JP3255004B2 - High strength steel material for welding excellent in toughness and arrestability and method for producing the same - Google Patents
High strength steel material for welding excellent in toughness and arrestability and method for producing the sameInfo
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- JP3255004B2 JP3255004B2 JP07275696A JP7275696A JP3255004B2 JP 3255004 B2 JP3255004 B2 JP 3255004B2 JP 07275696 A JP07275696 A JP 07275696A JP 7275696 A JP7275696 A JP 7275696A JP 3255004 B2 JP3255004 B2 JP 3255004B2
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- arrestability
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Description
【０００１】[0001]
【発明の属する技術分野】本発明は、直接焼入れ焼戻し
処理による例えば厚鋼板などの高張力鋼材およびその製
造方法に係り、特に溶接性と靱性さらにはアレスト性に
優れた780 N/mm2以上の引張強さを有する高張力鋼材お
よびその製造方法に関する。The present invention relates to relates to a process for producing a high tensile steel and its, eg steel plate by direct quenching and tempering process, particularly weldability and toughness more 780 N / mm 2 or more having excellent arrestability your high-tensile steel material has a tensile strength of
Yobiso process for the preparation of.
【０００２】[0002]
【従来の技術】ペンストック・圧力容器などの大型化に
伴い省資材、運搬・施工コスト削減の観点から鋼材には
一層の高強度化が求められており、引張強さ950 N/mm2
級の高張力鋼板がペンストック分野に適用された例もあ
る。[Prior Art] With the increase in size of penstocks and pressure vessels, steel materials are required to have higher strength from the viewpoint of saving resources and reducing transportation and construction costs, and have a tensile strength of 950 N / mm 2
In some cases, high-grade high-strength steel sheets have been applied to the penstock field.
【０００３】これまで、この種類の高張力鋼材の製造に
あたっては熱間圧延後の再加熱、そして焼入れ・焼戻し
処理が適用されてきたが、厚肉材の中心部の強度・靱性
を保証するために添加合金元素を多くせざるを得なかっ
た。そのため、焼入れ時、冷却速度の大きい表層部近傍
では過剰焼入れとなり靱性が低下するほか、溶接性の低
下により予熱温度を高くして溶接する必要があった。Hitherto, reheating after hot rolling, and quenching and tempering have been applied in the production of this type of high-strength steel material. However, in order to guarantee the strength and toughness of the central part of a thick material. It was necessary to increase the number of additional alloy elements. For this reason, during quenching, excessive quenching occurs near the surface layer where the cooling rate is high, resulting in a decrease in toughness, and a decrease in weldability necessitates welding at a higher preheating temperature.
【０００４】この問題に対し、近年、熱間圧延後直ちに
焼入れを行い、その後焼戻しを行う方法が開発され、再
加熱分のコストが低減できるというメリットも生まれる
ことから、いくつかの提案がなされた。In order to solve this problem, in recent years, a method has been developed in which quenching is performed immediately after hot rolling and then tempering is performed, and there is also an advantage that the cost for reheating can be reduced. .
【０００５】例えば、特公平６−70248 号公報の開示す
る方法は、焼入れの直前に軽圧下圧延を行い、特に表層
部の変形帯確保による過剰焼入れ防止を狙ったもので、
継手部の衝撃特性確保のため、Tiフリーを特徴としてい
る。しかしながら、安定的に所望の高強度を得ることは
困難である。[0005] For example, the method disclosed in Japanese Patent Publication No. 6-70248 is to perform light reduction rolling immediately before quenching, and particularly to prevent excessive quenching by securing a deformation zone in the surface layer.
Features Ti-free to ensure the impact characteristics of the joint. However, it is difficult to stably obtain a desired high strength.
【０００６】また、特公昭62−196326号公報は、Ti添加
によりＢの焼入れ性向上に寄与する働きを活用し、低温
域の圧下により表層部の靱性を向上させる方法を開示し
ているが、この方法によりペンストックなどのアレスト
性が要求される分野へ適用するためには多量のNiが必要
であり、経済的観点より実際的とは言い難い。ここに、
「アレスト性」とは、脆性亀裂伝播特性である。Japanese Patent Publication No. Sho 62-196326 discloses a method for improving the toughness of the surface layer by reducing the temperature in a low temperature range by utilizing the function of contributing to the improvement of the hardenability of B by adding Ti. This method requires a large amount of Ni to be applied to fields where arrestability is required, such as penstock, and is not practical from an economic viewpoint. here,
"Arrestability" is a brittle crack propagation characteristic.
【０００７】[0007]
【発明が解決しようとする課題】従来技術である特公平
６−70248 号公報の開示する方法は、AlによるＮの固定
がTiに比べ確実でないことから、焼入れ性向上に寄与す
る有効Ｂ量が確保できないという問題があり、また、特
公昭62−196326号公報の開示する方法は、特にNbに関す
る規定がなく、変形帯維持による微細化効果が期待でき
ないことから、多量のNi添加は必須となり、実用性の点
で問題である。According to the method disclosed in Japanese Patent Publication No. 6-70248, which is a conventional technique, the amount of effective B contributing to the improvement of hardenability is reduced because the fixing of N by Al is not as secure as that of Ti. There is a problem that it cannot be secured, and the method disclosed in Japanese Patent Publication No. Sho 62-196326 does not particularly have a provision regarding Nb, and since a refinement effect by maintaining a deformation zone cannot be expected, a large amount of Ni addition is indispensable. This is problematic in terms of practicality.
