JPH08283899A - Steel plate reduced in anisotropy and having high toughness and high tensile strength and its production - Google Patents
Steel plate reduced in anisotropy and having high toughness and high tensile strength and its productionInfo
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- JPH08283899A JPH08283899A JP8723095A JP8723095A JPH08283899A JP H08283899 A JPH08283899 A JP H08283899A JP 8723095 A JP8723095 A JP 8723095A JP 8723095 A JP8723095 A JP 8723095A JP H08283899 A JPH08283899 A JP H08283899A
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、靭性が優れた引張強さ
７８０N/mm2 以上級の高張力鋼板及びその製造方法に関
するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength steel sheet having excellent toughness and a tensile strength of 780 N / mm 2 or more, and a method for producing the same.
【０００２】[0002]
【従来の技術】昨今、安全上の視点から原子力発電所建
設が極めて困難になりつつある反面、電力需要は伸びる
一方であり特に夏期ピーク時の消費量は極めて高い。こ
のような情勢の中で火力や水力発電所建設は産業界の急
務であり、特に急激な電力使用量変動の調整用発電に不
可欠な大型揚水発電にかかる期待は大きい。特に、高い
落差のペンストックを有した大型揚水発電の建設は急務
であり、これにともなう高水圧に耐える高張力鋼板も必
要である。2. Description of the Related Art Recently, from the viewpoint of safety, the construction of a nuclear power plant is becoming extremely difficult, but the demand for electric power is increasing and the consumption amount is particularly high at the peak of summer. Under such circumstances, the construction of thermal power plants and hydroelectric power plants is an urgent task of industry, and there is great expectation for large-scale pumped storage power generation, which is indispensable for power generation for adjusting sudden fluctuations in power consumption. In particular, there is an urgent need to construct a large-scale pumped storage power generation with a high pen head stock, and a high-strength steel plate that can withstand the high water pressure that accompanies this is also required.
【０００３】このような用途に供される高張力鋼板の中
で特に多量の需要が期待されるのが直管部等に使用され
る引張強さ７８０N/mm2 以上級の高張力鋼板であるが、
これらは施工メーカーによって冷間で曲げ加工され水圧
鉄管に供される。この際、鋼板に特性の異方性すなわち
圧延方向（Ｌ方向）と圧延方向に対して垂直な方向（Ｃ
方向）での引張および靭性に差があれば、この曲げ加工
によってこれらの差がさらに拡大され、構造物としての
破壊の亀裂進展等に不安定要因をもたらし、安全上大き
な問題となり得る。Among the high-strength steel sheets used for such applications, particularly high demand is expected for high-strength steel sheets having a tensile strength of 780 N / mm 2 or more used for straight pipes and the like. But,
These are cold-bent by the construction manufacturer and used for penstock. At this time, the anisotropy of properties of the steel sheet, that is, the rolling direction (L direction) and the direction perpendicular to the rolling direction (C
If there is a difference in tensile strength and toughness in (direction), these differences will be further magnified by this bending work, leading to instability factors in crack development of fracture as a structure, which can be a major safety issue.
【０００４】そこで、本用途に供される７８０N/mm2 以
上級の高張力鋼板は、機械的特性の異方性が極めて小さ
いものでなければならない。かかる目的に使用される高
張力鋼板の製造方法の公知技術としては、たとえば特開
昭６２−５４０１９号公報に記載されている方法がある
が、圧延の温度域が低温域であるため異方性を生み、上
記要求に合致しない製造方法である。Therefore, the 780 N / mm 2 or higher grade high-strength steel sheet used for this purpose must have extremely small anisotropy in mechanical properties. As a known technique for producing a high-strength steel sheet used for such a purpose, there is a method described in, for example, Japanese Patent Laid-Open No. 62-54019, but since the rolling temperature range is a low temperature range, it is anisotropic. It is a manufacturing method that does not meet the above requirements.
【０００５】[0005]
【発明が解決しようとする課題】本発明は、構造物にお
いて不安定要因を回避する異方性の小さな高靭性高張力
鋼及びその製造方法を提供するものである。本発明は、
このような事情に鑑み考案されたもので、基本的に焼入
れ性に優れた鋼組成を有するスラブの圧延を９３０℃以
上の再結晶温度域で終了し、圧延層状加工組織を完全に
再結晶させて集合組織を極力除去し、且つ左記加工組織
への析出物ＢＮの核生成を抑えることで、焼入れ・焼も
どし後の母材の靭性および引張特性の異方性を僅少にし
ようというものである。DISCLOSURE OF THE INVENTION The present invention provides a high toughness and high strength steel having small anisotropy and avoiding an instability factor in a structure, and a manufacturing method thereof. The present invention
It was devised in view of such circumstances, and basically, rolling of a slab having a steel composition having excellent hardenability is completed in a recrystallization temperature region of 930 ° C. or higher to completely recrystallize the rolled layered work structure. Is used to minimize the anisotropy of the toughness and tensile properties of the base material after quenching and tempering, by removing the texture as much as possible and suppressing the nucleation of precipitates BN in the worked structure. .
