JPH05125481A - High tensile strength steel material having high toughness and low yield ratio and its production - Google Patents
High tensile strength steel material having high toughness and low yield ratio and its productionInfo
- Publication number
- JPH05125481A JPH05125481A JP28801391A JP28801391A JPH05125481A JP H05125481 A JPH05125481 A JP H05125481A JP 28801391 A JP28801391 A JP 28801391A JP 28801391 A JP28801391 A JP 28801391A JP H05125481 A JPH05125481 A JP H05125481A
- Authority
- JP
- Japan
- Prior art keywords
- steel
- yield ratio
- strength
- steel material
- quenching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Heat Treatment Of Steel (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、土木・建築分野等にお
ける構造物の安全性確保のために要望されている高靱性
低降伏比高張力厚鋼材とその製造方法に関し、詳しくは
構造物の塑性変形能および耐破壊性能を向上させた、建
築用低降伏比高張力鋼材とその製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-toughness low-yield ratio high-strength thick steel material and a method for producing the same, which are demanded for ensuring the safety of structures in the fields of civil engineering and construction. TECHNICAL FIELD The present invention relates to a low yield ratio high tensile steel material for construction, which has improved plastic deformability and fracture resistance, and a manufacturing method thereof.
【０００２】[0002]
【従来の技術】一般に土木・建築用としてはJIS G 3106
級の鋼材が多く用いられてきたが、近年、特に建築用の
分野では鋼構造物が大型化および高層化する傾向が見ら
れ、強度、施工性の点ばかりでなく、耐震性をも考慮し
た材料設計が求められてるようになってきている。その
ため靱性に富む低降伏比高張力鋼板が要求されるように
なってきている。大地震の際の鋼構造物の全面崩壊を防
ぐため、降伏後の変形時の鋼材の吸収エネルギーを増加
させるのであって、具体的には鋼材の塑性変形能を向上
させる、つまり補歪エネルギーを増加させるのである。[Prior Art] Generally JIS G 3106 for civil engineering and construction
Many grades of steel have been used, but in recent years, especially in the field of construction, there is a tendency for steel structures to increase in size and height, and in consideration of not only strength and workability but also earthquake resistance. Material design is being demanded. Therefore, low yield ratio and high tensile strength steel sheets with high toughness have been demanded. In order to prevent the total collapse of the steel structure in the event of a large earthquake, the absorbed energy of the steel material at the time of deformation after yielding is increased.Specifically, the plastic deformability of the steel material is improved, that is, the complementary strain energy is increased. Increase it.
【０００３】一般に引張強さが40 kgf/mm2級の軟鋼で
は、その降伏比の値が約60〜70％程度と低いのに対し、
鋼の引張強さを増大させるにつれて降伏比は高くなる傾
向にある。例えば、近年使用量の増加しつつある引張強
さ90 kgf/mm2以上の高張力鋼は、焼入れ−焼戻しによる
製造方法で得た鋼材は、焼戻しベイナイト単相組織から
なり、その降伏比の値が95％以上と高くなるため、建造
物の設計上の要注意事項とされている。In general, mild steel having a tensile strength of 40 kgf / mm 2 has a low yield ratio of about 60 to 70%, while
The yield ratio tends to increase as the tensile strength of steel increases. For example, high-strength steel with a tensile strength of 90 kgf / mm 2 or more, which has been increasing in use in recent years, is a steel material obtained by a manufacturing method by quenching-tempering, which consists of a tempered bainite single-phase structure, and the value of its yield ratio. Is higher than 95%, so it is considered to be a cautionary note in the design of buildings.
【０００４】そこで近年、焼入れ−焼戻しによる製造に
代わり、焼き入れ→２相域焼入れ→焼戻し処理( 以下、
Q −L −T 処理という、Quench−Lamellartizing Quenc
h −Temper) により、従来のベイナイト単相組織からフ
ェライト＋ベイナイト＋マルテンサイト３相組織とし、
軟質のフェライト相を生成させ、低降伏比化をはかる製
造方法が提案されている。 (“低降伏比80キロ級高張力
鋼およびその溶接部の基本特性”溶接学会論文集、３−
３、1985)等。Therefore, in recent years, instead of manufacturing by quenching-tempering, quenching → two-phase region quenching → tempering treatment (hereinafter
Quench-Lamellartizing Quenc called Q-L-T processing
h-Temper) to change from the conventional bainite single phase structure to ferrite + bainite + martensite 3 phase structure,
A manufacturing method has been proposed in which a soft ferrite phase is generated to reduce the yield ratio. (“Basic Properties of 80 kg Class High Yield Steel with Low Yield Ratio and Its Welds”, Welding Society Papers, 3-
3, 1985) etc.