【０００８】かくして、本発明の目的は、直接焼入れ焼
戻し処理による経済的な鋼材製造に当たり、高強度・高
靱性に加えて、優れた溶接性およびアレスト性を具備し
た高張力鋼材およびその製造方法を提供することであ
る。[0008] Thus, an object of the present invention, per the economical steel production by direct quenching and tempering process, in addition to high strength, high toughness, good high-tensile steel and its manufacturing method provided with the weldability and arrestability It is to provide.
【０００９】より具体的には、本発明の目的は、TS:780
N/mm2以上、Ｃeq：0.42以上、Ｐcm：0.30以下を満足す
る溶接性、靱性およびアレスト性に優れた高強度の高張
力鋼材およびその経済的な製造方法を提供することであ
る。More specifically, an object of the present invention is to provide a TS: 780
N / mm 2 or more, Ceq: 0.42 or more, Pcm: weldability satisfying 0.30 or less, is to provide an economical process for producing a high tensile steel and its excellent high strength toughness and arrestability.
【００１０】[0010]
【課題を解決するための手段】本発明者らは、上記課題
を解決するために種々検討を重ねた結果、下記のように
Ｎを0.005 ％以下に制限するとともにTiの添加によりＮ
の確実な固定を図り、これによりＢの作用効果を確保す
るとともにNbを添加して回復・再結晶の遅延を図るとい
う鋼組成と、特定の圧延条件および熱処理条件とを組み
合わせることにより、直接焼入れ法によっても所望の特
性を安定して得ることができることを見い出し、本発明
を完成した。The present inventors have conducted various studies to solve the above-mentioned problems, and as a result, as described below, N is limited to 0.005% or less and N is added by adding Ti.
Direct quenching by combining the steel composition, which ensures the effect of B, thereby securing the effect of B and delays recovery and recrystallization by adding Nb, and specific rolling conditions and heat treatment conditions It has been found that desired characteristics can be stably obtained by the method, and the present invention has been completed.
【００１１】ここに、本発明の要旨は、重量％で、Ｃ：
0.06〜0.16％、Si：0.50％以下、望ましくは0.15％以
下、Mn：0.60〜1.50％、Cr：0.05〜1.20％、Mo：0.05〜
1.00％、Ｖ：0.005 〜0.10％、Nb：0.005 〜0.03％、so
l.Al：0.01〜0.10％、Ti：0.005 〜0.03％、Ｎ：≦0.00
5 ％、Ｂ：0.0005〜0.0025％、さらに所望によりCu：0.
05〜1.00％、Ni：0.05〜3.00％、Zr：0.01〜0.15％の１
種または２種以上、および／またはCa：0.001 〜0.008
％、残部Feおよび不可避的不純物から成る組成を有する
鋼を950 〜1150℃に加熱、均熱後900 ℃以下の温度範囲
で累積圧下率が50％以上の熱間圧延を施し、引き続き70
0 ℃以上の温度から直接焼入れし、その後、Ac1 点以下
の温度で焼戻すことを特徴とする靱性およびアレスト性
の優れた溶接用高張力鋼材の製造方法である。Here, the gist of the present invention is that C:
0.06-0.16%, Si: 0.50% or less, desirably 0.15% or less, Mn: 0.60-1.50%, Cr: 0.05-1.20%, Mo: 0.05-
1.00%, V: 0.005 to 0.10%, Nb: 0.005 to 0.03%, so
l. Al: 0.01 to 0.10%, Ti: 0.005 to 0.03%, N: ≦ 0.00
5%, B: 0.0005-0.0025%, and optionally Cu: 0.
05 to 1.00%, Ni: 0.05 to 3.00%, Zr: 0.01 to 0.15%
Species or two or more species and / or Ca: 0.001 to 0.008
%, The balance of Fe and the unavoidable impurities is heated to 950-1150 ° C, and after soaking, hot rolling is performed at a temperature range of 900 ° C or less and a cumulative draft of 50% or more.
A method for producing a high-strength steel material for welding having excellent toughness and arrestability , characterized by directly quenching at a temperature of 0 ° C. or higher and then tempering at a temperature of 1 point or less of Ac.
【００１２】このように本発明によれば、特に、有効
Ｂ量を確保するため、Alに較べ格段にＮの固定能の高い
TiとＮの規定を行うこと、そして所定量の有効Ｂ量を
確保することによる焼入れ性確保が達成され、アレスト
性の優れた組織を板厚中心まで確保できること、そし
て、Nbによる変形帯維持効果による破面単位の微細化
効果が図られるのである。特に本発明によれば、例えば
ペンストック用の板厚25〜100 mmという厚板の高張力鋼
材が安価に得られるのであり、その実用上の意義は大き
い。別の観点からは、本発明は、重量％で、 Ｃ：0.06〜
0.16％、Si：0.50％以下、望ましくは0.15％以下、 Mn：
0.60〜1.50％、Cr：0.05〜1.20％、Mo：0.05〜1.00％、
Ｖ：0.005 〜0.10％、Nb：0.005 〜0.03％、sol.Al：0.
