JPH06264143A - Production of steel tube with low yield ratio for construction use by cold forming - Google Patents
Production of steel tube with low yield ratio for construction use by cold formingInfo
- Publication number
- JPH06264143A JPH06264143A JP5273293A JP5273293A JPH06264143A JP H06264143 A JPH06264143 A JP H06264143A JP 5273293 A JP5273293 A JP 5273293A JP 5273293 A JP5273293 A JP 5273293A JP H06264143 A JPH06264143 A JP H06264143A
- Authority
- JP
- Japan
- Prior art keywords
- less
- steel
- yield ratio
- temperature
- steel pipe
- 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.)
- Withdrawn
Links
Landscapes
- Heat Treatment Of Steel (AREA)
Abstract
Description
【発明の詳細な説明】Detailed Description of the Invention
【0001】[0001]
【産業上の利用分野】本発明は建築、土木分野におい
て、各種構造物に用いる冷間成形による低降伏比鋼管の
製造法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a low yield ratio steel pipe by cold forming for various structures in the fields of construction and civil engineering.
【0002】[0002]
【従来の技術】一般的に、鋼材に対し冷間加工を加える
と加工硬化によりYP、TSが上昇し、TSに比べYP
の上昇が大きいため降伏比(以下YRと呼ぶ)も上昇し
てしまい、冷間成形による鋼管は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。2. Description of the Related Art Generally, when cold working is applied to steel, YP and TS rise due to work hardening, and YP and TS are higher than TS.
The yield ratio (hereinafter referred to as YR) also increases due to the large increase in the steel, and the cold-formed steel pipe has a drawback that it is difficult to apply to a building structure because the plastic deformation capacity after yielding is small.
【0003】一方、低YR鋼管の製造法としては遠心鋳
造法、鋼管での熱処理(焼入、焼戻)等があるが、遠心
鋳造法はその生産性の低さ、経済性の面で、鋼管の熱処
理ではその経済性、鋼管の寸法精度の面で、鋼板の冷間
成形により製造した鋼管に比べ劣っていた。On the other hand, there are centrifugal casting method, heat treatment (quenching and tempering) in steel tube, etc. as the manufacturing method of the low YR steel pipe, but the centrifugal casting method has low productivity and economical efficiency. The heat treatment of the steel pipe was inferior to the steel pipe manufactured by cold forming the steel plate in terms of its economical efficiency and dimensional accuracy of the steel pipe.
【0004】[0004]
【発明が解決しようとする課題】本発明は、鋼板の冷間
成形によるYRが低い鋼管の製造技術を提供するもので
ある。本発明法に基づいて製造した鋼管は、低YRで且
つ高い生産性、経済性及び寸法精度を有している。SUMMARY OF THE INVENTION The present invention provides a technique for manufacturing a steel pipe having a low YR by cold forming a steel plate. The steel pipe manufactured based on the method of the present invention has low YR and high productivity, economy and dimensional accuracy.
【0005】[0005]
【課題を解決するための手段】前述の課題を克服し目的
を達成するための具体的手段を下記(1)、(2)に示
す。 (1)重量比でC 0.01〜0.20%、Si 0.
5%以下、Mn 0.5〜1.6%、P 0.03%以
下、S 0.01%以下、Ti 0.005〜0.02
5%、Al 0.06%以下、N 0.006%以下を
含有し、残部が鉄および不可避的不純物からなる鋼を9
00〜1200℃の温度範囲に再加熱して、950℃以
下の累積圧下量が30%以上で仕上温度がAr3 +12
0℃以下Ar3 −20℃以上となるように圧延を行った
後、鋼板をAr3 −20℃〜Ar3−100℃まで空冷
し、続いてこの温度から200℃以下まで焼き入れし、
Ac1 変態点以下の温度範囲で焼戻処理を施し、且つY
R≦80−0.8×t/Dに制御した鋼板を用いてt/
D≦10%の範囲で冷間成形により鋼管を製作すること
を特徴とする板厚100mm以下、管軸方向のYRが80
%以下である建築用低降伏比600N/mm2 級鋼管の製造
法。[Means for Solving the Problems] Specific means for overcoming the above problems and achieving the object are shown in the following (1) and (2). (1) C 0.01 to 0.20% by weight and Si 0.
