JPH0615689B2 - Method of manufacturing low yield ratio high strength steel - Google Patents
Method of manufacturing low yield ratio high strength steelInfo
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- JPH0615689B2 JPH0615689B2 JP62122194A JP12219487A JPH0615689B2 JP H0615689 B2 JPH0615689 B2 JP H0615689B2 JP 62122194 A JP62122194 A JP 62122194A JP 12219487 A JP12219487 A JP 12219487A JP H0615689 B2 JPH0615689 B2 JP H0615689B2
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Description
【発明の詳細な説明】 ［産業上の利用分野］ 本発明は低降伏比高張力鋼の製造方法に関するものであ
る。TECHNICAL FIELD The present invention relates to a method for producing a high yield steel having a low yield ratio.
［従来の技術］ 近年、建築構造物の大型化に伴い、経済性、安全性等の
面から高張力鋼の需要は着実な増加を示している。建築
構造物に使用される鋼材は主に梁や柱に使用される。こ
のために高強度化が要求され、また柱に使用されるもの
は高強度化とともに厚肉化が要求されている。さらには
耐震設計を行なうために塑性変形能力の優れた低降伏比
鋼（例えば降伏比：７０％以下）が要求されている。[Prior Art] In recent years, with the increase in size of building structures, the demand for high-strength steel has shown a steady increase in terms of economic efficiency and safety. Steel materials used for building structures are mainly used for beams and columns. For this reason, high strength is required, and those used for columns are required to have high strength and thick wall. Further, a low yield ratio steel (for example, yield ratio: 70% or less) having an excellent plastic deformation capability is required to perform seismic design.
従来高張力鋼板は調質処理（いわゆるＱＴ，ＤＱＴ）に
よって製造されてきているが、調質高張力鋼は降伏比が
約90％と高く、降伏後の塑性変形能力が小さいため建築
構造物には適用しにくいという欠点があった。Conventionally, high-strength steel sheets have been manufactured by heat treatment (so-called QT, DQT), but heat-treated high-strength steel has a high yield ratio of approximately 90% and has a small plastic deformation capacity after yielding, making it suitable for building structures. Has the drawback of being difficult to apply.
これに対して熱処理を施さないいわゆる非調質で高張力
化を図る製造方法として、制御圧延・制御冷却を組合せ
た方法があり、調質鋼に比較して降伏比を低くすること
が可能となる。On the other hand, there is a method that combines controlled rolling and controlled cooling as a manufacturing method that achieves so-called non-heat treated and high tensile strength without heat treatment, and it is possible to lower the yield ratio compared to heat treated steel. Become.
最近、特開昭59−211528号公報によれば、水冷開始温度
をＡｒ３−20℃〜Ａｒ３−80℃とし、水冷停止温度を35
0 〜650 ℃とした板厚40mmまでの低降伏比非調質鋼の製
造方法が開示されている。Recently, according to JP-A-59-211528, the water cooling initiation temperature and Ar 3 -20 ℃ ~Ar 3 -80 ℃ , the water cooling stop temperature 35
A method for producing a low yield ratio non-heat treated steel having a thickness of 40 mm at 0 to 650 ° C is disclosed.
［発明が解決しようとする問題点］ しかしながら、非調質処理によって鋼を製造する場合、
板厚が30mm以上となると板厚中心部の冷却速度が遅くな
り、マルテンサイト組織が生成しにくくなると同時にフ
ェライトやベイナイトが多く生成し、所定の強度を満足
しないという問題点がある。[Problems to be Solved by the Invention] However, when steel is produced by non-heat treatment,
If the plate thickness is 30 mm or more, the cooling rate at the central part of the plate thickness becomes slow, and it becomes difficult to form a martensite structure, and at the same time, a large amount of ferrite and bainite are formed, and there is a problem that the predetermined strength is not satisfied.
