JPH076034B2 - High-strength steel with excellent brittle fracture initiation characteristics in welds - Google Patents
High-strength steel with excellent brittle fracture initiation characteristics in weldsInfo
- Publication number
- JPH076034B2 JPH076034B2 JP62014287A JP1428787A JPH076034B2 JP H076034 B2 JPH076034 B2 JP H076034B2 JP 62014287 A JP62014287 A JP 62014287A JP 1428787 A JP1428787 A JP 1428787A JP H076034 B2 JPH076034 B2 JP H076034B2
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- JP
- Japan
- Prior art keywords
- weight
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- steel
- concentration
- brittle fracture
- 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 - Fee Related
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 59
- 239000010959 steel Substances 0.000 title claims description 59
- 230000000977 initiatory effect Effects 0.000 title claims description 5
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 11
- 150000002910 rare earth metals Chemical class 0.000 claims description 11
- 239000012535 impurity Substances 0.000 claims description 8
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 230000003068 static effect Effects 0.000 claims 1
- 238000003466 welding Methods 0.000 description 15
- 229910000734 martensite Inorganic materials 0.000 description 12
- 229910052802 copper Inorganic materials 0.000 description 9
- 229910052759 nickel Inorganic materials 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- 229910052758 niobium Inorganic materials 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 229910001566 austenite Inorganic materials 0.000 description 4
- 238000001816 cooling Methods 0.000 description 4
- 238000005096 rolling process Methods 0.000 description 4
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 238000005098 hot rolling Methods 0.000 description 3
- 230000009466 transformation Effects 0.000 description 3
- 229910052720 vanadium Inorganic materials 0.000 description 3
- 229910000859 α-Fe Inorganic materials 0.000 description 3
- 238000000137 annealing Methods 0.000 description 2
- 239000010953 base metal Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 239000003208 petroleum Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 229910000746 Structural steel Inorganic materials 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910001563 bainite Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000004453 electron probe microanalysis Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 238000009864 tensile test Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 150000003568 thioethers Chemical class 0.000 description 1
Landscapes
- Heat Treatment Of Steel (AREA)
Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、石油生産用ジャケット型プラットホーム等の
構造材に関するものであり、溶接部の脆性破壊発生特性
に優れ、石油生産用ジャケット型プラットホームのノー
ド部に適した厚肉の鋼材に関するものである。Description: TECHNICAL FIELD The present invention relates to a structural material such as a jacket type platform for petroleum production, which has excellent brittle fracture occurrence characteristics of a welded portion and is excellent in the characteristics of a jacket type platform for petroleum production. The present invention relates to a thick steel material suitable for the node portion.
（従来の技術） 近年、石油生産用ジャケット型プラットホームの建設が
行われているが、石油生産用ジャケット型プラットホー
ムの海中にあるジャケットは波浪や潮流の影響を受け
る。特に、鋼管が交差する格点部は応力集中も高く、溶
接で接合されているので、特に厳しい脆性破壊発生特性
が要求される。(Prior Art) In recent years, a jacket type platform for oil production has been constructed, but the jacket in the sea of the jacket type platform for oil production is affected by waves and tidal currents. In particular, since the stress concentration is high in the graded portion where the steel pipes intersect and they are joined by welding, particularly severe brittle fracture occurrence characteristics are required.
上述した用途に使用される板厚が50〜200mmの極厚鋼材
をＫ型開先に加工して、多層溶接で接合したストレート
ボンド部に疲労ノッチを導入し、−10℃の温度でCOD試
験を行うと、板厚が厚いことと、多層溶接により生じる
島状マルテンサイト等の低温変態生成物のためにCOD特
性が劣化する。A very thick steel material with a plate thickness of 50 to 200 mm used for the above-mentioned applications is processed into a K-shaped groove and a fatigue notch is introduced into the straight bond part joined by multilayer welding, and a COD test is performed at a temperature of -10 ° C. When this is done, the COD characteristics deteriorate due to the thick plate and low-temperature transformation products such as island martensite produced by multi-layer welding.
