%) Cr exhibits a function of improving hardenability and is inexpensive, so is added for the purpose of securing strength. When the Cr content is 0.05% or more, it is effective in increasing the strength. On the other hand, when the Cr content exceeds 1.6%, toughness and weldability are deteriorated. Therefore, in the present invention, the Cr content is limited to 0.05% or more and 1.6% or less. From a similar perspective,
It is desirable that the upper limit of the Cr content be 0.9% and the lower limit be 0.2%.
【００２８】(Nb：0.005 〜0.1 ％)Nbは、0.005 ％以上
含有することにより、スラブ加熱時に結晶粒粗大化を抑
制する他、Nb（Ｃ、Ｎ）のピンニング効果により未再結
晶領域を拡大し、特に母材靱性を向上させる。一方、Nb
含有量が0.1 ％を超えると著しく靱性を損ねる。そこ
で、本発明では、Nb含有量は0.005 ％以上0.1 ％以下と
限定する。同様の観点から、Nb含有量の上限は0.04％、
下限は0.008 ％であることがそれぞれ望ましい。(Nb: 0.005 to 0.1%) By containing 0.005% or more of Nb, crystal grains are not coarsened during slab heating, and an unrecrystallized region is expanded by the pinning effect of Nb (C, N). In particular, the base material toughness is improved. On the other hand, Nb
If the content exceeds 0.1%, the toughness is significantly impaired. Therefore, in the present invention, the Nb content is limited to 0.005% or more and 0.1% or less. From the same viewpoint, the upper limit of the Nb content is 0.04%,
The lower limit is desirably 0.008%.
【００２９】(Ti：0.005 〜0.1 ％)Tiは、0.005 ％以上
含有することにより、スラブ加熱時に結晶粒粗大化を抑
制する他、析出物の生成を通して強度上昇に寄与し、ま
た、AlＮ生成の抑制を通してスラブの表面性状を向上さ
せる。一方、Ti含有量が0.1 ％を超えると著しく靱性を
損ねる。そこで、本発明では、Ti含有量は0.005 ％以上
0.1 ％以下と限定する。同様の観点から、Ti含有量の上
限は0.02％、下限は0.008 ％であることがそれぞれ望ま
しい。(Ti: 0.005 to 0.1%) By containing 0.005% or more of Ti, in addition to suppressing the coarsening of grains during slab heating, it contributes to the increase in strength through the formation of precipitates and also the formation of AlN. Improve the surface properties of the slab through suppression. On the other hand, if the Ti content exceeds 0.1%, the toughness is significantly impaired. Therefore, in the present invention, the Ti content is 0.005% or more.
Limited to 0.1% or less. From the same viewpoint, it is preferable that the upper limit of the Ti content is 0.02% and the lower limit is 0.008%.
【００３０】さらに、本発明では、いっそうの強度の向
上のために、Cu、Ni、Mo、Ｖ、Ｗ、REM およびCaのうち
の少なくとも１種を任意添加元素として含有してもよ
い。以下、これらの任意添加元素についても説明する。Further, in the present invention, at least one of Cu, Ni, Mo, V, W, REM and Ca may be contained as an optional additive element for further improving the strength. Hereinafter, these optional elements will be described.
【００３１】(Cu：1.0 ％以下)Cuは、析出強化元素であ
って、強度上昇に効果がある。しかし、Cu含有量が1.0
％を超えるとスケール発生により鋼板の表面性状を著し
く劣化させ、さらには、靱性の劣化を招く。そこで、Cu
を添加する場合には、その含有量は1.0 ％以下と限定す
ることが望ましい。(Cu: 1.0% or less) Cu is a precipitation strengthening element and is effective in increasing the strength. However, when the Cu content is 1.0
%, The generation of scale significantly deteriorates the surface properties of the steel sheet, and further causes the deterioration of toughness. Then, Cu
In the case where is added, its content is preferably limited to 1.0% or less.
