JPH0414179B2 - - Google Patents
Info
- Publication number
- JPH0414179B2 JPH0414179B2 JP60232733A JP23273385A JPH0414179B2 JP H0414179 B2 JPH0414179 B2 JP H0414179B2 JP 60232733 A JP60232733 A JP 60232733A JP 23273385 A JP23273385 A JP 23273385A JP H0414179 B2 JPH0414179 B2 JP H0414179B2
- Authority
- JP
- Japan
- Prior art keywords
- less
- cod
- ccod
- steel
- tmcp
- 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.)
- Expired - Lifetime
Links
- 229910000831 Steel Inorganic materials 0.000 claims description 50
- 239000010959 steel Substances 0.000 claims description 50
- 238000005204 segregation Methods 0.000 claims description 21
- 238000010438 heat treatment Methods 0.000 claims description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 238000009749 continuous casting Methods 0.000 claims description 10
- 238000010791 quenching Methods 0.000 claims description 10
- 230000000171 quenching effect Effects 0.000 claims description 10
- 238000005496 tempering Methods 0.000 claims description 10
- 238000011282 treatment Methods 0.000 claims description 9
- 239000012535 impurity Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 229910052799 carbon Inorganic materials 0.000 claims description 2
- RMLPZKRPSQVRAB-UHFFFAOYSA-N tris(3-methylphenyl) phosphate Chemical compound CC1=CC=CC(OP(=O)(OC=2C=C(C)C=CC=2)OC=2C=C(C)C=CC=2)=C1 RMLPZKRPSQVRAB-UHFFFAOYSA-N 0.000 claims 4
- 239000000463 material Substances 0.000 description 12
- 229910000734 martensite Inorganic materials 0.000 description 11
- 238000012360 testing method Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 10
- 238000003466 welding Methods 0.000 description 10
- 238000005096 rolling process Methods 0.000 description 7
- 238000001816 cooling Methods 0.000 description 5
- 230000001965 increasing effect Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 229910001566 austenite Inorganic materials 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 229910001567 cementite Inorganic materials 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000004615 ingredient Substances 0.000 description 2
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000003303 reheating Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000000611 regression analysis Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
（産業上の利用分野）
本発明は溶接部のCOD（Ｃrack Ｏpening Ｄ
isplacement）特性に優れた高張力鋼にかかわる
ものである。
（従来の技術）
近年、海底石油資源の開発が活発に進められ、
その開発海域も寒冷海域へと発展しつつある。そ
れにつれて、設置される海洋構造物も大形化し、
また低温で使用されることと合わさつて、通常溶
接施工により建造される構造物の安全性が益々重
要視されるようになつてきた。従来、構造物の安
全性を決定する溶接部の靭性はシヤルピー試験に
よつて評価してきたが、近年ではBS5762規格に
あるようにCOD試験によつて評価されるように
なつてきた。
COD試験は直接、構造物の設計に使用できる
破壊靭性値が測定できるのみならず、従来シヤル
ピー試験では検出できなかつた、ミクロ的な脆化
をも検出できるという利点を持つている。ところ
が従来から製造されている鋼材の溶接部の靭性
を、このようなCOD試験で評価すると、たとえ
ばH.G.Pisarsky等の論文（OTC Report 4043、
13th Annual OTC in Houston、1981年５月）
のFig・１にみられるように必ずしも十分な靭性
を持つているとは言いがたい場合が多いのが現状
である。
（発明が解決しようとする問題点）
本発明は海洋構造物の大型化、低温海域の使用
に対して潜在き裂が如何なる部分に存在しても十
分なる安全性を確保可能な優れたCOD特性を有
する鋼材を提供する事を目的としている。
（問題を解決するための手段）
即ち、本発明者等は前記の実状に鑑み、溶接入
熱が１〜7kJ／mmで溶接される多層盛り溶接継手
の局部脆化域を溶接熱サイクル再現試験によつて
調査した。最初、高温に加熱され粗粒化した
Fusion Line近傍の部分が、次の溶接熱によつて
800℃付近の温度に再加熱された部分が再脆化部
であることが判つた。又その脆化の原因が再加熱
冷却時に発生した島状マルテンサイトによること
が判明した。これらの脆化部分はさらに後続の溶
接によつて、400〜500℃に加熱され、その島状マ
ルテンサイトがフエライトとセメンタイトに分解
することがあり、その場合は脆化部は解消され
る。しかし脆化部の解消の程度は鋼材の種類によ
つて、大きな差が有ることが判つた。従つて成分
範囲を適正なものにすることによつて、かかる脆
化部の解消が計られることが判明した。
また、連続鋳造によつて得られるスラブの中心
偏析部に相当する部分の偏析の度合によつて、鋼
材溶接部のCOD特性が影響されることも見出し
た。
さらに、かかる鋼材について後述のTMCP
（Thermo−mechanical control process）処理、
または焼入焼戻し熱処理を施すことにより、強度
の確保も可能であるという知見も得た。
本発明は以上のごとき知見にもとづいてなされ
たものであり、その要旨とするところは、連続鋳
造スラブより製造され、TMCP処理または焼入
焼戻し熱処理を受けた鋼であつて、重量％で
Ｃ 0.03〜0.13％、
Si 0.05〜0.40％、
Mn 0.80〜1.60％、
Ｐ 0.010％以下、
Ｓ 0.010％以下、
Nb 0.003〜0.010％、
Al 0.010〜0.050％、
Ｎ 0.0040％以下、
Ti 0.005〜0.015％、
残部鉄及び不可避不純物よりなり、またはこれ
