JPH02190423A - Manufacture of steel plate having excellent ctod properties in weld zone - Google Patents
Manufacture of steel plate having excellent ctod properties in weld zoneInfo
- Publication number
- JPH02190423A JPH02190423A JP668989A JP668989A JPH02190423A JP H02190423 A JPH02190423 A JP H02190423A JP 668989 A JP668989 A JP 668989A JP 668989 A JP668989 A JP 668989A JP H02190423 A JPH02190423 A JP H02190423A
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel plate
- steel
- toughness
- weld
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 58
- 239000010959 steel Substances 0.000 title claims abstract description 58
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000005496 tempering Methods 0.000 claims abstract description 10
- 229910052796 boron Inorganic materials 0.000 claims abstract description 9
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 7
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 5
- 239000012535 impurity Substances 0.000 claims abstract description 5
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 4
- 229910052802 copper Inorganic materials 0.000 claims abstract description 3
- 229910052758 niobium Inorganic materials 0.000 claims abstract description 3
- 229910052720 vanadium Inorganic materials 0.000 claims abstract description 3
- 229910052748 manganese Inorganic materials 0.000 claims abstract 4
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract 4
- 229910052710 silicon Inorganic materials 0.000 claims abstract 3
- 238000003466 welding Methods 0.000 claims description 18
- 238000005096 rolling process Methods 0.000 claims description 14
- 238000000034 method Methods 0.000 claims description 8
- 238000010791 quenching Methods 0.000 claims description 2
- 230000000171 quenching effect Effects 0.000 claims description 2
- 238000001816 cooling Methods 0.000 abstract description 10
- 238000005098 hot rolling Methods 0.000 abstract description 2
- 229910052717 sulfur Inorganic materials 0.000 abstract 2
- 229910052782 aluminium Inorganic materials 0.000 abstract 1
- 229910052742 iron Inorganic materials 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 20
- 239000006104 solid solution Substances 0.000 description 14
- 239000010953 base metal Substances 0.000 description 11
- 239000000463 material Substances 0.000 description 10
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 9
- 239000002244 precipitate Substances 0.000 description 6
- 229910001566 austenite Inorganic materials 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000009467 reduction Effects 0.000 description 5
- 238000007670 refining Methods 0.000 description 4
- 230000006866 deterioration Effects 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 238000009863 impact test Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 238000005204 segregation Methods 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 230000000087 stabilizing effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000002542 deteriorative effect Effects 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 238000013001 point bending Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
- 235000013619 trace mineral Nutrition 0.000 description 1
- 239000011573 trace mineral Substances 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】
〈産業上の利用分野〉
この発明は、低温海域での海洋構造物や寒冷地のライン
パイプ用等として好適な溶接用高張力鋼板の製造方法に
関するものである。DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for producing a high-strength steel plate for welding, which is suitable for use in marine structures in low-temperature sea areas, line pipes in cold regions, and the like.
（従来技術とその課題〉
例えば氷海域に設置される海洋構造物や寒冷地向けのラ
インパイプ、或いは船舶やＬＰＧタンク等に供される溶
接用高張力鋼板では、使用目的に応じた十分な強度が要
求されることは勿論、優れた溶接部靭性を備えているこ
とが欠かせない条件となっている。(Prior art and its issues) For example, high-strength steel plates for welding used in marine structures installed in icy areas, line pipes for cold regions, ships, LPG tanks, etc. do not have sufficient strength depending on the purpose of use. Of course, excellent weld toughness is an essential condition.
ところで、高張力鋼板の溶接部靭性には“鋼板中の固溶
Ｎ量”と１ミクロ組織の粗さ”が大きな影響を及ぼすこ
とが知られており、そのため鋼材の製造条件に工夫を凝
らして
（ａ） 固溶Ｎ量の低減。By the way, it is known that the "amount of solid solute N in the steel plate" and the roughness of the microstructure have a large effect on the weld joint toughness of high-strength steel plates. (a) Reduction of solid solution N amount.
（ｂ） ミクロ＆ｌ１ｖａの微細化
の２つの条件を両立させ、これによって優れた溶接部の
靭性を有する高張力鋼を得る方法も幾つか提案された（
例えば特開昭６１−１９４１１３号。(b) Several methods have been proposed to achieve both micro and l1va refinement conditions and thereby obtain high-strength steel with excellent weld toughness (
For example, JP-A-61-194113.
特開昭６２−５６５１８号等）。しかし、上述した従来
の溶接用高張力鋼は、何れも、靭性の要求値がシャルピ
ー衝撃試験値（例えばｖＥ−ｈｏｔ≧３．５ｋｇｆ−ｍ
）で定められている場合には仕様を満足するものの、使
用実態により即応した目安が得られるとして最近注目さ
れるようになってきた“ＣＴＯＤ特性（疲れ切欠き付３
点曲げ試験による開口変位量特性）′による要求値（例
えばδ−１゜１≧０．５ｍ）を必ずしも安定して満足し
ないと言うことが指摘されていた。JP-A No. 62-56518, etc.). However, in all of the conventional high-strength steels for welding described above, the required toughness value is the Charpy impact test value (for example, vE-hot≧3.5kgf-m
), it satisfies the specifications, but the CTOD characteristic (with fatigue notch 3
It has been pointed out that the required value (for example, δ-1°1≧0.5m) according to the opening displacement characteristics determined by the point bending test is not always consistently satisfied.
この原因は、溶接部に存在する局所的脆化域にある。即
ち、従来の溶接用高張力鋼板では溶接部にどうしても局
所的な脆化域が生じてしまうので、試験片全域の平均的
靭性を示すシャルピー衝撃特性は良好な値を示したとし
ても、試験片中の最低靭性値部分の影響を大きく受ける
ＣＴＯＤ特性は、前記局所脆化域の存在故に低温度での
仕様を満足しないこととなる訳である。The cause of this is the localized embrittlement zone present in the weld. In other words, in conventional high-strength steel plates for welding, localized embrittlement areas inevitably occur in the weld, so even if the Charpy impact properties, which indicate the average toughness of the entire test piece, show a good value, the test piece The CTOD characteristics, which are greatly influenced by the lowest toughness value part, do not meet the specifications at low temperatures due to the presence of the localized embrittlement region.