（発明が解決しようとする問題点） 鋼管用極厚鋼板の接合には、通常の入熱量が5kJ/mm以下
でサブマージアーク溶接又はシールドメタルアーク溶接
が用いられ、板厚が厚いことから多層溶接となる。多層
溶接を行った場合、溶接熱により生成した粗大粒が次パ
スによりAr3点とAc1点の２相域に加熱された領域（ICCG
HAZと称す）が、COD特性が最も悪いことは知られてい
る。これは、母材がAr3とAl1の２相域に加熱された際、
旧オーステナイト粒界に島状マルテンサイトが生成する
ためであり、この島状マルテンサイトは脆性破壊発生特
性を悪化させる。島状マルテンサイトは、350℃以上の
温度で長時間加熱することにより、フェライトと炭化物
に分解する。しかし、通常の溶接の場合には、350℃以
上に加熱されている時間が短いために島状マルテンサイ
トは分解せず、COD特性が改善されない。(Problems to be solved by the invention) Submerged arc welding or shield metal arc welding with a normal heat input of 5 kJ / mm or less is used for joining ultra-thick steel plates for steel pipes, and since the plate thickness is thick, multi-layer welding Becomes When multi-layer welding is performed, coarse particles generated by welding heat are heated to the two-phase region of Ar 3 point and Ac 1 point by the next pass (ICCG
HAZ) is known to have the worst COD characteristics. This is because when the base material is heated to the two-phase region of Ar 3 and Al 1 ,
This is because island martensite is generated at the former austenite grain boundary, and this island martensite deteriorates the brittle fracture initiation property. Island martensite decomposes into ferrite and carbide when heated at a temperature of 350 ° C or higher for a long time. However, in the case of normal welding, the island-shaped martensite does not decompose and the COD characteristics are not improved because the time of heating to 350 ° C. or higher is short.
本発明者等は、幅0.5mmのＸ線マイクロアナライザー（E
PMA）で鋼板のＰ濃度の最大値を測定し、COD試験による
溶接部の脆性破壊発生特性との関連について調査した。
この結果、鋼板のＰ濃度の最大値を0.25mm2（0.5mm×0.
5mm）当り0.08％以下にすることにより、島状マルテン
サイトの生成が抑えられ、仮に生成しても溶接部全ての
島状マルテンサイトが溶接時の熱により、フェライトと
炭化物となりCOD特性が改善されることが判った。The present inventors have developed an X-ray micro analyzer (E
The maximum P concentration of the steel sheet was measured by PMA), and the relationship with the brittle fracture occurrence characteristics of the welded portion by the COD test was investigated.
As a result, the maximum P concentration of the steel sheet was 0.25 mm 2 (0.5 mm × 0.
5 mm) 0.08% or less, the formation of island martensite is suppressed, and even if it is formed, all the island martensite in the weld will become ferrite and carbide due to the heat during welding, and COD characteristics will be improved. I found out that
（問題点を解決するための手段） 本発明は、 C:0.03〜0.15重量％、 Si:0.05〜0.50重量％、 Mn:0.5〜2.0重量％、 Al:0.005〜0.05重量％、 P:0.010重量％以下、 を含み、残部は不可避的不純物を除き実質的にFeから成
る鋼で、且つ0.5mm×0.5mmの面積当りのＰ濃度の板厚方
向の最大値が0.08％以下であることを特徴とする溶接部
の脆性破壊発生特性の優れた高強度鋼、 C:0.03〜0.15重量％、 Si:0.05〜0.50重量％、 Mn:0.5〜2.0重量％、 Al:0.005〜0.05重量％、 P:0.010重量％以下、 に加えて、0.03重量％以下のNb、0.1重量％以下のＶ、
1.0重量％以下のNi、1.0重量％以下のCuのうち一種又は
二種以上を含み、残部は不可避的不純物を除き実質的に
Feから成る鋼で、且つ0.5mm×0.5mmの面積当りのＰ濃度
の板厚方向の最大値が0.08％以下であることを特徴とす
る溶接部の脆性破壊発生特性の優れた高強度鋼、 C:0.03〜0.15重量％、 Si:0.05〜0.50重量％、 Mn:0.5〜2.0重量％、 Al:0.005〜0.05重量％、 P:0.010重量％以下、 に加えて、0.01重量％以下のTi、0.02重量％以下の希土
類金属のうち一種又は二種以上を含有し、残部は不可避
的不純物を除き実質的にFeから成る鋼で、且つ0.5mm×
0.5mmの面積当りのＰ濃度の板厚方向の最大値が0.08％
以下であることを特徴とする溶接部の脆性破壊発生特性
の優れた高強度鋼、 更に、 C:0.03〜0.15重量％、 Si:0.05〜0.50重量％、 Mn:0.5〜2.0重量％、 Al:0.005〜0.05重量％、 P:0.010重量％以下、 に加えて、0.03重量％以下のNb、0.1重量％以下のＶ、
1.0重量％以下のNi、1.0重量％以下のCuのうち一種又は
二種以上を含有し、更に加えて0.01重量％以下のTi、0.