5% or less, Mn 0.5 to 1.6%, P 0.03% or less, S 0.01% or less, Ti 0.005 to 0.02
Steel containing 5%, Al 0.06% or less, N 0.006% or less, and the balance iron and unavoidable impurities
It is reheated to a temperature range of 00 to 1200 ° C., the cumulative reduction amount of 950 ° C. or less is 30% or more, and the finishing temperature is Ar 3 +12.
After rolling to 0 ° C. or lower and Ar 3 −20 ° C. or higher, the steel sheet is air-cooled to Ar 3 −20 ° C. to Ar 3 −100 ° C., and subsequently quenched from this temperature to 200 ° C. or lower,
Tempered in the temperature range below the Ac 1 transformation point, and Y
Using a steel plate controlled to R ≦ 80−0.8 × t / D, t /
Steel pipes are manufactured by cold forming within the range of D ≦ 10%, the plate thickness is 100 mm or less, and the YR in the pipe axis direction is 80.
% Yield 600N / mm 2 class steel pipe for building with low yield ratio.
【0006】(2)重量比でC 0.01〜0.20
%、Si 0.5%以下、Mn 0.5〜1.6%、P
0.03%以下、S 0.01%以下、Ti 0.0
05〜0.025%、Al 0.06%以下、N 0.
006%以下さらにNi 0.05〜1.0%、Cu
0.05〜0.5%、Cr 0.05〜1.0%、Mo
0.05〜1.0%、Nb 0.005〜0.03%、
V 0.005〜0.05%、Ca 0.001〜0.
006%の1種または2種以上を含有し、残部が鉄およ
び不可避的不純物からなる鋼を900〜1200℃の温
度範囲に再加熱して、950℃以下の累積圧下量が30
%以上で仕上温度がAr3 +120℃以下Ar3 −20
℃以上となるように圧延を行った後、鋼板をAr3 −2
0℃〜Ar3 −100℃まで空冷し、続いてこの温度か
ら200℃以下まで焼き入れし、Ac1 変態点以下の温
度範囲で焼戻処理を施し、且つYR≦80−0.8×t
/Dに制御した鋼板を用いてt/D≦10%の範囲で冷
間成形により鋼管を製作することを特徴とする板厚10
0mm以下、管軸方向のYRが80%以下である建築用低
降伏比600N/mm2 級鋼管の製造法。(2) C 0.01 to 0.20 in weight ratio
%, Si 0.5% or less, Mn 0.5 to 1.6%, P
0.03% or less, S 0.01% or less, Ti 0.0
05-0.025%, Al 0.06% or less, N 0.
006% or less, Ni 0.05 to 1.0%, Cu
0.05-0.5%, Cr 0.05-1.0%, Mo
0.05-1.0%, Nb 0.005-0.03%,
V 0.005-0.05%, Ca 0.001-0.
Steel containing 006% of 1 type or 2 types or more and the balance consisting of iron and inevitable impurities is reheated to a temperature range of 900 to 1200 ° C., and a cumulative reduction amount of 950 ° C. or less is 30
% Or more and the finishing temperature is Ar 3 + 120 ° C. or less Ar 3 -20
After rolling to a temperature of ℃ or more, the steel plate is Ar 3 -2
Air cooling from 0 ° C to Ar 3 -100 ° C, followed by quenching from this temperature to 200 ° C or lower, tempering treatment in the temperature range of Ac 1 transformation point or lower, and YR ≤ 80-0.8xt.
A steel plate manufactured by cold forming in the range of t / D ≦ 10% using a steel plate controlled to be / D.
Manufacturing method for low yield ratio 600N / mm 2 class steel pipe for construction with 0mm or less and YR in the axial direction of 80% or less.