【００３２】(Ni：2.0 ％以下)Niは、強度および靱性を
ともに向上させるために有効な元素である。しかし、Ni
含有量が2.0 ％を超えるとコストの上昇を招く。そこ
で、Niを添加する場合には、その含有量は2.0 ％以下と
限定することが望ましい。(Ni: 2.0% or less) Ni is an element effective for improving both strength and toughness. But Ni
If the content exceeds 2.0%, the cost will increase. Therefore, when adding Ni, it is desirable to limit the content to 2.0% or less.
【００３３】(Mo：1.0 ％以下)Moは、強度の向上に有効
な元素であるが、Mo含有量が1.0 ％を超えると靱性を損
なう。そこで、Moを添加する場合には、その含有量は1.
0 ％以下と限定することが望ましい。(Mo: 1.0% or less) Mo is an element effective for improving the strength, but if the Mo content exceeds 1.0%, the toughness is impaired. Therefore, when adding Mo, the content is 1.
It is desirable to limit it to 0% or less.
【００３４】(Ｖ：0.1 ％以下)Ｖは、強度の向上に有効
な元素であるが、Ｖ含有量が0.1 ％を超えると靱性を損
なう。そこで、Ｖを添加する場合には、その含有量は0.
1 ％以下と限定することが望ましい。(V: 0.1% or less) V is an element effective for improving the strength, but if the V content exceeds 0.1%, the toughness is impaired. Therefore, when V is added, its content is 0.
It is desirable to limit it to 1% or less.
【００３５】(Ｗ：1.0 ％以下)Ｗは、強度の向上に有効
な元素であるが、Ｗ含有量が1.0 ％を超えると靱性を損
なう。そこで、Ｗを添加する場合には、その含有量は1.
0 ％以下と限定することが望ましい。(W: 1.0% or less) W is an element effective for improving the strength, but if the W content exceeds 1.0%, the toughness is impaired. Therefore, when adding W, the content is 1.
It is desirable to limit it to 0% or less.
【００３６】(REM ：0.02％以下)REM は、強度の向上に
有効であるが、REM 含有量が0.02％を超えると経済性を
損なう。そこで、REM を添加する場合には、その含有量
は0.02％以下と限定することが望ましい。(REM: 0.02% or less) REM is effective in improving the strength, but if the REM content exceeds 0.02%, the economic efficiency is impaired. Therefore, when adding REM, it is desirable to limit the content to 0.02% or less.
【００３７】(Ca：0.02％以下)Caは、介在物の形態制御
効果を通して靱性の向上に有効であるが、Ca含有量が0.
02％を超えると靱性を損なう。そこで、Caを添加する場
合には、その含有量は0.02％以下と限定することが望ま
しい。(Ca: 0.02% or less) Ca is effective in improving the toughness through the effect of controlling the morphology of inclusions.
If it exceeds 02%, toughness is impaired. Therefore, when adding Ca, it is desirable to limit the content to 0.02% or less.
【００３８】本発明では、AlおよびＢはいずれも実質的
に含有しない。すなわち、Alはセメンタイトの析出を遅
らせる効果を有するため、結果的にＭＡの生成量を増加
させる。通常の鋼では、脱酸や加熱時の結晶粒の微細化
を図るために添加するが、本発明では、ＭＡ量を極力低
減させるためにAlは添加しない。一方、Ｂは焼入れ時に
オーステナイト粒界に偏析し、フェライト変態を遅らせ
焼入れ性を向上させる。しかしながら、マトリックスに
固溶した単体のＢはマトリックスの靱性を著しく損なう
ためにＢは添加しない。In the present invention, neither Al nor B is substantially contained. That is, since Al has an effect of delaying the precipitation of cementite, the amount of generated MA is increased as a result. In ordinary steel, it is added to achieve deoxidation and refinement of crystal grains during heating, but in the present invention, Al is not added in order to minimize the amount of MA. On the other hand, B segregates at austenite grain boundaries during quenching, delays ferrite transformation and improves quenchability. However, since B alone as a solid solution in the matrix significantly impairs the toughness of the matrix, B is not added.