にさらにCu0.50％以下、またはこれにさらに
Ni1.00％以下、またはこれにさらにCu0.05％以下
及びNi1.00％以下を含有し、かつ元のスラブの中
央部に相当する板内位置で板厚中心部の偏析を含
む0.3mm厚、50×50mm面積での平均分析値を用い
て得られる次式
Ccod＝［Ｃ（％）］＋［Mn（％）］／６＋［Si（
％）］／24＋［Ni（％）］／40＋［Nb（％）］＋５×［
Ｐ（％）］
による偏析パラメターのCcodの計算値がCcod≦
0.60であることを特徴とする溶接部のCOD特性の
優れた高張力鋼にある。
以下に本発明を詳細に説明する。
（作用）
まず最初に本発明において連続鋳造材を対象と
するのは、偏析パターンが単純で製造上管理しや
すく、かつ対策が立てやすいためである。次に本
発明の鋼は、TMCP処理または焼入焼戻し熱処
理を受けることを前提とするものである。ここで
言うTMCP処理とは、スラブ1000℃以上に加熱
し、適当な圧延を加え、さらに900℃以下の未再
結晶温度域で50％以上の圧延を与えた後、空冷以
上の冷却速度で冷却する処理である。また、ここ
で言う焼入焼戻し熱処理とは、圧延された鋼材を
オーステナイト温度域に再加熱し、その後急冷し
て焼きを入れ、500〜650℃に焼戻しする熱処理で
ある。これらいずれの手段によつても、下記に示
すような成分系の鋼について、その強度を48Kg
ｆ／mm2以上確保可能となるものである。即ち本発
明の対象となる鋼は、引張強さ48Kgｆ／mm2以上を
有するものであつて、このような強度を対象にし
たのは、軟鋼に比べて合金含有量が高く、溶接部
のCODが容易に得られないためである。
次に本発明における成分限定の理由を述べる。
まず、Ｃは0.03％未満では強度上昇に効果が無
い。また、島状マルテンサイトは一部オーステナ
イト化した部分にＣが拡散し、高Ｃのマルテンサ
イトとなるため0.13％超では溶接部のCODが確保
できない。
次にSiは島状マルテンサイトを作り易くする元
素で、0.40％超ではCODを確保できないので0.40
％以下にする必要があり、特に0.30％以下が望ま
しい。一方0.05％未満の場合は脱酸が不十分とな
り、鋼材の内部欠陥を増加せしめるため、0.05％
以上とした。
また、Mnは0.80％未満では強度上昇の効果が
無く、1.60％超では急激に溶接部のCODが減少す
るため1.60％以下とした。
一方、Ｐは溶接部粗粒域での粒界割れを、旧オ
ーステナイト粒界に出来た島状マルテンサイトと
の相互作用によつて助長するため0.010％以下と
した。
また、Ｓも硫化物系介在物を作り、脆性破壊の
基点となるため、低いほうが良好で、0.010％以
下とした。
次に、Nbは母材では析出物を形成しているが、
溶接部の粗粒域では溶解固溶し、次の溶接熱によ
り800℃付近に加熱冷却された時、島状マルテン
サイトを形成し易くする。またその後の溶接ビー
ドによつて400〜500℃に加熱された時、NbはＣ
の拡散を抑え、島状マルテンサイトのフエライト
とセメントタイトへの分解を抑制しCODの回復
を阻害する。Nbが0.01％以下なら、これらの影
響が少なく、CODは容易に回復する。しかしな
がら、本発明の鋼は後述するように、Ｎの含有量
を低く抑えるものであり、このため母材の結晶粒
を細かくするAlNが十分生成しないためNbの炭
化物を利用する必要が有る。しかし0.003％未満
ではその効果がないため、下限を0.003％とした。
又、Alは鋼材の内部欠陥を防止するための十
分な脱酸を行うため0.010％以上の添加が必要で
あり、0.050％を超えると急激にCODを劣化せし
めるので上限を0.050％とした。
さらに、Ｎは島状マルテンサイトの分解を阻害
する元素であり、Ｎが0.0040％超ではCODを著し
く低下せしめるため、上限を0.0040％とした。
また、TiはＮと結合してTiNを形成し、固溶
のＮを減少せしめ、CODを向上せしめる。Tiが
0.005％未満では効果が無く、0.015％超では却つ
てCODを低下させる。
以上が本発明の基本成分系であるが、本発明に
おいてはこの他に、板厚の増大による強度低下
や、溶接後の応力除去焼きなましによる強度低下
を防止する目的で、Cu0.50％以下、またはNi1.00
％以下、またはCu0.50％以下及びNi1.00％以下を
含有させることができる。
まず、Cuはフエライト組織に固溶して、強度
を高める効果をもつが、0.50超ではCuの析出物を
作り、母材の靭性を低下せしめる。
また、NiはCuと同様な固溶硬化元素であり、
強度上昇効果を有する。しかし、Niが1.0％超で
は、かえつて島状マルテンサイトを形成しやすく
し、CODを低下させる。
本発明の鋼は以上のような成分組成を有するも
のであるが、これらの限定条件を満足したとして
も、実際の鋼では偏析が問題となる。そこで偏析
部のCODに及ぼす影響を、第１表に示す化学成
分の鋼を300ton転炉で溶製し検討した。
(Industrial Application Field) The present invention is applicable to COD ( Crack O Pening D) of welded parts.
This relates to high-strength steel with excellent isplacement properties. (Conventional technology) In recent years, the development of offshore oil resources has been actively promoted.
The development area is also developing into a colder area. Along with this, the size of the marine structures installed has also increased.
In addition, in conjunction with the fact that structures are used at low temperatures, the safety of structures normally constructed by welding has become increasingly important. Traditionally, the toughness of welds, which determines the safety of structures, has been evaluated using the Charpy test, but in recent years it has come to be evaluated using the COD test as specified in the BS5762 standard. The COD test has the advantage of not only being able to directly measure fracture toughness values that can be used in the design of structures, but also being able to detect microscopic embrittlement that could not be detected with the conventional Shapey test. However, when the toughness of conventionally manufactured steel welds is evaluated by such a COD test, for example, a paper by HGPisarsky et al.
13th Annual OTC in Houston, May 1981)
