JP2001011566A - High tensile strength steel excellent in toughness of weld zone and its production - Google Patents
High tensile strength steel excellent in toughness of weld zone and its productionInfo
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- JP2001011566A JP2001011566A JP11181622A JP18162299A JP2001011566A JP 2001011566 A JP2001011566 A JP 2001011566A JP 11181622 A JP11181622 A JP 11181622A JP 18162299 A JP18162299 A JP 18162299A JP 2001011566 A JP2001011566 A JP 2001011566A
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】この発明は、溶接部の靭性に
優れた高張力鋼に関し、特に小〜中入熱溶接におけるＨ
ＡＺ靭性に優れた高張力鋼およびその製造方法を提供す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength steel having excellent toughness at a welded portion, and more particularly, to a high-strength steel in small to medium heat welding.
Provided is a high-strength steel excellent in AZ toughness and a method for producing the same.
【０００２】[0002]
【従来の技術】近年、北海、北極海などの寒冷海域にお
いて活発に進められている海底石油・天然ガス資源の開
発に用いられる構造物は、破壊した場合の被害の大きさ
から脆性破壊に対する考慮が必要とされ、使用される海
洋構造物用鋼材はその溶接部に極めて優れた低温靭性が
要求されている。2. Description of the Related Art In recent years, structures used for the development of offshore oil and natural gas resources which are being actively promoted in cold seas such as the North Sea and the Arctic Ocean are considered for brittle fracture due to the magnitude of damage when destroyed. Therefore, the steel material for offshore structures used is required to have extremely excellent low-temperature toughness in the welded portion.
【０００３】鋼材の低温靭性を評価する有効な手段とし
て、英国規格ＢＳ５７６２（１９７９）に規定されるＣ
ＴＯＤ試験が用いられ、疲労予亀裂を評価部に発生させ
ることにより、極めて微小部分の脆性亀裂発生抵抗特性
の評価が行なわれている。[0003] As an effective means for evaluating the low-temperature toughness of steel, C as specified in British Standard BS5762 (1979) is used.
The TOD test is used to evaluate a brittle crack initiation resistance characteristic of a very small portion by generating a pre-fatigue crack in an evaluation portion.
【０００４】一方、厚鋼板の溶接は通常、多層溶接さ
れ、溶接熱影響部（ＨＡＺ）には複雑な熱履歴を受けた
局所脆化域が発生する。特に１３５０℃以上に加熱され
た粗粒域（ＣＧＨＡＺ），およびＡｃ1〜Ａｃ3の温度に
再加熱された粗粒域（Ｉｎｔｅｒｃｒｉｔｉｃａｌ ｒ
ｅｈｅａｔｅｄ ＣＧＨＡＺ）が最も靭性が劣化する。
そのため、米国石油協会ではＡＰＩＲＰ２Ｚ（１９８
７）において、ＣＧＨＡＺが予亀裂の先端に一定の割合
以上になるように加工の詳細な規定を盛り込んでいる。[0004] On the other hand, welding of a thick steel plate is usually performed by multi-layer welding, and a local embrittlement zone receiving a complicated heat history is generated in a heat affected zone (HAZ). In particular, a coarse-grained region (CGHAZ) heated to 1350 ° C. or higher, and a coarse-grained region (Intercritical r) reheated to a temperature of Ac1 to Ac3
(CGHAZ) is the most deteriorated in toughness.
For this reason, the American Petroleum Institute has proposed APIIR2Z (198
In 7), detailed specifications of the processing are incorporated so that CGHAZ is at a predetermined ratio or more at the tip of the pre-crack.
【０００５】ＨＡＺ靭性の劣化は結晶粒径、島状マルテ
ンサイト（ＭＡ）や上部ベイナイトなどの硬化相などの
影響が大きいことが知られており、例えば、特公昭５５
−２６１６４号公報などでは、微細なＴｉ窒化物を鋼中
に確保することによって、ＨＡＺのオーステナイト粒を
小さくし、靭性を向上させる方法が開示されている。ま
た、特公平４−１４１７９号公報や特開平４−１１６１
３５号公報では、成分調整により島状マルテンサイトの
析出状態を制御する方法が開示され、特開平３−２６４
６１４号公報ではＴｉ窒化物とＭｎＳの複合析出物をフ
ェライト変態核として活用し、ＨＡＺ組織を改善する方
法が提案されている。It is known that the deterioration of HAZ toughness is greatly affected by the crystal grain size, the hardened phase such as island martensite (MA) and upper bainite.
Japanese Patent No. 26164 discloses a method of securing fine Ti nitride in steel, thereby reducing austenite grains of HAZ and improving toughness. In addition, Japanese Patent Publication No. 4-14179 and Japanese Patent Laid-Open No.
Japanese Patent Application Publication No. 35-264 discloses a method of controlling the precipitation state of island martensite by adjusting the components.
No. 614 proposes a method for improving the HAZ structure by utilizing a composite precipitate of Ti nitride and MnS as a ferrite transformation nucleus.
【０００６】しかし、極寒地で使用される海洋構造物用
鋼材のように、厳格な脆性破壊発生特性の評価が必要な
場合、例えば、近年、開発が計画されているサハリン沖
の石油・天然ガス開発プロジェクトでは要求限界ＣＴＯ
Ｄ値が靭性保証温度−４０℃において０．２５ｍｍ以上
と厳しい特性が要求されているが、前述した先行文献に
記載された技術ではシャルピー衝撃試験で高い靭性が得
られたものでも、必要な脆性亀裂発生特性の得られない
場合があり、ＣＴＯＤ試験評価においても安定した特性
の得られる技術が要望されている。However, when strict evaluation of brittle fracture occurrence characteristics is required, such as steel materials for marine structures used in extremely cold regions, for example, oil and natural gas development off Sakhalin, which is being recently developed, is planned. In the project, the required limit CTO
Although the D value is required to be as strict as 0.25 mm or more at the toughness assurance temperature of −40 ° C., the technique described in the above-mentioned prior art requires high brittleness even if high toughness is obtained in the Charpy impact test. In some cases, crack generation characteristics cannot be obtained, and there is a demand for a technique capable of obtaining stable characteristics even in CTOD test evaluation.