【００３９】ただし、AlもＢも原料鉄鉱石中に極微量で
はあるが不可避に含有される場合があり、ここでいう
「実質的に含有しない」とは、この不可避的な微量の含
有は許容する趣旨である。However, both Al and B may be inevitably contained in the raw iron ore, though in a very small amount, and the term “substantially not contained” as used herein means that the inevitable minute content is acceptable. The purpose is to do.
【００４０】(炭素当量Ｃeq:0.30 〜0.45％)炭素当量Ｃ
eqは、焼入れ性を示す指標としてこれまで広く用いられ
ている。炭素当量Ｃeqを0.30以上0.45以下に調整するこ
とにより、本発明が対象とする強度レベル：50〜60kgf/
mm2 を実現できる。そこで、本発明では、炭素当量Ｃeq
は、0.30以上0.45％以下と限定する。(Carbon equivalent Ceq: 0.30 to 0.45%) Carbon equivalent C
eq has been widely used as an index indicating hardenability. By adjusting the carbon equivalent Ceq to 0.30 or more and 0.45 or less, the strength level targeted by the present invention: 50-60 kgf /
mm 2 can be realized. Therefore, in the present invention, the carbon equivalent Ceq
Is limited to 0.30 or more and 0.45% or less.
【００４１】上記以外の組成は、Feおよび不可避的不純
物である。この本発明にかかる靱性に優れた高張力鋼板
は、Ｃ量およびSi量が(2) 式を満足するとともにフェラ
イト・ベイナイト組織を呈する。Compositions other than those described above are Fe and inevitable impurities. The high-tensile steel sheet having excellent toughness according to the present invention has a C content and a Si content satisfying the formula (2) and exhibits a ferrite bainite structure.
【００４２】すなわち、本発明にかかる高張力鋼板は、
Alを非添加としているため、Ｃ含有量およびSi含有量と
上部ベイナイト比率ＦBU (％) との間に、（2)式により
規定される関係、すなわちＣ≦3.2/(Si0.32 ×ＦBU) を
満足することにより、ＭＡの生成量を低減して、確実に
靱性の向上を図ることができる。That is, the high-tensile steel sheet according to the present invention comprises:
Since Al is not added, the relationship defined by equation (2) between the C content and the Si content and the upper bainite ratio F BU (%), that is, C ≦ 3.2 / (Si 0.32 × F BU) By satisfying (1), it is possible to reduce the amount of generated MA and to surely improve the toughness.
【００４３】図１(a) 〜図１(c) は、いずれも、板厚24
mm、Ｘ開先およびSAW3.0kJ/mm の条件からなる溶接部に
ついてF.L.ノッチシャルピ衝撃試験を行った場合に、Ｃ
含有量およびSi含有量が、F.L.ノッチシャルピ吸収エネ
ルギに与える影響を示すグラフであり、図１(a) は上部
ベイナイト比率ＦBUが100 ％である場合を示し、図１
(b) は上部ベイナイト比率ＦBUが90％である場合を示
し、さらに、図１(c) は上部ベイナイト比率ＦBUが80％
である場合を示す。FIGS. 1 (a) to 1 (c) each show a plate thickness of 24.
mm, X groove and SAW3.0kJ / mm, when the FL notch Charpy impact test was performed
FIG. 1A is a graph showing the effect of the content and the Si content on the FL notch Charpy absorbed energy. FIG. 1A shows the case where the upper bainite ratio F BU is 100%, and FIG.
(b) shows the case where the upper bainite ratio F BU is 90%, and FIG. 1 (c) shows the case where the upper bainite ratio F BU is 80%.
Is shown.