【０００６】[0006]
【課題を解決するための手段】本発明の要旨は以下の通
りである。 （１）重量比で、Ｃ：０．０７〜０．１５％、Ｓｉ：
０．０２〜０．５％、Ｍｎ：０．４〜１．５％、Ｃｕ：
０．２％〜０．８％、Ｎｉ：０．８〜３．５％、Ｃｒ：
０．２〜１．０％、Ｍｏ：０．１〜１．０％、Ｖ：０．
０１〜０．１％、Ａｌ：０．０２〜０．１％、Ｂ：０．
０００３〜０．００２％、Ｎ：０．００４％以下、残部
Ｆｅ及び不可避的不純物からなる鋼組成を有し、且つ鋼
板表面に平行な結晶面が（１００）面に平行な加工組織
を有しない異方性の小さな高靭性高張力鋼。The gist of the present invention is as follows. (1) C: 0.07 to 0.15% by weight ratio, Si:
0.02-0.5%, Mn: 0.4-1.5%, Cu:
0.2% to 0.8%, Ni: 0.8 to 3.5%, Cr:
0.2-1.0%, Mo: 0.1-1.0%, V: 0.
01-0.1%, Al: 0.02-0.1%, B: 0.
0003 to 0.002%, N: 0.004% or less, a steel composition having the balance Fe and inevitable impurities, and a crystal plane parallel to the steel plate surface does not have a work structure parallel to the (100) plane. High toughness and high strength steel with small anisotropy.
【０００７】（２）（１）記載の鋼組成に、更に、Ｔ
ｉ：０．００５〜０．０３％、Ｎｂ：０．００３〜０．
０５％の１種または２種を含有せしめた鋼成分からなる
上記（１）記載の異方性の小さな高靭性高張力鋼。 （３）（１）もしくは（２）記載の鋼組成に、更に、Ｃ
ａ：０．００１〜０．０１％を含有せしめた鋼組成から
なる上記（１）記載の異方性の小さな高靭性高張力鋼。 （４）（１）もしくは（３）記載の鋼組成からなるスラ
ブを、１０５０〜１２００℃に加熱し、熱間圧延の仕上
げ圧延において仕上げ最終１パス前温度９３０℃以上で
圧延を行い、冷却後、該鋼板をＡｃ3 点以上に加熱後焼
入れ、続いてＡｃ1 点以下の温度で焼もどしすることを
特徴とする異方性の小さな高靭性高張力鋼板の製造方
法。(2) In addition to the steel composition described in (1), T
i: 0.005 to 0.03%, Nb: 0.003 to 0.
The high-toughness high-strength steel with small anisotropy according to (1) above, which comprises a steel component containing 05% of one or two kinds. (3) In addition to the steel composition described in (1) or (2), C
a: A high toughness high tensile steel with small anisotropy according to the above (1), which has a steel composition containing 0.001 to 0.01%. (4) A slab composed of the steel composition described in (1) or (3) is heated to 1050 to 1200 ° C., and in finishing rolling of hot rolling, rolling is performed at a temperature of 930 ° C. or more before finishing final one pass, and after cooling. A method for producing a high-toughness high-strength steel sheet with small anisotropy, which comprises heating the steel sheet to an Ac 3 point or higher and then quenching it and then tempering it at a temperature of an Ac 1 point or lower.
【０００８】（５）（１）もしくは（３）記載の鋼組成
からなるスラブを、１０５０〜１２００℃に加熱し、熱
間圧延の仕上げ圧延において仕上げ最終１パス前温度９
３０℃以上で圧延を行い、該鋼板を圧延後直ちに水冷
し、その後これをＡｃ1 点以下の温度で焼もどしするこ
とを特徴とする異方性の小さな高靭性高張力鋼板の製造
方法。(5) A slab composed of the steel composition described in (1) or (3) is heated to 1050 to 1200 ° C., and in the finish rolling of hot rolling, the temperature before the final finishing one pass 9
A method for producing a high-strength, high-strength steel sheet with small anisotropy, which comprises rolling at 30 ° C. or higher, cooling the steel sheet with water immediately after rolling, and then tempering it at a temperature of Ac 1 point or lower.