【0007】[0007]
【作用】以下、本発明について説明する。発明者らの研
究によれば、冷間加工後のYRを低くするには冷間加工
前の鋼板の材質制御、特にYRを低く制御することが必
要であることを見いだした。そこで本発明のポイントは
(1)冷間加工に供する鋼板に必要なYR値、(2)そ
のYR値以下に制御する製造法にある。The present invention will be described below. According to the research conducted by the inventors, it has been found that in order to reduce YR after cold working, it is necessary to control the material quality of the steel sheet before cold working, and particularly to control YR low. Therefore, the point of the present invention resides in (1) a YR value required for a steel sheet to be subjected to cold working, and (2) a manufacturing method in which the YR value is controlled to be the YR value or less.
【0008】再加熱温度を900〜1200℃の範囲に
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図るためである。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組織
となるため鋼の靭性が著しく劣化する。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Nb、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。The reason for limiting the reheating temperature to the range of 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 do not become extremely coarse during heating, and if the heating temperature exceeds this temperature, the austenite grains become coarsely mixed grains, and the structure after transformation becomes a coarse bainite structure. Is significantly deteriorated. 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, when precipitation hardening elements such as Nb and V are added, they do not form a solid solution sufficiently and the balance of strength and toughness deteriorates. Therefore, it is necessary to set the lower limit to 900 ° C.
【0009】上述のような条件で加熱したスラブを、9
50℃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Ar3 +120℃以下Ar3 −20℃以
上となるように圧延する。これは未再結晶域での圧延を
行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、仕上温度があまりにも高
すぎるとオーステナイト粒の微細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 +120℃とす
る必要がある。The slab heated under the above conditions was
Rolling is performed so that the cumulative reduction amount in the unrecrystallized region of 50 ° C. or less is 30% or more and the finishing temperature is Ar 3 + 120 ° C. or less and Ar 3 −20 ° C. or more. This is because the austenite grains are made finer by rolling in the unrecrystallized region. The lower limit of the finishing temperature was set to Ar 3 -20 ° C. is
This is because the toughness is not deteriorated by rolling in the (γ + α) region below the excessive transformation point. 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 + 120 ° C.
【0010】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 −1
00℃の間から常温まで焼入し、その後Ac1 変態点以
下の温度範囲で焼戻処理を行う必要がある。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焼入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。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。Next, the cooling conditions after rolling are as follows. This is air cooling after completion of rolling and the steel sheet temperature is Ar 3 -20 ° C. to Ar 3 -1.
It is necessary to quench from a temperature of 00 ° C. to room temperature and then to perform tempering treatment in a temperature range below the Ac 1 transformation point. The reason for this is that an appropriate amount of pro-eutectoid ferrite is precipitated and then untransformed austenite enriched with carbon is quenched to obtain a final structure of ferrite-bainite-martensite. 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.
【0011】さらに冷間成形(t/D≦10%)前の鋼
板のYR値を(80−0.8×t/D)以下に制御す
る。これは冷間成形後のYR値を80%以下に制御する
ためで、これ以上のYR値の鋼板では冷間成形によるY
Rの上昇により、鋼管でのYRが80%を超えてしま
う。Further, the YR value of the steel sheet before cold forming (t / D ≦ 10%) is controlled to be (80-0.8 × t / D) or less. This is to control the YR value after cold forming to 80% or less, and for steel plates with YR values higher than this, the Y by cold forming is used.
The increase in R causes YR in the steel pipe to exceed 80%.
【0012】次に成分範囲の限定理由について説明す
る。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0.0
1〜0.20%とした。Siは脱酸上、鋼に必然的に含
まれる元素であるが、Si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0.5%とし
た。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1.6%とした。Next, the reason for limiting the component range will be described. 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 such a viewpoint, C is 0.0
It was set to 1 to 0.20%. Si is an element that is inevitably contained in steel for deoxidation, but Si is an element that is unfavorable for HAZ toughness and weldability, so its upper limit was made 0.5%. Mn is an extremely important element that improves strength and toughness at the same time, and 0.5% or more is necessary. However, if added in a large amount, weldability, deterioration of toughness of the base metal and HAZ are deteriorated, so the upper limit is 1.6. %.