As shown in Fig. 1, the current situation is that in many cases it cannot be said that the steel has sufficient toughness. (Problems to be Solved by the Invention) The present invention has excellent COD characteristics that can ensure sufficient safety even when latent cracks exist in any part of marine structures that are used in large-scale offshore structures and in low-temperature sea areas. The purpose is to provide steel materials with (Means for solving the problem) That is, in view of the above-mentioned actual situation, the present inventors performed a welding heat cycle reproduction test on the local embrittlement region of a multi-layer welded joint welded at a welding heat input of 1 to 7 kJ/mm. The survey was conducted by Initially, it was heated to high temperatures and became coarse grained.
The area near the Fusion Line is affected by the next welding heat.
It was found that the part that was reheated to a temperature of around 800°C was a re-embrittlement part. It was also found that the cause of the embrittlement was island martensite generated during reheating and cooling. These embrittled portions are further heated to 400 to 500° C. during subsequent welding, and the island-like martensite may decompose into ferrite and cementite, in which case the embrittled portions are eliminated. However, it was found that the degree of elimination of embrittlement varies greatly depending on the type of steel material. Therefore, it has been found that such brittle parts can be eliminated by adjusting the range of ingredients to an appropriate range. It was also discovered that the COD characteristics of steel welds are affected by the degree of segregation in the central segregation area of the slab obtained by continuous casting. Furthermore, regarding such steel materials, TMCP
(Thermo-mechanical control process) treatment,
It was also found that strength can be ensured by applying quenching and tempering heat treatment. The present invention has been made based on the above knowledge, and the gist thereof is to provide a steel manufactured from a continuous casting slab and subjected to TMCP treatment or quenching and tempering heat treatment, which has a carbon content of 0.03% by weight. ~0.13%, Si 0.05~0.40%, Mn 0.80~1.60%, P 0.010% or less, S 0.010% or less, Nb 0.003~0.010%, Al 0.010~0.050%, N 0.0040% or less, Ti 0.005~0.015%, balance Consists of iron and unavoidable impurities, or in addition Cu0.50% or less, or in addition
0.3mm thickness containing 1.00% or less Ni, or 0.05% or less Cu and 1.00% or less Ni, and including segregation at the center of the plate thickness at a position within the plate corresponding to the center of the original slab , the following formula obtained using the average analysis value in a 50 × 50 mm area: Ccod = [C (%)] + [Mn (%)] / 6 + [Si (
%)]/24+[Ni(%)]/40+[Nb(%)]+5×[
P (%)] The calculated value of Ccod of the segregation parameter is Ccod≦
It is a high tensile steel with excellent COD characteristics of the welded part, characterized by a COD of 0.60. The present invention will be explained in detail below. (Function) First of all, the present invention targets continuous casting materials because the segregation pattern is simple, easy to manage in production, and easy to take countermeasures. Next, the steel of the present invention is premised on being subjected to TMCP treatment or quenching and tempering heat treatment. The TMCP treatment here refers to heating the slab to 1000℃ or higher, applying appropriate rolling, and then applying 50% or more rolling in the non-recrystallization temperature range of 900℃ or lower, and then cooling it at a cooling rate faster than air cooling. This is the process of Moreover, the quenching and tempering heat treatment referred to herein is a heat treatment in which a rolled steel material is reheated to an austenite temperature range, then rapidly cooled to be quenched, and then tempered to 500 to 650°C. By any of these methods, the strength of steel with the composition shown below can be estimated at 48 kg.