さらに非調質によって鋼を製造した場合、焼戻し処理を
行なわないために板厚中心部と表層部の硬度差が大きい
という問題点もある。Further, when steel is manufactured by non-heat treatment, there is a problem that the hardness difference between the center part of the plate thickness and the surface part is large because the tempering process is not performed.
この発明は上記のような問題点を解消するためになされ
たもので、高強度でかつ降伏比が低く、建築構造物に適
した低降伏比高張力鋼を得ることを目的とする。The present invention has been made in order to solve the above problems, and an object thereof is to obtain a high-strength steel having a low yield ratio and a high yield ratio and a low yield ratio suitable for a building structure.
［問題点を解決するための手段］ 本発明は従来の問題点を改善することのできる低降伏比
高張力鋼を得ることを目的とするものであり、その要旨
はＣ 0.01〜0.20％、Ｓｉ 0.6％以下、Ｍｎ 0.5〜2.
2％、Ａｌ 0.001〜0.1％、Ｎ 0.006％以下、もしくは
必要により、Ｎｉ 1.0％以下、Ｍｏ 1.0％以下、Ｃｕ
1.0％以下、Ｃｒ 1.0％以下、Ｖ 0.1％以下、Ｎｂ
0.1％以下、Ｔｉ 0.1％以下、Ｂ 0.003％以下、Ｃ
ａ 0.003％以下、ＲＥＭ 0.01％以下の一種または二
種以上を含有させ、残部Ｆｅ及び不可避的不純物からな
る鋼片を900〜1200℃の温度範囲に加熱し、900℃以下の
累積圧下量が30％以上かつ仕上温度がＡｒ３＋80℃以下
Ａｒ３−20℃以上となるように圧延を行なった後、鋼板
をＡｒ３−20℃〜Ａｒ３−100℃まで空冷し、続いてこ
の温度から300℃以下の温度まで２℃／秒以上の冷却速
度で冷却、その後Ａｃ１以下の温度で焼戻し処理を行な
うことを特徴とする。[Means for Solving Problems] The present invention aims to obtain a high yield strength steel having a low yield ratio capable of overcoming the conventional problems, and the gist thereof is C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.
2%, Al 0.001 to 0.1%, N 0.006% or less, or if necessary, Ni 1.0% or less, Mo 1.0% or less, Cu
1.0% or less, Cr 1.0% or less, V 0.1% or less, Nb
0.1% or less, Ti 0.1% or less, B 0.003% or less, C
a 0.003% or less, REM 0.01% or less of one or more kinds are contained, and a steel slab composed of the balance Fe and unavoidable impurities is heated to a temperature range of 900 to 1200 ° C, and a cumulative reduction amount of 900 ° C or less is 30 % Or more and the finishing temperature is Ar 3 + 80 ° C. or less, and the rolling is performed so as to be Ar 3 −20 ° C. or more, and then the steel sheet is air-cooled to Ar 3 −20 ° C. to Ar 3 −100 ° C., and then 300 ° C. from this temperature. It is characterized in that it is cooled to a temperature of not higher than 0 ° C. at a cooling rate of not lower than 2 ° C./second, and then tempered at a temperature of not higher than Ac 1 .
以下に本発明における加熱圧延冷却条件の限定理由につ
いて詳細に説明する。The reasons for limiting the heating, rolling and cooling conditions in the present invention will be described in detail below.
加熱温度を900〜1200℃に限定した理由は、加熱時のオ
ーステナイト粒を小さく保ち圧延組織の細粒化をはかる
ためである。1200℃は加熱時のオーステナイト粒が極端
に粗大化しない上限温度であって、加熱温度がこれを超
えるとオーステナイト粒が粗大混粒化し、変態後の組織
が粗大なベイナイトとなるため鋼の靭性が著しく劣化す
る。The reason for limiting the heating temperature to 900 to 1200 ° C. is to keep the austenite grains at the time of heating small and to make the rolling structure finer. 1200 ° C is the upper limit temperature at which the austenite grains during heating do not become extremely coarse, and if the heating temperature exceeds this temperature, the austenite grains become coarsely mixed grains, and the structure after transformation becomes coarse bainite, so the toughness of the steel increases. Remarkably deteriorates.