【0013】本発明鋼において不純物であるP、Sをそ
れぞれ0.03%、0.01%以下とした理由は、母
材、溶接部の低温靭性をより一層向上させるためであ
る。Pの低減は粒界破壊を防止し、S量の低減はMnS
による靭性の劣化を防止する。好ましいP、S量はそれ
ぞれ0.01%、0.005%以下である。The reason why the impurities P and S in the steel of the present invention are 0.03% and 0.01% or less, respectively, is to further improve the low temperature toughness of the base material and the welded portion. Reduction of P prevents grain boundary destruction, and reduction of S amount reduces MnS
To prevent deterioration of toughness. The preferred P and S contents are 0.01% and 0.005% or less, respectively.
【0014】Tiは炭窒化物を形成してHAZ靭性を向
上させる。Al量が少ない場合、Tiの酸化物を形成し
HAZ靭性を向上させるが、0.005%未満では効果
がなく、0.025%を超えるとHAZ靭性に好ましく
ない影響があるため、0.005〜0.025%に限定
する。Ti forms carbonitrides and improves HAZ toughness. When the amount of Al is small, Ti oxide is formed to improve the HAZ toughness, but if it is less than 0.005%, it has no effect, and if it exceeds 0.025%, it has an unfavorable effect on the HAZ toughness. Limited to ~ 0.025%.
【0015】Alは一般に脱酸上鋼に含まれる元素であ
るが、Si及びTiによっても脱酸は行われるので本発
明鋼については下限は限定しない。しかしAl量が多く
なると鋼の清浄度が悪くなり、溶接部の靭性が劣化する
ので上限を0.06%とした。Al is generally an element contained in deoxidized upper steel, but since Si and Ti also perform deoxidation, the lower limit is not limited for the steel of the present invention. However, if the amount of Al increases, the cleanliness of the steel deteriorates and the toughness of the welded portion deteriorates, so the upper limit was made 0.06%.
【0016】Nは一般的に不可避的不純物として鋼中に
含まれるものであるが、Nb、Vと結合して炭窒化物を
形成して強度を増加させ、またTiNを形成して前述の
ようにHAZの性質を高める。このためN量として最低
0.001%が必要である。しかしながらN量が多くな
るとHAZ靭性の劣化や連続鋳造スラブの表面キズの発
生等を助長するので、その上限を0.006%とした。N is generally contained in steel as an unavoidable impurity, but it is combined with Nb and V to form a carbonitride to increase the strength, and TiN is formed to form the same as described above. Enhances the properties of HAZ. Therefore, the N content must be at least 0.001%. However, if the amount of N increases, it deteriorates the HAZ toughness and the occurrence of surface flaws in the continuously cast slab, so the upper limit was made 0.006%.
【0017】本発明鋼の基本成分は以上のとおりであ
り、十分に目的を達成できるが、さらに目的に対し特性
を高めるため、以下に述べる元素即ちCu、Ni、C
r、Mo、Nb、V、Caを選択的に添加すると強度、
靭性の向上について、さらに好ましい結果が得られる。The basic components of the steel of the present invention are as described above, and the object can be sufficiently achieved. However, in order to further improve the characteristics for the object, the elements described below, namely Cu, Ni, and C.
Strength is obtained by selectively adding r, Mo, Nb, V, and Ca.
Further favorable results are obtained with respect to improvement in toughness.