It is possible to secure f/mm 2 or more. In other words, the steel targeted by the present invention has a tensile strength of 48 Kgf/mm 2 or more, and the steel targeted for such strength has a higher alloy content than mild steel and has a lower COD of the welded part. This is because it is not easily obtained. Next, the reason for limiting the ingredients in the present invention will be described. First, C has no effect on increasing strength if it is less than 0.03%. In addition, in the island-like martensite, C diffuses into the partially austenitized portion and becomes a high-C martensite, so if it exceeds 0.13%, the COD of the welded part cannot be ensured. Next, Si is an element that facilitates the formation of island-like martensite, and if it exceeds 0.40%, COD cannot be secured, so 0.40%
% or less, and 0.30% or less is particularly desirable. On the other hand, if it is less than 0.05%, deoxidation will be insufficient and internal defects in the steel will increase, so 0.05%
That's all. In addition, if Mn is less than 0.80%, there is no effect of increasing strength, and if it exceeds 1.60%, the COD of the weld zone will decrease rapidly, so it was set to 1.60% or less. On the other hand, P was set at 0.010% or less because it promotes grain boundary cracking in the coarse grain region of the weld zone through interaction with island martensite formed at prior austenite grain boundaries. In addition, since S also forms sulfide-based inclusions and becomes a starting point for brittle fracture, the lower the content, the better, and the content was set at 0.010% or less. Next, although Nb forms precipitates in the base metal,
It dissolves into a solid solution in the coarse grain region of the weld zone, and when heated and cooled to around 800°C by the next welding heat, it becomes easy to form island-like martensite. Also, when heated to 400-500℃ by the subsequent welding bead, Nb
This suppresses the diffusion of martensite, inhibits the decomposition of island martensite into ferrite and cementite, and inhibits COD recovery. If Nb is 0.01% or less, these effects are small and COD can be easily recovered. However, as will be described later, in the steel of the present invention, the N content is kept low, and therefore AlN, which makes the crystal grains of the base material fine, is not sufficiently produced, so it is necessary to use Nb carbide. However, if it is less than 0.003%, it has no effect, so the lower limit was set at 0.003%. In addition, Al needs to be added in an amount of 0.010% or more to perform sufficient deoxidation to prevent internal defects in steel materials, and if it exceeds 0.050%, the COD will rapidly deteriorate, so the upper limit was set at 0.050%. Furthermore, N is an element that inhibits the decomposition of island-like martensite, and if N exceeds 0.0040%, the COD is significantly reduced, so the upper limit was set at 0.0040%. Furthermore, Ti combines with N to form TiN, which reduces solid solution N and improves COD. Ti is
If it is less than 0.005%, it will have no effect, and if it exceeds 0.015%, it will actually reduce COD. The above is the basic component system of the present invention, but in the present invention, in addition to this, Cu0.50% or less, Cu0.50% or less, or Ni1.00
% or less, or Cu 0.50% or less and Ni 1.00% or less. First, Cu dissolves in the ferrite structure and has the effect of increasing strength, but if it exceeds 0.50, Cu precipitates are formed and the toughness of the base material is reduced. In addition, Ni is a solid solution hardening element similar to Cu,
Has a strength increasing effect. However, if Ni exceeds 1.0%, island-like martensite is more likely to be formed and the COD is lowered. Although the steel of the present invention has the above-mentioned composition, even if these limiting conditions are satisfied, segregation becomes a problem in actual steel. Therefore, we investigated the effect of segregated areas on COD by melting steel with the chemical composition shown in Table 1 in a 300 ton converter.