一方加熱温度が低すぎると、圧延終了温度が下がりすぎ
るため、十分な材質向上効果が期待できない。またＮ
ｂ，Ｖなどの析出硬化元素添加時には、これらが十分に
固溶せず強度、靭性バランスが劣化する。このために下
限を900℃とする必要がある。On the other hand, if the heating temperature is too low, the rolling finish temperature will be too low, and a sufficient material improvement effect cannot be expected. Also N
When a precipitation hardening element such as b or V is added, these do not sufficiently form a solid solution and the balance of strength and toughness deteriorates. Therefore, it is necessary to set the lower limit to 900 ° C.
上述のような条件で加熱したスラブを、900℃以下の未
再結晶域での累積圧下量を30％以上とし、仕上温度がＡ
ｒ３＋80℃以下Ａｒ３−20℃以上となるように圧延す
る。The slab heated under the conditions as described above has a cumulative reduction amount of 30% or more in the unrecrystallized region of 900 ° C or less and a finishing temperature of A
Rolling is performed so that r 3 + 80 ° C. or lower and Ar 3 −20 ° C. or higher.
これは未再結晶域での圧延を行なうことによって、オー
ステナイト粒の細粒化を図るためである。仕上温度の下
限をＡｒ３−20℃としたのは、過度の変態点以下の（γ
＋α）域圧延によって靭性を劣化させないためである。
一方、仕上温度が余りにも高すぎると、オーステナイト
粒の細粒化効果が期待できず靭性が劣化する。このため
に上限をＡｒ３＋80℃とする必要がある。This is because the austenite grains are made finer by rolling in the unrecrystallized region. The lower limit of the finishing temperature is set to Ar 3 −20 ° C. because the temperature is below the excessive transformation point (γ
This is because the + α) area rolling does not deteriorate the toughness.
On the other hand, if the finishing temperature is too high, the effect of refining the austenite grains cannot be expected and the toughness deteriorates. Therefore, it is necessary to set the upper limit to Ar 3 + 80 ° C.
次に圧延後の冷却条件であるが、これは圧延終了後空冷
し鋼板温度がＡｒ３−20℃〜Ａｒ３−100℃の間から２
℃／秒以上の冷却速度で300℃以下の温度まで冷却し、
その後Ａｃ１以下の温度で焼戻し処理を行なう必要があ
る。Next is the cooling condition after rolling, which is air cooling after completion of rolling and the steel plate temperature is between Ar 3 −20 ° C. and Ar 3 −100 ° C.
Cool at a cooling rate of ℃ / sec or more to a temperature of 300 ℃ or less,
After that, it is necessary to perform tempering treatment at a temperature of Ac 1 or lower.
この理由は適量の初析フェライトを析出せしめた後、炭
素が濃縮された未変態オーステナイトを比較的速い冷却
速度で冷却することによって、最終組織をフェライト＝
ベイナイト＝マルテンサイトとするためである。The reason for this is that after depositing an appropriate amount of pro-eutectoid ferrite, the untransformed austenite enriched with carbon is cooled at a relatively high cooling rate, so that the final structure of ferrite =
This is because bainite = martensite.
組織をベイナイト＝マルテンサイトとするために２℃／
秒以上の冷却速度が必要である。冷却開始温度の下限を
Ａｒ３−100℃としたのは、これ以下の温度であるとフ
ェライトの析出量が多くなり、強度が低下するためであ
る。また、上限をＡｒ３−20℃としたのは、これ以上の
温度であるとフェライトの析出量が少なく降伏強度が低
くならず、低降伏比鋼が得られないからである。2 ° C / to make the structure bainite = martensite
Cooling rate of more than 2 seconds is required. The lower limit of the cooling start temperature is set to Ar 3 -100 ° C., because if the temperature is lower than this, the precipitation amount of ferrite increases and the strength decreases. Further, the upper limit is set to Ar 3 −20 ° C., because at a temperature higher than this, the precipitation amount of ferrite is small and the yield strength is not lowered, so that a low yield ratio steel cannot be obtained.