02重量％以下の希土類金属のうち一種又は二種以上を含
有し、残部は不可避的不純物を除き実質的にFeから成る
鋼で、且つ0.5mm×0.5mmの面積当りのＰ濃度の板厚方向
の最大値が0.08％以下であることを特徴とする溶接部の
脆性破壊発生特性の優れた高強度鋼、とすることで前述
した問題点を解決した。(Means for Solving Problems) The present invention provides C: 0.03 to 0.15% by weight, Si: 0.05 to 0.50% by weight, Mn: 0.5 to 2.0% by weight, Al: 0.005 to 0.05% by weight, P: 0.010% by weight. % Or less, and the balance is steel consisting essentially of Fe except inevitable impurities, and the maximum value of P concentration in the plate thickness direction per area of 0.5 mm × 0.5 mm is 0.08% or less. High-strength steel with excellent brittle fracture occurrence characteristics of welds, C: 0.03 to 0.15 wt%, Si: 0.05 to 0.50 wt%, Mn: 0.5 to 2.0 wt%, Al: 0.005 to 0.05 wt%, P: 0.010 wt% or less, 0.03 wt% or less Nb, 0.1 wt% or less V,
Contains 1.0% by weight or less of Ni and 1.0% by weight or less of Cu, and one or more of them, and the balance is substantially except inevitable impurities.
A high-strength steel excellent in brittle fracture occurrence characteristics of a weld, which is a steel composed of Fe and has a maximum P concentration in the plate thickness direction of 0.08% or less per area of 0.5 mm × 0.5 mm, C: 0.03 to 0.15% by weight, Si: 0.05 to 0.50% by weight, Mn: 0.5 to 2.0% by weight, Al: 0.005 to 0.05% by weight, P: 0.010% by weight or less, and 0.01% by weight or less of Ti, Steel containing one or more of 0.02% by weight or less of rare earth metals, the balance being steel consisting essentially of Fe, excluding inevitable impurities, and 0.5 mm ×
The maximum value of P concentration per 0.5 mm area in the plate thickness direction is 0.08%
High-strength steel with excellent brittle fracture occurrence characteristics of welds characterized by the following: C: 0.03 to 0.15 wt%, Si: 0.05 to 0.50 wt%, Mn: 0.5 to 2.0 wt%, Al: 0.005 to 0.05 wt%, P: 0.010 wt% or less, 0.03 wt% or less Nb, 0.1 wt% or less V,
1.0% by weight or less of Ni, 1.0% by weight or less of Cu containing one or more kinds, further 0.01% by weight or less of Ti, 0.
02% by weight or less of one or more rare earth metals, with the balance being steel consisting essentially of Fe excluding inevitable impurities, and having a P concentration per area of 0.5 mm × 0.5 mm in the plate thickness direction The above-mentioned problems were solved by using a high-strength steel having excellent brittle fracture occurrence characteristics of welds, which has a maximum value of 0.08% or less.
（作 用） C:C含有量は、石油生産用ジャケット型プラットホーム
等の構造用鋼として必要な強度を得るためには0.03重量
％以上添加する必要がある。一方、溶接硬化性及び溶接
割れ感受性を考慮して、その上限を0.15重量％以下とす
る。(Working) The C: C content must be added at 0.03% by weight or more to obtain the strength required for structural steel such as jacket type platforms for oil production. On the other hand, considering the weld hardenability and the weld crack sensitivity, the upper limit is set to 0.15% by weight or less.
Si:Siは、脱酸の都合上0.05重量％以上必要である。Si
の添加量を増加させれば強度は上昇するが、0.50重量％
を超えると、母材の靱性を劣化させるために上限を0.50
重量％以下とする。Si: Si is required to be 0.05% by weight or more for convenience of deoxidation. Si
The strength increases with the addition of 0.5%, but 0.50% by weight
When it exceeds, the upper limit is 0.50 to deteriorate the toughness of the base metal.
It should be less than or equal to weight%.
Mn:Mnは、母材に延性と強度を与えるために、0.5重量％
以上添加する必要がある。しかし、その添加量が2.0重
量％を超えると、溶接硬化性を著しく上昇させるので、
その上限を2.0重量％とする。Mn: Mn is 0.5% by weight to give ductility and strength to the base metal.
It is necessary to add above. However, if the addition amount exceeds 2.0% by weight, the weld hardenability is remarkably increased.
The upper limit is 2.0% by weight.
Al:Alは、鋼の脱酸のために0.005重量％以上必要である
が、その添加量が0.050重量％を超えると溶接部の靱性
が著しく劣化するので、上限を0.050重量％とする。Al: Al is required to be 0.005% by weight or more for deoxidizing the steel, but if the addition amount exceeds 0.050% by weight, the toughness of the welded portion is significantly deteriorated, so the upper limit is made 0.050% by weight.