【０００７】これに対し、特開平５−２４７５３１号公
報や特開平６−２８５６０２号公報では、ＣＴＯＤ値が
安定的に確保される鋼の製造技術が開示されているが、
Ｔｉ酸化物の微細分散化は容易でなく、製造安定性の観
点からも好ましくない。[0007] On the other hand, Japanese Patent Application Laid-Open Nos. Hei 5-247531 and Hei 6-285602 disclose a technique for producing steel in which a CTOD value is stably ensured.
It is not easy to finely disperse the Ti oxide, which is not preferable from the viewpoint of production stability.
【０００８】[0008]
【発明が解決しようとする課題】上述したように、極寒
地でのＣＴＯＤ特性に優れた海洋構造物用鋼材を安定的
に製造できる方法は現在、提案されていない。本発明
は、以上の点に鑑みなされたもので、その目的は、主に
極寒地で使用される海洋構造物を対象とし、小〜中入熱
の多層盛溶接部で−４０℃以下の温度において、ＣＴＯ
Ｄ特性に優れる鋼材およびその特性が安定的に得られる
製造方法を提供することにある。As described above, a method for stably producing steel for offshore structures having excellent CTOD characteristics in extremely cold regions has not been proposed at present. The present invention has been made in view of the above points, and its object is to target a marine structure mainly used in an extremely cold region, and to have a temperature of -40 ° C or lower in a multi-pass weld of small to medium heat input. In, CTO
An object of the present invention is to provide a steel material having excellent D characteristics and a production method capable of stably obtaining the characteristics.
【０００９】[0009]
【課題を解決するための手段】本発明者らは上記課題を
達成するため、ＣＴＯＤ特性に及ぼすミクロ組織の影響
を母材、溶接部について詳細に検討を行ない以下の知見
を得た。（１）連続鋳造鋼片の加熱温度を１０５０〜１
２５０℃とした場合、鋼板内部の化学組成が均一化さ
れ、異常組織の生成が防止される。（２）Ｓｉ添加量を
０．０１〜０．１０％とした場合、ＭＡの生成が抑制さ
れる。Means for Solving the Problems In order to achieve the above object, the present inventors have studied in detail the effects of the microstructure on the CTOD characteristics for the base metal and the welded parts and have obtained the following findings. (1) The heating temperature of the continuously cast steel slab is 1050 to 1
When the temperature is set to 250 ° C., the chemical composition inside the steel sheet is made uniform, and the formation of an abnormal structure is prevented. (2) When the amount of Si added is 0.01 to 0.10%, the generation of MA is suppressed.
【００１０】（３）ｓｏｌ．Ａｌ量を０．０２５％以下
とした場合、フェライトの生成が促進され、ＭＡの生成
が抑制される。（４）Ｎ量を０．００３０％以下とした
場合、ベイナイト組織においてシャルピー試験でのシェ
ルフエネルギーが改善され、破壊に対する抵抗力が強ま
る。（５）鋼中に不可避的に混入するＢを５ｐｐｍ以下
とし、Ｔｉを添加した場合、ＣＧＨＡＺ（溶接熱影響部
粗粒域）の粗大化が抑制される。（６）Ｃａ添加によ
り、複合酸化物からの粒内フェライトの生成が促進さ
れ、脆性破壊発生抵抗が改善される。(3) sol. When the Al content is 0.025% or less, the formation of ferrite is promoted, and the formation of MA is suppressed. (4) When the N content is 0.0030% or less, the shelf energy in the Charpy test is improved in the bainite structure, and the resistance to fracture is increased. (5) When the amount of B unavoidably mixed into steel is set to 5 ppm or less and Ti is added, coarsening of CGHAZ (coarse grain region of the weld heat affected zone) is suppressed. (6) The addition of Ca promotes the generation of intragranular ferrite from the composite oxide and improves brittle fracture initiation resistance.
【００１１】本発明はこれらの知見に更に製造条件に関
する検討を加えてなされたものである。すなわち、本発
明は １．重量％で、Ｃ：０．０１〜０．１０％、Ｓｉ：０．
０１〜０．１０％、Ｍｎ：１．０〜２．０％、Ｓ：０．
００５％以下、Ｃｕ：１．０％以下、Ｎｉ：２．０％以
下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：０．００３
０％以下、Ｔｉ：０．００５〜０．０２５％、Ｂ：０．
０００５％以下、残部が実質的にＦｅからなることを特
徴とする溶接部靭性に優れた高張力鋼である。The present invention has been made by further studying the manufacturing conditions in addition to these findings. That is, the present invention provides: By weight%, C: 0.01-0.10%, Si: 0.
01 to 0.10%, Mn: 1.0 to 2.0%, S: 0.
005% or less, Cu: 1.0% or less, Ni: 2.0% or less, sol. Al: 0.025% or less, N: 0.003
0% or less, Ti: 0.005 to 0.025%, B: 0.
This is a high-strength steel having excellent weld toughness characterized in that the balance is substantially 0005% or less.
【００１２】２．重量％で、Ｃ：０．０１〜０．１０
％、Ｓｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．
０％、Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎ
ｉ：２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、
Ｎ：０．００３０％以下、Ｔｉ：０．００５〜０．０２
５％、Ｂ：０．０００５％以下、更に、Ｃａ：０．００
０５〜０．００５％、ＲＥＭ：０．００３〜０．０３０
％の一種以上を含有し、残部が実質的にＦｅからなるこ
とを特徴とする溶接部靭性に優れた高張力鋼である。2. In weight%, C: 0.01-0.10
%, Si: 0.01-0.10%, Mn: 1.0-2.
0%, S: 0.005% or less, Cu: 1.0% or less, N
i: 2.0% or less, sol. Al: 0.025% or less,
N: 0.0030% or less, Ti: 0.005 to 0.02
5%, B: 0.0005% or less, and Ca: 0.00
05-0.005%, REM: 0.003-0.030
%, And the balance is substantially made of Fe.