このようなことから、本発明の目的は、低温域での溶接
構造物等に適用して従来材以上に十分な信転性が得られ
るところの、降伏点が３６ｋｇｆ／−以上で、かつ溶接
入熱量：８〜２００ ｋＪ／ｃｍにて溶接した際の溶接
部の一３０℃におけるＣＴＯＤ特性（δ−８゜、）が０
．５龍以上を満足する“溶接部ＣＴＯＤ特性の優れた高
張力鋼板”を安定して製造し得る技術の確立に置かれた
。Therefore, it is an object of the present invention to have a yield point of 36 kgf/- or more and a weldable material that can be applied to welded structures in a low temperature range and has sufficient reliability than conventional materials. Heat input: When welding at 8 to 200 kJ/cm, the CTOD characteristic (δ-8°,) at 30°C of the welded part is 0.
．． The aim was to establish a technology that could stably manufacture "high-strength steel plates with excellent weld CTOD characteristics" that satisfied the 5-Dragon rating or higher.
く課題を解決するための手段〉
本発明者等は、上記目的を達成すべ（種々の実験を繰り
返しながら研究を重ねた結果、「溶接部靭性の改善には
、前記特開昭６１−１９４１１３号公報や特開昭６２−
５６５１８号公報にも記載されている如く “固溶Ｎ量
の低減”及び“ミクロ１ｌＪｌ織の微細化”の両立が不
可欠であって、その手段として微量元素Ｃ５ｏｌ−ＡＩ
＋ Ｔｔ＋ Ｂ ＊ Ｎ）の最適バランス確保が重要で
あるが、このような鋼において、同時にＳｉの低減がＣ
ＴＯＤ特性の改善に極めて有効である上、Ｃｅｑも大き
な影響を及ぼす」との新しい知見を得るに至った。Means for Solving the Problems> The inventors of the present invention have found that in order to achieve the above-mentioned object (as a result of repeated research and repeated various experiments), ``To improve the toughness of welded joints, Publications and JP-A-62-
As stated in Publication No. 56518, it is essential to achieve both "reducing the amount of solid solute N" and "refining the micro 1lJl texture", and as a means to achieve this, the trace element C5ol-AI
+ Tt + B * N) is important, but in such steel, at the same time, the reduction of Si is
We have obtained new knowledge that "not only is it extremely effective in improving TOD characteristics, but Ceq also has a large influence."
つまり、本発明者等の研究により、次の諸点が確認され
た訳である。In other words, the following points were confirmed through research by the present inventors.
ａ）“局所的脆化域”は局部的なＣ濃化域における高マ
ルテンサイトの存在により形成されるため、ＣｔＲ化を
抑制することによって局所的脆化域を減少させることが
できる。a) "Local embrittlement areas" are formed by the presence of high martensite in local C-enriched areas, so the local embrittlement areas can be reduced by suppressing CtR formation.
ｂ）ところが、ＳｌはＣの拡散を抑制する作用を有して
いてＣの局部的濃化を維持する方向に働く元素であり、
従ってこれを減らすと局所的脆化域が減少してＣＴＯＤ
値が著しく改善される。b) However, Sl is an element that has the effect of suppressing the diffusion of C and works in the direction of maintaining the local concentration of C.
Therefore, if this is reduced, the local embrittlement area will be reduced and CTOD
value is significantly improved.
Ｃ）加えて、ＣｅｑもＣＴＯＤ値に少なからぬ影響を及
ぼすため、Ｃｅｑの調整をも併せて実施するとＣＴＯＤ
値の更に顕著な改善が可能となる。C) In addition, Ceq also has a considerable influence on the CTOD value, so if you also adjust Ceq, the CTOD
Even more significant improvements in values are possible.
本発明は、上記知見等に基づいてなされたものであり、
ｒｃ：０．０３〜０．１２％（以降、成分割合を表わす
％は重量％とする）。The present invention has been made based on the above findings, etc. rc: 0.03 to 0.12% (hereinafter, % representing the component ratio is expressed as weight %).
Ｓｉ ： ０．０１％を超え０．０５％未満。Si: More than 0.01% and less than 0.05%.
Ｍｎ ： ０．７０〜１．６０％、 Ｐ：０．０１
０％以下。Mn: 0.70-1.60%, P: 0.01
Less than 0%.
Ｓ ： ０．００５％以下、 ｓｏｌ、 Ａｉ！ ：
０．００１〜０．０１０％。S: 0.005% or less, sol, Ai! :
0.001-0.010%.
Ｔｉ ： （）、００５〜０．０２０％、 Ｂ ：
０．０００３〜０．００１２％。Ti: (), 005-0.020%, B:
0.0003-0.0012%.
Ｎ ： ０．００４０〜０．００６０％、 Ｃａ ：
０．００４０％以下を含有するか、或いは更に
Ｃｕ ： ０．５０％以下、 Ｎｉ ： １．００
％以下。N: 0.0040-0.0060%, Ca:
Contains 0.0040% or less, or further contains Cu: 0.50% or less, Ni: 1.00
%below.
Ｖ：０．０４％以下、 Ｎｂ ： ０．０３％以下
の少なくとも１種をも含むと共に（但し、Ｔｉ／Ｎ＝１
．５〜３．４）、残部がＦｅ及び不可避不純物から成り
、かつ式
で表わされる炭素当量（Ｃｅｑ）が０．３８％以下であ
る鋼を９００〜１２００℃の温度域に訓熱して熱間圧延
し、８００℃以上の仕上げ温度で所定の板厚に圧延して
から直ちに室温まで急冷した後、２００〜４５０℃の温
度域で焼戻すことによって、溶接部靭性の優れた溶接用
高張力鋼板を安定に製造し得るようにした点」
を特徴とするものである。Contains at least one of V: 0.04% or less and Nb: 0.03% or less (however, Ti/N=1
．． 5 to 3.4), the balance consists of Fe and unavoidable impurities, and the carbon equivalent (Ceq) expressed by the formula is 0.38% or less, heated to a temperature range of 900 to 1200 ° C. and hot rolled. By rolling the plate to a specified thickness at a finishing temperature of 800°C or higher, immediately quenching it to room temperature, and then tempering it in a temperature range of 200 to 450°C, we can produce a high-strength steel plate for welding with excellent weld toughness. It is characterized by the fact that it can be manufactured stably.