01〜0.10％、 Ti：0.005 〜0.03％、Ｎ：≦0.005 ％、
Ｂ：0.0005〜0.0025％、 さらに所望により Cu：0.05〜1.
00％、Ni：0.05〜3.00％、Zr：0.01〜0.15％の１種また
は２種以 上、 および／またはCa：0.001 〜0.008 ％、 残
部Feおよび不可避的不純物から成る組成を有する鋼を、
950 〜1150℃に加熱、均熱後900 ℃以下の温度範囲で累
積圧下率が50％以上の熱間圧延を施し、引き続き700 ℃
以上の温度から直接焼入れし、その後、Ac 1 点以下の温
度で焼戻すことによって、得られる靱性およびアレスト
性の優れた溶接用高張力鋼材である。 As described above, according to the present invention, in particular, in order to secure an effective B amount, the fixing ability of N is much higher than that of Al.
Ensuring the hardenability by specifying Ti and N, and securing a predetermined amount of effective B, ensuring a structure with excellent arrestability up to the center of the sheet thickness, and the effect of Nb to maintain the deformation zone Thus, the effect of miniaturization of each fracture surface can be achieved. In particular, according to the present invention, a high-strength steel material having a plate thickness of, for example, 25 to 100 mm for pen stock can be obtained at low cost, and its practical significance is great. In another aspect, the present invention provides a method for preparing a composition , comprising :
0.16%, Si: 0.50% or less, desirably 0.15% or less, Mn:
0.60-1.50%, Cr: 0.05-1.20%, Mo: 0.05-1.00%,
V: 0.005 to 0.10%, Nb: 0.005 to 0.03%, sol.
01 to 0.10%, Ti: 0.005 to 0.03%, N: ≦ 0.005%,
B: 0.0005 to 0.0025%, and optionally Cu: 0.05 to 1.
00%, Ni: 0.05 ~ 3.00%, Zr: 0.01 ~ 0.15%
On two or more kinds, and / or Ca: 0.001 to 0.008%, the remaining
Steel having a composition consisting of part Fe and unavoidable impurities,
Heat to 950 to 1150 ° C.
Hot rolling with a rolling reduction of 50% or more, followed by 700 ° C
Quenching directly from the above temperature, then the temperature below Ac 1 point
Toughness and arrest obtained by tempering
High strength steel for welding with excellent resistance.
【００１３】[0013]
【発明の実施の形態】以下、本発明をその作用効果とと
もに詳述する。なお、本明細書において特に断りがない
限り「％」は「重量％」を表すものとする。まず、本発
明において上述のように鋼組成を限定した理由について
説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail together with its operation and effects. In this specification, “%” means “% by weight” unless otherwise specified. First, the reason why the steel composition is limited in the present invention as described above will be described.
【００１４】Ｃ：Ｃは0.06％未満であると強度が不足す
るため、0.06％以上とし、また0.16％を超えると靱性・
溶接性を損ねるため、0.16％以下と制限した。C: If C is less than 0.06%, the strength is insufficient. Therefore, C is set to 0.06% or more.
In order to impair the weldability, it was limited to 0.16% or less.
【００１５】Si：Siは焼入性向上による強度確保のため
に添加するが、0.50％を超えると島状マルテンサイトの
生成を促すことによって、鋼材の靱性を著しく低下させ
るために0.50％以下とする。ただし、望ましくは0.15％
以下である。Si: Si is added to secure strength by improving hardenability, but if it exceeds 0.50%, the formation of island-like martensite is promoted, so that the toughness of the steel material is significantly reduced. I do. However, preferably 0.15%
It is as follows.
【００１６】Mn：Mnは焼入れ性と強度・靱性をともに確
保するために0.60％以上添加する必要があるが、1.50％
を超えて多量に添加すると溶接性の確保が困難になるほ
か、著しく靱性・等方性を損ねるMnＳの生成を助長し高
張力鋼として不適となる。そこで、Mn添加量を0.60％以
上、1.50％以下と制限する。Mn: Mn must be added in an amount of 0.60% or more in order to secure both hardenability and strength / toughness.
If it is added in a large amount exceeding 0.1%, it becomes difficult to secure the weldability, and the generation of MnS, which significantly impairs the toughness and isotropy, is promoted and becomes unsuitable as a high-tensile steel. Therefore, the amount of Mn added is limited to 0.60% or more and 1.50% or less.
【００１７】Cr：Crは0.05％以上の添加により焼入れ性
を高める働きを発揮するため、強度・靱性の向上に有効
であるが、1.2 ％を超えると靱性を著しく劣化させるの
で、0.05％以上1.20％以下と制限する。Cr: Cr exerts the function of enhancing the hardenability by adding 0.05% or more, and is effective in improving the strength and toughness. However, when it exceeds 1.2%, the toughness is remarkably deteriorated. %.