【０００５】しかしながら、かかる方法によれば低降伏
比化は達成されるものの、応力−歪曲線形状はラウンド
型となり補歪エネルギーは小さく、降伏後の塑性変形能
が十分でないため改善の余地がある。However, although a low yield ratio can be achieved by such a method, the stress-strain curve has a round shape, the complementary strain energy is small, and the plastic deformability after yield is insufficient, so there is room for improvement. ..
【０００６】特開昭64−52023 号公報にはQ −L −T 処
理による低降伏比高張力鋼板の製造方法が開示されてい
るが、これはもっぱらNb添加効果を利用するものであっ
て、CrおよびMo配合例にあっても、V と同様に強度確保
のために添加しているにすぎない。特開平３−115524号
公報にも、Nb含有低降伏比高張力鋼板の製造方法が開示
されているが、この場合にはMoの添加例が明らかにされ
ることがない。Japanese Unexamined Patent Publication (Kokai) No. 64-52023 discloses a method for producing a high yield steel sheet having a low yield ratio by a Q-L-T treatment, which exclusively utilizes the Nb addition effect. Even in the Cr and Mo compounding examples, just like V, they are added only to secure the strength. Japanese Unexamined Patent Publication No. 3-115524 also discloses a method for producing a Nb-containing high-strength steel sheet with a low yield ratio, but in this case, an example of adding Mo is not disclosed.
【０００７】[0007]
【発明が解決しようとする課題】ところで、図２は応力
−歪曲線形状と補歪エネルギーの模式図であり、鋼材の
塑性変形能は、図２中斜線部Ａに示される補歪エネルギ
ーＡの大小によって表わされ、大きい方が望ましい。そ
のためには、低降伏比はもちろんのこと、明確な降伏棚
を形成させることが必須条件である。降伏後の吸収エネ
ルギーを大きくする必要があるからである。図２におい
てＢ部分が降伏棚を表している。By the way, FIG. 2 is a schematic diagram of the stress-strain curve shape and the complementary strain energy, and the plastic deformability of the steel material corresponds to the complementary strain energy A shown in the shaded area A in FIG. Represented by size, larger is preferred. For that purpose, it is indispensable to form not only a low yield ratio but also a clear yield shelf. This is because it is necessary to increase the absorbed energy after yielding. In FIG. 2, the portion B represents the yielding shelf.
【０００８】従来の鋼をＱ−Ｌ−Ｔ処理した場合、焼戻
し温度を低くすることにより低ＹＲ化はたやすくでき
る。しかし、降伏棚の形成のためには焼戻し温度を高く
する必要があり、低ＹＲ化と降伏棚の形成との両立は困
難であった。ここに、本発明の目的は、低ＹＲ化と降伏
棚の形成とを両立させ、かつ、溶接施工が可能である高
靱性低降伏比高張力鋼材とその安定した製造方法を提供
することである。When the conventional steel is subjected to the QLT treatment, it is easy to reduce the YR by lowering the tempering temperature. However, it is necessary to raise the tempering temperature in order to form a yield shelf, and it has been difficult to achieve both low YR and formation of a yield shelf. An object of the present invention is to provide a high-toughness low-yield-ratio high-strength steel material capable of achieving both low YR and formation of a yielding shelf and performing welding, and a stable manufacturing method thereof. ..
【０００９】本発明のより具体的な目的は、引張強さ90
kgf/mm2以上、降伏強さ70 kgf/mm2以上、降伏比85％以
下の特性を有する建築用として特に適する高靱性低降伏
比高張力鋼材とその製造方法を提供することである。A more specific object of the present invention is tensile strength 90
It is to provide a high-toughness low-yield ratio high-strength steel material particularly suitable for construction, which has characteristics of kgf / mm 2 or more, yield strength of 70 kgf / mm 2 or more, and yield ratio of 85% or less, and a manufacturing method thereof.
【００１０】[0010]
【課題を解決するための手段】本発明者は、かかる目的
を達成すべく検討の結果、化学成分と熱処理条件を限定
することに着目し、Ｃ、Cr、Mo、Nb、V 、B などの多数
の合金元素を配合することによって焼入性上昇によって
強度を確保するとともに、Cr/Mo に比を0.4 〜1.0 とす
ることで、450 〜550 ℃という低温焼戻しが可能とな
り、予想外にも低ＹＲ化と降伏棚の形成とを両立させ得
ることを知り、本発明を完成した。Means for Solving the Problems As a result of study to achieve such an object, the present inventor has focused on limiting chemical components and heat treatment conditions, and has found that C, Cr, Mo, Nb, V, B, etc. By blending many alloying elements, the strength can be secured by increasing the hardenability, and by setting the ratio of Cr / Mo to 0.4 to 1.0, low temperature tempering of 450 to 550 ° C is possible, which is unexpectedly low. The present invention has been completed, knowing that it is possible to achieve both YR conversion and formation of a yielding shelf.