【０００９】[0009]
【作用】本発明鋼板の主たる特徴は、基本的に焼入れ性
に優れた鋼組成を有するスラブを、粗大析出物ＢＮが完
全に溶解する１０５０℃以上、且つオースナイト粒の顕
著な粗大化が起こらない１２００℃以下で加熱し、熱間
圧延の仕上げ最終１パス前温度９３０℃以上の再結晶域
温度で圧延を終了することにより、圧延層状加工組織を
直ちに完全に再結晶させて集合組織を極力除去し、且つ
左記加工組織への析出物ＢＮの核生成を抑え、望ましく
は該鋼板を圧延後直ちに水冷して焼きもどすか、あるい
は圧延放冷後の該鋼板を再加熱焼入れして焼もどしする
ことにより、母材の靭性および引張特性の異方性を僅少
にしようというものである。加工組織については、後述
の製造条件の限定理由とともに詳細に説明する。The main features of the steel sheet of the present invention are that a slab having a steel composition that is basically excellent in hardenability is heated to 1050 ° C. or higher at which coarse precipitates BN are completely dissolved, and austenite grains are significantly coarsened. By heating at less than 1200 ° C and finishing at the recrystallization temperature of 930 ° C or more before the final final pass of hot rolling, the rolling layered work structure is immediately completely recrystallized and the texture is maximized. Remove and suppress the nucleation of precipitates BN in the work structure described on the left, desirably, the steel sheet is water-cooled and tempered immediately after rolling, or the steel sheet after rolling and cooling is reheat-quenched and tempered. Therefore, the anisotropy of the toughness and tensile properties of the base material should be minimized. The processed structure will be described in detail together with the reasons for limiting the manufacturing conditions described below.
【００１０】次に、本発明の鋼組成の限定理由を説明す
る。Ｃは、最低限の焼入れ性確保上０．０７％以上が必
要であるが、０．１５％を越える添加により溶接性が著
しく低下する。よってＣの添加範囲は０．０７〜０．１
５％である。Next, the reasons for limiting the steel composition of the present invention will be explained. C is required to be 0.07% or more to ensure the minimum hardenability, but if added in excess of 0.15%, the weldability will be significantly reduced. Therefore, the addition range of C is 0.07 to 0.1
5%.
【００１１】Ｓｉは、脱酸材および焼入れ性確保の点か
ら重要であり、最低０．０２％を必要とするが、０．５
％を越える添加により母材の靭性と溶接性を低下させ、
且つ溶接継手ボンド部組織を粗くしかつ島状マルテンサ
イト組織を現出させてこの部位の靭性をも著しく低下さ
せる。したがってＳｉの添加範囲は０．０２〜０．５％
とする。Si is important from the viewpoint of securing a deoxidizing material and hardenability, and requires at least 0.02%, but 0.5
% To reduce the toughness and weldability of the base metal,
In addition, the weld joint bond structure is roughened and the island martensite structure is exposed to significantly reduce the toughness of this portion. Therefore, the addition range of Si is 0.02-0.5%
And
【００１２】Ｍｎは、Ｓを固定して熱間加工時の粒界割
れを防止する効果と焼入れ性の点から必須な元素であり
最低０．４％を必要とするが、１．５％を越える添加に
より、溶接性を低下させ且つ熱間加工時の粒界へのＣｕ
偏析を助長する。したがってＭｎの添加範囲は０．４〜
１．５％とする。[0012] Mn is an essential element from the viewpoint of the effect of fixing S to prevent grain boundary cracking during hot working and the hardenability, and requires at least 0.4%, but 1.5% is required. If added over, it deteriorates weldability and Cu to grain boundaries during hot working.
Promote segregation. Therefore, the addition range of Mn is 0.4 to
1.5%.
【００１３】Ｃｕは固溶・析出強化による強度確保上必
要不可欠な元素であり、本発明においては、最低０．２
％を必要とするが、０．８％を越える添加により溶接性
を低下させ且つ熱間加工時の粒界への偏析割れを引き起
こす。したがってＣｕの添加範囲は０．２〜０．８％と
する。Cu is an essential element for securing strength by solid solution / precipitation strengthening. In the present invention, at least 0.2
%, But addition of more than 0.8% deteriorates weldability and causes segregation cracks at grain boundaries during hot working. Therefore, the addition range of Cu is 0.2 to 0.8%.
【００１４】Ｎｉは焼入れ性とマトリックスの靭性確保
上不可欠の重要元素であり、最低０．８％を必要とする
が、３．５％を越える添加により溶接性と熱間加工性を
著しく低下させる。したがって、Ｎｉの添加範囲は０．
８〜３．５％とする。Ni is an important element indispensable for ensuring hardenability and matrix toughness, and requires at least 0.8%, but if it exceeds 3.5%, weldability and hot workability are remarkably reduced. . Therefore, the addition range of Ni is 0.
8 to 3.5%.
【００１５】Ｃｒは焼入れ性確保上重要なの元素であり
最低０．２％を必要とするが、１．０％を越える添加に
より靭性と溶接性を低下させる。したがって、Ｃｒの添
加範囲は０．２〜１．０％とする。Cr is an important element for ensuring the hardenability and needs to be at least 0.2%, but if added in excess of 1.0%, the toughness and weldability deteriorate. Therefore, the Cr addition range is 0.2 to 1.0%.