P:Pは、結晶粒界に偏析して粒界破壊の原因となると共
に靭性を大幅に劣化させる。また、ICCGHAZ部の島状マ
ルテンサイト量を増加させ、脆性破壊発生特性を大幅に
劣化させるので、Ｐの含有量の上限は0.010重量％とす
る。P: P segregates at the grain boundaries to cause grain boundary fracture and significantly deteriorates toughness. Further, since the amount of island martensite in the ICCGHAZ portion is increased and the brittle fracture initiation property is significantly deteriorated, the upper limit of the P content is 0.010% by weight.
Nb:Nbは、熱間圧延において、未再結晶領域を拡大して
オーステナイト中に変態後のフェライト粒を小さくして
靱性を向上させるばかりでなく、熱間圧延後の加速冷却
において最終組織のベイナイト、マルテンサイト等の低
温変態生成物の量を増加でき強度を大幅に上昇させるこ
とができる。しかし、0.03重量％を超えて添加すると、
割れ性を劣化させると共に溶接部の応力除去焼鈍後の靱
性を劣化させるので、Nbの添加量の上限を0.03重量％と
する。Nb: Nb not only improves the toughness by expanding the unrecrystallized region in hot rolling to reduce ferrite grains after transformation in austenite but also bainite of the final structure in accelerated cooling after hot rolling. The amount of low temperature transformation products such as martensite can be increased, and the strength can be significantly increased. However, if added in excess of 0.03% by weight,
Since the crackability is deteriorated and the toughness of the welded part after stress relief annealing is deteriorated, the upper limit of the amount of Nb added is set to 0.03% by weight.
V:Vは、Nbと同様に強度と靱性を向上させるために添加
するが、0.1重量％を超えると溶接部の応力除去焼鈍後
の靱性を劣化させるので、その上限は1.0重量％とす
る。V: V is added to improve strength and toughness like Nb, but if it exceeds 0.1% by weight, the toughness of the welded part after stress relief annealing is deteriorated, so its upper limit is made 1.0% by weight.
Ni:Niは、溶接熱影響部の硬化性及び靱性に悪い影響を
与えることなく鋼の強度と靱性を向上させることができ
るために添加するが、コスト面よりその上限を1.0重量
％とする。Ni: Ni is added because it can improve the strength and toughness of steel without adversely affecting the hardenability and toughness of the weld heat affected zone, but its upper limit is 1.0% by weight from the viewpoint of cost.
Cu:Cuは、Niと同じ作用効果を奏する他の耐食性を向上
させるが、1.0重量％を超えて添加すると熱間脆性が生
じ易くなるので、その上限を1.0重量％とする。Cu: Cu improves corrosion resistance, which has the same effect as Ni, but if added in an amount exceeding 1.0% by weight, hot brittleness tends to occur, so the upper limit is made 1.0% by weight.
Ti:Tiは、鋼中にTiNとして存在して、溶接熱影響部のオ
ーステナイト粒の成長を抑制する。しかし、その添加量
が0.01重量％を超えると、次パスにより融点付近まで急
熱されるボンド部でTiNが分解して固溶Tiとなった場
合、溶接熱影響部の硬度が上昇しCOD値が劣下する。こ
のため、Tiの添加量の上限は0.01重量％以下とする。Ti: Ti exists as TiN in steel and suppresses the growth of austenite grains in the heat affected zone of welding. However, if the addition amount exceeds 0.01% by weight, if TiN decomposes into solid solution Ti at the bond part that is rapidly heated to near the melting point by the next pass, the hardness of the weld heat affected zone increases and the COD value increases. Be inferior. Therefore, the upper limit of the amount of Ti added is 0.01% by weight or less.
希土類金属（REM）:REMは、鋼中でREM（O,S）として存
在し、このREMの硫化物、酸化物は溶接部のボンド部に
於いても安定しており、TiNと同様にオーステナイト粒
の成長を抑制して、靱性を向上させる。しかし、0.02重
量％を超えて添加すると、鋼の清浄度が低下し、鋼の靱
性が劣下するので、上限を0.02重量％とする。Rare earth metal (REM): REM exists as REM (O, S) in steel, and the sulfides and oxides of this REM are stable even at the bond part of the welded portion, and similar to austenite, TiN. It suppresses grain growth and improves toughness. However, if added in excess of 0.02% by weight, the cleanliness of the steel will deteriorate and the toughness of the steel will deteriorate, so the upper limit is made 0.02% by weight.
次にＰ濃度の最大値を限定した理由について述べる。Next, the reason for limiting the maximum P concentration will be described.