次に成分範囲の限定理由について説明する。Next, the reason for limiting the component range will be described.
Ｃは母材の強度を確保するために必要であるが、多量に
含有させると靭性あるいは溶接性を損なうために適量の
添加が必要となる。このような観点からＣは0.01〜0.2
％とした。C is necessary in order to secure the strength of the base material, but if it is contained in a large amount, toughness or weldability is impaired, so an appropriate amount of C must be added. From this point of view, C is 0.01 to 0.2
%.
Ｓｉは脱酸上、鋼に必然的に含まれる元素であるが、Ｓ
ｉはＨＡＺ靭性及び溶接性上好ましくない元素であるた
め、その上限を0.6％とした。Si is an element necessarily contained in steel for deoxidation, but S
Since i is an unfavorable element in terms of HAZ toughness and weldability, its upper limit was set to 0.6%.
Ｍｎは強度靭性を同時に向上せしめる極めて重要な元素
であり、0.5％以上は必要であるが、多量に添加すると
溶接性、母材及びＨＡＺの靭性劣化を招くためその上限
を2.2％とした。Mn is an extremely important element that simultaneously improves the strength and toughness, and 0.5% or more is necessary, but if added in a large amount, the weldability and the toughness of the base material and HAZ deteriorate, so the upper limit was made 2.2%.
Ａｌは脱酸上必然的に含有される元素であるが、0.001
％未満では脱酸が不十分となり、母材靭性が劣化するた
め下限を0.001％とした。一方0.1％を超えると鋼の清浄
度及びＨＡＺ靭性が劣化するため上限を0.1％とした。Al is an element necessarily contained in deoxidation, but 0.001
If it is less than 0.1%, deoxidation becomes insufficient and the toughness of the base material deteriorates, so the lower limit was made 0.001%. On the other hand, if it exceeds 0.1%, the cleanliness and HAZ toughness of the steel deteriorate, so the upper limit was made 0.1%.
Ｎは溶鋼中に不可避的に混入し、鋼の靭性を劣化させる
ために、その上限を0.006％とした。N is inevitably mixed in the molten steel and deteriorates the toughness of the steel, so its upper limit was made 0.006%.
次に上述の成分及び製造プロセスにさらにＮｉ 0.1〜
1.0％、Ｍｏ 1.0％以下、Ｃｕ 1.0％以下、Ｃｒ 1.0
％以下、Ｖ 0.1％以下、Ｎｂ 0.1％以下、Ｔｉ 0.1
％以下、Ｂ 0.003％以下、Ｃａ 0.003％以下、ＲＥＭ
0.01％以下の一種または二種以上を含有させることがで
きる。Next, in addition to the above components and manufacturing process, Ni 0.1 to
1.0%, Mo 1.0% or less, Cu 1.0% or less, Cr 1.0
% Or less, V 0.1% or less, Nb 0.1% or less, Ti 0.1
% Or less, B 0.003% or less, Ca 0.003% or less, REM
0.01% or less of one kind or two or more kinds can be contained.
これらの元素を含有させる主たる目的は、本発明鋼の特
徴を損なうことなく、強度、靭性の向上及び製造板厚の
拡大を可能にするところにあり、その添加量は溶接性及
びＨＡＺ靭性等の面から自ずと制限されるべき性質のも
のである。The main purpose of containing these elements is to enable the improvement of strength and toughness and the expansion of the production plate thickness without impairing the characteristics of the steel of the present invention, and the addition amount thereof is such as weldability and HAZ toughness. It is of a nature that should be naturally limited.