【００４４】図１(a) 〜図１(c) にグラフで示すよう
に、Ｃ：0.03〜0.10％、Si：0.10〜0.40％およびＣ≦3.
2/(Si0.32 ×ＦBU) を満足することにより、継手部の−
40℃における衝撃吸収エネルギvE-80(atFL) が100(J)以
上を確保することができる。As shown in the graphs of FIGS. 1A to 1C, C: 0.03 to 0.10%, Si: 0.10 to 0.40%, and C ≦ 3.
2 / (Si 0.32 × F BU )
The impact absorption energy vE -80 (atFL) at 40 ° C can be 100 (J) or more.
【００４５】この本発明にかかる高張力鋼板は、継手部
のF.L.ノッチシャルピー衝撃試験の−40℃における衝撃
吸収エネルギvE-40(atFL) が100(J)超であり、充分な溶
接金属や溶接熱影響部の靱性を有する。このため、この
高張力鋼板は、例えば圧力容器や海洋構造物等の構造部
材として充分に使用することができる。また、この本発
明にかかる高張力鋼板は、高価な合金元素の含有量を極
力抑制しているため、コストの上昇を抑制することがで
きる。The high-strength steel sheet according to the present invention has an impact absorption energy vE -40 (atFL) at −40 ° C. of the FL notch Charpy impact test of the joint portion of more than 100 (J), and has a sufficient weld metal or weld strength. It has the toughness of the heat-affected zone. Therefore, this high-tensile steel plate can be sufficiently used as a structural member such as a pressure vessel or an offshore structure. Further, in the high-tensile steel sheet according to the present invention, since the content of expensive alloy elements is suppressed as much as possible, an increase in cost can be suppressed.
【００４６】この本発明にかかる高張力鋼板を製造する
には、上部ベイナイト比率を確実に制御することが必要
である。このためには、(i) 水冷によって強度および靱
性を確保する場合には、スラブ加熱温度と、圧延仕上げ
温度と、水冷開始温度および停止温度等とを、また(ii)
オフライン熱処理により強度および靱性を確保する場合
には、スラブ加熱温度と、圧延仕上げ温度と、熱処理温
度および保持時間等とを、適宜制御すればよい。In order to manufacture the high-tensile steel sheet according to the present invention, it is necessary to control the upper bainite ratio reliably. For this purpose, (i) when securing strength and toughness by water cooling, the slab heating temperature, rolling finish temperature, water cooling start temperature and stop temperature, etc., and (ii)
When strength and toughness are ensured by off-line heat treatment, the slab heating temperature, the rolling finish temperature, the heat treatment temperature, the holding time, and the like may be appropriately controlled.
【００４７】[0047]
【実施例】表１に示す鋼組成および炭素当量Ｃeqを有す
る鋼片に、適宜条件で、スラブ加熱、熱間圧延および水
冷を行って、表１に示す上部ベイナイト比率ＦBUを有す
る板厚が24mmの厚鋼板１〜30を得た。なお、厚鋼板１の
製造条件を表３にまとめて例示する。EXAMPLES The steel strip having a steel composition and the carbon equivalent Ceq shown in Table 1, in appropriate conditions, slab heating, by performing hot rolling and water cooling, the plate thickness with upper bainite ratio F BU shown in Table 1 24 mm thick steel plates 1 to 30 were obtained. In addition, the manufacturing conditions of the thick steel plate 1 are collectively illustrated in Table 3.
【００４８】[0048]
【表１】 [Table 1]
【００４９】[0049]
【表２】 [Table 2]
【００５０】[0050]
【表３】 [Table 3]
【００５１】表１における厚鋼板No.1〜厚鋼板No.18
は、本発明で規定する組成を満足する鋼種であり、厚鋼
板No.19 〜厚鋼板No.30 は、本発明で規定する組成を満
足しない鋼種である。なお、表１における＊印は、本発
明の範囲を満足しないことを示す。In Table 1, thick steel plate No. 1 to thick steel plate No. 18
Is a steel type that satisfies the composition specified by the present invention, and heavy steel plates No. 19 to No. 30 are steel types that do not satisfy the composition specified by the present invention. In addition, * mark in Table 1 shows that the range of the present invention is not satisfied.