厚肉鋼板の多層溶接部の靱性はICCGHAZの靱性で決ま
り、通常の厚肉鋼板の場合にはICCGHAZで生成した島状
マルテンサイトが分解しない領域が生じるために溶接部
全体の靱性が優れない。その理由としては、局所的にＰ
濃度が高い領域がICCGHAZ部と重なった場合には、島状
マルテンサイトの量および径が大きくなり、また島状マ
ルテンサイトが溶接時の熱により分解しにくくなったた
めである。The toughness of multi-layer welds of thick steel plates is determined by the toughness of ICCGHAZ, and in the case of ordinary thick steel plates, the toughness of the entire weld is not good because the island martensite generated in ICCGHAZ does not decompose. The reason is that P is locally
This is because when the high-concentration region overlaps with the ICCGHAZ portion, the amount and diameter of island martensite increase, and the island martensite becomes difficult to decompose due to heat during welding.
本発明者等はC:0.07重量％、Si:0.13重量％、Mn:1.5重
量％、P:0.002〜0.005重量％、S:0.003重量％、Al:0.02
5重量％、Ti:0.005重量％、N:0.0025重量％の組成成分
で、厚み50mmの供試鋼を第１図に示すようにＫ型開先に
して、第１表に示す溶接条件で多層溶接した。この溶接
継手より、ノッチをボンドに入れたCOD試験片を採取
し、−10℃にて試験を行った。試験後のCOD試験片を第
２図に示すように切断し、斜線をほどこした面につい
て、以下の方法によりＰの分析を行った。これらの供試
鋼の板厚方向に、且つ鋼板全体の全板厚にわたり、Ｘ線
マイクロアナライザーで幅0.5mm、長さ0.5mm、即ち面積
0.25mm2についてＰ濃度を測定した。各供試鋼について
測定したＰ濃度の最大値と、溶接部のノッチがボンドに
入った−10℃におけるCOD値との関係を第３図に示す
が、Ｐ濃度の最大値が0.08％を超えるとCOD値は大幅に
劣化することが同図より判る。このことにより、本発明
では、面積が0.25mm2当りのＰ濃度の最大値を0.08％と
した。なおＰの分析を行った面は、COD試験を行ったボ
ンドから10mmだけ離れているが、この程度の距離であれ
ば、偏析の程度に差が無いことは、判っている。The present inventors have found that C: 0.07% by weight, Si: 0.13% by weight, Mn: 1.5% by weight, P: 0.002-0.005% by weight, S: 0.003% by weight, Al: 0.02%.
5% by weight, Ti: 0.005% by weight, N: 0.0025% by weight, a sample steel with a thickness of 50 mm was made into a K-shaped groove as shown in Fig. 1, and multi-layered under the welding conditions shown in Table 1. Welded. From this welded joint, a COD test piece having a notch in the bond was taken and tested at -10 ° C. After the test, the COD test piece was cut as shown in FIG. 2 and the surface having the diagonal lines was analyzed for P by the following method. With the X-ray microanalyzer, the width of 0.5 mm and the length of 0.5 mm, that is, the area, in the plate thickness direction of these sample steels and over the entire plate thickness of the entire steel plate
The P concentration was measured for 0.25 mm 2 . Fig. 3 shows the relationship between the maximum P concentration measured for each sample steel and the COD value at -10 ° C when the notch of the weld entered the bond. The maximum P concentration exceeds 0.08%. It can be seen from the figure that the COD value deteriorates significantly. Therefore, in the present invention, the maximum value of the P concentration per area of 0.25 mm 2 is 0.08%. The surface on which P was analyzed is separated from the bond subjected to the COD test by 10 mm, but it is known that there is no difference in the degree of segregation at this distance.
本発明の高強度鋼は、通常の製鋼工程を経て、造塊−分
塊又は連続鋳造によりスラブとし、以下の工程を経て板
厚となる。 The high-strength steel of the present invention is made into a slab by an ingot-segmentation or continuous casting through a normal steel-making process, and a plate thickness is obtained through the following steps.
これらのスラブは1250℃以上に加熱した後、1000℃以上
の温度で、、１パス当り10％以上の圧下を施し全体で20
％以上の圧延を施した後、1000℃以上に保持しつつ再度
1250℃以上の温度に10時間以上保持後、空冷して圧延用
素材にする。次いで、この圧延用素材を900℃以上の温
度に加熱し、熱間圧延を施して鋼板とする。After heating these slabs to 1250 ° C or higher, they are rolled down at a temperature of 1000 ° C or higher at a rate of 10% or more per pass for a total of 20%.