【表】
偏析状態は連続鋳造の条件を変化させること、
及びスラブを厚板圧延する前に1300℃の高温に加
熱し偏析元素を拡散させることによつて、種々変
化させた。このような偏析状態の異なるスラブを
1200℃に加熱し、TMCP圧延を行い50mm厚鋼板
を作製し試験した。溶接継手は第２表に示すよう
な溶接条件で、第２図に示す寸法形状の開先を有
する母材Ｓより作製し、各鋼板につき３本ずつ
BS5762に従つて試験した。なおノツチ位置は
Fusion Lineに沿つて入れ、試験温度は−10℃で
ある。試験に供した鋼板は、溶接前に予め試験片
採取位置近傍で、板厚中心部の偏析を含む0.3mm
厚、50×50mm面積の部分から成分分析試料を採取
し、偏析部の成分含有量を測定しておいた。[Table] The segregation state can be changed by changing the conditions of continuous casting.
Various changes were made by heating the slab to a high temperature of 1300°C to diffuse the segregated elements before rolling the slab into a thick plate. These slabs with different segregation states are
It was heated to 1200°C and subjected to TMCP rolling to produce a 50mm thick steel plate and tested. The welded joints were made from base material S having a groove with the dimensions and shape shown in Figure 2 under the welding conditions shown in Table 2, and three joints were made for each steel plate.
Tested according to BS5762. The notch position is
The test temperature is -10°C. Before welding, the steel plate used for the test had a thickness of 0.3 mm, including segregation at the center of the plate thickness, near the specimen collection location.
A component analysis sample was taken from a 50 x 50 mm thick area, and the component content in the segregated area was measured.
【表】【table】
【表】【table】
【表】
偏析部の成分含有量とCOD値を重回帰分析し、
次式の偏析部パラメター（Ccod）を求めた。
Ccod＝［Ｃ（％）］＋［Mn（％）］／６＋［Si（
％）］／24＋［Ni（％）］／40＋［Nb（％）］＋５×［
Ｐ（％）］
この偏析パラメターとCODとの関係を第１図
に示す。この図から明らかなように、Ccodが
0.60以下であれば、−10℃におけるCOD値が0.25
mm以上となり、良好な溶接部COD特性が得られ
る。以上の理由により、上式で求めたCcod値を
0.60以下と定めた。
以下、実施例により本発明の効果をさらに具体
的に示す。
（実施例）
第３表にNo.17〜No.24の本発明鋼とNo.１〜No.16の
比較鋼を対比した結果を示す。母材の機械的性質
として、JIS5号試験片による引張試験結果および
−40℃における２mmＶノツチシヤルピー試験の吸
収エネルギーを示した。溶接継手のCODとして
先の第２表に示した溶接条件及び第２図に示す開
先で溶接継手を作成し、同様にBS5762規格に従
つて−10℃で試験した結果を示した。なおCOD
試験片断面寸法は50×100mmである。
比較鋼No.１〜No.16総て連続鋳造によつて製造さ
れた250mmスラブを使用し、TMCP以外は通常の
厚板圧延を実施し、その後900℃で焼きならし熱
処理または900℃焼入、620℃焼戻し熱処理によつ
て製造された鋼である。又、TMCP鋼は厚板圧
延を1200℃加熱、800℃仕上げ、その後500℃まで
水冷する工程を採用した鋼である。
一方、本発明鋼は連続鋳造によつて250mmスラ
ブをつくり、1300℃で10hr均熱拡散処理をした
後、厚板圧延を1200℃加熱、仕上げ温度800℃で、
その後500℃まで水冷したTMCP鋼、または1200
℃に加熱、通常の厚板圧延を実施した後、900℃
に再加熱して焼入し、620℃×30min焼戻し熱処
理して製造した鋼である。[Table] Multiple regression analysis of the component content and COD value of the segregated part,
The segregation part parameter (Ccod) was calculated using the following equation. Ccod=[C(%)]+[Mn(%)]/6+[Si(
%)]/24+[Ni(%)]/40+[Nb(%)]+5×[
P (%)] The relationship between this segregation parameter and COD is shown in FIG. It is clear from this figure that Ccod
If it is 0.60 or less, the COD value at -10℃ is 0.25
mm or more, and good weld COD characteristics can be obtained. For the above reasons, the Ccod value calculated using the above formula is
It was set as 0.60 or less. Hereinafter, the effects of the present invention will be illustrated more specifically by Examples. (Example) Table 3 shows the results of comparing the invention steels No. 17 to No. 24 and the comparison steels No. 1 to No. 16. As for the mechanical properties of the base material, the results of a tensile test using a JIS No. 5 test piece and the absorbed energy of a 2 mm V notch pea test at -40°C are shown. As the COD of welded joints, welded joints were prepared under the welding conditions shown in Table 2 and the groove shown in Figure 2, and the results were similarly tested at -10°C in accordance with the BS5762 standard. Furthermore, COD
The cross-sectional dimensions of the test piece are 50 x 100 mm. Comparative Steel No. 1 to No. 16 were all 250 mm slabs manufactured by continuous casting, and except for TMCP, ordinary thick plate rolling was performed, followed by normalizing heat treatment at 900°C or quenching at 900°C. , is a steel manufactured by 620℃ tempering heat treatment. In addition, TMCP steel is a steel that uses a process of rolling a thick plate, heating it to 1200℃, finishing it at 800℃, and then water-cooling it to 500℃. On the other hand, for the steel of the present invention, a 250mm slab was made by continuous casting, and after soaking and diffusion treatment at 1300℃ for 10 hours, the steel was rolled into a thick plate by heating at 1200℃ and finishing temperature at 800℃.