【００１６】Ｍｏは、析出強化と固溶強化による強化効
果及び焼入れ性確保の点から最低０．１％の添加を必要
とするが、１．０％を越える添加により溶接性と熱間加
工性を著しく低下させる。したがって、Ｍｏの添加範囲
は０．１〜１．０％とする。Mo is required to be added at least 0.1% from the viewpoint of strengthening effect by precipitation strengthening and solid solution strengthening and securing hardenability, but if added over 1.0%, weldability and hot workability are required. Is significantly reduced. Therefore, the Mo addition range is 0.1 to 1.0%.
【００１７】Ｖは、焼入れ性と翼状Ｖ炭窒化物等の炭窒
化物の析出強化による強化効果の点から最低０．０１％
を必要とするが、０．１％を超える添加は母材及び溶接
継手の靭性を著しく低下させ且つ溶接性も低下させる。
したがって、Ｖの添加範囲は０．０１〜０．１％であ
る。V is at least 0.01% from the viewpoint of hardenability and strengthening effect by precipitation strengthening of carbonitrides such as wing-shaped V carbonitride.
However, the addition of more than 0.1% remarkably lowers the toughness of the base material and the welded joint and also lowers the weldability.
Therefore, the addition range of V is 0.01 to 0.1%.
【００１８】Ｎｂは、添加されることによって、炭窒化
物として析出して析出強化及び結晶粒の細粒化に有効で
あるため最低０．００３％を必要とするが、０．０５％
を超えると母材及び溶接継手靭性を低下させる。したが
って、Ｎｂの添加範囲は０．００３〜０．０５％であ
る。When Nb is added, it precipitates as a carbonitride and is effective for precipitation strengthening and grain refinement, so 0.003% is required at a minimum, but 0.05%
If it exceeds 1.0, the toughness of the base material and the welded joint is reduced. Therefore, the Nb addition range is 0.003 to 0.05%.
【００１９】Ａｌは重要な元素である。すなわち脱酸材
として重要であるばかりでなく、圧延中に固溶ＮをＡｌ
Ｎとしてトラップして固溶Ｂのオーステナイト粒界への
偏析を助け焼入れ性を高める効果を併せ持ち、この効果
が０．０２％以上の添加から顕著化する。しかるに０．
１％以上の添加により酸化物系介在物Ａｌ2 Ｏ3 の生を
まねき靭性を著しく低下させる。よって最適範囲は０．
０２〜０．１％とする。Al is an important element. That is, not only is it important as a deoxidizing material, but solid solution N is added to Al during rolling.
It is trapped as N and also has the effect of assisting the segregation of solid solution B to the austenite grain boundaries and enhancing the hardenability, and this effect becomes remarkable from the addition of 0.02% or more. However, 0.
Addition of 1% or more causes the formation of oxide inclusions Al 2 O 3 and significantly reduces the toughness. Therefore, the optimum range is 0.
It is set to 02 to 0.1%.
【００２０】Ｔｉは微細なＴｉＮとして析出してＮをト
ラップすることにより、ＡｌＮの作用と同じく固溶Ｂの
オーステナイト粒界への偏析を助ける効果を持ち最低
０．００５％の添加を必要とするが、０．０３％を超え
るとＴｉＮの粗大化が顕著化し靭性を低下させる。した
がって、Ｔｉの添加範囲は０．００５〜０．０３％であ
る。By depositing Ti as fine TiN and trapping N, Ti has the effect of assisting the segregation of solid solution B to the austenite grain boundaries in the same manner as AlN, and requires addition of at least 0.005%. However, if it exceeds 0.03%, the coarsening of TiN becomes remarkable and the toughness is reduced. Therefore, the addition range of Ti is 0.005 to 0.03%.
【００２１】Ｂは本発明中もっとも重要な役割を果た
す。すなわち、オーステナイト粒界に偏析してフェライ
トの生成を抑制することによって焼入れ性を確保する重
要な元素であり最低０．０００３％の添加を必要とす
る。しかし、０．００２％を超える添加でＢＮの粗大析
出が起こり靭性の著しい低下をまねく。よってその添加
範囲には制限があり、０．０００３〜０．００２％がそ
の範囲である。B plays the most important role in the present invention. That is, it is an important element that secures hardenability by suppressing the formation of ferrite by segregating at the austenite grain boundaries, and it is necessary to add at least 0.0003%. However, addition of more than 0.002% causes coarse precipitation of BN, resulting in a significant decrease in toughness. Therefore, the addition range is limited, and 0.0003 to 0.002% is the range.
【００２２】Ｎは炭窒化物の形成により靭性全般に悪影
響を及ぼすためその含有を０．００５％以下に制限する
必要がある。ＣａはＭｎＳ等の非金属介在物の球状化に
極めて有効であり異方性を小さくするために有効であ
り、この効果のためには０．００１％以上が必要である
が、０．０１％以上の添加は靭性をかえって低下させ
る。よってＣａの添加範囲は０．００１〜０．０１％と
する。Since N has an adverse effect on overall toughness due to the formation of carbonitrides, its content must be limited to 0.005% or less. Ca is extremely effective in spheroidizing non-metallic inclusions such as MnS and is effective in reducing anisotropy, and 0.001% or more is necessary for this effect, but 0.01% The above additions rather reduce toughness. Therefore, the range of addition of Ca is 0.001 to 0.01%.