【００５２】これらの厚鋼板No.1〜厚鋼板No.30 から試
料No.1〜試料No.30 を切り出して、走査型電子顕微鏡ま
たは透過型電子顕微鏡を用いて組織観察を行うことによ
り上部ベイナイト比率ＦBUを測定して3.2/(Si0.32 ×Ｆ
BU) を求めるとともに、F.L.ノッチシャルピー衝撃試験
を行って、継手部の−40℃における衝撃吸収エネルギvE
-40(atFL) を測定した。なお、試料No.1〜試料No.30 に
ついての溶接条件は、開先形状：Ｘ開先、溶接方法：SA
W 、入熱：3.0kJ/mmとした。3.2/(Si0.32 ×ＦBU) を表
１に示すとともに、衝撃吸収エネルギvE-40(atFL)を表
２にまとめて示す。なお、表２における**印は不芳デー
タであることを示す。Samples No. 1 to No. 30 were cut out from these thick steel plates No. 1 to No. 30, and the structure was observed using a scanning electron microscope or a transmission electron microscope to obtain the upper bainite. Measure the ratio F BU to 3.2 / (Si 0.32 × F
BU ) and conduct a FL notch Charpy impact test to determine the impact absorption energy vE of the joint at -40 ° C.
-40 (atFL) was measured. The welding conditions for sample No. 1 to sample No. 30 were as follows: groove shape: X groove, welding method: SA
W, heat input: 3.0 kJ / mm. 3.2 / (Si 0.32 × F BU ) is shown in Table 1, and the shock absorption energy vE -40 (atFL) is shown in Table 2. In addition, ** mark in Table 2 shows that it is bad data.
【００５３】表２における試料No.1〜試料No.18 は、鋼
種の組成、炭素当量Ｃeqおよび組織がいずれも本発明の
範囲を満足する本発明例である。試料No.1〜試料No.18
は、いずれも、継手部の−40℃における衝撃吸収エネル
ギvE-40(atFL) が100(J)超であり、溶接金属や溶接熱影
響部の靱性の目標を充分に満足する。このため、試料N
o.1〜試料No.18 は、例えば圧力容器や海洋構造物等の
構造部材として好適に使用することができる。Sample Nos. 1 to 18 in Table 2 are examples of the present invention in which the composition of the steel type, the carbon equivalent Ceq, and the structure all satisfy the scope of the present invention. Sample No.1 to Sample No.18
In any of the above, the impact absorption energy vE -40 (atFL) at −40 ° C. of the joint is more than 100 (J), which sufficiently satisfies the toughness targets of the weld metal and the heat affected zone. Therefore, sample N
o.1 to Sample No. 18 can be suitably used as structural members such as pressure vessels and marine structures.
【００５４】これに対し、試料No.19 は、Ｃ含有量およ
び炭素当量Ｃeqがともに本発明の範囲を下回るため、溶
接部靱性の目標値を満足できなかった。試料No.20 は、
Si含有量が本発明の範囲を上回るため、溶接部靱性の目
標値を満足できなかった。On the other hand, in Sample No. 19, both the C content and the carbon equivalent Ceq were below the range of the present invention, and thus the target value of the weld toughness could not be satisfied. Sample No. 20
Since the Si content exceeded the range of the present invention, the target value of the weld toughness could not be satisfied.