【００１８】Mo：Moは0.05％以上の添加により強度の向
上に有効であるが、1.0 ％を超えて添加すると靱性を損
なうため0.05％以上1.0 ％以下と限定する。Mo: Mo is effective in improving strength by adding 0.05% or more, but if added in excess of 1.0%, the toughness is impaired, so the content is limited to 0.05% or more and 1.0% or less.
【００１９】Nb：Nbは特に本発明において重要な元素で
ある。Nbはスラブ加熱時に結晶粒粗大化を抑制するほ
か、焼戻し時に粒内にNb(C,N) として析出し、降伏強度
向上に寄与する働きを有する。さらに、本発明において
特に強調すべき効果はNbによる回復・再結晶遅滞効果で
ある。Nb: Nb is an important element particularly in the present invention. Nb not only suppresses crystal grain coarsening during slab heating, but also precipitates as Nb (C, N) in the grains during tempering and contributes to improving yield strength. Further, an effect to be particularly emphasized in the present invention is a recovery / recrystallization delay effect by Nb.
【００２０】このような効果は500 N/mm2 クラスのα組
織主体の低強度鋼ではこれまで盛んに利用されてきた。
本発明においてはこれをベイナイト−マルテンサイト主
体の高強度鋼へも適用を拡大したものである。しかし、
従来のNb添加による効果は、フェライト・パーライト組
織を前提に考えられていたのであるが、本発明の場合に
はこのような前例がないため、Nb添加の効果は予測でき
なかったが、本発明のように直接焼入れプロセス利用で
あれば、ベイナイト−マルテンサイト主体の高強度鋼に
あっても同様のNb添加による回復・再結晶遅滞効果が達
成されることが分かった。Such an effect has been actively used in low-strength steel mainly composed of α-structure of 500 N / mm 2 class.
In the present invention, this is applied to bainite-martensite-based high-strength steel. But,
The effect of the conventional Nb addition was considered on the premise of a ferrite-pearlite structure, but in the case of the present invention, there is no such precedent, and the effect of the Nb addition could not be predicted. It was found that the same recovery / recrystallization delay effect by the addition of Nb can be achieved even in a high-strength steel mainly composed of bainite-martensite if the direct quenching process is used.
【００２１】ところで、仕上げ圧延終了後、焼入れによ
って微細なパケットサイズを有する組織にするためには
圧延によって導入された変形帯の維持が不可欠である。
しかしながら、実生産ライン上では圧延機から水冷装置
への移動時間が少なからず存在し、かかる間に変形帯が
回復によって解消してしまうほか、再結晶によりさらに
圧延による粒微細化効果を解消する場合もある。By the way, after finishing rolling, it is essential to maintain the deformed zone introduced by rolling in order to obtain a structure having a fine packet size by quenching.
However, on the actual production line, there is a considerable amount of time to move from the rolling mill to the water cooling device, and during this time, the deformed zone is eliminated by recovery, and the grain refinement effect by rolling is further eliminated by recrystallization. There is also.
【００２２】この課題に対して、Nbは回復・再結晶遅滞
効果を発揮し、圧延により導入した変形帯の焼入れまで
の維持に対して有用な元素である。また、Nbは0.005 ％
未満ではその効果があらわれず、0.03％超では継手靱性
を著しく損なう結果となる。したがって、0.005 ％以上
0.03％以下と限定した。[0022] In response to this problem, Nb is an element that exhibits a recovery / recrystallization delay effect and is useful for maintaining the deformed zone introduced by rolling up to quenching. Also, Nb is 0.005%
If it is less than 0.03%, the effect is not exhibited, and if it exceeds 0.03%, the toughness of the joint is significantly impaired. Therefore, 0.005% or more
Limited to 0.03% or less.
【００２３】sol.Al：sol.Alは、γ粒の微細化に寄与す
る元素として有効であり0.01％以上の添加によりその有
効性を発揮し、0.10％を超えると靱性の低下をもたら
す。Sol.Al: sol.Al is effective as an element contributing to the refinement of γ grains, and exhibits its effectiveness when added in an amount of 0.01% or more, and causes a decrease in toughness when it exceeds 0.10%.
【００２４】Ti：Tiはγ粒の微細化、固溶Ｎの固定によ
る有効Ｂ量確保のために不可欠な元素であってかかる効
果を発揮させるためには0.005 ％以上の添加が必要とな
るが、0.03％を超えて添加すると靱性の低下を招くた
め、0.005 ％以上0.03％以下と限定した。Ti: Ti is an element indispensable for refining γ grains and securing an effective B amount by fixing solid solution N. To exert such an effect, it is necessary to add 0.005% or more. , More than 0.03% leads to a decrease in toughness, so the content is limited to 0.005% or more and 0.03% or less.