ＮｉはＨＡＺの硬化性及び靭性に悪影響を与えることな
く、母材の強度、靭性を向上させる特性をもつが、1.0
％を超えるとＨＡＺの硬化性及び靭性上好ましくないた
め、上限を1.0％とした。Ni has the property of improving the strength and toughness of the base metal without adversely affecting the hardenability and toughness of the HAZ, but 1.0
%, The HAZ hardenability and toughness are not preferable, so the upper limit was made 1.0%.
Ｍｏは母材の強度、靭性を共に向上させる元素である
が、1.0％を超えると溶接部靭性及び溶接性の劣化を招
き好ましくないため、上限を1.0％とした。Mo is an element that improves both the strength and toughness of the base metal, but if it exceeds 1.0%, it deteriorates the toughness and weldability of the welded portion and is not preferable, so the upper limit was made 1.0%.
ＣｕはＮｉとほぼ同様の効果を持つと共に、耐食性、耐
水素誘起割れ特性にも効果がある。しかし、1.0％を超
えると圧延中にＣｕ−クラックが発生し製造が困難にな
る。このため、上限を1.0％とした。Cu has substantially the same effect as Ni, and also has an effect on the corrosion resistance and hydrogen-induced cracking resistance. However, if it exceeds 1.0%, Cu-cracks are generated during rolling, which makes manufacturing difficult. Therefore, the upper limit is set to 1.0%.
Ｃｒは母材の強度を高め、耐水素誘起割れ特性等にも効
果を有するが、1.0％を超えるとＨＡＺの硬化性を増大
させ、靭性及び溶接性の低下が大きくなり好ましくな
い。このため上限を1.0％とした。Cr enhances the strength of the base metal and has an effect on hydrogen-induced cracking resistance and the like, but if it exceeds 1.0%, the hardenability of the HAZ is increased, and the toughness and weldability are greatly reduced, which is not preferable. Therefore, the upper limit was made 1.0%.
Ｖは析出硬化に有効であるが、0.1％を超えると溶接性
の劣化を招き好ましくないため、上限を0.1％とした。V is effective for precipitation hardening, but if it exceeds 0.1%, it deteriorates weldability and is not preferable. Therefore, the upper limit was made 0.1%.
Ｎｂは析出硬化に有効であるが、0.1％を超えると靭性
の劣化を招き好ましくないため、上限を0.1％とした。Nb is effective for precipitation hardening, but if it exceeds 0.1%, toughness is deteriorated, which is not preferable, so the upper limit was made 0.1%.
Ｔｉはオーステナイト粒の細粒化に有効であるが、0.1
％を超えると溶接性の劣化を招き好ましくないため、上
限を0.1％とした。Ti is effective for making austenite grains finer, but 0.1
%, The weldability deteriorates, which is not preferable, so the upper limit was made 0.1%.
Ｂは高強度化に有効であるが、0.003％を超えるとＨＡ
Ｚ靭性を著しく劣化させるので上限を0.003％とした。B is effective for strengthening, but if it exceeds 0.003%, HA
Since the Z toughness is remarkably deteriorated, the upper limit was made 0.003%.
Ｃａ，ＲＥＭはＭｎＳを球状化させシャルピー吸収エネ
ルギー衝撃値を向上させる他、圧延によって延伸化した
ＭｎＳと水素による内部欠陥の発生を防止する。ＲＥＭ
の含有量については0.01％を超えて添加すると、ＲＥＭ
−ＳまたはＲＥＭ−Ｏ−Ｓが大量に生成して大型介在物
となり、鋼の靭性のみならず清浄度を害しまた溶接性に
悪影響を及ぼす。このため上限を0.01％とした。Ca and REM improve the Charpy absorbed energy impact value by spheroidizing MnS and prevent the generation of internal defects due to MnS stretched by rolling and hydrogen. REM
When the content exceeds 0.01%, REM
A large amount of —S or REM-OS is generated and becomes a large inclusion, which not only impairs the toughness of the steel but also the cleanliness and adversely affects the weldability. Therefore, the upper limit was made 0.01%.
ＣａについてもＲＥＭと同様の硬化を持ちその上限は0.