【００１１】ここに、本発明の要旨とするところは、重
量％で、Ｃ:0.08 〜0.20％、 Si:0.03 〜0.30％、
Mn:0.80 〜1.60％、Cr:0.20 〜0.70％、 Mo:0.40
〜0.70％、 Ｖ:0.03 〜0.10％、Nb:0.005〜0.050 ％、
Al:0.02 〜0.09％、 Ｂ:0.0003 〜0.0050％、Ti:
0.005〜0.050 ％、 Ｎ:0.0045 ％以下、Ｃeq: 0.50〜
0.65％、ＰCM: 0.32％以下、かつ、Cr／Mo: 0.40 以上
1.00以下、残部Feおよび不可避的不純物から成る鋼組成
を有する高靱性低降伏比高張力鋼材である。Here, the gist of the present invention is, in weight%, C: 0.08 to 0.20%, Si: 0.03 to 0.30%,
Mn: 0.80 to 1.60%, Cr: 0.20 to 0.70%, Mo: 0.40
~ 0.70%, V: 0.03 ~ 0.10%, Nb: 0.005 ~ 0.050%,
Al: 0.02-0.09%, B: 0.0003-0.0050%, Ti:
0.005 to 0.050%, N: 0.0045% or less, C eq : 0.50 to
0.65%, P CM : 0.32% or less, and Cr / Mo: 0.40 or more
A high-toughness low-yield ratio high-strength steel material having a steel composition of 1.00 or less and the balance Fe and unavoidable impurities.
【００１２】ただし、 Ｃeq＝Ｃ＋1/24Si＋1/6Mn ＋1/5Cr ＋1/4Mo ＋1/40Ni＋1/14V ・・・(1) ＰCM＝Ｃ＋1/30Si＋1/20Mn＋1/20Cu＋1/60Ni＋1/20Cr＋1/15Mo＋1/10V ＋5B ・・・(2) また、別の面からは、本発明は、上述の鋼組成を有する
鋼片を熱間加工後、Ac3 点 〜 950℃の温度域から焼入
れ、次いで直ちに780 〜Ac3−30℃の温度域に加熱して
から２相域焼入れしてから450 〜 550℃の温度域で焼戻
しすることを特徴とする、高靱性低降伏比高張力鋼材の
製造方法である。However, C eq = C + 1 / 24Si + 1 / 6Mn + 1 / 5Cr + 1 / 4Mo + 1 / 40Ni + 1 / 14V ・ ・ ・ (1) P CM = C + 1 / 30Si + 1 / 20Mn + 1 / 20Cu + 1 / 60Ni + 1 / 20Cr + 1 / 15Mo + 1 / 10V + 5B .. (2) From another aspect, the present invention provides an Ac 3 point after hot working a steel piece having the above-described steel composition. It is characterized by quenching from a temperature range of 950 to 950 ° C, then immediately heating it to a temperature range of 780 to Ac 3 -30 ° C, quenching in a two-phase region, and then tempering in a temperature range of 450 to 550 ° C. It is a method for producing a high-strength steel material having a low toughness and a low yield ratio.
【００１３】[0013]
【作用】次に、本発明において上述のように鋼組成およ
び製造条件を限定した理由を述べる。 Ｃ:Ｃは鋼板の焼入れ性の向上に最も有効な成分である
が、0.08％未満では20 kgf/mm2以上の強度を確保するに
は困難であり、また0.20％超の添加ではＰCM、Ｃeqの顕
著な上昇を招き溶接性、靱性の著しい低下を生じる。Next, the reasons for limiting the steel composition and manufacturing conditions as described above in the present invention will be described. C: C is the most effective component for improving the hardenability of steel sheet, but if it is less than 0.08%, it is difficult to secure a strength of 20 kgf / mm 2 or more, and if it exceeds 0.20%, P CM , This causes a marked increase in C eq , resulting in a marked decrease in weldability and toughness.
【００１４】Si:Siは脱酸材として有効であるが、0.03
％未満ではその効果が不十分であり、一方0.30％を超え
ると低Si化による靱性の向上が認められない。 Mn:Mnは焼入れ性の向上、強度確保のために0.50％以上
添加するが、1.60％を超える添加は溶接性や加工性を劣
化させる。好ましくは0.50〜1.50％である。Si: Si is effective as a deoxidizer, but 0.03
%, The effect is insufficient. On the other hand, if it exceeds 0.30%, improvement in toughness due to low Si content is not observed. Mn: Mn is added in an amount of 0.50% or more for improving hardenability and securing strength, but addition of more than 1.60% deteriorates weldability and workability. It is preferably 0.50 to 1.50%.
【００１５】Cr:Crは焼入れ性を上昇させ、強度確保の
ために重要であり、0.20％以上の添加によりその効果は
顕著に認められるが、0.70％を超えるとその効果は飽和
するとともに、溶接性が低下する。Cr: Cr increases the hardenability and is important for securing the strength. Addition of 0.20% or more shows the remarkable effect, but if it exceeds 0.70%, the effect saturates and welding Sex decreases.