【００２５】Ｎ：ＮはAlＮ、TiＮの生成によって初期γ
粒の粗大化抑制に寄与するが、0.005 ％を超えて添加す
ると固溶Ｎが増大し靱性が劣化する。よって、0.005 ％
以下と限定した。N: N is initially γ due to the formation of AlN and TiN.
It contributes to the suppression of coarsening of grains, but if it is added in excess of 0.005%, solute N increases and toughness deteriorates. Therefore, 0.005%
Limited to the following.
【００２６】Ｂ：Ｂは本発明において微量の添加で焼入
れ性を著しく向上させるため、極めて重要な元素であ
り、0.0005％以上の添加が必要であるが、0.0025％を超
えて添加すると靱性が著しく劣化するため、Ｂの添加量
は0.0005％以上0.0025％以下と限定した。B: In the present invention, B is a very important element in order to remarkably improve the hardenability by adding a very small amount, and it is necessary to add B in an amount of 0.0005% or more. Due to deterioration, the amount of B added is limited to 0.0005% or more and 0.0025% or less.
【００２７】Cu：Cuは任意添加元素であり、0.05％以上
の添加により強度上昇のために有効な元素であるが、1.
0 ％超添加するとスケール発生により鋼材の表面性状を
著しく劣化させる。したがって、それを添加する場合に
は0.05％以上1.0 ％以下と制限する。Cu: Cu is an optional additive element, and is an element effective for increasing the strength by adding 0.05% or more.
If added in excess of 0%, the surface properties of the steel material are significantly deteriorated due to scale formation. Therefore, when it is added, it is limited to 0.05% or more and 1.0% or less.
【００２８】Ni：Niも任意添加元素であるが、強度・靱
性を向上させるために有効な元素であり、0.05％以上添
加しないと靱性の向上は認められず、多量に添加すると
コストの上昇を招くため、添加する場合、3.0 ％以下に
制限する。Ni: Ni is also an optional additive element, but is an effective element for improving strength and toughness. No improvement in toughness is observed unless 0.05% or more is added, and the cost increases when added in a large amount. If added, limit the content to 3.0% or less.
【００２９】Zr：Zrは析出によって鋼の強度向上に寄与
するが、含有量が0.01％に満たなければ所望の効果が得
られず、0.15％を超えると靱性を劣化させることから、
Zrの添加量は0.01％以上0.15％以下と限定した。Zr: Zr contributes to the improvement of the strength of steel by precipitation. However, if the content is less than 0.01%, the desired effect cannot be obtained, and if it exceeds 0.15%, the toughness is deteriorated.
The amount of Zr added was limited to 0.01% or more and 0.15% or less.
【００３０】Ca：Caも任意添加元素であって、Ca添加に
は、硫化物系非金属介在物の形態を制御することによ
り、亀裂進展抵抗を高めることができ、結果的に靱性向
上に寄与する作用がある。0.001 ％未満であるとその効
果は少なく、0.008 ％を超えると非金属介在物の量が増
加し、これらの性能が損なわれる傾向が現れるようにな
ることから、その含有量は0.001 ％以上0.008 ％以下と
規定した。このようにして構成される本発明にかかる鋼
組成は、溶接性確保の観点からは、その好適態様にあっ
ては、Ｃeq：0.42以上、Ｐcm：0.30以下に制限される。Ca: Ca is also an optional additive element. In addition of Ca, by controlling the form of the sulfide-based nonmetallic inclusion, the crack propagation resistance can be increased, and as a result, the toughness is improved. Has the effect of doing. If the content is less than 0.001%, the effect is small, and if it exceeds 0.008%, the amount of nonmetallic inclusions increases, and the performance tends to be impaired. Therefore, the content is 0.001% or more and 0.008% or more. It is specified as follows. The steel composition according to the present invention thus configured is limited to Ceq: 0.42 or more and Pcm: 0.30 or less from a viewpoint of securing weldability in a preferred embodiment.
【００３１】さらに本発明によれば、以上の組成を有す
る鋼から連続鋳造法または鋼塊法により得られたスラブ
に対して、以下のような(1) ないし(3) の各工程から成
る加工熱処理を経て溶接用高張力鋼材が製造されるので
ある。Further, according to the present invention, a slab obtained by continuous casting or ingot casting from steel having the above composition is processed by the following steps (1) to (3). High-strength steel for welding is manufactured through heat treatment.
【００３２】(1) 950 〜1150℃に加熱、均熱 (2) 900 ℃以下の温度範囲で累積圧下率が50％以上の熱
間圧延により所望の厚みまで減厚し、 (3) 700 ℃以上の温度から直接焼入れし、そして (4) その後、Ac1 点以下の温度で焼戻す。(1) Heating to 950 to 1150 ° C and soaking. (2) Reduced to a desired thickness by hot rolling with a cumulative draft of 50% or more in a temperature range of 900 ° C or less. (3) 700 ° C Quenching directly from the above temperature, and (4) then tempering at a temperature below Ac 1 point.