【００２３】次に、本願発明の主をなす鋼板製造条件に
ついて説明する。本発明の鋼板は、鋼組成と合わせて鋼
板製造条件を特定することによって、加工組織及び析出
物（ＢＮ）の析出状態を制御して始めて得られるもので
ある。Next, the steel plate manufacturing conditions, which are the main features of the present invention, will be described. The steel sheet of the present invention is obtained only by controlling the work structure and the precipitation state of precipitates (BN) by specifying the steel sheet manufacturing conditions together with the steel composition.
【００２４】スラブは、オーステナイト粒界の顕著な粗
大化が起こらない１２００℃以下で、且つスラブに含ま
れる析出物ＢＮを解離させ得る１０５０℃以上で加熱
し、加熱後直ちに圧延し、仕上げ最終１パス前温度が９
３０℃以上で圧延を終了させなければならない。加熱温
度が１２００℃を超えると靭性低下が顕著であり、また
逆に１０５０℃を下回るとＢのオーステナイト粒界偏析
量が減少するため焼入れ性が著しく低下する。The slab is heated at 1200 ° C. or lower at which no significant coarsening of austenite grain boundaries does not occur and at 1050 ° C. or higher at which the precipitate BN contained in the slab can be dissociated, and immediately rolled after heating to finish 1 Pre-pass temperature is 9
The rolling must be completed at 30 ° C or higher. When the heating temperature exceeds 1200 ° C., the toughness is remarkably deteriorated. On the contrary, when the heating temperature is lower than 1050 ° C., the austenite grain boundary segregation amount of B is decreased and the hardenability is remarkably deteriorated.
【００２５】一方、圧延仕上げ１パス前温度が９３０℃
を下回ると鋼板の圧延最終仕上がり温度が部分的もしく
は完全未再結晶状態となり、冷却後も圧延方向に平行な
層状の加工組織が残り、これら加工組織のうち鋼板板面
に平行な結晶面が（１００）面に平行な加工組織は、冷
却後の焼入れ・焼もどしによっても消失せず残る。On the other hand, the temperature before one pass of rolling finish is 930 ° C.
When the temperature falls below the value, the final rolling temperature of the steel sheet becomes a partial or completely unrecrystallized state, and after cooling, a layered work structure parallel to the rolling direction remains, and among these work structures, the crystal plane parallel to the steel plate surface ( The processed structure parallel to the (100) plane does not disappear even after quenching / tempering after cooling and remains.
【００２６】そして、これら加工組織は鋼板の靭性レベ
ルを低下させ且つ靭性値に異方性をもたらす。同様に、
上記加工組織は圧延中もしくは圧延後において析出物Ｂ
Ｎの核生成サイトとなり、これらＢＮはすみやかに粗大
化して靭性レベルの全体的な低下および異方性をもたら
す。These work structures lower the toughness level of the steel sheet and bring anisotropy in the toughness value. Similarly,
The above-mentioned processed structure has a precipitate B during or after rolling.
As nucleation sites for N, these BNs rapidly coarsen, leading to an overall reduction in toughness level and anisotropy.
【００２７】ここで言う異方性は、シャルピー試験片の
長手方向を圧延方向に対し垂直とした場合（Ｃ方向試験
片）、これの衝撃値が、圧延方向に平行な試験片（Ｌ方
向試験片）の衝撃値より低い現象を指す。The anisotropy mentioned here means that when the longitudinal direction of the Charpy test piece is perpendicular to the rolling direction (C direction test piece), the impact value of this is parallel to the rolling direction (L direction test piece). (1) A phenomenon that is lower than the impact value.
【００２８】圧延後、望ましくはＢＮの粗大化をより一
層抑制させる効果を発揮させるため直ちに水冷するか、
あるいは圧延放冷後、Ａｃ3 点以上の温度での再加熱焼
入れを施す。焼入れの目的は析出強化元素のＭｏやＶの
溶体化と組織の緻密化である。After rolling, it is desirable to immediately cool with water to exert the effect of further suppressing coarsening of BN, or
Alternatively, after cooling by rolling, reheating and quenching is performed at a temperature of Ac 3 or higher. The purpose of quenching is to make the precipitation strengthening elements Mo and V into solution and to densify the structure.
【００２９】焼入れ後、焼入れで得られたマルテンサイ
ト組織もしくは下部ベイナイト組織中の格子間Ｃの拡
散、変態転位組織の回復、およびＭｏ、Ｖの析出物生成
による析出強化を目的としてＡｃ1 点以下の温度で焼き
もどすことが必要である。After quenching, Ac 1 point or less for the purpose of diffusion of interstitial C in the martensite structure or lower bainite structure obtained by quenching, recovery of transformation dislocation structure, and precipitation strengthening by formation of Mo and V precipitates. It is necessary to temper at the temperature of.