【００１６】Mo:Moも同じく焼入れ性を向上させて強度
を上昇させるために重要な元素であるが、その積極的な
添加は降伏棚の形成のための焼戻し温度の上昇をもたら
し、かえって降伏棚の形成を阻害するとともに降伏比の
上昇を生じるため、0.70％を超えた添加は望ましくな
い。そこで強度上昇に効果のあるよう0.40％以上0.70％
以下の添加とする。Mo: Mo is also an important element for improving the hardenability and increasing the strength, but its aggressive addition causes an increase in the tempering temperature for forming the yield shelf, and rather the yield shelf. Addition of 0.70% is not desirable because it inhibits the formation of Al and increases the yield ratio. Therefore 0.40% or more and 0.70% to increase strength
The following additions are made.
【００１７】Ｖ:ＶはMo、Crと同様、焼入れ性を上昇さ
せ、溶接熱影響部の軟化度を軽減し、強度確保のために
重要であるが、0.03％未満ではその効果は小さく、0.10
％超の添加によりその効果は飽和するため、0.03％以上
0.10％以下とする。V: V, like Mo and Cr, is important for increasing the hardenability, reducing the softening degree of the weld heat affected zone, and ensuring strength, but if it is less than 0.03%, its effect is small and 0.10.
%, The effect will be saturated, so 0.03% or more
0.10% or less.
【００１８】Nb:Nbは焼入れ時のオーステナイト粒の微
細化を促進するため積極的な添加を必要とする。0.005
％未満ではその効果は小さく、0.050 ％超でその効果が
飽和する。したがって、本発明にあってはNb添加量を0.
005 〜0.050 ％とする。Nb: Nb needs to be positively added in order to promote the refinement of austenite grains during quenching. 0.005
If it is less than%, the effect is small, and if it exceeds 0.050%, the effect is saturated. Therefore, in the present invention, the amount of Nb added is 0.
005 to 0.050%.
【００１９】Al:Alは脱酸材およびＮの固定のために重
要であるが、0.02％未満では脱酸材としての効果が小さ
いだけでなく、Ｎの固定も困難である。また、0.09％超
の添加によりその効果は飽和するとともに、靱性が著し
く低下する。0.02％以上0.09％以下に制限する。Al: Al is important for fixing the deoxidizer and N, but if it is less than 0.02%, not only the effect as the deoxidizer is small, but also N is difficult to fix. Further, the addition of more than 0.09% saturates the effect and significantly reduces the toughness. Limit 0.02% or more and 0.09% or less.
【００２０】Ｂ:Ｂは焼入れ性向上のために重要で、0.0
003％未満の場合、その効果は認められない。一方、0.0
05 ％でその効果は飽和する。0.0003〜0.005 ％に制限
する。好ましくは、0.0005〜0.005 ％である。B: B is important for improving hardenability and is 0.0
If less than 003%, the effect is not recognized. On the other hand, 0.0
The effect is saturated at 05%. Limit to 0.0003 to 0.005%. Preferably, it is 0.0005 to 0.005%.
【００２１】Ti:Tiはスラブの表面性状の改善、溶接継
手靱性の向上に効果がある。そこで0.005 ％以上0.050
％以下の添加とする。好ましくは0.005 〜0.030 ％であ
る。 Ｎ:ＮはＢと結合してＢＮとなり、Ｂの焼入れ性を低減
してしまうため極力少ないほうが望ましい。しかし、極
度の低減はコストの上昇を招くため0.0045％以下とす
る。Ti: Ti is effective in improving the surface properties of the slab and improving the toughness of the welded joint. So 0.005% or more 0.050
% Or less. It is preferably 0.005 to 0.030%. Since N: N is combined with B to form BN, which reduces the hardenability of B, it is desirable that the amount is as small as possible. However, the extreme reduction causes an increase in cost, so 0.0045% or less is set.
【００２２】Ｃeq:Ｃeqは強度、溶接性の指標として有
効であるが、90 kgf/mm2以上の引張強さをＱ−Ｌ−Ｔ処
理によって得るには0.50％以上が必要である。一方、溶
接のことを考慮し、上限を0.65％とする。 ＰCM:ＰCMは溶接性の指標として重要であり、あまり高
いと割れ防止予熱温度が高くなり、溶接施工能率の面か
らあまり好ましくないため、上限を0.32とする。好まし
くは、0.20〜0.32％である。C eq : C eq is effective as an index of strength and weldability, but 0.50% or more is required to obtain a tensile strength of 90 kgf / mm 2 or more by the QLT treatment. On the other hand, considering welding, the upper limit is set to 0.65%. P CM : P CM is important as an index of weldability, and if it is too high, the crack prevention preheating temperature becomes high, which is not preferable in terms of welding work efficiency, so the upper limit is made 0.32. Preferably, it is 0.20 to 0.32%.