【００３３】まず、以上の制御圧延方法について以下に
詳述するが、鋼塊の加熱温度は微量に添加したNbを十分
固溶させてNbの種々の効果を得る必要があるため、950
℃以上の高温であることが望ましい。しかし、1150℃を
超えるとγ粒の粗大化が顕著となり、靱性の低下につな
がる。さらに、粗粒に起因する圧延異方性の増大を招く
ことから、加熱温度は950 ℃以上1150℃以下と限定す
る。First, the above-mentioned controlled rolling method will be described in detail below. The heating temperature of the steel ingot is 950 because it is necessary to sufficiently dissolve a small amount of added Nb to obtain various effects of Nb.
It is desirable that the temperature be higher than or equal to ° C. However, when the temperature exceeds 1150 ° C., the coarsening of γ grains becomes remarkable, leading to a decrease in toughness. Further, the heating temperature is limited to 950 ° C. or higher and 1150 ° C. or lower, because the rolling anisotropy is increased due to coarse grains.
【００３４】次に、圧下の温度範囲に関する規定である
が、900 ℃を超えた温度域での圧下によって生成された
変形帯はNb添加の成分系であっても圧下直後に回復によ
って解消されることから、変形帯によるγ→マルテンサ
イトあるいはベイナイト変態時のパケットサイズまでへ
の微細化を論じる場合の圧下に関する温度範囲は900℃
以下とした。Next, as to the temperature range of the reduction, the deformation zone generated by the reduction in the temperature range exceeding 900 ° C. is eliminated by the recovery immediately after the reduction even in the Nb-added component system. Therefore, the temperature range for the reduction when discussing the miniaturization to the packet size at the time of transformation from γ to martensite or bainite by the deformation zone is 900 ° C.
It was as follows.
【００３５】また、かかる温度域での累積圧下率が50％
未満では破面単位微細化効果が有効に発揮されない。し
たがって、累積圧下率は50％以上と限定した。好ましく
は、70％以上である。Further, the cumulative rolling reduction in such a temperature range is 50%.
If it is less than 1, the effect of unitizing the fracture surface is not effectively exhibited. Therefore, the cumulative rolling reduction is limited to 50% or more. Preferably, it is at least 70%.
【００３６】ここに、図１は、後述の実施例における例
No.1と同じ鋼組成の鋼材にその例の加工熱処理を基本と
して900 ℃以下の温度域での累積圧下率を変えたときの
Ｖノッチシャルピー遷移温度をグラフにまとめたもので
あり、かかる温度域での累積圧下率が50％未満では破面
単位微細化効果が有効に発揮されないことが分かる。FIG. 1 shows an example in an embodiment to be described later.
This graph summarizes the V-notch Charpy transition temperature when the cumulative rolling reduction in a temperature range of 900 ° C or less is changed for a steel material with the same steel composition as No. 1 based on the thermomechanical heat treatment of that example. It can be seen that if the cumulative rolling reduction in the region is less than 50%, the effect of unitizing the fracture surface cannot be effectively exhibited.
【００３７】次に、焼入れ温度は焼入れ性を確保するた
めに高温から焼入れを行うことが望ましい。また、700
℃未満からの水冷では焼入れ性が確保されず、強度不足
になることから焼入れ温度は700 ℃以上とした。そして
最後に焼戻し処理を行うが、焼戻し処理は従来通りの方
法に基づけばよく、γ化を防ぐため、Ac1 点以下の適当
な温度にて焼戻しすればよい。Next, the quenching temperature is desirably quenched from a high temperature in order to secure the quenchability. Also, 700
Water hardening at a temperature lower than ℃ does not ensure quenching properties and results in insufficient strength, so the quenching temperature was set to 700 ° C or higher. Finally, a tempering treatment is performed. The tempering treatment may be based on a conventional method, and may be performed at an appropriate temperature of 1 point or less of Ac in order to prevent γ conversion.
【００３８】以上詳述してきた本発明にかかる方法によ
り、低温靱性およびアレスト性に優れた本発明にかかる
高張力鋼材を確実に得ることができる。さらに、本発明
を実施例を用いて詳述するが、これは本発明の例示であ
ってこれにより本発明が不当に制限されるものではな
い。By the method according to the present invention described in detail above, a high-tensile steel material according to the present invention excellent in low-temperature toughness and arrestability can be reliably obtained. Further, the present invention will be described in detail with reference to Examples, which are illustrative of the present invention and do not unduly limit the present invention.
【００３９】[0039]
【実施例】表１に示す組成を有する鋼塊を表２に示す条
件にて制御圧延を行って板厚が50mmの試料No.1〜12を得
た。EXAMPLES Ingots having the composition shown in Table 1 were subjected to controlled rolling under the conditions shown in Table 2 to obtain Sample Nos. 1 to 12 having a thickness of 50 mm.
【００４０】これらの試料について、引張試験を行って
降伏点・引張強さを測定するとともにシャルピー衝撃試
験を行ってその遷移温度を測定した。また、高圧負荷箇
所への適用の際に不可欠な脆性破壊伝播停止性能を調査
するために温度勾配型ESSO試験を行った。それらの試験
も表２中に示す。The samples were subjected to a tensile test to measure the yield point and the tensile strength, and to a Charpy impact test to measure the transition temperature. In addition, a temperature gradient type ESSO test was performed to investigate the brittle fracture propagation arrest performance indispensable for application to high pressure load locations. The tests are also shown in Table 2.