【００５５】試料No.21 は、Mn含有量および炭素当量Ｃ
eqがともに本発明の範囲を下回るため、溶接部靱性の目
標値を満足できなかった。試料No.22 は、Cr含有量およ
び炭素当量Ｃeqがともに本発明の範囲を上回るため、溶
接部靱性の目標値を満足できなかった。Sample No. 21 had a Mn content and carbon equivalent C
Since both eq were below the range of the present invention, the target value of the weld toughness could not be satisfied. In Sample No. 22, both the Cr content and the carbon equivalent Ceq exceeded the ranges of the present invention, and thus the target value of the weld toughness could not be satisfied.
【００５６】試料No.23 は、Nb含有量が本発明の範囲を
下回るため、溶接部靱性の目標値を満足できなかった。
試料No.24 は、Ti含有量が本発明の範囲を下回るため、
溶接部靱性の目標値を満足できなかった。Sample No. 23 failed to satisfy the target value of weld toughness because the Nb content was below the range of the present invention.
Sample No. 24 had a Ti content below the range of the present invention,
The target value of weld toughness could not be satisfied.
【００５７】試料No.25 は、Cu含有量が本発明の範囲を
上回るため、溶接部靱性の目標値を満足できなかった。
試料No.26 は、Ni含有量が本発明の範囲を上回るため、
溶接部靱性の目標値を満足できなかった。Sample No. 25 failed to satisfy the target value of weld toughness because the Cu content exceeded the range of the present invention.
Sample No. 26 has a Ni content exceeding the range of the present invention,
The target value of weld toughness could not be satisfied.
【００５８】試料No.27 は、Mo含有量および炭素当量Ｃ
eqがともに本発明の範囲を上回るため、溶接部靱性の目
標値を満足できなかった。試料No.28 は、Ｖ含有量が本
発明の範囲を上回るため、溶接部靱性の目標値を満足で
きなかった。Sample No. 27 had a Mo content and carbon equivalent C
Since both eq exceeded the range of the present invention, the target value of the weld toughness could not be satisfied. Sample No. 28 could not satisfy the target value of weld toughness because the V content exceeded the range of the present invention.
【００５９】試料No.29 は、Ｗ含有量が本発明の範囲を
上回るため、溶接部靱性の目標値を満足できなかった。
さらに、試料No.30 は、3.2/(Si0.32 ×ＦBU) が本発明
の範囲を下回るため、溶接部靱性の目標値を満足できな
かった。Sample No. 29 failed to meet the target value of weld toughness because the W content exceeded the range of the present invention.
Further, in Sample No. 30, 3.2 / (Si 0.32 × F BU ) was less than the range of the present invention, so that the target value of the weld toughness could not be satisfied.
【００６０】（変形形態）実施形態および実施例の説明
では、鋼材が鋼板である場合を例にとった。しかし、本
発明は鋼板には限定されず、例えば鋼管や形鋼等といっ
た鋼板以外の鋼材に対しても、同様に適用される。(Modification) In the description of the embodiments and examples, the case where the steel material is a steel plate is taken as an example. However, the present invention is not limited to steel plates, and is similarly applied to steel materials other than steel plates, such as steel pipes and section steels.
【００６１】[0061]
【発明の効果】以上詳細に説明したように、本発明によ
り、靱性に優れた高張力鋼材、具体的には、例えばアー
ク溶接やビーム溶接等の溶接施工により工作される構造
物の構造部材に適用するのに適した経済性および靱性に
優れた高張力鋼材を提供すること、より具体的には、継
手部の−40℃における衝撃吸収エネルギvE-40(atFL) が
100(J)超であり、例えば圧力容器や海洋構造物等の構造
部材として使用するのに好適な経済性および靱性に優れ
た高張力鋼材を提供することが可能となった。かかる効
果を有する本発明の意義は、極めて著しい。As described above in detail, according to the present invention, a high-tensile steel material having excellent toughness, specifically, a structural member of a structure machined by welding such as arc welding or beam welding is used. To provide a high-strength steel material with excellent economy and toughness suitable for application, and more specifically, the impact absorption energy vE -40 (atFL) at -40 ° C of the joint part.