【００３０】[0030]
［実施例１］表１に示す成分範囲の鋼を溶製後、以下の
製造方法いずれかで供試鋼板を製造した。 製造方法Ａ：スラブを１１５０℃で加熱して熱間圧延を
行ない、９５０℃で圧延を仕上げ５０mm厚鋼板とし、直
ちに水冷した。水冷後、６３０℃の温度で焼もどしを施
して供試鋼板とした。[Example 1] After steel having a composition range shown in Table 1 was melted, a test steel plate was manufactured by any of the following manufacturing methods. Manufacturing method A: A slab was heated at 1150 ° C. to perform hot rolling, the rolling was finished at 950 ° C. to a 50 mm thick steel plate, and immediately water-cooled. After cooling with water, tempering was performed at a temperature of 630 ° C. to obtain a test steel plate.
【００３１】製造方法Ｂ：スラブを１１２０℃で加熱し
て熱間圧延を行ない、９４０℃で圧延を仕上げ５０mm厚
鋼板とし、放冷した。冷却完了後、該鋼板を９１０℃に
再加熱して水焼入れした後、６２０℃の温度で焼もどし
を施して供試鋼板とした。Manufacturing method B: The slab was heated at 1120 ° C. to carry out hot rolling, and the rolling was finished at 940 ° C. into a steel plate having a thickness of 50 mm, and the plate was allowed to cool. After completion of cooling, the steel sheet was reheated to 910 ° C., water-quenched, and then tempered at a temperature of 620 ° C. to obtain a test steel sheet.
【００３２】[0032]
【表１】 [Table 1]
【００３３】[0033]
【表２】 [Table 2]
【００３４】[0034]
【表３】 [Table 3]
【００３５】[0035]
【表４】 [Table 4]
【００３６】製造したそれぞれの鋼板の鋼板板厚１／４
の部位のＬ方向およびＣ方向の降伏強さ、引張強さ、−
４０℃での衝撃吸収エネルギー（vE-40 ）の成績を同表
中に示す。なお、引張試験はＪＩＳ Ｚ ２２０１ ４
号試験片を用い、ＪＩＳ Ｚ２２０４に準拠して行なっ
た。また衝撃試験は、ＪＩＳ Ｚ ２２０２ ４号試験
片を用い、ＪＩＳ Ｚ ２２４２に準拠して行なった。
また、鋼板板面法線方向はＸ線で測定し、この方向が
（１００）面法線方向に対して±５°以内にあればこの
面を（１００）面と見なした。Steel plate thickness of each manufactured steel plate 1/4
Y-direction and C-direction yield strength, tensile strength,
The results of impact absorption energy (vE-40) at 40 ° C are shown in the same table. The tensile test is conducted according to JIS Z 22014.
No. test piece was used in accordance with JIS Z2204. The impact test was performed according to JIS Z 2242 using a JIS Z 2204 No. 4 test piece.
Further, the normal direction of the steel plate surface was measured by X-ray, and if this direction was within ± 5 ° with respect to the (100) surface normal direction, this surface was regarded as the (100) surface.
【００３７】表１に示す鋼のうちNo．１〜No. １７は本
発明実施例であり、No. １２〜No.３３は本発明の範囲
外の比較例である。比較例鋼No. １８は、Ｃが本発明の
下限を下回るため強度・靭性が低い。比較例No. １９及
びNo. ２１は、それぞれＳｉ及びＭｎが本発明の下限を
下回るため強度・靭性が低い。比較例No. ２０及びNo.
２２は、それぞれＳｉ及びＭｎが本発明の上限を上回る
ため靭性が低い。Among the steels shown in Table 1, No. Nos. 1 to 17 are Examples of the present invention, and Nos. 12 to 33 are Comparative Examples outside the scope of the present invention. Comparative Steel No. 18 has a low strength and toughness because C is below the lower limit of the present invention. Comparative Examples No. 19 and No. 21 have low strength and toughness because Si and Mn are below the lower limits of the present invention, respectively. Comparative Examples No. 20 and No.
No. 22 has low toughness because Si and Mn respectively exceed the upper limits of the present invention.