【００４１】試料No.1〜９はHT950 を狙って製造したも
のであるが、Nb非添加の試料No.5、Ti非添加の試料No.
7、Ｂ非添加の試料No.8、Ｎ上限外れの試料No.9はいず
れも適正な制御圧延を施しているにも拘わらず、強度が
目標を下回っているほかアレスト性も劣位を示してい
る。Samples Nos. 1 to 9 were manufactured with the aim of HT950. Sample No. 5 containing no Nb and Sample No. 5 containing no Ti were used.
7, Sample No. 8 with no B added and Sample No. 9 out of the upper limit of N show that the strength is below the target and the arrestability is also inferior, despite the proper controlled rolling. I have.
【００４２】また、化学成分の適合している試料No.4に
おいても焼入れ温度規定外れ(4-b)、加熱温度規定外れ
(4-c) 、900 ℃以下の累積圧下率未達(4-d) のものは、
いずれも強度・アレスト性ともに劣位を示している。In addition, the quenching temperature is out of the specified range (4-b) and the heating temperature is out of the specified range even in sample No. 4 in which the chemical components are compatible.
(4-c) and those with a cumulative reduction of 900 ° C or less (4-d)
In both cases, both strength and arrestability are inferior.
【００４３】試料No.10 〜12はHT780 を狙って製造した
ものであるが、Nb非添加の試料No.11 、Ti非添加の試料
No.12 はいずれも適正な制御圧延を施しても強度が目標
を下回っているほかアレスト性も劣位を示している。ま
た、化学成分の適合している試料No.10 においても焼入
れ温度外れ(10-b)、加熱温度外れ(10-c)は、いずれも強
度・アレスト性ともに劣位を示している。Samples Nos. 10 to 12 were manufactured with the aim of HT780. Sample No. 11 containing no Nb and Sample No.
In No.12, the strength was below the target and the arrestability was inferior even when the appropriate controlled rolling was performed. In addition, in Sample No. 10 in which the chemical components are compatible, the quenching temperature deviation (10-b) and the heating temperature deviation (10-c) all show inferior in both strength and arrestability.
【００４４】[0044]
【表１】 [Table 1]
【００４５】[0045]
【表２】 [Table 2]
【００４６】[0046]
【発明の効果】近年、高張力化・厚肉化の要求が年々増
大しているペンストック用鋼板あるいは圧力容器用鋼板
などの大型構造物に使用することができる、靱性および
アレスト性に優れた溶接用高張力鋼板およびその製造法
を提供する本発明の意義は著しい。Recently, according to the present invention, can be used in large structures, such as high tensile reduction and thickness penstock steel plate or pressure vessel steel plate demand for thickening is increasing year by year, toughness and
Significance of the present invention to provide a method of producing high strength steel sheet for excellent welding arrestability and its is remarkable.
【図１】900 ℃以下の温度での累積圧下率とＶノッチシ
ャルピー遷移温度との関係を示すグラフである。FIG. 1 is a graph showing the relationship between the cumulative rolling reduction at a temperature of 900 ° C. or less and the V-notch Charpy transition temperature.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 占部 健 茨城県鹿嶋市大字光３番地 住友金属工 業株式会社鹿島製鉄所内 (56)参考文献 特開 平４−293718（ＪＰ，Ａ) 特開 平３−232923（ＪＰ，Ａ) 特公 平６−17507（ＪＰ，Ｂ２) (58)調査した分野(Int.Cl.7，ＤＢ名) C21D 8/00 - 8/10 C22C 38/00 - 38/60 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Ken Urabe 3 Kaji-shi, Kashima-shi, Ibaraki Sumitomo Metal Industries, Ltd. Kashima Works (56) References JP-A-4-293718 (JP, A) JP Hei 3 232923 (JP, A) JP 6-17507 (JP, B2) (58) Fields investigated (Int. Cl. 7 , DB name) C21D 8/00-8/10 C22C 38/00-38 / 60
Claims (6)
〜1.50％、 Cr：0.05〜1.20％、 Mo：0.05〜1.00％、 Ｖ：0.00
5 〜0.10％、 Nb：0.005 〜0.03％、 sol.Al：0.01〜0.10％、 Ti：0.005 〜0.03％、 Ｎ：0.005 ％以下、 Ｂ：0.00
05〜0.0025％、 残部Feおよび不可避的不純物から成る組成を有する鋼を
950 〜1150℃に加熱、均熱後900 ℃以下の温度範囲で累
積圧下率が50％以上の熱間圧延を施し、引き続き700 ℃
以上の温度から直接焼入れし、その後、Ac1 点以下の温
度で焼戻すことを特徴とする靱性およびアレスト性の優
れた溶接用高張力鋼材の製造方法。C .: 0.06 to 0.16%, Si: 0.50% or less, Mn: 0.60% by weight
~ 1.50%, Cr: 0.05 ~ 1.20%, Mo: 0.05 ~ 1.00%, V: 0.00
5 to 0.10%, Nb: 0.005 to 0.03%, sol.Al: 0.01 to 0.10%, Ti: 0.005 to 0.03%, N: 0.005% or less, B: 0.00
Steel with a composition of 05-0.0025%, balance Fe and unavoidable impurities
Heated to 950-1150 ℃, soaked and then hot-rolled with a cumulative draft of 50% or more in the temperature range of 900 ℃ or less, then 700 ℃
A method for producing a high-strength steel material for welding having excellent toughness and arrestability, characterized by quenching directly from the above temperature and then tempering at a temperature of 1 point or less of Ac.