% Rolling over, hold again at 1000 ℃ or more,
After keeping at a temperature of 1250 ° C or higher for 10 hours or more, it is air-cooled into a material for rolling. Next, the material for rolling is heated to a temperature of 900 ° C. or higher and hot rolled to obtain a steel plate.
（実施例） 第２表に鋼の組成成分と母材の強度ならびに靱性、Ｐ濃
度の最大値、及び溶接継手のボンドにノッチを入れてCO
Dを調べた結果を示す。(Examples) Table 2 shows the compositional components of steel, the strength and toughness of the base material, the maximum P concentration, and the notch in the bond of the welded joint.
The result of having investigated D is shown.
鋼番号1,2,4,5,8〜11及び17〜20は連続鋳造によりスラ
ブとした。このうち、鋼番号1,2は連続鋳造したスラブ
を圧延用素材とし、鋼番号３は分塊圧延を施しスラブと
し圧延用素材とした。Steel Nos. 1,2,4,5,8-11 and 17-20 were slabs by continuous casting. Among them, Steel Nos. 1 and 2 were continuously cast slabs used as rolling materials, and Steel No. 3 was subjected to slabbing to make slabs and used as rolling materials.
鋼番号4,5,8〜11及び17〜20のスラブは1250℃以上の温
度に加熱後、1000℃以上の温度で１パス当り11％の圧下
率で圧延を施し全体で21％の圧延を施し、1000℃以上の
温度に保持した状態で、再度1280℃〜1320℃の温度に加
熱し、この温度で10〜20時間保持し、空冷して圧延用素
材とした。The slabs with steel numbers 4,5, 8-11 and 17-20 are heated to a temperature of 1250 ° C or higher, and then rolled at a temperature of 1000 ° C or higher at a reduction rate of 11% per pass, for a total of 21% rolling. After being applied and kept at a temperature of 1000 ° C or higher, it was heated again to a temperature of 1280 ° C to 1320 ° C, kept at this temperature for 10 to 20 hours, and air-cooled to obtain a material for rolling.
また、鋼番号6,7及び12〜16は分塊圧延によりスラブと
した後、1280〜1320℃の温度に加熱し、1000℃以上べ１
パス当り11％の圧下率で圧延を施し全体で21％の圧延を
施した後、1000℃以上の温度に保持した状態で再度1280
〜1320℃の温度に加熱し、この温度範囲に10〜20時間保
持し、空冷し圧延用素材とした。Steel Nos. 6, 7 and 12-16 were slabs by slabbing and then heated to a temperature of 1280-1320 ° C and 1000 ° C or higher.
After rolling at a reduction rate of 11% per pass and a total rolling rate of 21%, re-holding at a temperature of 1000 ° C or higher, 1280 again.
It was heated to a temperature of ~ 1320 ° C, kept in this temperature range for 10 to 20 hours, and air-cooled to obtain a material for rolling.
これらの圧延用素材を960〜1050℃の温度に加熱し、740
℃までに熱間圧延を終了し板厚50mmの鋼板とした後、鋼
番１〜17と20は直ちに５℃／秒の冷却速度で480℃まで
加速冷却した；鋼板18,19は５℃／秒の冷却速度で室温
まで加速冷却し、次いで600℃で１時間の熱処理を行っ
た。These rolling materials are heated to a temperature of 960 to 1050 ℃,
After the hot rolling was completed by 50 ° C to make a steel plate with a thickness of 50 mm, steel Nos. 1 to 17 and 20 were immediately accelerated cooled to 480 ° C at a cooling rate of 5 ° C / sec; steel plates 18 and 19 were 5 ° C / After accelerated cooling to room temperature at a cooling rate of 2 seconds, heat treatment was performed at 600 ° C. for 1 hour.
これらの鋼板を第１図に示す開先に加工後、第１表に示
す溶接条件でサブマージアーク溶接した。これらの溶接
継手より、断面が50mm×100mmで、疲労ノッチ位置を第
４図の位置にするCOD試験片を採取した。疲ノッチの導
入及び試験方法はBS5762:1979によった。また、前記各
鋼板のＬ方向から引張試験片を採取し、Ｃ方向からＶノ
ッチシャルピー試験片を各々採取した。These steel sheets were processed into the groove shown in FIG. 1 and then subjected to submerged arc welding under the welding conditions shown in Table 1. From these welded joints, COD test pieces having a cross section of 50 mm × 100 mm and having a fatigue notch position as shown in FIG. 4 were sampled. Introduction of fatigue notch and test method were according to BS5762: 1979. Further, a tensile test piece was taken from the L direction of each of the steel plates, and a V notch Charpy test piece was taken from the C direction.