【００１３】３．重量％で、Ｃ：０．０１〜０．１０
％、Ｓｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．
０％、Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎ
ｉ：２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、
Ｎ：０．００３０％以下、Ｔｉ：０．００５〜０．０２
５％、Ｂ：０．０００５％以下、更に、Ｃｒ：０．１〜
０．５％、Ｍｏ：０．０５〜０．３０％、Ｖ：０．０１
〜０．１０％、Ｎｂ：０．００５〜０．０４０％の一種
または二種以上を含有し、残部が実質的にＦｅからなる
ことを特徴とする溶接部靭性に優れた高張力鋼である。3. In weight%, C: 0.01-0.10
%, Si: 0.01-0.10%, Mn: 1.0-2.
0%, S: 0.005% or less, Cu: 1.0% or less, N
i: 2.0% or less, sol. Al: 0.025% or less,
N: 0.0030% or less, Ti: 0.005 to 0.02
5%, B: 0.0005% or less, and Cr: 0.1 to
0.5%, Mo: 0.05 to 0.30%, V: 0.01
0.10%, Nb: 0.005 to 0.040%, and the balance is substantially Fe, and the balance is substantially Fe. .
【００１４】４．重量％で、Ｃ：０．０１〜０．１０
％、Ｓｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．
０％、Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎ
ｉ：２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、
Ｎ：０．００３０％以下、Ｔｉ：０．００５〜０．０２
５％、Ｂ：０．０００５％以下、残部が実質的にＦｅか
らなる連続鋳造鋼片を、１０５０〜１２５０℃の温度に
加熱し、次いで９００℃以下の温度範囲で累積圧下率２
５％以上の熱間圧延を施し、その後直ちに１〜５０℃／
ｓｅｃの冷却速度で５５０℃以下の温度まで冷却し、次
いで、５００℃以上Ａｃ1以下の温度で時効処理を施す
ことを特徴とする溶接部靭性に優れた高張力鋼の製造方
法である。4. In weight%, C: 0.01-0.10
%, Si: 0.01-0.10%, Mn: 1.0-2.
0%, S: 0.005% or less, Cu: 1.0% or less, N
i: 2.0% or less, sol. Al: 0.025% or less,
N: 0.0030% or less, Ti: 0.005 to 0.02
5%, B: 0.0005% or less, the continuous cast steel slab substantially consisting of Fe is heated to a temperature of 1050 to 1250 ° C, and then a cumulative rolling reduction 2 in a temperature range of 900 ° C or less.
Hot rolling of 5% or more, and immediately thereafter, 1-50 ° C /
This is a method for producing a high-strength steel having excellent weld toughness, characterized by cooling to a temperature of 550 ° C. or lower at a cooling rate of sec and then performing aging treatment at a temperature of 500 ° C. to Ac1.
【００１５】５．重量％で、Ｃ：０．０１〜０．１０
％、Ｓｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．
０％、Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎ
ｉ：２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、
Ｎ：０．００３０％以下、Ｔｉ：０．００５〜０．０２
５％、Ｂ：０．０００５％以下、更に、Ｃａ：０．００
０５〜０．００５％、ＲＥＭ：０．００３〜０．０３０
％の一種以上を含有し、残部が実質的にＦｅからなる連
続鋳造鋼片を、１０５０〜１２５０℃の温度に加熱し、
次いで９００℃以下の温度範囲で累積圧下率２５％以上
の熱間圧延を施し、その後直ちに１〜５０℃／ｓｅｃの
冷却速度で５５０℃以下の温度まで冷却し、次いで、５
００℃以上Ａｃ1以下の温度で時効処理を施すことを特
徴とする溶接部靭性に優れた高張力鋼の製造方法であ
る。[0015] 5. In weight%, C: 0.01-0.10
%, Si: 0.01-0.10%, Mn: 1.0-2.
0%, S: 0.005% or less, Cu: 1.0% or less, N
i: 2.0% or less, sol. Al: 0.025% or less,
N: 0.0030% or less, Ti: 0.005 to 0.02
5%, B: 0.0005% or less, and Ca: 0.00
05-0.005%, REM: 0.003-0.030
% Of a continuous cast steel slab containing 1% or more and the balance substantially consisting of Fe is heated to a temperature of 1050 to 1250 ° C,
Then, hot rolling is performed at a cumulative rolling reduction of 25% or more in a temperature range of 900 ° C or less, and immediately thereafter, cooling is performed at a cooling rate of 1 to 50 ° C / sec to a temperature of 550 ° C or less.
This is a method for producing a high-strength steel having excellent weld toughness, characterized by performing aging treatment at a temperature of from 00 ° C. to Ac1.
【００１６】６．重量％で、Ｃ：０．０１〜０．１０
％、Ｓｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．
０％、Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎ
ｉ：２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、
Ｎ：０．００３０％以下、Ｔｉ：０．００５〜０．０２
５％、Ｂ：０．０００５％以下、更に、Ｃｒ：０．１〜
０．５％、Ｍｏ：０．０５〜０．３０％、Ｖ：０．０１
〜０．１０％、Ｎｂ：０．００５〜０．０４０％の一種
以上を含有し、残部が実質的にＦｅからなる連続鋳造鋼
片を、１０５０〜１２５０℃の温度に加熱し、次いで９
００℃以下の温度範囲で累積圧下率２５％以上の熱間圧
延を施し、その後直ちに１〜５０℃／ｓｅｃの冷却速度
で５５０℃以下の温度まで冷却し、次いで、５００℃以
上Ａｃ1以下の温度で時効処理を施すことを特徴とする
溶接部靭性に優れた高張力鋼の製造方法である。6. In weight%, C: 0.01-0.10
%, Si: 0.01-0.10%, Mn: 1.0-2.