続いて、本発明において素材鋼の成分割合並びに鋼板の
製造条件を前記の如くに限定した理由を、その作用と共
に詳述する。Next, the reason why the component ratio of the material steel and the manufacturing conditions of the steel plate are limited as described above in the present invention will be explained in detail together with their effects.
く作用〉
Ａ）素材鋼の成分割合
Ｃは母材に所定強度（降伏点： ３６ｋｇｆ／−以上）
を確保するために添加される元素であるが、その含有量
が０．０３％未満では上記所望強度の確保がなされず、
一方、０．１２％を超えて含有させると溶接部の靭性劣
化を招くようになる。従って、Ｃ含有量は０．０３〜０
．１２％と定めた。A) The component ratio C of the material steel is the specified strength of the base material (yield point: 36 kgf/- or more)
This element is added to ensure the above-mentioned strength, but if its content is less than 0.03%, the desired strength cannot be achieved.
On the other hand, if the content exceeds 0.12%, the toughness of the weld zone will deteriorate. Therefore, the C content is 0.03~0
．． It was set at 12%.
Ｓｉ
Ｓｔは鋼の脱酸元素として有用なものであるので０．０
１％を超える含有量を確保する必要があるが、本発明で
はＳｉ含有量を０．０５％未満に抑えることが極めて重
要である。即ち、本発明が対象とする鋼においては、Ｓ
ｉ含有量を特に０．０５％未満とすることによって初め
て溶接部ＣＴＯＤ特性の著しい向上効果が確保できるよ
うになる。従って、Ｓｉ含有量は０．０１〜０．０５％
と定めた。SiSt is useful as a deoxidizing element for steel, so 0.0
Although it is necessary to ensure a Si content of more than 1%, it is extremely important in the present invention to suppress the Si content to less than 0.05%. That is, in the steel targeted by the present invention, S
Only by setting the i content to less than 0.05% can a significant improvement in the CTOD characteristics of the weld zone be ensured. Therefore, the Si content is 0.01-0.05%
It was determined that
Ｍｎ
母材に所望強度を確保するためにはＭｎ含有Ｎ：０．７
０％以上を確保する必要があるが、１．６０％を超えて
含有させると溶接部の靭性劣化を招くようになることか
ら、Ｍｎ含有量は０．７０〜１．６０％と定めた。Mn In order to ensure the desired strength in the base material, Mn content N: 0.7
Although it is necessary to ensure a Mn content of 0% or more, if the Mn content exceeds 1.60%, the toughness of the weld zone will deteriorate, so the Mn content is set at 0.70 to 1.60%.
Ｐは凝固時に偏析し易い元素であり、Ｐの偏析は溶接部
の硬化をもたらす。更に、Ｐの偏析はＣの偏析を促進し
て局所脆化域を生成させる。従って、Ｐの含有量は低い
ほど望ましいが、その含有量を０．０１０％以下に抑え
れば所望の溶接部靭性を確保することが可能となること
から、Ｐ含有量を０．０１０％以下と限定した。P is an element that tends to segregate during solidification, and the segregation of P causes hardening of the weld. Furthermore, the segregation of P promotes the segregation of C to generate local embrittlement regions. Therefore, the lower the P content is, the more desirable it is, but if the content is kept below 0.010%, it is possible to secure the desired weld toughness. limited to.
Ｓは鋼の延性及び靭性を劣化させる不純物元素であるが
、その含有量を０．００５％以下に低減することで前記
不都合の抑制がなされることから、Ｓ含有量は０．００
５％以下と定めた。S is an impurity element that deteriorates the ductility and toughness of steel, but the above disadvantages can be suppressed by reducing its content to 0.005% or less, so the S content is 0.00% or less.
It has been set at 5% or less.
ｓｏｆ、Ａｆ
ｓｏｌ、ＡＩは、鋼の脱酸作用に加えてＡＩＮとして析
出してオーステナイト粒の微細化による母材靭性改善作
用を有しているが、その含有量が０．００１％未満であ
ると前記作用による所望の効果が得られない。しかし、
溶接時に高温（約１２００℃以上）に加熱される溶接ボ
ンド部近傍ではＡｆＮは再固溶を生じ、溶接後の冷却時
には冷却速度が速いため再析出できないこととなる。従
って、ＡＩＮは溶接ボンド部近傍の組織微細化には効果
がないばかりか、むしろ再固溶することによって固溶Ｎ
Ｎを増加させ、溶接部の靭性を劣化させる。そのため、
ｓｏｆ、ＡＩ量は必要最小限にとどめることが必要であ
る。そして、ｓｏｌ、ＡＩ量の低減は固溶Ｎ量の増加を
通じてＴｉＮ及びＢＮの析出量の増加をもたらす。In addition to deoxidizing the steel, sof, Af sol, and AI precipitate as AIN and improve the toughness of the base metal by refining austenite grains, but their content is less than 0.001%. In this case, the desired effect due to the above action cannot be obtained. but,
AfN re-dissolves in the vicinity of the weld bond which is heated to a high temperature (approximately 1200° C. or higher) during welding, and cannot re-precipitate during cooling after welding because the cooling rate is fast. Therefore, not only is AIN ineffective in refining the structure near the weld bond, but it is also caused by solid solution N.
Increases N and deteriorates the toughness of the weld. Therefore,
It is necessary to keep the amount of sof and AI to the necessary minimum. Further, the reduction in the amount of sol and AI brings about an increase in the amount of TiN and BN precipitated through an increase in the amount of solid solution N.