003％である。Ca has the same hardening as REM and its upper limit is 0.
It is 003%.
本発明鋼は不純物としてＳおよびＰを含有するが、通常
Ｓは0.01％以下、Ｐは0.01％以下であり、低いほど母
材、溶接部靭性は向上する。Ｓは0.01％以下、Ｐは0.01
％以下が望ましい。The steel of the present invention contains S and P as impurities, but usually S is 0.01% or less and P is 0.01% or less. The lower the content, the higher the base metal and weld zone toughness. S is 0.01% or less, P is 0.01
% Or less is desirable.
［実施例］ 第１表には供試鋼の化学成分を、第２表には製造条件お
よび材質特性を示す。[Examples] Table 1 shows the chemical composition of the test steel, and Table 2 shows the manufacturing conditions and material properties.
第１表において鋼Ａ，Ｂ，Ｄ，Ｆ，ＧはＴＳ60kg／mm2
クラス、鋼ＣはＴＳ70kg／mm2クラス、鋼ＥはＴＳ80kg
／mm2クラスを目標にしたものである。In Table 1, steels A, B, D, F and G are TS60kg / mm 2
Class, Steel C is TS70kg / mm 2 class, Steel E is TS80kg
/ Mm 2 class is the target.
本発明に従って製造した鋼板はいずれも降伏比70％以下
を達成しており、かつ所定の強度および低温靭性を満足
している。Each of the steel sheets manufactured according to the present invention has achieved a yield ratio of 70% or less, and satisfies predetermined strength and low temperature toughness.
これに対して比較鋼Ａ２は冷却速度が遅く強度が低下し
ている。Ｂ２は仕上温度が高いために結晶粒の細粒化が
十分成されておらず靭性が劣化している。Ｃ２は900℃
以下の圧下率が低いために結晶粒の細粒化が十分成され
ておらず靭性が劣化している。Ｄ２は加熱温度が高いた
めに結晶粒の細粒化が十分成されておらず靭性が劣化し
ている。On the other hand, Comparative Steel A2 has a slow cooling rate and a low strength. Since B2 has a high finishing temperature, the grain size of the crystal grains is not sufficiently reduced and the toughness is deteriorated. C2 is 900 ° C
Since the rolling reduction is low, the grain size of the crystal grains is not sufficiently reduced and the toughness is deteriorated. Since the heating temperature of D2 is high, the grain size of the crystal grains is not sufficiently reduced and the toughness is deteriorated.
Ｅ２は冷却開始温度が低いために強度が低下している。
Ｆ２は冷却停止温度が高いために強度が低下している。
Ｇ２は冷却開始温度が高いために降伏比が高くなってい
る。Ｇ３は仕上温度が低いために靭性が劣化している。The strength of E2 is low because the cooling start temperature is low.
The strength of F2 is low because the cooling stop temperature is high.
Since G2 has a high cooling start temperature, the yield ratio is high. Since G3 has a low finishing temperature, its toughness is deteriorated.
［発明の効果］ 本発明は圧延終了後、適量のフェライトが析出する温度
まで鋼板を空冷し、続いてこの温度から焼入れ焼戻しす
ることによって組織がフェライト＝ベイナイト＝マルテ
ンサイトとなり、低降伏比高張力鋼が製造可能となる。 [Effect of the Invention] According to the present invention, after rolling is finished, the steel sheet is air-cooled to a temperature at which an appropriate amount of ferrite is precipitated, and then quenched and tempered from this temperature to change the structure to ferrite = bainite = martensite, resulting in a low yield ratio and high tensile strength. Steel can be manufactured.