0%, S: 0.005% or less, Cu: 1.0% or less, N
i: 2.0% or less, sol. Al: 0.025% or less,
N: 0.0030% or less, Ti: 0.005 to 0.02
5%, B: 0.0005% or less, and Cr: 0.1 to
0.5%, Mo: 0.05 to 0.30%, V: 0.01
A continuous cast steel slab containing at least one of 0.15% and 0.15% Nb: 0.005% to 0.040%, with the balance substantially consisting of Fe, is heated to a temperature of 1050 to 1250 ° C.
Hot rolling is performed at a cumulative draft of 25% or more in a temperature range of 00 ° C or less, and then immediately cooled at a cooling rate of 1 to 50 ° C / sec to a temperature of 550 ° C or less, and then a temperature of 500 ° C or more and Ac1 or less. This is a method for producing a high-strength steel having excellent weld toughness, characterized by subjecting to aging treatment.
【００１７】[0017]
【発明の実施の形態】本発明では母材、溶接部のＣＴＯ
Ｄ特性を向上させるため、成分組成、製造条件を規定
し、ミクロ組織を最適化する。以下、本発明について詳
細に説明する。BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a CTO of a base material and a welded portion is used.
In order to improve the D characteristics, the composition of the components and the manufacturing conditions are specified, and the microstructure is optimized. Hereinafter, the present invention will be described in detail.
【００１８】１．成分組成 Ｃ：０．０１〜０．１０％ Ｃは鋼板として必要な強度を得るため、０．０１％以上
添加するが、０．１０％を超えると溶接性、溶接割れ感
受性が低下するため、０．０１〜０．１０％とする。1. Component composition C: 0.01 to 0.10% C is added in an amount of 0.01% or more to obtain the necessary strength as a steel sheet. However, if it exceeds 0.10%, the weldability and the susceptibility to weld cracking decrease. It is set to 0.01 to 0.10%.
【００１９】Ｓｉ：０．０１〜０．１０％ Ｓｉは脱酸、固溶強化に有効であるが、ＨＡＺ部靭性に
対しては悪影響を及ぼし、特にＣＴＯＤ特性に大きな影
響を与える。０．０１％未満ではその脱酸、固溶強化効
果が十分でなく、０．１０％を超えるとＭＡの生成抑制
効果が低下し、ＨＡＺ部の局所脆化域の靭性向上が期待
できなくなるため、０．０１〜０．１０％添加する。Si: 0.01 to 0.10% Si is effective for deoxidation and solid solution strengthening, but has an adverse effect on the toughness of the HAZ portion, and particularly has a great effect on the CTOD characteristics. If it is less than 0.01%, the effect of deoxidation and solid solution strengthening is not sufficient, and if it exceeds 0.10%, the effect of suppressing the formation of MA is reduced, and improvement in toughness in the local embrittlement region of the HAZ cannot be expected. , 0.01 to 0.10%.
【００２０】Ｍｎ：１．０〜２．０％ Ｍｎは母材の焼入れ性を確保するため添加する。１．０
％未満ではその効果が十分でなく、２．０％を超えると
溶接硬化性を著しく劣化させるため、１．０〜２．０％
添加する。Mn: 1.0 to 2.0% Mn is added to secure the hardenability of the base material. 1.0
%, The effect is not sufficient, and if it exceeds 2.0%, the weld hardenability is remarkably deteriorated.
Added.
【００２１】Ｓ：０．００５％以下 Ｓは有害な不純物で、できるだけ低減することが望まし
いが、極端な低下は生産コストを上昇させるため、Ｓ
ｉ、Ｃａ添加による靭性改善効果に悪影響を及ぼさない
含有量として０．００５％を上限とする。S: 0.005% or less S is a harmful impurity, and it is desirable to reduce it as much as possible. However, an extreme decrease increases production cost.
The upper limit is 0.005% as a content that does not adversely affect the toughness improving effect due to the addition of i and Ca.
【００２２】Ｃｕ：１．０％以下 Ｃｕは強度・靭性を向上させるため、添加するが、過剰
な添加は溶接割れ感受性を劣化させるため１．０％を上
限とする。Cu: 1.0% or less Cu is added in order to improve strength and toughness. However, excessive addition deteriorates weld cracking susceptibility, so the upper limit is 1.0%.
【００２３】Ｎｉ：２．０％以下 Ｎｉは溶接性を劣化させることなく強度及び靭性を向上
させ、熱間圧延中のＣｕ割れを防止するため添加する
が、２．０％を超える過剰な添加は溶接割れ感受性の劣
化やコストを上昇させるため、２．０％以下とする。Ni: 2.0% or less Ni is added to improve strength and toughness without deteriorating weldability and to prevent Cu cracking during hot rolling, but excessive addition exceeding 2.0% Is set to 2.0% or less in order to deteriorate welding crack susceptibility and increase costs.
【００２４】Ｎ：０．００３０％以下 Ｎは過剰に含有されると転位を固着し、靭性を著しく劣
化させる。特にベイナイト組織の場合、シャルピー試験
でのシェルフエネルギーを低下させ、破壊に対する抵抗
力を弱めるため、上限を０．００３０％とする。特に優
れたＨＡＺ靭性を必要とする場合、０．００２５％以下
とするのが好ましい。N: 0.0030% or less When N is contained excessively, it fixes dislocations and remarkably deteriorates toughness. In particular, in the case of a bainite structure, the upper limit is made 0.0030% in order to reduce the shelf energy in the Charpy test and weaken the resistance to fracture. When particularly excellent HAZ toughness is required, the content is preferably 0.0025% or less.
【００２５】ｓｏｌ．Ａｌ：０．０２５％以下 ｓｏｌ．Ａｌは脱酸のため添加するが、過剰な添加はＭ
Ａの生成を助長し、ＨＡＺ靭性を劣化させるため、上限
を０．０２５％とする。Sol. Al: 0.025% or less sol. Al is added for deoxidation, but excessive addition is
The upper limit is made 0.025% in order to promote the formation of A and deteriorate the HAZ toughness.