【００３８】比較例No. ２３は、Ｃｕが本発明の下限を
下回るため強度が低い。比較例No.２４は、Ｃｕが本発
明の上限を上回るため強度・靭性が低い。比較例No. ２
５は、Ｎｉが本発明の下限を下回るため強度・靭性が低
い。比較例No. ２６は、Ｃｒが本発明の下限を下回るた
め強度・靭性が低く、No. ２８はＭｏが下限を下回るた
め強度・靭性が低い。No. ２７は、Ｃｒが本発明の上限
を上回るため靭性が低い。比較例No. ２９は、Ｖが本発
明の下限を下回って添加されているため強度が低く、N
o. ３０は、Ｖが上限を上回るため靭性が低い。Comparative Example No. 23 has a low strength because Cu is below the lower limit of the present invention. Comparative Example No. 24 has low strength and toughness because Cu exceeds the upper limit of the present invention. Comparative example No. 2
In No. 5, since Ni is below the lower limit of the present invention, the strength and toughness are low. Comparative Example No. 26 has low strength and toughness because Cr is below the lower limit of the present invention, and No. 28 has low strength and toughness because Mo is below the lower limit. No. 27 has low toughness because Cr exceeds the upper limit of the present invention. Comparative Example No. 29 has a low strength because V is added below the lower limit of the present invention, and N
O. 30 has a low toughness because V exceeds the upper limit.
【００３９】比較例No. ３１は、Ｎｂが上限を上回るた
め靭性が低い。比較例No. ３２は、Ａｌが本発明の下限
を下回るため強度・靭性が低く、No. ３３は上限を上回
るため靭性が低い。比較例No. ３４は、Ｔｉが本発明の
上限を上回るため靭性が低い。比較例No. ３５は、Ｂが
本発明の下限を下回るため強度・靭性が低く、No. ３６
は上限を上回るため靭性が低いうえ異方性も強い。Comparative Example No. 31 has a low toughness because Nb exceeds the upper limit. Comparative Example No. 32 has a low strength and toughness because Al is below the lower limit of the present invention, and No. 33 has a low toughness because it exceeds the upper limit. Comparative Example No. 34 has low toughness because Ti exceeds the upper limit of the present invention. In Comparative Example No. 35, since B is below the lower limit of the present invention, the strength and toughness are low, and No. 36
Is less than the upper limit, the toughness is low and the anisotropy is strong.
【００４０】比較例No. ３７は、Ｎが本発明の上限を上
回って添加されているため靭性が低い。比較例No. ３８
は、Ｃａが本発明の上限を上回って添加されているため
靭性が低い。これらに対し、本発明実施例No. １〜No.
１７は、鋼板全般にわたって強度と靭性のバランスが申
し分ない特性を示す。Comparative Example No. 37 has a low toughness because N is added in an amount exceeding the upper limit of the present invention. Comparative Example No. 38
Has low toughness because Ca is added in an amount exceeding the upper limit of the present invention. On the other hand, the invention examples No. 1 to No.
No. 17 shows a property in which the balance between strength and toughness is satisfactory over the entire steel sheet.
【００４１】［実施例２］表２に示す本発明範囲内の成
分系の鋼を溶製後、表３で示すような製造条件で４８mm
厚の供試鋼板とし、それぞれの鋼板板厚１／４の部位の
Ｌ方向およびＣ方向の降伏強さ、引張強さ、−４０℃で
の衝撃吸収エネルギー（vE-40 ）の成績を同表中に示
す。[Example 2] 48 mm under the manufacturing conditions as shown in Table 3 after smelting the steel of the component system within the scope of the present invention shown in Table 2
The thickness of the test steel sheet is the same, and the results of yield strength, tensile strength, and impact absorbed energy (vE-40) at -40 ° C in the L direction and C direction of each 1/4 thickness plate are shown in the table. Shown inside.
【００４２】[0042]
【表５】 [Table 5]
【００４３】[0043]
【表６】 [Table 6]
【００４４】なお、引張試験はＪＩＳ Ｚ ２２０１
４号試験片を用い、ＪＩＳ Ｚ ２２０４に準拠して行
なった。また衝撃試験は、ＪＩＳ Ｚ ２２０２ ４号
試験片を用い、ＪＩＳ Ｚ ２２４２に準拠して行なっ
た。また、鋼板板面法線方向はＸ線で測定し、この方向
が（１００）面法線方向に対して±５°以内にあればこ
の面を（１００）面と見なした。The tensile test is conducted according to JIS Z 2201.
The test was performed according to JIS Z 2204 using a No. 4 test piece. The impact test was performed according to JIS Z 2242 using a JIS Z 2204 No. 4 test piece. Further, the normal direction of the steel plate surface was measured by X-ray, and if this direction was within ± 5 ° with respect to the (100) surface normal direction, this surface was regarded as the (100) surface.
【００４５】表３に示す供試鋼のうち、Ａ〜Ｃは本発明
の例であり、Ｄ〜Ｉは熱処理が異なる比較例である。比
較例Ｄ及びＥは、加熱温度が本発明の下限を下回るのた
め強度・靭性が低く、Ｆ及びＧは上限を上回るため靭性
が低い。比較例Ｈ〜Ｉは、仕上げ１パス前温度が本発明
の下限を下回るため板面方位が（１００）面に平行なた
め靭性が低く且つ異方性も大きい。これらに対し、本発
明実施例Ａ〜Ｃは強度、靭性すべてが申し分ない特性を
示す。Among the test steels shown in Table 3, A to C are examples of the present invention, and D to I are comparative examples having different heat treatments. In Comparative Examples D and E, since the heating temperature is below the lower limit of the present invention, strength / toughness is low, and F and G are above the upper limit, so toughness is low. In Comparative Examples HI, the temperature before the first pass of finishing is lower than the lower limit of the present invention, and the plate orientation is parallel to the (100) plane, so the toughness is low and the anisotropy is large. On the other hand, Examples A to C of the present invention exhibit satisfactory characteristics in terms of strength and toughness.