第２表に、鋼板の強度、靱性及び溶接部の溶融線の−10
℃、−30℃のCOD特性を示す。なお、COD試験は１つの試
験温度につき各３本づつ行った。Table 2 shows the strength, toughness of the steel sheet and -10 of the fusion line of the welded part.
Shows COD characteristics at ℃ and -30 ℃. The COD test was performed three times for each test temperature.
鋼番号１〜３はＰ含有量が本発明の範囲を超えているも
の、或いはＰ含有量が本発明の範囲にあってもＰ濃度の
最大値が高いものであり、いずれも溶接部の溶融線のCO
D特性が劣っていた。 Steel Nos. 1 to 3 have a P content exceeding the range of the present invention, or have a high maximum P concentration even if the P content is within the range of the present invention. Line CO
The D characteristics were inferior.
また、鋼番号４はＰ含有量も低く、Ｐ濃度の最大値も0.
058％と低いために、優れたCOD特性を示した。更に、鋼
番号５はNbを、鋼番号６はCu,Ni,Nbを、鋼番号７はCu,N
i,Vを、鋼番号８はNiを、鋼番号９はTiを、鋼番号10はT
i,REMを、鋼番号11はNb,Tiを、鋼番号12はCu,Ni,Tiを、
鋼番号13はCu,Ni,Tiを、鋼番号14はCu,Ni,V,Tiを、鋼番
号15はCu,Ni,Nb,Ti,REMを、鋼番号16はCu,Ni,Nb,V,Ti,R
EMを、鋼番号17はCuを、鋼番号18はCu,Niを、鋼番号19
はCu,Ni,Nb,Ti,REMを、鋼番号20はＶを本発明で規定す
る範囲内で添加したものである。鋼番号５〜20は、どの
鋼板についてもCOD特性が優れている。また、Cu,Ni,Nb,
Vを添加することにより強度が向上した。Steel No. 4 has a low P content and the maximum P concentration is 0.
Since it was as low as 058%, it showed excellent COD characteristics. Steel No. 5 is Nb, Steel No. 6 is Cu, Ni, Nb, Steel No. 7 is Cu, N.
i, V, Steel number 8 is Ni, Steel number 9 is Ti, Steel number 10 is T
i, REM, steel number 11 is Nb, Ti, steel number 12 is Cu, Ni, Ti,
Steel No. 13 is Cu, Ni, Ti, Steel No. 14 is Cu, Ni, V, Ti, Steel No. 15 is Cu, Ni, Nb, Ti, REM, Steel No. 16 is Cu, Ni, Nb, V , Ti, R
EM, Steel No. 17 is Cu, Steel No. 18 is Cu, Ni, Steel No. 19
Indicates that Cu, Ni, Nb, Ti, and REM have been added, and steel number 20 indicates that V has been added within the range specified in the present invention. Steel Nos. 5 to 20 have excellent COD characteristics for all steel sheets. In addition, Cu, Ni, Nb,
The strength was improved by adding V.
（発明の効果） 以上説明したように本発明鋼は、溶接部のCOD特性が優
れ、溶接部の脆性破壊発生特性が優れた高強度鋼であ
る。(Effects of the Invention) As described above, the steel of the present invention is a high-strength steel having excellent COD characteristics in the welded portion and excellent brittle fracture occurrence characteristics in the welded portion.
第１図は、Ｋ型の開先形状を示す図であり、 第２図は、マクロEPMAによりＰを分析した面を示す図で
あり、 第３図は、0.07％Ｃ−0.31％Si−1.5％Mn−0.002〜0.00
8％Ｐ−0.003％Ｓ−0.025％Al−0.005％Ti−0.0025％Ｎ
鋼のＰ濃度の最大値とCOD値との関係を示す図であり、 第４図は、COD試験片のノッチ位置を示す図である。FIG. 1 is a diagram showing a K-shaped groove shape, FIG. 2 is a diagram showing a surface of P analyzed by macro EPMA, and FIG. 3 is 0.07% C-0.31% Si-1.5. % Mn-0.002 to 0.00
8% P-0.003% S-0.025% Al-0.005% Ti-0.0025% N
It is a figure which shows the relationship between the maximum value of P concentration of steel, and a COD value, and FIG. 4 is a figure which shows the notch position of a COD test piece.
Claims (4)
る鋼で、且つ0.5mm×0.5mmの面積当りのＰ濃度の板厚方
向の最大値が0.08％以下であることを特徴とする溶接部
の脆性破壊発生特性の優れた高強度鋼。1. C: 0.03 to 0.15% by weight, Si: 0.05 to 0.50% by weight, Mn: 0.5 to 2.0% by weight, Al: 0.005 to 0.05% by weight, P: 0.010% by weight or less, and the balance is unavoidable. Characteristic of steel consisting essentially of Fe, excluding static impurities, and having a maximum P concentration in the plate thickness direction per area of 0.5 mm × 0.5 mm of 0.08% or less. Excellent high strength steel.