【0018】次に、前記添加元素とその添加量について
説明する。Niは溶接性、HAZ靭性に悪影響を及ぼす
ことなく、母材の強度、靭性を向上させるが、0.05
%以下では効果が薄く、1.0%以上では極めて高価に
なるため経済性を失うので、上限は1.0%とした。C
uはNiとほぼ同様な効果を持つほか、Cu析出物によ
る強度の増加や耐食性や耐候性の向上にも効果を有す
る。この場合Cu量が0.5%を超えるとその析出効果
が著しく熱処理において過度の析出効果によりYRの低
下が困難になり、また0.05%以下では効果がないの
でCu量は0.05〜0.5%に限定する。Next, the above-mentioned additional element and its addition amount will be described. Ni improves the strength and toughness of the base metal without adversely affecting the weldability and HAZ toughness.
% Or less, the effect is thin, and if 1.0% or more, the cost is extremely high and the economy is lost. Therefore, the upper limit was made 1.0%. C
u has an effect similar to that of Ni, and also has an effect of increasing strength due to Cu precipitates and improving corrosion resistance and weather resistance. In this case, when the amount of Cu exceeds 0.5%, the precipitation effect is remarkable, and it becomes difficult to lower YR due to the excessive precipitation effect in the heat treatment. Limited to 0.5%.
【0019】Moは母材の強度、靭性を共に向上させる
元素であるが、0.05%以下では効果が薄く、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0.05〜1.0%に限定する。Mo is an element that improves both the strength and toughness of the base material, but if the content is 0.05% or less, the effect is small and 1.0
%, The weld zone toughness and weldability are deteriorated, which is not preferable, so the content is limited to 0.05 to 1.0%.
【0020】Crは母材及び溶接部の強度を高める元素
であり、Cr量が0.5%以上で耐候性も向上するが、
1.0%を超えると溶接性やHAZ靭性を劣化させ、ま
た0.05%以下では効果が薄い。従ってCr量は0.
05〜1.0%とする。Cr is an element that enhances the strength of the base material and the welded portion. When the amount of Cr is 0.5% or more, the weather resistance is also improved.
If it exceeds 1.0%, the weldability and HAZ toughness are deteriorated, and if it is 0.05% or less, the effect is small. Therefore, the Cr amount is 0.
05 to 1.0%.
【0021】Nbは微細な炭窒化物を形成し、強度を増
加させ、またHAZ靭性を向上させる。しかし、0.0
05%以下では効果がなく、0.03%を超えると熱処
理で過度の析出効果により鋼板のYR低下の妨げにな
る。VはNbとほぼ同じ効果をもつ元素であるが、Nb
に比較して析出効果能はやや劣る。0.005%以下で
は効果が少なく、0.05%を超えると熱処理で過度の
析出効果により鋼板のYR低下の妨げになる。Nb forms fine carbonitrides to increase strength and improve HAZ toughness. But 0.0
If it is less than 05%, there is no effect, and if it exceeds 0.03%, the YR of the steel sheet is hindered due to the excessive precipitation effect in the heat treatment. V is an element that has almost the same effect as Nb, but Nb
The precipitation effect is slightly inferior to that of. If it is less than 0.005%, the effect is small, and if it exceeds 0.05%, the YR of the steel sheet is hindered by the excessive precipitation effect in the heat treatment.
【0022】Caは硫化物(MnS)の形態を制御し、
シャルピー吸収エネルギーを増加させ低温靭性を向上さ
せる効果がある。しかしCa量は0.001%未満では
実用上効果がなく、0.006%を超えるとCaO、C
aSが多量に生成して大型介在物となり、鋼の靭性のみ
ならず清浄度も害し溶接性、耐ラメラテア性にも悪影響
を与えるので、Ca添加量の範囲を0.001〜0.0
06%とする。Ca controls the morphology of sulfide (MnS),
It has the effect of increasing Charpy absorbed energy and improving low temperature toughness. However, if the amount of Ca is less than 0.001%, there is no practical effect, and if it exceeds 0.006%, CaO, C
A large amount of aS is generated and becomes large inclusions, which not only impairs the toughness of steel but also the cleanliness and adversely affects the weldability and lamella tear resistance. Therefore, the range of Ca addition amount is 0.001 to 0.0
It is set to 06%.