TMCP steel then water cooled to 500℃ or 1200℃
After heating to 900℃ and carrying out normal plate rolling
This steel is manufactured by reheating, quenching, and tempering at 620°C for 30 minutes.
【表】【table】
【表】
第３表から判るように、本発明鋼においては各
成分を限定すると同時に、偏析パラメターを0.60
以下にすることによつて、いずれも継手CODの
優れた、引張強さ48Kg／mm2以上の高張力鋼が得ら
れた。これに対し比較鋼ではNo.１のように偏析パ
ラメターが0.60以下であつてもNb含有量が0.026
％と本発明範囲の上限を超えた成分範囲の為
CODが低い値となつている。同様に他の成分に
ついても本発明範囲の上限を越えて外れた鋼はた
とえ偏析パラメターが0.60以下であつても、いず
れも低COD値となつている。またその反対に成
分が範囲内にあつても、偏析パラメターが0.60超
となつたNo.15のような鋼は低COD値となつてい
る。さらに、No.９鋼のようにNbが本発明範囲の
下限未満である為、CODは良好であるが母材の
強度が低くしかも靭性も低い値となつている。こ
のように本発明範囲を満足しない場合は母材特性
も良好でCOD特性の優れた鋼を得る事が出来な
い。
（発明の効果）
以上の実施例からも明らかなように、本発明鋼
によれば継手COD特性の極めて優れた高張力鋼
を提供する事が可能であり、産業上の効果は極め
て顕著である。[Table] As can be seen from Table 3, in the steel of the present invention, each component is limited and at the same time the segregation parameter is set to 0.60.
By doing the following, high tensile steel with excellent joint COD and tensile strength of 48 Kg/mm 2 or more was obtained. On the other hand, in comparison steel, even if the segregation parameter is 0.60 or less like No. 1, the Nb content is 0.026.
% and the component range exceeds the upper limit of the present invention range.
COD has become a low value. Similarly, steels with other components exceeding the upper limit of the present invention range have low COD values even if the segregation parameter is 0.60 or less. On the other hand, even if the composition is within the range, steels such as No. 15 with a segregation parameter exceeding 0.60 have a low COD value. Furthermore, as in No. 9 steel, Nb is less than the lower limit of the present invention range, so although the COD is good, the strength of the base metal is low and the toughness is also low. As described above, if the range of the present invention is not satisfied, it is impossible to obtain a steel with good base material properties and excellent COD properties. (Effects of the invention) As is clear from the above examples, the steel of the present invention makes it possible to provide high-strength steel with extremely excellent joint COD characteristics, and the industrial effects are extremely significant. .
第１図は偏析パラメター（Ccod）と−10℃に
おけるCOD値との関係を示す図、第２図は実施
例及び偏析パラメター実験に用いられた開先の寸
法形状を示す図である。
Ｓ：母材。
FIG. 1 is a diagram showing the relationship between the segregation parameter (Ccod) and the COD value at -10°C, and FIG. 2 is a diagram showing the dimensions and shapes of the grooves used in the examples and segregation parameter experiments. S: Base material.