【００２３】Cr/Mo:一方、焼入れ性上昇による強度アッ
プを図るため、Ｃ、Cr、Mo、Ｖ、Nb等添加しているが、
その際、Cr/Mo のバランスが鋼材の引張時の応力−歪曲
線形状に大きく影響を及ぼす。本発明にあっては上記C
r、Moの添加範囲内で、0.40≦Cr／Mo≦1.00とする。こ
れは、Cr、Moともに焼入れ性を高める元素であるが、Mo
の方が２相域焼入れ時のベイナイト相生成に効果が大き
く、強度上昇の寄与が大きいものの、過量添加の場合、
軟質のフェライト相の生成が極めて小さくなり、降伏比
の上昇をもたらすこと、一方、Crはフェライト生成元素
であり、２相域焼入れ時フェライトの形成を促進するこ
との相乗効果により、低降伏比高張力鋼が製造できるこ
とによる。Cr / Mo: On the other hand, C, Cr, Mo, V, Nb, etc. are added in order to increase the strength by increasing the hardenability.
At that time, the balance of Cr / Mo has a great influence on the stress-strain curve shape of the steel material at the time of tension. In the present invention, the above C
Within the range of addition of r and Mo, 0.40 ≦ Cr / Mo ≦ 1.00. This is an element that enhances the hardenability of both Cr and Mo.
Is more effective in the formation of bainite phase during quenching in the two-phase region and contributes significantly to the increase in strength, but in the case of excessive addition,
The generation of soft ferrite phase becomes extremely small, resulting in an increase in yield ratio. On the other hand, Cr is a ferrite forming element, and the synergistic effect of promoting the formation of ferrite during quenching in the two-phase region results in a high yield ratio. This is because tensile steel can be manufactured.
【００２４】次に、図１は本発明にかかる製造方法の好
適熱処理パターンを示す線図であり、かかる製造工程に
おける製造条件の限定理由は以下の通りである。まず、
上述のような鋼組成を有する鋼片は、例えば1000〜1150
℃に加熱してから通常の熱間加工を実施し、成形後、Ｑ
−Ｌ−Ｔ処理を施す。Next, FIG. 1 is a diagram showing a preferable heat treatment pattern of the manufacturing method according to the present invention, and the reasons for limiting the manufacturing conditions in the manufacturing process are as follows. First,
Steel billets having the above steel composition are, for example, 1000 to 1150.
After heating to ℃, normal hot working is performed, and after molding, Q
-L-T processing is performed.
【００２５】前段の焼入処理において、焼入れ温度はAc
3 以上950 ℃以下とする。この前段の焼入処理は２相域
焼入れ前に均一な焼入れ組織 (ベイナイトまたはベイナ
イト＋一部マルテンサイト) を形成させるために行うも
のである。建設用建材の鋼板として一様伸び特性を向上
させるためオーステナイト粒は細かい方が望ましく、そ
のため焼入温度はAc3 点以上950 ℃以下と限定する。具
体的には900 ℃が望ましい。通常焼入れは水焼入によっ
て行う。In the first quenching treatment, the quenching temperature is Ac
More than 3 and less than 950 ℃. This first-stage quenching treatment is performed to form a uniform quenching structure (bainite or bainite + partly martensite) before quenching in the two-phase region. Austenite grains are preferably fine in order to improve the uniform elongation property as a steel sheet for construction materials, so the quenching temperature is limited to the Ac 3 point or more and 950 ° C or less. Specifically, 900 ℃ is desirable. Usually quenching is done by water quenching.
【００２６】次いで２相域焼入を行うが、このときの焼
入温度は、強度調整・降伏比に大きく影響し、Ac3 点に
近い方が低降伏比を維持しつつ、高強度化を図ることが
可能である。建築用鋼材として溶接による施行を考慮
し、低Ｃeq低ＰCMで90 kgf/mm2級の強度を得ることを目
的としているため、２相域中でも高めの温度とする。そ
のためには780 ℃以上Ac3 −30℃以下とする。望ましく
は800 〜810 ℃がよい。この場合にも通常は水焼入を行
う。Next, quenching is carried out in a two-phase region. The quenching temperature at this time has a great influence on the strength adjustment / yield ratio, and the closer to the Ac 3 point, the higher the yield strength while maintaining the low yield ratio. It is possible to plan. Considering welding as a building steel material, the aim is to obtain 90 kgf / mm 2 class strength with low C eq and low P CM , so the temperature is higher even in the two-phase region. For that purpose, the temperature should be 780 ° C or higher and Ac 3 -30 ° C or lower. It is preferably 800 to 810 ° C. Also in this case, water quenching is usually performed.