【0023】[0023]
【実施例】周知の転炉、連続鋳造、厚板工程により鋼板
を製造し、その後冷間成形で鋼管を製作し、その強度、
靭性について調査した。表1の1〜9に本発明鋼、10
〜18に比較鋼の化学成分を示す。表2に本発明鋼と比
較鋼の鋼板製造条件とその機械的性質を示す。表2の本
発明鋼1〜9は、鋼管での強度、靭性がバランスよく達
成できており、YRも80%以下となっている。[Example] A steel plate is manufactured by a well-known converter, continuous casting, and thick plate process, and then a steel pipe is manufactured by cold forming.
The toughness was investigated. Inventive steels 10 to 1 to 9 in Table 1
18 to 18 show the chemical composition of comparative steels. Table 2 shows the steel plate manufacturing conditions and the mechanical properties of the present invention steel and the comparative steel. The steels 1 to 9 of the present invention in Table 2 have achieved a well-balanced strength and toughness in the steel pipe, and the YR is also 80% or less.
【0024】これに対し比較鋼10では仕上温度が高い
ために結晶粒の細粒化が十分になされておらず、靭性が
劣化している。比較鋼11は950℃以下の圧下率が低
いために結晶粒の細粒化が十分になされておらず、靭性
が劣化している。比較鋼12では加熱温度が高いために
結晶粒の細粒化が十分になされておらず、靭性が劣化し
ている。比較鋼13では冷却開始温度が低いために強度
が低下している。比較鋼14では冷却開始温度が高いた
めに、鋼板のYRが高くなり鋼管のYRも高くなってい
る。比較鋼15では仕上温度が低いために、靭性が劣化
している。比較鋼16では鋼板の降伏比(YR)が高い
(>80−0.8×t/D)ために、鋼管のYRが高く
なっている。比較鋼17ではNbが高いために、鋼板の
YRが高く鋼管でのYRも高くなっている。比較鋼18
ではVが高いために、鋼板のYRが高く鋼管でのYRも
高くなっている。On the other hand, in Comparative Steel 10, since the finishing temperature is high, the grain size of the crystal grains is not sufficiently reduced, and the toughness is deteriorated. Comparative Steel 11 has a low rolling reduction of 950 ° C. or lower, so that the crystal grains are not sufficiently refined and the toughness is deteriorated. In Comparative Steel 12, since the heating temperature is high, the grain size of the crystal grains is not sufficiently reduced, and the toughness is deteriorated. In Comparative Steel 13, the strength is lowered because the cooling start temperature is low. In Comparative Steel 14, since the cooling start temperature is high, the YR of the steel plate is high and the YR of the steel pipe is also high. In Comparative Steel 15, the toughness is deteriorated because the finishing temperature is low. In Comparative Steel 16, the YR of the steel pipe is high because the yield ratio (YR) of the steel plate is high (> 80−0.8 × t / D). Since the comparative steel 17 has a high Nb, the YR of the steel plate is high and the YR of the steel pipe is also high. Comparative steel 18
However, since V is high, YR of the steel plate is high and YR of the steel pipe is also high.
【0025】[0025]
【表1】 [Table 1]
【0026】[0026]
【表2】 [Table 2]
【0027】[0027]
【発明の効果】本発明の化学成分及び製造法で製造した
鋼管は、YRが低く降伏後の塑性変形能力に優れた鋼管
である。その結果、建築、橋梁等の構造物の安全性を大
きく高めることができる。INDUSTRIAL APPLICABILITY The steel pipe manufactured by the chemical composition and manufacturing method of the present invention has a low YR and an excellent plastic deformation ability after yielding. As a result, the safety of structures such as buildings and bridges can be greatly improved.