1.0重量％以下のNi、1.0重量％以下のCuのうち一種又は
二種以上を含み、残部は不可避的不純物を除き実質的に
Feから成る鋼で、且つ0.5mm×0.5mmの面積当りのＰ濃度
の板厚方向の最大値が0.08％以下であることを特徴とす
る溶接部の脆性破壊発生特性の優れた高強度鋼。2. C: 0.03 to 0.15% by weight, Si: 0.05 to 0.50% by weight, Mn: 0.5 to 2.0% by weight, Al: 0.005 to 0.05% by weight, P: 0.010% by weight or less, and 0.03% by weight. % Or less Nb, 0.1% by weight or less V,
Contains 1.0% by weight or less of Ni and 1.0% by weight or less of Cu, and one or more of them, and the balance is substantially except inevitable impurities.
A high-strength steel excellent in brittle fracture occurrence characteristics of a weld, which is a steel made of Fe and has a maximum P concentration in the plate thickness direction of 0.08% or less per area of 0.5 mm × 0.5 mm.
類金属のうち一種又は二種以上を含有し、残部は不可避
的不純物を除き実質的にFeから成る鋼で、且つ0.5mm×
0.5mmの面積当りの板厚方向のＰ濃度の最大値が0.08％
以下であることを特徴とする溶接部の脆性破壊発生特性
の優れた高強度鋼。3. C: 0.03 to 0.15% by weight, Si: 0.05 to 0.50% by weight, Mn: 0.5 to 2.0% by weight, Al: 0.005 to 0.05% by weight, P: 0.010% by weight or less, and 0.01% by weight % Ti, 0.02 wt% or less of one or more kinds of rare earth metals, the balance is steel consisting essentially of Fe except inevitable impurities, and 0.5 mm ×
Maximum P concentration in the plate thickness direction per 0.5 mm area is 0.08%
A high-strength steel excellent in brittle fracture initiation characteristics of welds characterized by the following.
1.0重量％以下のNi、1.0重量％以下のCuのうち一種又は
二種以上を含有し、更に加えて0.01重量％以下のTi、0.
02重量％以下の希土類金属のうち一種又は二種以上を含
有し、残部は不可避的不純物を除き実質的にFeから成る
鋼で、且つ0.5mm×0.5mmの面積当りのＰ濃度の板厚方向
の最大値が0.08％以下であることを特徴とする溶接部の
脆性破壊発生特性の優れた高強度鋼。4. C: 0.03 to 0.15% by weight, Si: 0.05 to 0.50% by weight, Mn: 0.5 to 2.0% by weight, Al: 0.005 to 0.05% by weight, P: 0.010% by weight or less, and 0.03% by weight. % Or less Nb, 0.1% by weight or less V,
1.0% by weight or less of Ni, 1.0% by weight or less of Cu containing one or more kinds, further 0.01% by weight or less of Ti, 0.
02% by weight or less of one or more rare earth metals, with the balance being steel consisting essentially of Fe excluding inevitable impurities, and having a P concentration per area of 0.5 mm × 0.5 mm in the plate thickness direction Is a high strength steel with excellent brittle fracture initiation characteristics of welds, which has a maximum value of 0.08% or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62014287A JPH076034B2 (en) | 1987-01-26 | 1987-01-26 | High-strength steel with excellent brittle fracture initiation characteristics in welds |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62014287A JPH076034B2 (en) | 1987-01-26 | 1987-01-26 | High-strength steel with excellent brittle fracture initiation characteristics in welds |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63183152A JPS63183152A (en) | 1988-07-28 |
| JPH076034B2 true JPH076034B2 (en) | 1995-01-25 |
Family
ID=11856881
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62014287A Expired - Fee Related JPH076034B2 (en) | 1987-01-26 | 1987-01-26 | High-strength steel with excellent brittle fracture initiation characteristics in welds |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH076034B2 (en) |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS57143470A (en) * | 1981-03-02 | 1982-09-04 | Nippon Steel Corp | High tensile steel with high cod value |
| JPS60184663A (en) * | 1984-02-29 | 1985-09-20 | Kawasaki Steel Corp | High-tensile steel for low temperature service for welding with large heat input |
-
1987
- 1987-01-26 JP JP62014287A patent/JPH076034B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63183152A (en) | 1988-07-28 |
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