Claims (1)
または焼入焼戻熱処理を受けた鋼であつて、重量
％で Ｃ 0.03〜0.13％、 Si 0.05〜0.40％、 Mn 0.80〜1.60％、 Ｐ 0.010％以下． Ｓ 0.010％以下、 Nb 0.003〜0.010％、 Al 0.010〜0.050％、 Ｎ 0.0040％以下、 Ti 0.005〜0.015％、 残部鉄及び不可避不純物よりなりかつ元のスラ
ブの中央部に相当する板内位置で板厚中心部の偏
析を含む0.3mm厚、50×50mm面積での平均分析値
を用いて得られる次式 Ccod＝［Ｃ（％）］＋［Mn（％）］／６＋［Si（
％）］／24＋［Ni（％）］／40＋［Nb（％）］＋５×［
Ｐ（％）］ による偏析パラメータのCcodの計算値がCcod≦
0.60であることを特徴とする溶接部のCOD特性の
優れた高張力鋼。 ２ 連続鋳造スラブより製造され、TMCP処理
または焼入焼戻熱処理を受けた鋼であつて、重量
％で Ｃ 0.03〜0.13％、 Si 0.05〜0.40％、 Mn 0.80〜1.60％、 Cu 0.50％以下． Ｐ 0.010％以下． Ｓ 0.010％以下、 Nb 0.003〜0.010％、 Al 0.010〜0.050％、 Ｎ 0.0040％以下、 Ti 0.005〜0.015％、 残部鉄及び不可避不純物よりなりかつ元のスラ
ブの中央部に相当する板内位置で板厚中心部の偏
析を含む0.3mm厚、50×50mm面積での平均分析値
を用いて得られる次式 Ccod＝［Ｃ（％）］＋［Mn（％）］／６＋［Si（
％）］／24＋［Ni（％）］／40＋［Nb（％）］＋５×［
Ｐ（％）］ による偏析パラメータのCcodの計算値がCcod≦
0.60であることを特徴とする溶接部のCOD特性の
優れた高張力鋼。 ３ 連続鋳造スラブより製造され、TMCP処理
または焼入焼戻熱処理を受けた鋼であつて、重量
％で Ｃ 0.03〜0.13％、 Si 0.05〜0.40％、 Mn 0.80〜1.60％、 Ni 1.00％以下． Ｐ 0.010％以下． Ｓ 0.010％以下、 Nb 0.003〜0.010％、 Al 0.010〜0.050％、 Ｎ 0.0040％以下、 Ti 0.005〜0.015％、 残部鉄及び不可避不純物よりなりかつ元のスラ
ブの中央部に相当する板内位置で板厚中心部の偏
析を含む0.3mm厚、50×50mm面積での平均分析値
を用いて得られる次式 Ccod＝［Ｃ（％）］＋［Mn（％）］／６＋［Si（
％）］／24＋［Ni（％）］／40＋［Nb（％）］＋５×［
Ｐ（％）］ による偏析パラメータのCcodの計算値がCcod≦
0.60であることを特徴とする溶接部のCOD特性の
優れた高張力鋼。 ４ 連続鋳造スラブより製造され、TMCP処理
または焼入焼戻熱処理を受けた鋼であつて、重量
％で Ｃ 0.03〜0.13％、 Si 0.05〜0.40％、 Mn 0.80〜1.60％、 Cu 0.50％以下． Ni 1.00％以下． Ｐ 0.010％以下． Ｓ 0.010％以下、 Nb 0.003〜0.010％、 Al 0.010〜0.050％、 Ｎ 0.0040％以下、 Ti 0.005〜0.015％、 残部鉄及び不可避不純物よりなりかつ元のスラ
ブの中央部に相当する板内位置で板厚中心部の偏
析を含む0.3mm厚、50×50mm面積での平均分析値
を用いて得られる次式 Ccod＝［Ｃ（％）］＋［Mn（％）］／６＋［Si（
％）］／24＋［Ni（％）］／40＋［Nb（％）］＋５×［
Ｐ（％）］ による偏析パラメータのCcodの計算値がCcod≦
0.60であることを特徴とする溶接部のCOD特性の
優れた高張力鋼。[Claims] 1. A steel manufactured from a continuous casting slab and subjected to TMCP treatment or quenching and tempering heat treatment, which contains C 0.03 to 0.13%, Si 0.05 to 0.40%, and Mn 0.80 to 1.60% by weight. , P 0.010% or less. S 0.010% or less, Nb 0.003 to 0.010%, Al 0.010 to 0.050%, N 0.0040% or less, Ti 0.005 to 0.015%, the balance being iron and unavoidable impurities, and at a position within the plate corresponding to the center of the original slab. The following formula Ccod = [C (%)] + [Mn (%)] / 6 + [Si (
%)]/24+[Ni(%)]/40+[Nb(%)]+5×[
P (%)] The calculated value of Ccod of the segregation parameter is Ccod≦
High tensile strength steel with excellent COD characteristics of welded parts, characterized by a COD of 0.60. 2 Steel manufactured from continuous casting slabs and subjected to TMCP treatment or quenching and tempering heat treatment, with weight percentages of C 0.03 to 0.13%, Si 0.05 to 0.40%, Mn 0.80 to 1.60%, and Cu 0.50% or less. P 0.010% or less. S 0.010% or less, Nb 0.003 to 0.010%, Al 0.010 to 0.050%, N 0.0040% or less, Ti 0.005 to 0.015%, the balance being iron and unavoidable impurities, and at a position within the plate corresponding to the center of the original slab. The following formula Ccod = [C (%)] + [Mn (%)] / 6 + [Si (
%)]/24+[Ni(%)]/40+[Nb(%)]+5×[
P (%)] The calculated value of Ccod of the segregation parameter is Ccod≦
High tensile strength steel with excellent COD characteristics of welded parts, characterized by a COD of 0.60. 3 Steel manufactured from continuous casting slabs and subjected to TMCP treatment or quenching and tempering heat treatment, containing 0.03 to 0.13% C, 0.05 to 0.40% Si, 0.80 to 1.60% Mn, and 1.00% or less Ni by weight. P 0.010% or less. S 0.010% or less, Nb 0.003 to 0.010%, Al 0.010 to 0.050%, N 0.0040% or less, Ti 0.005 to 0.015%, the balance being iron and unavoidable impurities, and at a position within the plate corresponding to the center of the original slab. The following formula Ccod = [C (%)] + [Mn (%)] / 6 + [Si (