このうち、ＴｉＮはＡＩＮよりも高い温度まで固溶しな
いため、溶接部の組織微細化及び固溶Ｎ量の低減に十分
寄与し、溶接部の靭性を改善する。一方、ＢＮは１１ｆ
Ｎと同様に高温で再固溶するが、Ｂの拡散速度が速いた
めに溶接後の冷却過程でＢＮとして再析出し、溶接部の
組織微細化及び固溶ＮＮの低減をもたらしてやはり溶接
部の靭性を改善する。Among these, TiN does not dissolve into solid solution at a temperature higher than that of AIN, so it sufficiently contributes to the refinement of the structure of the weld zone and the reduction of the amount of solid solution N, thereby improving the toughness of the weld zone. On the other hand, BN is 11f
Like N, it re-dissolves in solid solution at high temperatures, but due to the fast diffusion rate of B, it re-precipitates as BN during the cooling process after welding, resulting in a finer structure of the weld zone and a reduction in solid solution NN, which also causes the weld zone to deteriorate. improve toughness.
このようなＴｉＮ及びＢＮの効果を得るためには、ｓｏ
ｌ、ＡＩ量は０．０１０％以下とすることが必要になる
。In order to obtain such effects of TiN and BN, so
l, the amount of AI needs to be 0.010% or less.
従ッテ、ｓｏｊ、Ａｆ含有量は０．００１〜０．０１０
％と定めたが、できれば０．００１〜０．００６％に調
整するのが好ましい。Jutte, soj, Af content is 0.001-0.010
%, but it is preferably adjusted to 0.001 to 0.006% if possible.
Ｔｉ
Ｔｉは、高温域までも安定なＴｉＮを析出させて溶接部
の組織微細化をもたらし、溶接部の靭性を改善する作用
を有しているが、その含有量が０．００５％未満では前
記作用による所望の効果が得られず、一方、０．０２０
％を超えて含有させると母材及び溶接部の靭性低下を招
くから、Ｔｉ含有量はｏ、ｏｏｓ〜０．０２０％と定め
た。しかし、好ましくは０．０１０〜０．０１７％に調
整するのが良い。Ti Ti has the effect of precipitating TiN, which is stable even in high temperature ranges, resulting in a finer structure of the weld zone and improving the toughness of the weld zone, but if its content is less than 0.005%, the above-mentioned The desired effect was not obtained by the action, and on the other hand, 0.020
If the Ti content exceeds 0.0%, the toughness of the base metal and the welded part will be lowered, so the Ti content is determined to be 0.020% to 0.020%. However, it is preferably adjusted to 0.010 to 0.017%.
但し、Ｔｉ／Ｎの比が１．５未満ではＴｉＮの析出数が
少なくて上記の効果を確保できず、一方、上記比率が３
．４を超えると今度はＴｉＣを析出して溶接部の靭性劣
化を招くようになることからＴｉ／Ｎの比は１．５〜３
．４と定めたが、好ましくは２．０〜３．０に調整する
のが良い。However, if the Ti/N ratio is less than 1.5, the number of TiN precipitates will be small and the above effect cannot be secured;
．． If it exceeds 4, TiC will precipitate and the toughness of the weld will deteriorate, so the Ti/N ratio should be 1.5 to 3.
．． Although it is set as 4, it is preferably adjusted to 2.0 to 3.0.
Ｂは、Ｔｉと同様に窒化物を形成して溶接部の靭性を改
善する作用を有しているが、その機構はＴｉの場合とは
異なっている。即ち、ＢＮはＴｉＮに比べるとオーステ
ナイトに固溶しやすく、１０００℃以上の温度で容易に
固溶する。そのため、溶接時に高温に加熱される溶接ボ
ンド部近傍ではＢＮは完全に固溶するので、ＴｉＮと違
ってオーステナイト粒の粗大化抑制効果はない。しかし
、ＢはＴｉと異なり鋼中での拡散速度が速いため溶接後
の冷却過程で容易にＮと結合してＢＮとなって再析出し
、溶接部組織の微細化を通じて溶接部の靭性を改善する
。但し、Ｎと結びつ（量を超えてＢを添加した場合には
、固溶Ｂが溶接部の焼入性を向上させ、靭性を劣化させ
る。このためＢと結びつくだけの固溶Ｎ！ｌを確保する
ことが必要なため、前述したように本発明ではｓｏｆ、
Ａｆ量の低減を行った。Like Ti, B has the effect of forming nitrides and improving the toughness of the weld zone, but its mechanism is different from that of Ti. That is, BN is more easily dissolved in austenite than TiN, and is easily dissolved in solid solution at a temperature of 1000° C. or higher. Therefore, BN is completely dissolved in solid solution in the vicinity of the weld bond, which is heated to a high temperature during welding, and therefore, unlike TiN, it does not have the effect of suppressing coarsening of austenite grains. However, unlike Ti, B has a fast diffusion rate in steel, so it easily combines with N during the cooling process after welding and re-precipitates as BN, improving the toughness of the weld by refining the weld structure. do. However, if B is added in excess of the amount that binds with N, the solid solution B improves the hardenability of the weld and deteriorates the toughness. Therefore, the solid solution N! Since it is necessary to ensure sof, as mentioned above, in the present invention, sof,
The amount of Af was reduced.
そして、溶接入熱量：８〜２００ ｋＪ／ｃｍで形成さ
れた溶接部においてＢの上記の効果を得るためには、少
なくとも０．０００３％のＢ量を確保することが必要で
ある。しかし、０．００１２％を超えてＢを含有させる
と、固溶Ｂの焼入性向上効果により溶接部の靭性が劣化
する。従って、Ｂ含有量は０．０００３〜０．００１２
％と定めたが、好ましくはｏ、ｏｏｏｓ〜０．００１０
％に調整するのが良い。In order to obtain the above effects of B in a welded part formed with a welding heat input of 8 to 200 kJ/cm, it is necessary to ensure an amount of B of at least 0.0003%. However, when B is contained in an amount exceeding 0.0012%, the toughness of the weld zone deteriorates due to the hardenability improving effect of solid solution B. Therefore, the B content is 0.0003 to 0.0012
%, preferably o,ooos~0.0010
It is better to adjust it to %.
Ｎは、固溶状態で鋼中に存在した場合に溶接部の靭性を
劣化させる元素であるため、その含有量はできるだけ低
い方が望ましい。しかし、固溶Ｎ量の低減だけでは十分
な靭性が得られず、ミクロ組織の微細化を行うことが良
好な靭性を得るためには不可欠である。Since N is an element that deteriorates the toughness of the weld when it exists in steel in a solid solution state, it is desirable that its content be as low as possible. However, sufficient toughness cannot be obtained only by reducing the amount of solid solution N, and it is essential to refine the microstructure in order to obtain good toughness.