【００２７】焼戻し温度は鋼材の応力−歪曲線形状に最
も大きな影響を与える。建築用鋼材には条切り等の加工
を行い場合があり、焼入れによる応力の解放のため、焼
戻し温度は高い方が望ましい。しかし、焼戻し温度の上
昇に伴ない、降伏棚は明確になるものの、強度が低下
し、降伏比が著しく上昇する。そこで焼戻し温度は450
℃以上550 ℃以下、望ましくは500 ℃と設定する。The tempering temperature has the greatest effect on the stress-strain curve shape of steel. Since steel for construction may be subjected to processing such as stripping, it is desirable that the tempering temperature is high in order to release stress due to quenching. However, as the tempering temperature increases, the yield shelf becomes clear, but the strength decreases and the yield ratio significantly increases. So the tempering temperature is 450
The temperature should be set between ℃ and 550 ℃, preferably 500 ℃.
【００２８】[0028]
【実施例】ここで、実施例によって本発明の作用効果を
さらに具体的に説明する。表１に示す各鋼組成を有する
供試材を溶製し、造塊工程を経て得た鋼片を1120℃に加
熱し、仕上温度800 ℃で熱間圧延して厚さ20mmの熱延鋼
板とした。この熱延鋼板に900 ℃Ｑ→810 ℃Ｌ→500 ℃
Ｔの熱処理を施した。このようにして得られた供試材に
ついて引張試験を行い機械的特性の評価を行った。EXAMPLES Now, the effects of the present invention will be described more specifically by way of examples. 20 mm thick hot-rolled steel sheet was prepared by melting the test materials with the steel compositions shown in Table 1 and heating the billets obtained through the ingot making process to 1120 ° C and hot rolling at a finishing temperature of 800 ° C. And 900 ℃ Q → 810 ℃ L → 500 ℃ on this hot rolled steel sheet
Heat treatment of T was performed. A tensile test was performed on the test material thus obtained to evaluate the mechanical properties.
【００２９】結果は表２〜表４および図６ないし図９に
まとめて示す。図３ないし図５は、表１の代符１の鋼種
についてそれぞれ焼戻温度400 ℃、600 ℃、そして２相
域焼入温度850 ℃の条件下での応力−歪み曲線を示す。
いずれも本発明の範囲を外れたものであって、補歪エネ
ルギーが小さいことが分かる。The results are summarized in Tables 2 to 4 and FIGS. 6 to 9. FIGS. 3 to 5 show stress-strain curves under the conditions of tempering temperatures of 400.degree. C. and 600.degree. C. and two-phase region hardening temperature of 850.degree.
It is understood that all of them are out of the scope of the present invention and the complementary strain energy is small.
【００３０】図６ないし図８は、表１の代符１の鋼種に
ついて焼戻し温度および２相焼入温度を変更したときの
機械的特性への影響を示すグラフである。いずれの場合
においても本発明の範囲内の処理条件の場合に目的とす
る機械的特性が得られるのが分かる。なお、図６は表１
の代符１の鋼種を900 ℃Ｑ−810 ℃Ｌ−500 ℃Ｔ処理し
たときの応力−歪曲線である。図９は、表１の代符１の
鋼種を基本組成として表１中に示すCr/Mo 比を変えた場
合の同じく機械特性に及ぼす影響を示すグラフである。FIGS. 6 to 8 are graphs showing the influence on the mechanical properties when the tempering temperature and the two-phase quenching temperature are changed for the steel type of Algebra 1 in Table 1. It can be seen that in any case, the desired mechanical properties can be obtained under the processing conditions within the scope of the present invention. Table 1 is shown in FIG.
2 is a stress-strain curve when the steel type of Algebra 1 is subjected to 900 ° C. Q-810 ° C. L-500 ° C. T treatment. FIG. 9 is a graph showing the effect on the mechanical properties when the Cr / Mo ratio shown in Table 1 is changed with the basic composition of the substitute 1 steel type in Table 1.
【００３１】[0031]
【表１】 [Table 1]
【００３２】[0032]
【表２】 [Table 2]
【００３３】[0033]
【表３】 [Table 3]
【００３４】[0034]
【表４】 [Table 4]
【００３５】[0035]
【発明の効果】本発明によれば、引張強さ90 kgf/mm2以
上、降伏強さ70 kgf/mm2以上、降伏比85％以下の特性を
有する建築用として特に適する高靱性低降伏比高張力鋼
材が容易に得られるのであって、大型鋼構造物の安全性
確保のうえからも、その意義は大きい。EFFECTS OF THE INVENTION According to the present invention, a high toughness and low yield ratio particularly suitable for construction having a tensile strength of 90 kgf / mm 2 or more, a yield strength of 70 kgf / mm 2 or more and a yield ratio of 85% or less. Since high-strength steel materials can be easily obtained, it is significant in terms of ensuring the safety of large steel structures.
【図１】本発明にかかる熱処理パターンを示す線図であ
る。FIG. 1 is a diagram showing a heat treatment pattern according to the present invention.
【図２】補歪エネルギーを説明する応力−歪曲線図であ
る。FIG. 2 is a stress-strain curve diagram for explaining complementary strain energy.
【図３】比較例の応力−歪曲線図である。FIG. 3 is a stress-strain curve diagram of a comparative example.