【００２６】Ｔｉ：０．００５〜０．０２５％ Ｔｉは鋼中にＴｉＮとして存在し、ＨＡＺ部のオーステ
ナイト粒の成長を抑制するため０．００５％以上添加す
るが、０．０２５％を超える過剰な添加は、特に多層溶
接の場合において、ボンド部近傍においてＴｉＮが分解
して生じる固溶Ｔｉによる靭性劣化が生じるため０．０
０５〜０．０２５％とする。Ti: 0.005 to 0.025% Ti is present as TiN in the steel, and is added in an amount of 0.005% or more to suppress the growth of austenite grains in the HAZ portion. In particular, in the case of multi-layer welding, the toughness is deteriorated by solid solution Ti generated by decomposition of TiN in the vicinity of the bond portion, so
05 to 0.025%.
【００２７】Ｂ：０．０００５％以下 Ｂは本発明では不可避的不純物として扱う。０．０００
５％を超えて混入した場合、ＨＡＺ部を著しく硬化させ
るため上限を０．０００５％とする。B: 0.0005% or less B is treated as an unavoidable impurity in the present invention. 0.000
If the content exceeds 5%, the upper limit is made 0.0005% because the HAZ portion is remarkably hardened.
【００２８】本発明では以上の基本成分組成で十分にそ
の目的を達成することができるが、更に鋼の特性を向上
させるため、以下の元素を添加することができる。In the present invention, the above-mentioned basic component composition can sufficiently achieve the object, but the following elements can be added in order to further improve the properties of steel.
【００２９】Ｃａ：０．０００５〜０．００５％、ＲＥ
Ｍ：０．００３〜０．０３０％ Ｃａ，ＲＥＭは靭性を向上させる効果があり、その効果
を期待する場合、一種以上添加する。Ca: 0.0005-0.005%, RE
M: 0.003 to 0.030% Ca and REM have the effect of improving the toughness, and if that effect is expected, one or more of them are added.
【００３０】Ｃａは靭性を劣化させるＭｎＳの形態を変
化させ、Ａｌとともに複合酸化物を形成し、粒内フェラ
イトの発生核となり靭性を向上させるが、過剰な添加は
焼入れ性の低下により、靭性を劣化させるため、０．０
００５〜０．００５％とする。Ca changes the form of MnS, which degrades toughness, forms a composite oxide with Al, and serves as a nucleus for intragranular ferrite to improve toughness. Excessive addition lowers toughness due to a decrease in hardenability. 0.0
005 to 0.005%.
【００３１】ＲＥＭは鋼中で硫化物、酸化物として存在
し、オ−ステナイト粒の成長を抑制し、靭性を向上させ
るが、過剰な添加は清浄度の低下により、靭性を劣化さ
せるため、０．００３〜０．０３０％とする。REM is present as sulfides and oxides in steel and suppresses the growth of austenite grains and improves toughness. However, excessive addition lowers cleanliness and deteriorates toughness. 0.003 to 0.030%.
【００３２】Ｃｒ：０．１〜０．５％、Ｍｏ：０．０５
〜０．３０％、Ｖ：０．０１〜０．１０％、Ｎｂ：０．
００５〜０．０４０％ Ｃｒ，Ｍｏ，Ｖ，Ｎｂは母材の強度を高める効果があ
り、その効果を期待する場合、一種または二種以上添加
する。Cr: 0.1-0.5%, Mo: 0.05
~ 0.30%, V: 0.01 ~ 0.10%, Nb: 0.
005 to 0.040% Cr, Mo, V, and Nb have the effect of increasing the strength of the base material, and if that effect is expected, one or more of them are added.
【００３３】Ｃｒは焼入れ性の向上および析出硬化によ
り母材の強度を高めるが、０．１％未満ではその効果が
十分でなく、過剰な添加はＨＡＺ部の靭性を劣化させ、
および過度に硬化させるため、０．５％を上限とする。Cr enhances the strength of the base material by improving hardenability and precipitation hardening, but if its content is less than 0.1%, its effect is not sufficient, and excessive addition deteriorates the toughness of the HAZ portion,
And 0.5% is made the upper limit for excessive curing.
【００３４】Ｍｏは焼入れ性の向上と析出硬化により母
材の強度を高めるが、０．０５％未満ではその効果が十
分でなく、過剰な添加はＨＡＺ部の靭性を劣化させるた
め、０．３０％を上限とする。Mo enhances the strength of the base material by improving hardenability and precipitation hardening. However, if the content is less than 0.05%, the effect is not sufficient, and excessive addition deteriorates the toughness of the HAZ portion. % As the upper limit.
【００３５】Ｖは固溶強化および析出硬化により母材の
強度を高めるが、０．０１％未満ではその効果が十分で
なく、過剰な添加はＨＡＺ部の多層熱サイクルにより析
出し、脆化をもたらすため、０．１０％を上限とする。V enhances the strength of the base material by solid solution strengthening and precipitation hardening, but if it is less than 0.01%, its effect is not sufficient, and excessive addition causes precipitation by multi-layer thermal cycling of the HAZ portion, and embrittlement. Therefore, the upper limit is 0.10%.
【００３６】Ｎｂは圧延時にＮｂ（Ｃ，Ｎ）として析出
し、ピンニング効果により再結晶粒の粗大化を防止し、
更に析出硬化により母材の強度を高めるが、０．００５
％未満ではその効果が十分でなく、過剰な添加はＨＡＺ
の焼入れ性を上げ、溶接割れ感受性を劣化させるので、
０．０４０％を上限とする。Nb precipitates as Nb (C, N) during rolling, and prevents the recrystallized grains from becoming coarse by a pinning effect.
Further, the strength of the base material is increased by precipitation hardening.
%, The effect is not sufficient.
Increases the hardenability of the steel and degrades the susceptibility to weld cracking.
0.040% is made the upper limit.