%)]/24+[Ni(%)]/40+[Nb(%)]+5×[
P (%)] The calculated value of Ccod of the segregation parameter is Ccod≦
High tensile strength steel with excellent COD characteristics of welded parts, characterized by a COD of 0.60. 4 Steel manufactured from continuous casting slabs and subjected to TMCP treatment or quenching and tempering heat treatment, with weight percentages of C 0.03 to 0.13%, Si 0.05 to 0.40%, Mn 0.80 to 1.60%, and Cu 0.50% or less. Ni 1.00% or less. P 0.010% or less. S 0.010% or less, Nb 0.003 to 0.010%, Al 0.010 to 0.050%, N 0.0040% or less, Ti 0.005 to 0.015%, the balance being iron and unavoidable impurities, and at a position within the plate corresponding to the center of the original slab. The following formula Ccod = [C (%)] + [Mn (%)] / 6 + [Si (
%)]/24+[Ni(%)]/40+[Nb(%)]+5×[
P (%)] The calculated value of Ccod of the segregation parameter is Ccod≦
High tensile strength steel with excellent COD characteristics of welded parts, characterized by a COD of 0.60.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23273385A JPS6293346A (en) | 1985-10-18 | 1985-10-18 | High strength steel excellent in cod characteristics in weld zone |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23273385A JPS6293346A (en) | 1985-10-18 | 1985-10-18 | High strength steel excellent in cod characteristics in weld zone |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6293346A JPS6293346A (en) | 1987-04-28 |
| JPH0414179B2 true JPH0414179B2 (en) | 1992-03-12 |
Family
ID=16943926
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23273385A Granted JPS6293346A (en) | 1985-10-18 | 1985-10-18 | High strength steel excellent in cod characteristics in weld zone |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6293346A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012005330A1 (en) | 2010-07-09 | 2012-01-12 | 新日本製鐵株式会社 | Ni-CONTAINING STEEL SHEET AND PROCESS FOR PRODUCING SAME |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6421036A (en) * | 1987-07-14 | 1989-01-24 | Kawasaki Steel Co | High strength thick steel having superior cod characteristic in weld zone |
| FR2668169B1 (en) * | 1990-10-18 | 1993-01-22 | Lorraine Laminage | IMPROVED WELDING STEEL. |
| JP5924058B2 (en) | 2011-10-03 | 2016-05-25 | Ｊｆｅスチール株式会社 | High tensile strength steel sheet with excellent low temperature toughness of weld heat affected zone and method for producing the same |
| CN103695769B (en) * | 2013-12-26 | 2016-08-17 | 南阳汉冶特钢有限公司 | A kind of high-strength F H40 Marine Engineering Steel steel plate and production method thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61170541A (en) * | 1985-01-24 | 1986-08-01 | Kobe Steel Ltd | High strength hot rolled steel plate for wheel rim |
-
1985
- 1985-10-18 JP JP23273385A patent/JPS6293346A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61170541A (en) * | 1985-01-24 | 1986-08-01 | Kobe Steel Ltd | High strength hot rolled steel plate for wheel rim |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012005330A1 (en) | 2010-07-09 | 2012-01-12 | 新日本製鐵株式会社 | Ni-CONTAINING STEEL SHEET AND PROCESS FOR PRODUCING SAME |
| US8882942B2 (en) | 2010-07-09 | 2014-11-11 | Nippon Steel & Sumitomo Metal Corporation | Ni-added steel plate and method of manufacturing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6293346A (en) | 1987-04-28 |
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