【００４６】[0046]
【発明の効果】本発明により、引張強さ７８０N/mm2 以
上の異方性の小さな高靭性高張力鋼板の提供が可能とな
り産業界に与える効果は極めて大きいと言える。EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a high toughness and high strength steel sheet having a small anisotropy and a tensile strength of 780 N / mm 2 or more, and it can be said that the effect on the industrial world is extremely large.
Claims (5)
からなる鋼組成を有し、且つ鋼板表面に平行な結晶面が
（１００）面に平行な加工組織を有しない異方性の小さ
な高靭性高張力鋼。1. By weight ratio, C: 0.07 to 0.15%, Si: 0.02 to 0.5%, Mn: 0.4 to 1.5%, Cu: 0.2% to 0. 0.8%, Ni: 0.8 to 3.5%, Cr: 0.2 to 1.0%, Mo: 0.1 to 1.0%, V: 0.01 to 0.1%, Al: 0.02 to 0.1%, B: 0.0003 to 0.002%, N: 0.005% or less, a steel composition having the balance Fe and unavoidable impurities, and a crystal plane parallel to the steel plate surface Highly tough, high-strength steel with small anisotropy having no work structure parallel to the (100) plane.
有せしめた鋼成分からなる請求鋼１記載の異方性の小さ
な高靭性高張力鋼。2. A steel composition in which the steel composition according to claim 1 further contains one or two of Ti: 0.005 to 0.03% and Nb: 0.003 to 0.05%. A high-toughness, high-strength steel with small anisotropy according to claim 1.
に、 Ｃａ：０．００１〜０．０１％を含有せしめた鋼組成か
らなる請求項１記載の異方性の小さな高靭性高張力鋼。3. The steel composition according to claim 1 or 2, further comprising a steel composition containing Ca: 0.001 to 0.01%. steel.
るスラブを、１０５０〜１２００℃に加熱し、熱間圧延
の仕上げ圧延において仕上げ最終１パス前温度９３０℃
以上で圧延を行い、冷却後、該鋼板をＡｃ3 点以上に加
熱後焼入れ、続いてＡｃ1 点以下の温度で焼もどしする
ことを特徴とする異方性の小さな高靭性高張力鋼板の製
造方法。4. A slab comprising the steel composition according to claim 1 or 3 is heated to 1050 to 1200 ° C., and in final rolling of hot rolling, a temperature before final finishing one pass 930 ° C.
Rolling is performed as described above, after cooling, the steel sheet is heated to an Ac 3 point or more, then quenched, and subsequently tempered at a temperature of an Ac 1 point or less, and a high-toughness high-tensile steel sheet with small anisotropy is produced. Method.
るスラブを、１０５０〜１２００℃に加熱し、熱間圧延
の仕上げ圧延において仕上げ最終１パス前温度９３０℃
以上で圧延を行い、該鋼板を圧延後直ちに水冷し、その
後これをＡｃ1 点以下の温度で焼もどしすることを特徴
とする異方性の小さな高靭性高張力鋼板の製造方法。5. A slab comprising the steel composition according to claim 1 or 3 is heated to 1050 to 1200 ° C., and in finish rolling of hot rolling, a temperature before final finishing one pass 930 ° C.
A method for producing a high-toughness high-strength steel sheet with small anisotropy, which comprises rolling as described above, water-cooling the steel sheet immediately after rolling, and then tempering the steel sheet at a temperature of Ac 1 point or lower.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8723095A JPH08283899A (en) | 1995-04-12 | 1995-04-12 | Steel plate reduced in anisotropy and having high toughness and high tensile strength and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8723095A JPH08283899A (en) | 1995-04-12 | 1995-04-12 | Steel plate reduced in anisotropy and having high toughness and high tensile strength and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH08283899A true JPH08283899A (en) | 1996-10-29 |
Family
ID=13909065
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8723095A Withdrawn JPH08283899A (en) | 1995-04-12 | 1995-04-12 | Steel plate reduced in anisotropy and having high toughness and high tensile strength and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH08283899A (en) |
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| CN103874777A (en) * | 2011-10-03 | 2014-06-18 | 杰富意钢铁株式会社 | High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same |
| JPWO2013051231A1 (en) * | 2011-10-03 | 2015-03-30 | 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 |
| EP2765210A4 (en) * | 2011-10-03 | 2015-06-24 | Jfe Steel Corp | High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same |
| US9945015B2 (en) | 2011-10-03 | 2018-04-17 | Jfe Steel Corporation | High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same |
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