既に述べたように、本発明にあっては、溶接部のミクロ
組織微細化はＴｉＮ及びＢＮの均一な分散析出によって
もたらされるものであり、Ｔｉ及びＢと結合するＮの量
を最適量に制御することが重要である。即ち、Ｔｉ ：
０．００５〜０．０２０％、 Ｂ ： ０．０００３
〜０．００１２％、 ｓｏｌ、 ＡＩｌ： ０．００１
〜０．０１０％ｋｍ調整した本発明に係る鋼において溶
接部の靭性改善に有効な量のＴｉＮ及びＢＮを確保する
ためには、上記観点からＮ含有量は０．００４０％以上
確保する必要がある。一方、Ｎ含有量が０．００６０％
を超えると固溶Ｎ量が増加して溶接部の靭性劣化を招く
。As already mentioned, in the present invention, the microstructure refinement of the weld zone is brought about by uniformly dispersed precipitation of TiN and BN, and the amount of N combined with Ti and B is controlled to an optimum amount. It is important to. That is, Ti:
0.005-0.020%, B: 0.0003
~0.0012%, sol, AIl: 0.001
In order to ensure an effective amount of TiN and BN for improving the toughness of the weld in the steel according to the present invention adjusted to ~0.010%km, the N content must be at least 0.0040% from the above perspective. be. On the other hand, the N content is 0.0060%
If it exceeds 100%, the amount of solid solute N increases, leading to deterioration of the toughness of the weld.
従って、Ｎ含有量を０．００４０〜０．００６０％と限
定した。Therefore, the N content was limited to 0.0040 to 0.0060%.
Ｃａ
Ｃａは、極（微量で硫化物を球状化して母材の機械的性
質の異方性を減少させる作用や、Ｃａ（０，３）として
鋼中に均一に分散させることによって溶接部の組織を微
細化して靭性を改善する作用を示すが、０．００４０％
を超えて含有させてもその効果が飽和してしまうばかり
か、綱の清浄度を劣化させることから、Ｃａ含有量は０
．００４０％以下と定めた。Ca Ca has the effect of reducing the anisotropy of the mechanical properties of the base metal by spheroidizing sulfides in very small amounts, and improving the structure of the weld by uniformly dispersing it in the steel as Ca (0,3). It has the effect of improving toughness by making it finer, but 0.0040%
If the Ca content exceeds
．． It was set as 0.040% or less.
Ｃｕ、 Ｎｉ、 Ｖ、 びＮｂ
これらの成分は、何れも母材の強度及び溶接部の靭性を
安定化する作用を有しているので必要により１種又は２
種以上添加されるが、以下個別に添加量を制限した理由
を述べる。Cu, Ni, V, and Nb Each of these components has the effect of stabilizing the strength of the base metal and the toughness of the welded part, so one or two of these components may be used as necessary.
Although more than one species is added, the reasons for limiting the amount added will be explained below.
Ｃｕは、溶接部の靭性を劣化させることなく母材の強度
を上昇させる効果を有するため、その添加が母材の強度
の安定化に有効である。しかしながら、０．５０％を超
えて含有させると熱間延性の低下を招き、溶接時の高温
割れ感受性を高めることから、Ｃｕ含有量は０．５０％
以下と定めた。Since Cu has the effect of increasing the strength of the base metal without deteriorating the toughness of the weld, its addition is effective in stabilizing the strength of the base metal. However, if the Cu content exceeds 0.50%, it will cause a decrease in hot ductility and increase the susceptibility to hot cracking during welding, so the Cu content should be 0.50%.
It was determined as follows.
Ｎｉは、含有量が１．００％までは溶接部の靭性を劣化
させることなく母材の強度及び靭性の安定化に有効であ
るが、１．００％を超えて含有させると溶接部の靭性劣
化を招くことから、Ｎｉ含有量は１．００％以下と定め
た。Ni content up to 1.00% is effective in stabilizing the strength and toughness of the base metal without deteriorating the toughness of the weld, but if the content exceeds 1.00%, the toughness of the weld Since this would lead to deterioration, the Ni content was set at 1.00% or less.
する。do.
■は、母材の強度上昇に有効な成分であるが、０．０４
％を超えて含有させると溶接部の靭性劣化を招くことか
ら、■含有量は０．０４％以下と定めた。■ is an effective component for increasing the strength of the base material, but 0.04
If the content exceeds 0.04%, the toughness of the welded part will deteriorate, so the content was set at 0.04% or less.
Ｎｂは、母材の強度及び靭性の上昇に有効な成分である
が、０．０３％を超えて含有させると溶接部の靭性劣化
を招くことから、Ｎｂ含有量は０．０３％以下と定めた
。Nb is an effective component for increasing the strength and toughness of the base metal, but if it is contained in an amount exceeding 0.03%, the toughness of the weld zone will deteriorate, so the Nb content is set at 0.03% or less. Ta.
さて、上述のように鋼の化学成分組成を調整したとして
も、それだけでは溶接部のＣＴＯＤ特性（δ−１゜、）
を安定して０．５ｆ１１以上とすることはできず、これ
に加えて更に、式
で表わされる炭素当量（Ｃｅｑ）を０．３８％以下とす
ることによって初めて前記目標性能を満足することがで
きる。従って、鋼の炭素当量（Ｃｅｑ）を０．３８％以
下と限定した。Now, even if the chemical composition of the steel is adjusted as described above, it is not enough to change the CTOD characteristics (δ-1°,) of the welded part.
cannot be stably maintained at 0.5f11 or more, and in addition to this, the target performance can only be satisfied by setting the carbon equivalent (Ceq) expressed by the formula to 0.38% or less. . Therefore, the carbon equivalent (Ceq) of the steel was limited to 0.38% or less.