特徴とする請求項１記載の靱性およびアレスト性の優れ
た溶接用高張力鋼材の製造方法。2. The steel according to claim 2, further comprising one or more of Cu: 0.05 to 1.00%, Ni: 0.05 to 3.00%, and Zr: 0.01 to 0.15% by weight. A method for producing a high-tensile steel material for welding according to claim 1 having excellent toughness and arrestability.
1 〜0.008 ％を含有する請求項１または２記載の靱性お
よびアレスト性の優れた溶接用高張力鋼材の製造方法。3. The steel according to claim 1, further comprising:
The method for producing a high tensile strength steel material for welding according to claim 1 or 2, which contains 1 to 0.008%.
50％以下、Mn：0.60〜1.50％、Cr：0.05〜1.20％、Mo：
0.05〜1.00％、Ｖ：0.005 〜0.10％、Nb：0.005 〜0.03
％、sol.Al：0.01〜0.10％、Ti：0.005 〜0.03％、Ｎ：
0.005 ％以下、Ｂ：0.0005〜0.0025％、残部Feおよび不
可避的不純物から成る鋼組成を有する鋼を、950 〜1150
℃に加熱、均熱後900 ℃以下の温度範囲で累積圧下率が
50％以上の熱間圧延を施し、引き続き700 ℃以上の温度
から直接焼入れし、その後、Ac1 点以下の温度で焼戻す
ことによって、得られる靱性およびアレスト性の優れた
溶接用高張力鋼材。4. C .: 0.06 to 0.16% by weight, Si: 0.
50% or less, Mn: 0.60 to 1.50%, Cr: 0.05 to 1.20%, Mo:
0.05 to 1.00%, V: 0.005 to 0.10%, Nb: 0.005 to 0.03
%, Sol. Al: 0.01 to 0.10%, Ti: 0.005 to 0.03%, N:
Steel having a steel composition of 0.005% or less, B: 0.0005 to 0.0025%, balance Fe and unavoidable impurities, 950 to 1150%
℃, after soaking, the cumulative rolling reduction in the temperature range below 900 ℃
A high-tensile steel material for welding with excellent toughness and arrestability obtained by subjecting it to hot rolling of 50% or more, quenching directly from a temperature of 700 ° C or more, and then tempering at a temperature of 1 point or less of Ac.
特徴とする請求項４記載の靱性およびアレスト性の優れ
た溶接用高張力鋼材。5. The steel according to claim 1, further comprising one or more of Cu: 0.05 to 1.00%, Ni: 0.05 to 3.00%, and Zr: 0.01 to 0.15% by weight%. The high tensile strength steel material for welding according to claim 4, which has excellent toughness and arrestability.
001 〜0.008 ％を含有する請求項４または５記載の靱性
およびアレスト性の優れた溶接用高張力鋼材。6. The steel according to claim 1, further comprising, by weight%, Ca: 0.
The high tensile strength steel material for welding according to claim 4 or 5, which contains 001 to 0.008%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07275696A JP3255004B2 (en) | 1996-03-27 | 1996-03-27 | High strength steel material for welding excellent in toughness and arrestability and method for producing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07275696A JP3255004B2 (en) | 1996-03-27 | 1996-03-27 | High strength steel material for welding excellent in toughness and arrestability and method for producing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH09263828A JPH09263828A (en) | 1997-10-07 |
| JP3255004B2 true JP3255004B2 (en) | 2002-02-12 |
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ID=13498527
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| JP07275696A Expired - Fee Related JP3255004B2 (en) | 1996-03-27 | 1996-03-27 | High strength steel material for welding excellent in toughness and arrestability and method for producing the same |
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| JP4604917B2 (en) * | 2005-08-30 | 2011-01-05 | Ｊｆｅスチール株式会社 | 780 MPa class high strength steel sheet and method for producing the same |
| JP4358898B1 (en) | 2008-04-01 | 2009-11-04 | 新日本製鐵株式会社 | Method for producing high-tensile thick steel plate having a tensile strength of 780 MPa or more, excellent in weldability and joint low-temperature toughness |
| JP4551492B2 (en) | 2008-10-23 | 2010-09-29 | 新日本製鐵株式会社 | High-tensile steel plate having a tensile strength of 780 MPa or more with excellent weldability and a method for producing the same |
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| Publication number | Publication date |
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