Claims (2)
以下、 Mn:0.5〜1.6%、 P :0.03
%以下、 S :0.01%以下、 Ti:0.00
5〜0.025%、 Al:0.06%以下、 N :0.00
6%以下 を含有し、残部が鉄および不可避的不純物からなる鋼を
900〜1200℃の温度範囲に再加熱して、950℃
以下の累積圧下量が30%以上で仕上温度がAr3 +1
20℃以下Ar3 −20℃以上となるように圧延を行っ
た後、鋼板をAr3 −20℃〜Ar3 −100℃まで空
冷し、続いてこの温度から200℃以下まで焼き入れ
し、Ac1 変態点以下の温度範囲で焼戻処理を施し、且
つ降伏比(YR)≦80−0.8×t/D(t:板厚、
D:鋼管外径)に制御した鋼板を用いて冷間成形により
鋼管を製作することを特徴とする建築用低降伏比600
N/mm2級鋼管の製造法。1. A weight ratio of C: 0.01 to 0.20% and Si: 0.5%.
Hereinafter, Mn: 0.5 to 1.6%, P: 0.03
% Or less, S: 0.01% or less, Ti: 0.00
5 to 0.025%, Al: 0.06% or less, N: 0.00
Steel containing 6% or less and the balance consisting of iron and unavoidable impurities is reheated to a temperature range of 900 to 1200 ° C. to 950 ° C.
The following cumulative reduction is 30% or more and the finishing temperature is Ar 3 +1
After rolling to 20 ° C. or lower Ar 3 −20 ° C. or higher, the steel sheet is air-cooled to Ar 3 −20 ° C. to Ar 3 −100 ° C., and subsequently quenched from this temperature to 200 ° C. or lower, Ac A tempering process is performed in a temperature range of 1 transformation point or lower, and a yield ratio (YR) ≦ 80−0.8 × t / D (t: plate thickness,
D: Steel pipe outer diameter controlled) to produce a steel pipe by cold forming using a steel plate, and a low yield ratio for construction 600
N / mm 2 class steel pipe manufacturing method.
以下、 Mn:0.5〜1.6%、 P :0.03
%以下、 S :0.01%以下、 Ti:0.00
5〜0.025%、 Al:0.06%以下、 N :0.00
6%以下 さらに Ni:0.05〜1.0%、 Cu:0.05
〜0.5%、 Cr:0.05〜1.0%、 Mo:0.05
〜1.0%、 Nb:0.005〜0.03%、 V :0.00
5〜0.05%、 Ca:0.001〜0.006% の1種または2種以上を含有し、残部が鉄および不可避
的不純物からなる鋼を900〜1200℃の温度範囲に
再加熱して、950℃以下の累積圧下量が30%以上で
仕上温度がAr3 +120℃以下Ar3 −20℃以上と
なるように圧延を行った後、鋼板をAr3 −20℃〜A
r3 −100℃まで空冷し、続いてこの温度から200
℃以下まで焼き入れし、Ac1 変態点以下の温度範囲で
焼戻処理を施し、且つ降伏比(YR)≦80−0.8×
t/Dに制御した鋼板を用いて冷間成形により鋼管を製
作することを特徴とする建築用低降伏比600N/mm2 級
鋼管の製造法。2. C: 0.01 to 0.20% and Si: 0.5% by weight.
Hereinafter, Mn: 0.5 to 1.6%, P: 0.03
% Or less, S: 0.01% or less, Ti: 0.00
5 to 0.025%, Al: 0.06% or less, N: 0.00
6% or less Ni: 0.05 to 1.0%, Cu: 0.05
~ 0.5%, Cr: 0.05-1.0%, Mo: 0.05
-1.0%, Nb: 0.005-0.03%, V: 0.00
5 to 0.05%, Ca: 0.001 to 0.006%, containing 1 or 2 or more kinds, and the balance consisting of iron and unavoidable impurities, the steel is reheated to a temperature range of 900 to 1200 ° C. Then, after rolling such that the cumulative reduction amount of 950 ° C. or less is 30% or more and the finishing temperature is Ar 3 + 120 ° C. or less Ar 3 −20 ° C. or more, the steel sheet is Ar 3 −20 ° C. to A.