Ｂ）圧延加熱温度
鋼の熱間圧延に際しては、オーステナイト中に炭化物を
均一に固溶させるため９００℃以上に加熱することが必
要であるが、１２００℃を超えて加熱するとオーステナ
イト粒が粗大化し、これが圧延、再結晶によっても十分
微細化されずに母材の靭性劣化を招く場合がある。従っ
て、圧延加熱温度は９００〜１２００℃と定めたが、好
ましくは該加熱温度を９５０〜１１５０℃に調整するの
が良い。B) Rolling heating temperature When hot rolling steel, it is necessary to heat it to 900°C or higher in order to uniformly dissolve carbides in austenite, but heating above 1200°C will coarsen the austenite grains. This may not be sufficiently refined even by rolling or recrystallization, leading to deterioration in the toughness of the base material. Therefore, although the rolling heating temperature was determined to be 900 to 1200°C, it is preferable to adjust the heating temperature to 950 to 1150°C.
Ｃ）圧延仕上温度及び圧延後の冷却
本発明に係る鋼は、溶接部のＣＴＯＤ特性を確保するた
めにＣｅｑを低く制限しており、母材の強度を確保する
ためには圧延後の冷却速度を速くすることが必要である
。従って、圧延終了後直ちに水冷を行って室温まで急冷
することが必要である。C) Rolling finishing temperature and cooling after rolling In the steel according to the present invention, Ceq is limited to a low value in order to ensure the CTOD characteristics of the welded part, and the cooling rate after rolling is limited in order to ensure the strength of the base metal. It is necessary to speed up the process. Therefore, it is necessary to perform water cooling immediately after the rolling is completed to rapidly cool the product to room temperature.
更に、水冷において十分な冷却速度を確保するためには
、圧延仕上温度を８００℃以上とすることが必要である
。Furthermore, in order to ensure a sufficient cooling rate in water cooling, it is necessary to set the finishing rolling temperature to 800° C. or higher.
従って、圧延仕上温度を８００℃以上と限定しく好まし
くは８２０℃以上とするのが良い）、かつ仕上げ圧延後
直ちに室温まで急冷することと定めた。Therefore, it was decided that the finish rolling temperature should be limited to 800° C. or higher, preferably 820° C. or higher), and that the product should be rapidly cooled to room temperature immediately after finishing rolling.
０）焼戻し処理
一般に、水冷したままの鋼板は歪が多いために降伏点及
び靭性が低い。そのため、圧延後急冷した鋼板の焼戻し
処理が必要であるが、焼戻し温度が２００℃未満では降
伏点及び靭性の向上効果が十分でなく、一方、４５０℃
を超える温度で焼戻しを行うと引張強さが著しく低下す
ることから、焼戻し温度は２００〜４５０℃と定めた。0) Tempering treatment In general, steel plates that have been water-cooled have a low yield point and low toughness due to a large amount of strain. Therefore, it is necessary to temper the steel plate that has been rapidly cooled after rolling, but if the tempering temperature is less than 200°C, the yield point and toughness improvement effect will not be sufficient;
If tempering is performed at a temperature exceeding 200°C, the tensile strength will significantly decrease, so the tempering temperature was set at 200 to 450°C.
しかし、好ましくは３００〜４００℃で焼戻し処理を行
うのが良い。However, it is preferable to perform the tempering treatment at 300 to 400°C.
次いで、本発明の効果を実施例によって更に具体的に説
明する。Next, the effects of the present invention will be explained in more detail with reference to Examples.
〈実施例〉
第１表に示す化学組成の鋼塊（Ａ−Ｕ）を、熱間鍛造し
て厚さ１５０龍のスラブとした後、これを第２表に示す
条件で熱間圧延して室温まで水冷し、更に焼戻し処理し
て板厚３８１ＩＩの綱板を製造した。<Example> A steel ingot (A-U) with the chemical composition shown in Table 1 was hot-forged into a slab with a thickness of 150 mm, and then hot-rolled under the conditions shown in Table 2. It was water-cooled to room temperature and further tempered to produce a steel plate with a thickness of 381 II.
次に、得られた各鋼板について母材及び溶接継手部の機
械的特性を調査し、その結果を第２表に併せて示した。Next, the mechanical properties of the base metal and welded joints of each of the obtained steel plates were investigated, and the results are also shown in Table 2.
なお、母材の機械的性質は、圧延直角方向に鋼板の板厚
中心部からＪＩＳ４号丸棒引張試験片（平行部の直径：
１４鶴、平行部の長さ：５Ｑ＋ａｍ）と、ＪＩＳ Ａ号
シャルピー衝撃試験片（２１ｍＶノツチ）を採取して調
査した。The mechanical properties of the base material were measured using a JIS No. 4 round bar tensile test piece (diameter of the parallel part:
A No. 14 crane (length of parallel part: 5Q+am) and a JIS No. A Charpy impact test piece (21 mV notch) were collected and investigated.
また、溶接部のＣＴＯＤ特性及びシャルピー衝撃特性は
、第１図に示す溶接条件で溶接した溶接継手部について
調査した。ＣＴＯＤ特性は、全厚ＣＯＤ試験片（疲れ切
欠き付開口変位量試験片：ＢＳＩ−ＤＤ１９に準拠）を
用いて調査した。また、シャルピー衝撃特性は、表面か
ら６Ｈの位置よりＪＩＳ４号シャルピー衝撃試験片（２
ｍＶノツチ）を採取して調査した。Furthermore, the CTOD characteristics and Charpy impact characteristics of the welded joint were investigated using the welding conditions shown in FIG. The CTOD characteristics were investigated using a full thickness COD test piece (opening displacement test piece with fatigue notch: compliant with BSI-DD19). In addition, the Charpy impact properties were measured using a JIS No. 4 Charpy impact test piece (2
mV notch) was collected and investigated.
第２表に示される結果からも明らかなように、本発明に
よれば母材の強度及び靭性、並びに溶接継手部のＣＴＯ
Ｄ特性及びシャルピー衝撃特性が共に良好な高張力鋼板
が得られるのに対して、鋼板の製造条件が本発明で規定
する条件から外れている比較例では、母材の強度と靭性
は良好であるが、溶接継手部の靭性、特にＣＴＯＤ特性
が劣ることを確認できる。As is clear from the results shown in Table 2, according to the present invention, the strength and toughness of the base metal, and the CTO of the welded joint
A high-strength steel plate with good D properties and Charpy impact properties is obtained, whereas in comparative examples where the steel plate manufacturing conditions deviate from the conditions specified in the present invention, the strength and toughness of the base material are good. However, it can be confirmed that the toughness of the welded joint, especially the CTOD characteristics, is inferior.