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 Ｃ２２Ｃ 38/54 38/58 (56)参考文献 特開 昭60−67619（ＪＰ，Ａ) 特開 昭60−67621（ＪＰ，Ａ) 特開 昭60−149722（ＪＰ，Ａ)Continuation of front page (51) Int.Cl. 5 Identification number Office reference number FI Technical display location C22C 38/54 38/58 (56) Reference JP-A-60-67619 (JP, A) JP-A-60- 67621 (JP, A) JP-A-60-149722 (JP, A)
Claims (7)
じ）、 Ｓｉ 0.6％以下、 Ｍｎ 0.5〜2.2％、 Ａｌ 0.001〜0.1％、 Ｎ 0.006％以下、 残部Ｆｅ及び不可避的不純物からなる鋼片を900〜1200
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。1. A steel slab comprising C 0.01 to 0.20% (weight%, the same applies hereinafter), Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, and the balance Fe and unavoidable impurities. From 900 to 1200
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。2. One or two kinds of C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, V 0.1% or less, Nb 0.1% or less, And Ti 0.1% or less, and a steel slab consisting of the balance Fe and unavoidable impurities 900 to 1200
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。3. C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, Ni 1.0% or less, Mo 1.0% or less, Cu 1.0% or less, Cr 1.0% or less, 1 or 2 or more, Ti 0.1% or less, and a balance of 900 to 1200 for steel pieces consisting of Fe and unavoidable impurities.
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。4. C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, Ni 1.0% or less, Mo 1.0% or less, Cu 1.0% or less, Cr 1.0% or less, 1 or 2 or more and V 0.1% or less, Nb 0.1% or less, 1 or 2 or more and Ti 0.1% or less, and a steel slab composed of the balance Fe and unavoidable impurities 900 to 1200
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。5. C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, Ni 1.0% or less, Mo 1.0% or less, Cu 1.0% or less, Cr 1.0% or less, 1 or 2 or more and Ti 0.1% or less, B 0.003% or less, and Ca 0.003% or less, REM 0.01% or less, 1 or 2 types Residual Fe and unavoidable impurities 900- 1200
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。6. C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, Ni 1.0% or less, Mo 1.0% or less, Cu 1.0% or less, Cr 1.0% or less, 1 type or 2 types or more and V 0.1% or less, Nb 0.1% or less, 1 type or 2 types A steel slab composed of the balance Fe and unavoidable impurities is 900 to 1200
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
℃の温度範囲に加熱し、900℃以下の累積圧下量が30％
以上、かつ仕上温度がＡｒ３＋80℃以下Ａｒ３−20℃以
上となるように圧延を行なった後、鋼板をＡｒ３−20℃
〜Ａｒ３−100℃まで空冷し、続いてこの温度から300℃
以下の温度まで２℃／秒以上の冷却速度で冷却、その後
Ａｃ１以下の温度で焼戻し処理を行なうことを特徴とす
る低降伏比高張力鋼の製造方法。7. C 0.01 to 0.20%, Si 0.6% or less, Mn 0.5 to 2.2%, Al 0.001 to 0.1%, N 0.006% or less, Ni 1.0% or less, Mo 1.0% or less, Cu 1.0% or less, Cr 1.0% or less, one or more types and V 0.1% or less, Nb 0.1% or less, one or two types and Ti 0.1% or less, B 0.003% or less, and Ca 0.003% or less, REM 0.01% or less, one type Or, a steel slab consisting of two kinds of balance Fe and unavoidable impurities is 900 to 1200
Heating to the temperature range of ℃, the cumulative rolling reduction below 900 ℃ is 30%
Above, and after rolling so that the finishing temperature is Ar 3 + 80 ° C or less and Ar 3 -20 ° C or more, the steel plate is Ar 3 -20 ° C.