【００３７】２．製造条件 スラブ加熱温度：１０５０〜１２５０℃ 本発明では効率的な生産が可能な連続鋳造鋼片を使用す
る。連続鋳造鋼片は板厚中央部に偏析を生じ、圧延終了
後、硬くて脆い異常組織となり、靭性を著しく劣化させ
る。偏析による異常組織の発生を防止するため、鋼中成
分の均一化のため、スラブ加熱温度を１０５０℃以上と
する。2. Manufacturing conditions Slab heating temperature: 1050 to 1250 ° C In the present invention, a continuously cast steel slab that can be efficiently produced is used. Continuously cast steel slabs cause segregation at the center of the sheet thickness, and after rolling, have a hard and brittle abnormal structure and significantly deteriorate toughness. In order to prevent the occurrence of an abnormal structure due to segregation, the slab heating temperature is set to 1050 ° C. or higher in order to make the components in the steel uniform.
【００３８】しかし、加熱温度が１２５０℃を超えると
オーステナイト粒が粗大化し、圧延による微細化が不十
分となり靭性が劣化する。また、Ｎｂが添加される場
合、１２５０℃を超えて加熱されるとＮｂが全て固溶
し、Ｎｂ（Ｃ，Ｎ）によるピンニング効果が失われるた
め、１０５０〜１２５０℃とする。However, when the heating temperature exceeds 1250 ° C., the austenite grains become coarse, and the fineness by rolling becomes insufficient, and the toughness deteriorates. When Nb is added, if it is heated above 1250 ° C., all of Nb forms a solid solution, and the pinning effect by Nb (C, N) is lost.
【００３９】 熱間圧延条件：９００℃以下、累積圧下率２５％以上 熱間圧延ではフェライトを微細化し、優れた靭性を確保
するため、未再結晶温度域である９００℃以下におい
て、累積圧下率２５％以上の圧延を行う。 冷却条件：圧延後直ちに５５０℃以下まで、１〜５０℃
／ｓｅｃで冷却 圧延後の冷却におけるフェライト粗大化による靭性の劣
化と母材強度の低下を防止するため、圧延後直ちに５５
０℃以下まで、１〜５０℃／ｓｅｃで強制冷却を行う。 時効処理：５００℃以上Ａｃ1以下 母材の強度・靭性バランスを調整するため、５００℃以
上Ａｃ1以下の条件で時効処理を行う。Hot rolling conditions: 900 ° C. or less, cumulative rolling reduction 25% or more In hot rolling, in order to refine ferrite and secure excellent toughness, the cumulative rolling reduction is 900 ° C. or less in the non-recrystallization temperature range. Roll 25% or more. Cooling conditions: Immediately after rolling, to 550 ° C or less, 1 to 50 ° C
/ Sec In order to prevent deterioration of toughness and decrease in base metal strength due to ferrite coarsening during cooling after rolling, 55%
Forced cooling is performed at 1 to 50 ° C / sec to 0 ° C or less. Aging treatment: 500 ° C. or more and Ac1 or less In order to adjust the strength-toughness balance of the base material, aging treatment is performed at 500 ° C. or more and Ac1 or less.
【００４０】[0040]
【実施例】表1に供試鋼の化学組成を、表2に圧延条件と
母材の引張特性、衝撃特性、および溶接部の靭性値を示
す。化学組成はスラブの取鍋分析値による。引張り試験
はＪＩＳに準拠し、平行部１０ｍｍφの試験片を用いて
行った。溶接部の靭性評価は、Ｋ開先のサブマージアー
ク溶接（予熱無し、入熱：８〜５０ｋＪ／ｃｍ）継手に
おける板厚鉛直方向に生成した溶融線近傍について行っ
た。EXAMPLES Table 1 shows the chemical composition of the test steel, and Table 2 shows the rolling conditions, the tensile properties and impact properties of the base material, and the toughness values of the welds. Chemical composition is based on slab ladle analysis values. The tensile test was performed using a test piece having a parallel portion of 10 mmφ according to JIS. Evaluation of the toughness of the welded portion was performed in the vicinity of the melting line generated in the vertical direction in the plate thickness in the submerged arc welding (no preheating, heat input: 8 to 50 kJ / cm) joint with a K groove.
【００４１】ＣＴＯＤ試験はＷＥＳ１１０８（１９９
５）に準拠し、圧延方向をノッチ方向とし、板厚方向全
厚にノッチ加工した試験片を用い、試験温度―４０℃で
実施した。図1に溶接継手におけるＣＴＯＤ試験片の採
取位置を示す。鋼１〜１２は請求項１〜６記載の本願発
明の規定を全て満足するもので、母材、溶接部ともに優
れた特性が得られている。一方、鋼１３〜１７は請求項
４〜６記載の本願発明において圧延条件の規定を満足す
るが、化学組成に関する規定が発明範囲外となったもの
であり、継手靭性が劣っている。The CTOD test was performed using WES1108 (199
In accordance with 5), the rolling direction was set to the notch direction, and the test was performed at a test temperature of −40 ° C. using a test piece that was notched in the entire thickness direction. FIG. 1 shows a sampling position of a CTOD test piece in a welded joint. Steels 1 to 12 satisfy all the requirements of the present invention described in claims 1 to 6, and have excellent properties in both the base metal and the welded portion. On the other hand, steels 13 to 17 satisfy the requirements of the rolling conditions in the invention of claims 4 to 6, but the provisions relating to the chemical composition are out of the range of the invention, and the joint toughness is inferior.
【００４２】鋼１８〜２０は請求項４〜６記載の本願発
明において化学組成の規定は満足するが、圧延条件に関
する規定が発明範囲外となったもので、鋼１８はスラブ
加熱温度が低く、母材の引張り強度が低い。鋼１９はス
ラブ加熱温度が高く、鋼２０は圧延条件が不適当で継手
靭性が劣っている。The steels 18 to 20 satisfy the provisions of the chemical composition in the present invention according to claims 4 to 6, but the provisions concerning the rolling conditions are out of the range of the invention, and the steel 18 has a low slab heating temperature, Low tensile strength of base material. Steel 19 has a high slab heating temperature, and steel 20 has inadequate rolling conditions and poor joint toughness.