It is more than 100 (J), which makes it possible to provide a high-tensile steel material excellent in economy and toughness suitable for use as a structural member such as a pressure vessel or an offshore structure. The significance of the present invention having such an effect is extremely remarkable.
【図１】図１(a) 〜図１(c) は、いずれも、板厚24mm、
Ｘ開先およびSAW3.0kJ/mm の条件からなる溶接部につい
てF.L.ノッチシャルピ衝撃試験を行った場合に、Ｃ含有
量およびSi含有量が、F.L.ノッチシャルピ吸収エネルギ
に与える影響を示すグラフであり、図１(a) は上部ベイ
ナイト比率ＦBUが100 ％である場合を示し、図１(b) は
上部ベイナイト比率ＦBUが90％である場合を示し、さら
に、図１(c) は上部ベイナイト比率ＦBUが80％である場
合を示す。FIG. 1 (a) to FIG. 1 (c) each show a plate thickness of 24 mm,
FIG. 9 is a graph showing the effect of the C content and the Si content on the FL notch Charpy absorbed energy when a FL notch Charpy impact test was performed on a welded portion formed under the conditions of X groove and SAW 3.0 kJ / mm, 1 (a) shows the case where the upper bainite ratio F BU is 100%, FIG. 1 (b) shows the case where the upper bainite ratio F BU is 90%, and FIG. 1 (c) shows the case where the upper bainite ratio F BU is 90%. The case where the ratio F BU is 80% is shown.
Claims (2)
〜0.40％、Mn：0.6〜2.0 ％、Cr：0.05〜1.6 ％、Nb：
0.005 〜0.1 ％、Ti：0.005 〜0.1 ％を含有し、Alおよ
びＢを実質的に含有しないとともに下記(1) 式により規
定される炭素当量Ｃeqが0.30〜0.45％の範囲にあり、残
部Feおよび不可避的不純物からなる鋼組成を有し、Ｃ量
およびSi量が下記(2) 式を満足するとともにフェライト
・ベイナイト組織を呈することを特徴とする経済性およ
び靱性に優れた高張力鋼材。 【数１】 Ｃeq＝Ｃ＋Mn/6＋Si/24 ＋Ni/40 ＋Cr/5＋Mo/4＋Ｖ/14 ・・・・・・・(1) Ｃ≦3.2/(Si0.32 ×ＦBU) ・・・・・・・(2) ただし、符号ＦBUは上部ベイナイト比率 (％) を示す。C .: 0.03 to 0.10% by weight, Si: 0.10% by weight
~ 0.40%, Mn: 0.6 ~ 2.0%, Cr: 0.05 ~ 1.6%, Nb:
It contains 0.005 to 0.1%, Ti: 0.005 to 0.1%, contains substantially no Al and B, has a carbon equivalent Ceq defined by the following formula (1) in the range of 0.30 to 0.45%, and the balance Fe and A high-strength steel material having a steel composition comprising unavoidable impurities, having a C content and a Si content satisfying the following formula (2) and exhibiting a ferrite bainite structure, and having excellent economic efficiency and toughness. Ceq = C + Mn / 6 + Si / 24 + Ni / 40 + Cr / 5 + Mo / 4 + V / 14 (1) C ≦ 3.2 / (Si 0.32 × F BU ) 2) Here, the symbol F BU indicates the upper bainite ratio (%).