Air cool to r 3 -100 ° C., then continue from this temperature to 200
Quenched to ℃ or less, tempered in the temperature range of Ac 1 transformation point or less, and yield ratio (YR) ≦ 80-0.8 ×
A method for manufacturing a low yield ratio 600N / mm 2 class steel pipe for construction, characterized by manufacturing a steel pipe by cold forming using a steel sheet controlled to t / D.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5273293A JPH06264143A (en) | 1993-03-12 | 1993-03-12 | Production of steel tube with low yield ratio for construction use by cold forming |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5273293A JPH06264143A (en) | 1993-03-12 | 1993-03-12 | Production of steel tube with low yield ratio for construction use by cold forming |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH06264143A true JPH06264143A (en) | 1994-09-20 |
Family
ID=12923107
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP5273293A Withdrawn JPH06264143A (en) | 1993-03-12 | 1993-03-12 | Production of steel tube with low yield ratio for construction use by cold forming |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH06264143A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007119899A (en) * | 2005-09-28 | 2007-05-17 | Kobe Steel Ltd | 490 MPa-CLASS LOW-YIELD RATIO COLD-FORMED STEEL PIPE HAVING EXCELLENT WELDABILITY AND ITS PRODUCTION METHOD |
-
1993
- 1993-03-12 JP JP5273293A patent/JPH06264143A/en not_active Withdrawn
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007119899A (en) * | 2005-09-28 | 2007-05-17 | Kobe Steel Ltd | 490 MPa-CLASS LOW-YIELD RATIO COLD-FORMED STEEL PIPE HAVING EXCELLENT WELDABILITY AND ITS PRODUCTION METHOD |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4572748A (en) | Method of manufacturing high tensile strength steel plates | |
JPH0615689B2 (en) | Method of manufacturing low yield ratio high strength steel | |
JPH06128631A (en) | Production of high manganese ultrahigh tensile strength steel excellent in low temperature toughness | |
JP3228986B2 (en) | Manufacturing method of high strength steel sheet | |
JPH07109521A (en) | Production of 600n/mm2 class steel tube with low yield ratio for construction use by cold forming | |
JPH04285118A (en) | Production of hot forged non-heattreated steel having high strength and high toughness | |
JPH07150247A (en) | Production of steel tube with high strength and low yield ratio for construction use | |
JP3229107B2 (en) | Manufacturing method of low yield ratio high strength steel sheet with excellent uniform elongation | |
JP2529042B2 (en) | Manufacturing method of low yield ratio steel pipe for building by cold forming. | |
JPH03207814A (en) | Manufacture of low yield ratio high tensile strength steel plate | |
JP2529044B2 (en) | Manufacturing method of low yield ratio steel pipe for building by cold forming. | |
JPH0649541A (en) | Production of low yield ratio building steel pipe by cold forming | |
JPH06264143A (en) | Production of steel tube with low yield ratio for construction use by cold forming | |
JPH06264144A (en) | Production of steel tube with low yield ratio for construction use by cold forming | |
JP3497250B2 (en) | Method for producing low-yield ratio 590 N / mm2 class high strength steel with excellent weldability | |
JPS63179019A (en) | Manufacture of high tension steel plate having low yield ratio | |
JPH06128641A (en) | Production of steel tube with low yield ratio for construction use by cold forming | |
JP2529045B2 (en) | Manufacturing method of low yield ratio 60kgf / mm2 grade steel pipe for construction by cold forming | |
JP2708540B2 (en) | Method for producing high-strength steel sheet mainly composed of ferrite structure | |
JPH07207334A (en) | Production of high tension steel having excellent weldability and plastic deformability | |
JPH07207335A (en) | Production of high tensile steel which is excellent in weldability and high in uniform elongation | |
JPS63128117A (en) | Production of unnormalized high tensile steel | |
JPH06248336A (en) | Production of 780n/mm2 class high tensile strength steel excellent in weldability and reduced in yield ratio | |
JPH04314824A (en) | Production of 70kgf/mm2 class high tensile strength steel excelent in weldability and having low yield ratio | |
JPH0641632A (en) | Production of ni-reduced heat treated steel |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 20000530 |