なお、比較例のうちの試験番号１４及び１５では鋼板の
Ｓｉ含有量が高いため、得られた鋼板は溶接継手部にお
いてシャルピー衝撃特性が良好であるにもかかわらすＣ
ＴＯＤ特性に劣ったものとなっている。In addition, in test numbers 14 and 15 of the comparative examples, the Si content of the steel plates was high, so although the obtained steel plates had good Charpy impact properties at the welded joints, C
It has poor TOD characteristics.
また、試験番号２２〜２５は鋼板の化学組成は本発明で
規定する範囲内であるが、製造条件が本発明で規定する
条件を満たしていないために、得られた鋼板は母材の機
械的特性が劣るものとなっている。即ち、試験番号２２
で得られた鋼板は圧延加熱温度が高いため靭性が低く、
試験番号２３で得られた鋼板は仕上温度が低いために強
度が低い。更に、試験番号２４で得られた鋼板は焼戻し
温度が低いため降伏強さ及び靭性が低く、試験番号２５
で得られた鋼板は焼戻し温度が高いため引張強さが低い
。In addition, in test numbers 22 to 25, the chemical composition of the steel plate is within the range specified by the present invention, but because the manufacturing conditions do not meet the conditions specified by the present invention, the obtained steel plate is It has inferior characteristics. That is, test number 22
The steel plate obtained in this process has low toughness due to the high rolling heating temperature.
The steel plate obtained in Test No. 23 has low strength because the finishing temperature is low. Furthermore, the steel plate obtained in test number 24 had low yield strength and toughness due to the low tempering temperature, and the steel plate obtained in test number 25
The steel plate obtained in this process has low tensile strength due to the high tempering temperature.
一方、第２図は本実施例で製造した鋼板に基づき、鋼板
のＳｉ含有量と溶接部（サブマージアーク溶接部）ＣＴ
ＯＤ特性との関係をまとめたグラフであるが、この第２
図からも、鋼板のＳｉ含有量を０．０５％未満に調整し
た場合に初めて優れた溶接部ＣＴＯＤ特性が得られるこ
とを確認できる。On the other hand, Fig. 2 shows the Si content of the steel plate and the CT of the welded part (submerged arc welded part) based on the steel plate manufactured in this example.
This is a graph summarizing the relationship with OD characteristics, but this second
From the figure, it can be confirmed that excellent weld CTOD characteristics can only be obtained when the Si content of the steel plate is adjusted to less than 0.05%.
く効果の総括〉
以上に説明した如く、本発明によれば、十分な強度を有
することは勿論、優れた靭性及び溶接部ＣＴＯＤ特性を
示す高張力鋼板を安定して製造することができ、低温域
での溶接構造物等の信頼性を−段と高めることが可能と
なるなど、産業上極めて有用な効果が得られる。Summary of Effects> As explained above, according to the present invention, it is possible to stably produce a high-strength steel plate that not only has sufficient strength but also exhibits excellent toughness and weld CTOD characteristics, and Industrially, extremely useful effects can be obtained, such as making it possible to significantly improve the reliability of welded structures in the region.
第１図は、各溶接法での溶接条件を説明した図面である
。
第２図は、鋼板のＳｉ含有量と溶接部ＣＴＯＤ特性との
関係を示すグラフである。FIG. 1 is a diagram illustrating welding conditions for each welding method. FIG. 2 is a graph showing the relationship between the Si content of the steel plate and the CTOD characteristics of the welded part.
Claims (2)
５：０．００５％以下、ｓｏｌ．Ａｌ：０．００１〜０
．０１０％、Ｔｉ：０．００５〜０．０２０％、Ｂ：０
．０００３〜０．００１２％、Ｎ：０．００４０〜０．
００６０％、Ｃａ：０．００４０％以下を含有すると共
に（但し、Ｔｉ／Ｎ＝１．５〜３．４）、残部がＦｅ及
び不可避不純物から成り、かつ下記式で表わされる炭素
当量（Ｃｅｑ）が０．３８％以下である鋼を９００〜１
２００℃の温度域に加熱して熱間圧延し、８００℃以上
の仕上げ温度で所定の板厚に圧延してから直ちに室温ま
で急冷した後、２００〜４５０℃の温度域で焼戻すこと
を特徴とする、溶接用高張力鋼板の製造方法。 Ｃｅｑ＝Ｃ＋Ｓｉ／２４＋Ｍｎ／６＋Ｃｕ／１５＋Ｎｉ
／４０＋Ｃｒ／５＋Ｍｏ／４＋Ｖ／１４。(1) Weight percentage: C: 0.03 to 0.12%, Si: more than 0.01% and less than 0.05%, Mn: 0.70 to 1.60%, P: 0.010% or less ,
5: 0.005% or less, sol. Al: 0.001~0
．． 010%, Ti: 0.005-0.020%, B: 0
．． 0003-0.0012%, N: 0.0040-0.
0060%, Ca: 0.0040% or less (however, Ti/N = 1.5 to 3.4), the balance consists of Fe and inevitable impurities, and the carbon equivalent (Ceq) is represented by the following formula: 900-1 for steel with 0.38% or less
It is characterized by being heated to a temperature range of 200°C, hot rolled, rolled to a predetermined thickness at a finishing temperature of 800°C or higher, immediately quenched to room temperature, and then tempered at a temperature range of 200 to 450°C. A method for manufacturing high-strength steel plates for welding. Ceq=C+Si/24+Mn/6+Cu/15+Ni
/40+Cr/5+Mo/4+V/14.