i：2.0 ％以下、Mo：1.0 ％以下、Ｖ：0.1 ％以下、
Ｗ：1.0 ％以下、REM ：0.02％以下およびCa：0.02％以
下からなる群から選ばれた１種または２種以上を含有す
ることを特徴とする請求項１に記載された経済性および
靱性に優れた高張力鋼材。2. The composition according to claim 1, further comprising: Cu: 1.0% or less,
i: 2.0% or less, Mo: 1.0% or less, V: 0.1% or less,
2. The economy and toughness according to claim 1, wherein one or more kinds selected from the group consisting of W: 1.0% or less, REM: 0.02% or less and Ca: 0.02% or less are contained. Excellent high tensile steel material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24008499A JP3468168B2 (en) | 1999-08-26 | 1999-08-26 | High-strength steel sheet with excellent economy and toughness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24008499A JP3468168B2 (en) | 1999-08-26 | 1999-08-26 | High-strength steel sheet with excellent economy and toughness |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001064745A true JP2001064745A (en) | 2001-03-13 |
| JP3468168B2 JP3468168B2 (en) | 2003-11-17 |
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ID=17054255
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24008499A Expired - Fee Related JP3468168B2 (en) | 1999-08-26 | 1999-08-26 | High-strength steel sheet with excellent economy and toughness |
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| Country | Link |
|---|---|
| JP (1) | JP3468168B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1777315A1 (en) * | 2004-07-21 | 2007-04-25 | Nippon Steel Corporation | Steel for welded structure excellent in low temperature toughness of heat affected zone of welded part, and method for production thereof |
| JP2009115493A (en) * | 2007-11-02 | 2009-05-28 | Sumitomo Metal Ind Ltd | Arresting characteristic evaluation method of steel plate, and steel plate for arresting characteristic evaluation |
| JP2020204064A (en) * | 2019-06-14 | 2020-12-24 | 日本製鉄株式会社 | Weld metal for high energy density beam welded joint, high energy density beam welded joint, weld structure, steel pipe, steel material for high energy density beam welded joint, and method for manufacturing the same |
| JP2020204065A (en) * | 2019-06-14 | 2020-12-24 | 日本製鉄株式会社 | Weld metal for high energy density beam welded joint, high energy density beam welded joint, weld structure, and steel pipe |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100497706C (en) * | 2004-07-21 | 2009-06-10 | 新日本制铁株式会社 | Steel for welded structures excellent in low temperature toughness of weld heat affected zone and method of production of same |
-
1999
- 1999-08-26 JP JP24008499A patent/JP3468168B2/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1777315A1 (en) * | 2004-07-21 | 2007-04-25 | Nippon Steel Corporation | Steel for welded structure excellent in low temperature toughness of heat affected zone of welded part, and method for production thereof |
| EP1777315A4 (en) * | 2004-07-21 | 2008-05-07 | Nippon Steel Corp | Steel for welded structure excellent in low temperature toughness of heat affected zone of welded part, and method for production thereof |
| US7857917B2 (en) | 2004-07-21 | 2010-12-28 | Nippon Steel Corporation | Method of production of steel for welded structures excellent in low temperature toughness of weld heat affected zone |
| JP2009115493A (en) * | 2007-11-02 | 2009-05-28 | Sumitomo Metal Ind Ltd | Arresting characteristic evaluation method of steel plate, and steel plate for arresting characteristic evaluation |
| JP2020204064A (en) * | 2019-06-14 | 2020-12-24 | 日本製鉄株式会社 | Weld metal for high energy density beam welded joint, high energy density beam welded joint, weld structure, steel pipe, steel material for high energy density beam welded joint, and method for manufacturing the same |
| JP2020204065A (en) * | 2019-06-14 | 2020-12-24 | 日本製鉄株式会社 | Weld metal for high energy density beam welded joint, high energy density beam welded joint, weld structure, and steel pipe |
| JP7502589B2 (en) | 2019-06-14 | 2024-06-19 | 日本製鉄株式会社 | Weld metal of high energy density beam welded joint, high energy density beam welded joint, welded structure and steel pipe |
| JP7502588B2 (en) | 2019-06-14 | 2024-06-19 | 日本製鉄株式会社 | Weld metal for high energy density beam welded joint, high energy density beam welded joint, welded structure, steel pipe, steel material for high energy density beam welded joint and manufacturing method thereof |
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| Publication number | Publication date |
|---|---|
| JP3468168B2 (en) | 2003-11-17 |
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