【図４】比較例の応力−歪曲線図である。FIG. 4 is a stress-strain curve diagram of a comparative example.
【図５】比較例の応力−歪曲線図である。FIG. 5 is a stress-strain curve diagram of a comparative example.
【図６】本発明例の応力−歪曲線図である。FIG. 6 is a stress-strain curve diagram of an example of the present invention.
【図７】本発明の実施例の結果をまとめて示すグラフで
ある。FIG. 7 is a graph collectively showing the results of the examples of the present invention.
【図８】本発明の実施例の結果をまとめて示すグラフで
ある。FIG. 8 is a graph collectively showing the results of the examples of the present invention.
【図９】本発明の実施例の結果をまとめて示すグラフで
ある。FIG. 9 is a graph collectively showing the results of the examples of the present invention.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.5 識別記号 庁内整理番号 ＦＩ 技術表示箇所 // Ｃ２１Ｄ 1/18 Ｐ ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 5 Identification code Internal reference number FI technical display location // C21D 1/18 P
Claims (2)
0 〜1.60％、 Cr:0.20 〜0.70％、 Mo:0.40 〜0.70％、 Ｖ:0.0
3 〜0.10％、 Nb:0.005〜0.050 ％、 Al:0.02 〜0.09％、 Ｂ:0.0
003 〜0.0050％、 Ti:0.005〜0.050 ％、 Ｎ:0.0045 ％以下、 Ｃeq: 0.50〜0.65％、 ＰCM: 0.32％以下、 かつ、Cr／Mo : 0.40 以上1.00以下、残部Feおよび不可
避的不純物から成る鋼組成を有する高靱性低降伏比高張
力鋼材。 ただし、Ｃeq＝Ｃ＋1/24Si＋1/6Mn ＋1/5Cr ＋1/4Mo ＋
1/40Ni＋1/14V ＰCM＝Ｃ＋1/30Si＋1/20Mn＋1/20Cu＋1/60Ni＋1/20Cr＋
1/15Mo＋1/10V ＋5B1. By weight%, C: 0.08 to 0.20%, Si: 0.03 to 0.30%, Mn: 0.8
0 to 1.60%, Cr: 0.20 to 0.70%, Mo: 0.40 to 0.70%, V: 0.0
3 to 0.10%, Nb: 0.005 to 0.050%, Al: 0.02 to 0.09%, B: 0.0
003 to 0.0050%, Ti: 0.005 to 0.050%, N: 0.0045% or less, C eq : 0.50 to 0.65%, P CM : 0.32% or less, and Cr / Mo: 0.40 to 1.00 or less, balance Fe and unavoidable impurities Toughness low yield ratio high strength steel material having a steel composition consisting of. However, C eq = C + 1 / 24Si + 1 / 6Mn + 1 / 5Cr + 1 / 4Mo +
1 / 40Ni + 1 / 14V P CM = C + 1 / 30Si + 1 / 20Mn + 1 / 20Cu + 1 / 60Ni + 1 / 20Cr +
1 / 15Mo ＋ 1 / 10V ＋ 5B
間加工後、Ac3 点 〜 950℃の温度域から焼入れ、次いで
直ちに780 〜Ac3−30℃の温度域に加熱してから２相域
焼入れしてから450 〜 550℃の温度域で焼戻しすること
を特徴とする、高靱性低降伏比高張力鋼材の製造方法。2. A steel slab having the steel composition according to claim 1 is heat treated.