Ｓ：０．００５％以下、ｓｏｌ．Ａｌ：０．００１〜０
．０１０％、Ｔｉ：０．００５〜０．０２０％、Ｂ：０
．０００３〜０．００１２％、Ｎ：０．００４０〜０．
００６０％、Ｃａ：０．００４０％以下を含有し、更に Ｃｕ：０．５０％以下、Ｎｉ：１．００％以下、Ｖ：０
．０４％以下、Ｎｂ：０．０３％以下の少なくとも１種
をも含むと共に（但し、Ｔｉ／Ｎ＝１．５〜３．４）、
残部がＦｅ及び不可避不純物から成り、かつ下記式で表
わされる炭素当量（Ｃｅｑ）が０．３８％以下である鋼
を９００〜１２００℃の温度域に加熱して熱間圧延し、
８００℃以上の仕上げ温度で所定の板厚に圧延してから
直ちに室温まで急冷した後、２００〜４５０℃の温度域
で焼戻すことを特徴とする、溶接用高張力鋼板の製造方
法。 Ｃｅｑ＝Ｃ＋Ｓｉ／２４＋Ｍｎ／６＋Ｃｕ／１５＋Ｎｉ
／４０＋Ｃｒ／５＋Ｍｏ／４＋Ｖ／１４。(2) Weight percentage: C: 0.03 to 0.12%, Si: more than 0.01% and less than 0.05%, Mn: 0.70 to 1.60%, P: 0.010% or less ,
S: 0.005% or less, sol. Al: 0.001~0
．． 010%, Ti: 0.005-0.020%, B: 0
．． 0003-0.0012%, N: 0.0040-0.
0060%, Ca: 0.0040% or less, Cu: 0.50% or less, Ni: 1.00% or less, V: 0
．． 04% or less, Nb: 0.03% or less (however, Ti/N = 1.5 to 3.4),
A steel whose balance consists of Fe and unavoidable impurities and whose carbon equivalent (Ceq) expressed by the following formula is 0.38% or less is heated to a temperature range of 900 to 1200 ° C. and hot rolled,
A method for producing a high-strength steel plate for welding, which comprises rolling the steel plate to a predetermined thickness at a finishing temperature of 800°C or higher, immediately quenching it to room temperature, and then tempering it in a temperature range of 200 to 450°C. Ceq=C+Si/24+Mn/6+Cu/15+Ni
/40+Cr/5+Mo/4+V/14.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP668989A JPH02190423A (en) | 1989-01-13 | 1989-01-13 | Manufacture of steel plate having excellent ctod properties in weld zone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP668989A JPH02190423A (en) | 1989-01-13 | 1989-01-13 | Manufacture of steel plate having excellent ctod properties in weld zone |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02190423A true JPH02190423A (en) | 1990-07-26 |
Family
ID=11645321
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP668989A Pending JPH02190423A (en) | 1989-01-13 | 1989-01-13 | Manufacture of steel plate having excellent ctod properties in weld zone |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02190423A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007302949A (en) * | 2006-05-11 | 2007-11-22 | Nippon Steel Corp | Steel superior in toughness of weld heat-affected zone, and manufacturing method therefor |
| 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 |
| JP2013019014A (en) * | 2011-07-11 | 2013-01-31 | Jfe Steel Corp | Steel for weld structure superior in ctod property at large heat input weld heat affected zone, and production method thereof |
-
1989
- 1989-01-13 JP JP668989A patent/JPH02190423A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007302949A (en) * | 2006-05-11 | 2007-11-22 | Nippon Steel Corp | Steel superior in toughness of weld heat-affected zone, and manufacturing method therefor |
| JP4673788B2 (en) * | 2006-05-11 | 2011-04-20 | 新日本製鐵株式会社 | Steel excellent in toughness of weld heat-affected zone and method for producing the same |
| 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 |
| JP2013019014A (en) * | 2011-07-11 | 2013-01-31 | Jfe Steel Corp | Steel for weld structure superior in ctod property at large heat input weld heat affected zone, and production method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7935197B2 (en) | High strength steel plate | |
| US4521258A (en) | Method of making wrought high tension steel having superior low temperature toughness | |
| KR101388334B1 (en) | High tensile steel products excellent in the resistance to delayed fracture and process for production of the same | |
| JP7411072B2 (en) | High-strength, extra-thick steel material with excellent low-temperature impact toughness and method for producing the same | |
| JP2004232022A (en) | Dual phase type high tensile strength steel sheet having excellent elongation and stretch flanging property, and production method therefor | |
| JPS63241114A (en) | Manufacture of high toughness and high tension steel having superior resistance to stress corrosion cracking | |
| JP2000178645A (en) | Production of steel excellent in strength and toughness | |
| JP3546726B2 (en) | Method for producing high-strength steel plate with excellent HIC resistance | |
| JPH07278656A (en) | Production of low yield ratio high tensile strength steel | |
| JPS5810442B2 (en) | Manufacturing method for high-toughness, high-strength steel with excellent workability | |
| JP4385622B2 (en) | Manufacturing method of high-strength steel sheet | |
| JPH06128631A (en) | Production of high manganese ultrahigh tensile strength steel excellent in low temperature toughness | |
| JPH0425343B2 (en) | ||
| JPS6167717A (en) | Manufacture of high tension steel plate having superior strength and toughness in its weld heat-affected zone | |
| JPH02190423A (en) | Manufacture of steel plate having excellent ctod properties in weld zone | |
| JPS60181229A (en) | Production of low-yield ratio high-tension thick steel plate | |
| KR100448623B1 (en) | Method for manufacturing high Si added medium carbon wire rod to reduce decarburization depth of its surface | |
| JP2618785B2 (en) | Method for producing high Ni alloy clad steel sheet with excellent sour resistance and low temperature toughness | |
| JP3541746B2 (en) | High strength thick steel plate excellent in CTOD characteristics and method for producing the same | |
| JPS63179019A (en) | Manufacture of high tension steel plate having low yield ratio | |
| JPH09263831A (en) | Production of extra thick high strength bent pipe excellent in toughness at low temperature | |
| JPH07268457A (en) | Production of thick steel plate for line pipe, having high strength and high toughness | |
| JPH066750B2 (en) | Method for producing high strength ERW oil well steel pipe with excellent low temperature toughness | |
| JPH08225883A (en) | Production of high tensile strength steel plate excellent in strength and toughness | |
| JPH0742509B2 (en) | Method for producing ERW steel pipe with excellent low temperature toughness |