~ Ar 3 Air-cooled to -100 ℃, then from this temperature to 300 ℃
A method for producing a high-strength steel having a low yield ratio, which comprises cooling to the following temperature at a cooling rate of 2 ° C./second or more, and then performing tempering treatment at a temperature of Ac 1 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62122194A JPH0615689B2 (en) | 1987-05-19 | 1987-05-19 | Method of manufacturing low yield ratio high strength steel |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62122194A JPH0615689B2 (en) | 1987-05-19 | 1987-05-19 | Method of manufacturing low yield ratio high strength steel |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63286517A JPS63286517A (en) | 1988-11-24 |
| JPH0615689B2 true JPH0615689B2 (en) | 1994-03-02 |
Family
ID=14829896
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62122194A Expired - Lifetime JPH0615689B2 (en) | 1987-05-19 | 1987-05-19 | Method of manufacturing low yield ratio high strength steel |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0615689B2 (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2595092B2 (en) * | 1989-05-12 | 1997-03-26 | 株式会社神戸製鋼所 | Manufacturing method of high strength and high toughness steel |
| JPH0379716A (en) * | 1989-08-23 | 1991-04-04 | Kawasaki Steel Corp | Manufacture of low yield ratio high tensile strength steel having good weldability |
| JPH0737647B2 (en) * | 1990-08-27 | 1995-04-26 | 新日本製鐵株式会社 | Method for producing low yield ratio H-section steel excellent in fire resistance and toughness |
| JPH04297522A (en) * | 1990-10-01 | 1992-10-21 | Sumitomo Metal Ind Ltd | Production of ultrahigh tensile strength steel for construction use |
| JP2546954B2 (en) * | 1992-08-21 | 1996-10-23 | 新日本製鐵株式会社 | Method for manufacturing high-strength steel for construction with excellent fire resistance |
| JP2546953B2 (en) * | 1992-08-21 | 1996-10-23 | 新日本製鐵株式会社 | Method for manufacturing high-strength steel for construction with excellent fire resistance |
| US5454883A (en) * | 1993-02-02 | 1995-10-03 | Nippon Steel Corporation | High toughness low yield ratio, high fatigue strength steel plate and process of producing same |
| KR100266378B1 (en) * | 1994-09-20 | 2000-09-15 | 에모토 간지 | Bainite steel material of little scatter of quality and method of manufactureing the same |
| JP4854981B2 (en) * | 2005-04-15 | 2012-01-18 | 新日本製鐵株式会社 | Friction welded parts with excellent fatigue resistance and methods for improving the fatigue characteristics |
| JP5171327B2 (en) * | 2008-03-14 | 2013-03-27 | 株式会社神戸製鋼所 | Steel plate for skin plate excellent in thickness direction toughness of heat-affected zone with large heat input and manufacturing method thereof |
| JP5573265B2 (en) * | 2010-03-19 | 2014-08-20 | Ｊｆｅスチール株式会社 | High strength thick steel plate excellent in ductility with a tensile strength of 590 MPa or more and method for producing the same |
| CN102899576A (en) * | 2012-10-23 | 2013-01-30 | 鞍钢股份有限公司 | 590 MPa-grade low-yield-ratio automobile steel plate and production method thereof |
| KR102045641B1 (en) * | 2017-12-22 | 2019-11-15 | 주식회사 포스코 | High strength steel for arctic environment having excellent resistance to fracture in low temperature, and method for manufacturing the same |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5810442A (en) * | 1981-07-06 | 1983-01-21 | Ryoji Honma | Method for making milling machine automatically cyclic |
| JPS59211528A (en) * | 1983-05-17 | 1984-11-30 | Nippon Steel Corp | Production of non-tempered steel having low yield ratio |
| JPS6067619A (en) * | 1983-09-20 | 1985-04-18 | Nippon Steel Corp | Preparation of high tensile steel plate |
| JPS6067621A (en) * | 1983-09-22 | 1985-04-18 | Kawasaki Steel Corp | Preparation of non-refining high tensile steel |
| JPS60149722A (en) * | 1984-01-14 | 1985-08-07 | Nippon Steel Corp | Manufacture of cu added steel having superior toughness at low temperature in weld zone |
| JPS6277419A (en) * | 1985-09-30 | 1987-04-09 | Nippon Steel Corp | Production of high tensile steel having excellent arrest characteristic |
-
1987
- 1987-05-19 JP JP62122194A patent/JPH0615689B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63286517A (en) | 1988-11-24 |
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