After hot working, Ac3point Quench from the temperature range of ~ 950 ℃, then
Immediately 780 ~ Ac3Two-phase range after heating to -30 ℃
After quenching, temper in the temperature range of 450 to 550 ℃
A method for producing a high-toughness low-yield ratio high-strength steel material, characterized by:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28801391A JPH05125481A (en) | 1991-11-01 | 1991-11-01 | High tensile strength steel material having high toughness and low yield ratio and its production |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP28801391A JPH05125481A (en) | 1991-11-01 | 1991-11-01 | High tensile strength steel material having high toughness and low yield ratio and its production |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH05125481A true JPH05125481A (en) | 1993-05-21 |
Family
ID=17724683
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP28801391A Pending JPH05125481A (en) | 1991-11-01 | 1991-11-01 | High tensile strength steel material having high toughness and low yield ratio and its production |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH05125481A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100406398B1 (en) * | 1998-12-24 | 2004-02-14 | 주식회사 포스코 | A METHOD FOR MANUFACTURING TENSILE STRENGTH 60kg/㎟ GRADE PLATE HAVING SUPERIOR EARTHGUAKE RESISTANT |
| KR100406365B1 (en) * | 1998-12-21 | 2004-02-14 | 주식회사 포스코 | A METHOD OF MANUFACTURING 600MPa GRADE HIGH STRENGTH STEEL WITH LOW YIELD RATION |
| JP2008121092A (en) * | 2006-11-15 | 2008-05-29 | Jfe Steel Kk | Steel material with excellent fatigue crack propagation resistance, and its manufacturing method |
| JP2008174766A (en) * | 2007-01-16 | 2008-07-31 | Jfe Steel Kk | Steel having reduced residual stress and excellent fatigue crack propagation resistance charactristic |
| JP2012102402A (en) * | 2011-11-29 | 2012-05-31 | Jfe Steel Corp | Manufacturing method of steel member having excellent resistance property in fatigue crack propagation |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6468422A (en) * | 1987-09-10 | 1989-03-14 | Sumitomo Metal Ind | Production of high tensile steel plate for building |
| JPH03219012A (en) * | 1989-11-08 | 1991-09-26 | Kawasaki Steel Corp | Production of high tensile steel reduced in yield ratio and having superior weldability |
-
1991
- 1991-11-01 JP JP28801391A patent/JPH05125481A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6468422A (en) * | 1987-09-10 | 1989-03-14 | Sumitomo Metal Ind | Production of high tensile steel plate for building |
| JPH03219012A (en) * | 1989-11-08 | 1991-09-26 | Kawasaki Steel Corp | Production of high tensile steel reduced in yield ratio and having superior weldability |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100406365B1 (en) * | 1998-12-21 | 2004-02-14 | 주식회사 포스코 | A METHOD OF MANUFACTURING 600MPa GRADE HIGH STRENGTH STEEL WITH LOW YIELD RATION |
| KR100406398B1 (en) * | 1998-12-24 | 2004-02-14 | 주식회사 포스코 | A METHOD FOR MANUFACTURING TENSILE STRENGTH 60kg/㎟ GRADE PLATE HAVING SUPERIOR EARTHGUAKE RESISTANT |
| JP2008121092A (en) * | 2006-11-15 | 2008-05-29 | Jfe Steel Kk | Steel material with excellent fatigue crack propagation resistance, and its manufacturing method |
| JP2008174766A (en) * | 2007-01-16 | 2008-07-31 | Jfe Steel Kk | Steel having reduced residual stress and excellent fatigue crack propagation resistance charactristic |
| JP2012102402A (en) * | 2011-11-29 | 2012-05-31 | Jfe Steel Corp | Manufacturing method of steel member having excellent resistance property in fatigue crack propagation |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH10195591A (en) | High strength hot rolled steel sheet for thermal hardening excellent in stretch-flanging property and its production | |
| JPH08176659A (en) | Production of high tensile strength steel with low yield ratio | |
| JP3160329B2 (en) | Manufacturing method of heat resistant high strength bolt | |
| JPH10121200A (en) | High strength steel material for shear reinforcing bar, and its production | |
| JPH05125481A (en) | High tensile strength steel material having high toughness and low yield ratio and its production | |
| JP3228986B2 (en) | Manufacturing method of high strength steel sheet | |
| JPH1068016A (en) | Production of extra thick wide flange shape | |
| JPH07109521A (en) | Production of 600n/mm2 class steel tube with low yield ratio for construction use by cold forming | |
| JP2828755B2 (en) | Manufacturing method of low yield ratio 80 ▲ kgｆf / ▲ mm ▼▼ 2 上 class steel sheet with excellent weldability | |
| JP2706159B2 (en) | Method for producing low yield ratio high strength steel with good weldability | |
| JPH06340922A (en) | Production of low yield ratio high tensile strength steel pipe | |
| JPH06212255A (en) | Production of low yield ratio high tensile strength steel plate excellent in weatherability | |
| KR100406365B1 (en) | A METHOD OF MANUFACTURING 600MPa GRADE HIGH STRENGTH STEEL WITH LOW YIELD RATION | |
| JP2655956B2 (en) | Manufacturing method of low yield ratio refractory steel sheet for building structure | |
| JP3033459B2 (en) | Manufacturing method of non-heat treated high strength steel | |
| JP2541389B2 (en) | Method of manufacturing low yield ratio high strength steel | |
| JP3497250B2 (en) | Method for producing low-yield ratio 590 N / mm2 class high strength steel with excellent weldability | |
| JP2611565B2 (en) | Method for producing Cu-added steel with excellent low-temperature toughness in welds | |
| JP3212337B2 (en) | Production method of low yield ratio thick high strength steel with excellent weldability | |
| JPH06340924A (en) | Production of low yield ratio high tensile strength steel | |
| JPH06248336A (en) | Production of 780n/mm2 class high tensile strength steel excellent in weldability and reduced in yield ratio | |
| JPH051323A (en) | Production of high tensile strength steel excellent in weldability and brittle crack propagation arresting property | |
| JPH06158160A (en) | Production of high tensile strength heat treated steel excellent in cost effectiveness | |
| JP2000192144A (en) | Production of high strength pc steel rod | |
| JPH07207334A (en) | Production of high tension steel having excellent weldability and plastic deformability |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 19970708 |