【００４３】[0043]
【表１】 [Table 1]
【００４４】[0044]
【表２】 [Table 2]
【００４５】[0045]
【発明の効果】本発明法によれば、小〜中入熱の多層盛
溶接部で−４０℃以下の温度において、ＣＴＯＤ特性に
優れる鋼材および製造方法が安定的に得られ、極寒地で
使用される海洋構造物の安全性が著しく向上し、産業上
その効果は極めて大きい。According to the method of the present invention, a steel material having excellent CTOD characteristics and a production method can be stably obtained at a temperature of −40 ° C. or lower in a multi-pass weld of small to medium heat, and used in extremely cold regions. The safety of the offshore structures is greatly improved, and the effect is extremely large industrially.
【図１】Ｋ開先溶接継手部から採取したＣＴＯＤ試験片
の形状を示す図FIG. 1 is a view showing a shape of a CTOD test piece taken from a K-groove weld joint.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 高橋 和秀 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 (72)発明者 塚本 裕昭 東京都千代田区丸の内一丁目１番２号 日 本鋼管株式会社内 Ｆターム(参考） 4K032 AA01 AA02 AA04 AA08 AA11 AA14 AA16 AA19 AA21 AA22 AA23 AA24 AA29 AA31 AA35 AA36 AA40 BA01 CA02 CA03 CD02 CD03 CF01 CF02 ──────────────────────────────────────────────────続 き Continued on the front page (72) Kazuhide Takahashi, 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Hiroaki Tsukamoto 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nippon Kokan Co., Ltd. F term (reference) 4K032 AA01 AA02 AA04 AA08 AA11 AA14 AA16 AA19 AA21 AA22 AA23 AA24 AA29 AA31 AA35 AA36 AA40 BA01 CA02 CA03 CD02 CD03 CF01 CF02
Claims (6)
ｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．０％、
Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎｉ：
２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：
０．００３０％以下、Ｔｉ：０．００５〜０．０２５
％、Ｂ：０．０００５％以下、残部が実質的にＦｅから
なることを特徴とする溶接部靭性に優れた高張力鋼。(1) C: 0.01 to 0.10% by weight, S
i: 0.01 to 0.10%, Mn: 1.0 to 2.0%,
S: 0.005% or less, Cu: 1.0% or less, Ni:
2.0% or less, sol. Al: 0.025% or less, N:
0.0030% or less, Ti: 0.005 to 0.025
%, B: 0.0005% or less, with the balance substantially consisting of Fe, a high strength steel having excellent weld toughness.
ｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．０％、
Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎｉ：
２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：
０．００３０％以下、Ｔｉ：０．００５〜０．０２５
％、Ｂ：０．０００５％以下、更に、Ｃａ：０．０００
５〜０．００５％、ＲＥＭ：０．００３〜０．０３０％
の一種以上を含有し、残部が実質的にＦｅからなること
を特徴とする溶接部靭性に優れた高張力鋼。2. C: 0.01 to 0.10% by weight, S:
i: 0.01 to 0.10%, Mn: 1.0 to 2.0%,
S: 0.005% or less, Cu: 1.0% or less, Ni:
2.0% or less, sol. Al: 0.025% or less, N:
0.0030% or less, Ti: 0.005 to 0.025
%, B: 0.0005% or less, and Ca: 0.000%
5 to 0.005%, REM: 0.003 to 0.030%
A high-strength steel having excellent weld toughness, characterized in that it contains at least one of the following, and the balance substantially consists of Fe.
ｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．０％、
Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎｉ：
２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：
０．００３０％以下、Ｔｉ：０．００５〜０．０２５
％、Ｂ：０．０００５％以下、更に、Ｃｒ：０．１〜
０．５％、Ｍｏ：０．０５〜０．３０％、Ｖ：０．０１
〜０．１０％、Ｎｂ：０．００５〜０．０４０％の一種
または二種以上を含有し、残部が実質的にＦｅからなる
ことを特徴とする溶接部靭性に優れた高張力鋼。3. C: 0.01 to 0.10% by weight, S:
i: 0.01 to 0.10%, Mn: 1.0 to 2.0%,
S: 0.005% or less, Cu: 1.0% or less, Ni:
2.0% or less, sol. Al: 0.025% or less, N:
0.0030% or less, Ti: 0.005 to 0.025
%, B: 0.0005% or less, and Cr: 0.1 to
0.5%, Mo: 0.05 to 0.30%, V: 0.01
A high-strength steel having excellent weld toughness, characterized by containing one or more of Nb: 0.005 to 0.040%, and the balance substantially consisting of Fe.
ｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．０％、
Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎｉ：
２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：
０．００３０％以下、Ｔｉ：０．００５〜０．０２５
％、Ｂ：０．０００５％以下、残部が実質的にＦｅから
なる連続鋳造鋼片を、１０５０〜１２５０℃の温度に加
熱し、次いで９００℃以下の温度範囲で累積圧下率２５
％以上の熱間圧延を施し、その後直ちに１〜５０℃／ｓ
ｅｃの冷却速度で５５０℃以下の温度まで冷却し、次い
で、５００℃以上Ａｃ1以下の温度で時効処理を施すこ
とを特徴とする溶接部靭性に優れた高張力鋼の製造方
法。4. C: 0.01 to 0.10% by weight, S:
i: 0.01 to 0.10%, Mn: 1.0 to 2.0%,
S: 0.005% or less, Cu: 1.0% or less, Ni:
2.0% or less, sol. Al: 0.025% or less, N:
0.0030% or less, Ti: 0.005 to 0.025
%, B: 0.0005% or less, with the balance being substantially Fe, a continuous cast steel slab is heated to a temperature of 1050 to 1250 ° C, and then a cumulative rolling reduction of 25 in a temperature range of 900 ° C or less.
% Hot rolling at 1% to 50 ° C / s
A method for producing a high-strength steel having excellent weld toughness, comprising cooling at a cooling rate of ec to a temperature of 550 ° C. or less, and then subjecting it to aging at a temperature of 500 ° C. or more and Ac 1 or less.
ｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．０％、
Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎｉ：
２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：
０．００３０％以下、Ｔｉ：０．００５〜０．０２５
％、Ｂ：０．０００５％以下、更に、Ｃａ：０．０００
５〜０．００５％、ＲＥＭ：０．００３〜０．０３０％
の一種以上を含有し、残部が実質的にＦｅからなる連続
鋳造鋼片を、１０５０〜１２５０℃の温度に加熱し、次
いで９００℃以下の温度範囲で累積圧下率２５％以上の
熱間圧延を施し、その後直ちに１〜５０℃／ｓｅｃの冷
却速度で５５０℃以下の温度まで冷却し、次いで、５０
０℃以上Ａｃ1以下の温度で時効処理を施すことを特徴
とする溶接部靭性に優れた高張力鋼の製造方法。5. C: 0.01 to 0.10% by weight, S:
i: 0.01 to 0.10%, Mn: 1.0 to 2.0%,
S: 0.005% or less, Cu: 1.0% or less, Ni:
2.0% or less, sol. Al: 0.025% or less, N:
0.0030% or less, Ti: 0.005 to 0.025
%, B: 0.0005% or less, and Ca: 0.000%
5 to 0.005%, REM: 0.003 to 0.030%
Is heated to a temperature of 1050 to 1250 ° C., and hot rolling at a cumulative rolling reduction of 25% or more is performed in a temperature range of 900 ° C. or less. Immediately thereafter, it is cooled to a temperature of 550 ° C. or less at a cooling rate of 1 to 50 ° C./sec.
A method for producing a high-strength steel having excellent weld toughness, wherein aging treatment is performed at a temperature of 0 ° C. or more and Ac 1 or less.
ｉ：０．０１〜０．１０％、Ｍｎ：１．０〜２．０％、
Ｓ：０．００５％以下、Ｃｕ：１．０％以下、Ｎｉ：
２．０％以下、ｓｏｌ．Ａｌ：０．０２５％以下、Ｎ：
０．００３０％以下、Ｔｉ：０．００５〜０．０２５
％、Ｂ：０．０００５％以下、更に、Ｃｒ：０．１〜
０．５％、Ｍｏ：０．０５〜０．３０％、Ｖ：０．０１
〜０．１０％、Ｎｂ：０．００５〜０．０４０％の一種
以上を含有し、残部が実質的にＦｅからなる連続鋳造鋼
片を、１０５０〜１２５０℃の温度に加熱し、次いで９
００℃以下の温度範囲で累積圧下率２５％以上の熱間圧
延を施し、その後直ちに１〜５０℃／ｓｅｃの冷却速度
で５５０℃以下の温度まで冷却し、次いで、５００℃以
上Ａｃ1以下の温度で時効処理を施すことを特徴とする
溶接部靭性に優れた高張力鋼の製造方法。6. C: 0.01 to 0.10% by weight, S:
i: 0.01 to 0.10%, Mn: 1.0 to 2.0%,
S: 0.005% or less, Cu: 1.0% or less, Ni:
2.0% or less, sol. Al: 0.025% or less, N:
0.0030% or less, Ti: 0.005 to 0.025
%, B: 0.0005% or less, and Cr: 0.1 to
0.5%, Mo: 0.05 to 0.30%, V: 0.01
A continuous cast steel slab containing at least one of 0.15% and 0.15% Nb: 0.005% to 0.040%, with the balance substantially consisting of Fe, is heated to a temperature of 1050 to 1250 ° C.
Hot rolling is performed at a cumulative draft of 25% or more in a temperature range of 00 ° C or less, and then immediately cooled at a cooling rate of 1 to 50 ° C / sec to a temperature of 550 ° C or less, and then a temperature of 500 ° C or more and Ac1 or less. A method for producing a high-strength steel having excellent weld toughness, characterized by subjecting to aging treatment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18162299A JP3736209B2 (en) | 1999-06-28 | 1999-06-28 | High tensile steel with excellent weld toughness and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP18162299A JP3736209B2 (en) | 1999-06-28 | 1999-06-28 | High tensile steel with excellent weld toughness and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001011566A true JP2001011566A (en) | 2001-01-16 |
| JP3736209B2 JP3736209B2 (en) | 2006-01-18 |
Family
ID=16104017
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP18162299A Expired - Fee Related JP3736209B2 (en) | 1999-06-28 | 1999-06-28 | High tensile steel with excellent weld toughness and manufacturing method thereof |
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| Country | Link |
|---|---|
| JP (1) | JP3736209B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007197774A (en) * | 2006-01-26 | 2007-08-09 | Toshiba Corp | Heat-resistant cast steel |
| KR100957968B1 (en) | 2007-12-27 | 2010-05-17 | 주식회사 포스코 | High strength and toughness thick steel plate having excellent base metal ctod property and method for producing the same |
| US20130051720A1 (en) * | 2010-03-19 | 2013-02-28 | Ntn Corporation | Wheel Bearing Apparatus |
| WO2013051231A1 (en) | 2011-10-03 | 2013-04-11 | Ｊｆｅスチール株式会社 | High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same |
-
1999
- 1999-06-28 JP JP18162299A patent/JP3736209B2/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007197774A (en) * | 2006-01-26 | 2007-08-09 | Toshiba Corp | Heat-resistant cast steel |
| KR100957968B1 (en) | 2007-12-27 | 2010-05-17 | 주식회사 포스코 | High strength and toughness thick steel plate having excellent base metal ctod property and method for producing the same |
| US20130051720A1 (en) * | 2010-03-19 | 2013-02-28 | Ntn Corporation | Wheel Bearing Apparatus |
| US8905645B2 (en) * | 2010-03-19 | 2014-12-09 | Ntn Corporation | Wheel bearing apparatus |
| WO2013051231A1 (en) | 2011-10-03 | 2013-04-11 | Ｊｆｅスチール株式会社 | High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same |
| US9945015B2 (en) | 2011-10-03 | 2018-04-17 | Jfe Steel Corporation | High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3736209B2 (en) | 2006-01-18 |
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