JP3999915B2 - ERW steel pipe for cold forging with excellent workability and its manufacturing method - Google Patents
ERW steel pipe for cold forging with excellent workability and its manufacturing method Download PDFInfo
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Description
【０００１】
【発明の属する技術分野】
本発明は、優れた加工性が要求される自動車用、機械構造用電縫鋼管に関し、特定の成分と製造方法により優れた特性を有する加工性に優れた冷間鍛造用電縫鋼管とその製造方法に関する。
【０００２】
【従来の技術】
従来、冷間鍛造に際し、その変形抵抗を下げて冷間鍛造性の向上を図るために、軟質化処理が行われ、その手段の一つとしてセメンタイトの球状化焼鈍処理が行われている。この球状化焼鈍処理は、例えば特開昭５９−１３６４２１号公報などに見られるようにＡ1 点以上の温度に加熱した後、１０℃／ｈ程度の超徐冷で連続冷却する方法で行われている。しかしながら、これでは処理時間が非常に長くなり工業的に不利である。一方、焼鈍時間の短縮を目的として連続冷却の冷却速度を速くしたり、あるいはＡ1 点直下の保定時間を短くするような試み行うと、結果として強度、硬さが増加しいずれも軟質化の目的を達成できない。
【０００３】
【発明が解決しようとする課題】
冷間鍛造用電縫鋼管として加工性を向上させるためには電縫鋼管に造管後、熱処理により軟質化することが効果的である。本発明は加工性に優れた冷間鍛造用電縫鋼管とその製造方法を提供するものである。
【０００４】
【課題を解決するための手段】
その発明の要旨とするところは、重量％で、Ｃ：０．１０〜０．５０％、Ｓｉ：０．０１〜０．５０％、Ｍｎ：０．１〜２．０％、Ｓ：０．０３％以下、Ｐ：０．０３％以下、Ａｌ：０．０１〜０．１０％、Ｎ：０．００３０％以下に、さらに必要に応じて、Ｃｒ：０．０５〜１．０％、Ｎｉ：０．１〜２．０％、Ｃｕ：０．１〜２．０％、Ｍｏ：０．０５〜１．０％、Ｖ：０．０３〜０．２％、Ｔｉ：０．０１〜０．２％、Ｎｂ：０．０１〜０．２％、Ｂ：０．００１％以下、Ｃａ：０．０００２〜０．００２０％のうち一種または二種以上含有し、残部が鉄および不可避不純物からなり組織中の炭化物の占める割合が面積率にして３０％以下、炭化物の球状化率が８０％以上で、かつ硬さがＨｖ１００〜１８０であることを特徴とする加工性に優れた冷間鍛造用電縫鋼管であり、これらの電縫鋼管を製造する方法としては電縫鋼管を（ＡＣ1 点−１００℃）〜ＡＣ1 点に再加熱し、その温度で５〜１８０分保持した後、空冷することである。または、電縫溶接部の均一化を図るためにＡＣ3 点〜（ＡＣ3 点＋５０℃）に再加熱し、その後（ＡＣ1 点−１００℃）〜ＡＣ1 点未満の温度まで空冷し、その温度で５〜１８０分保持した後、空冷することである。
【０００５】
【発明の実施の形態】
本発明の特徴は組織中の炭化物の占める割合が面積率にして３０％以下でこの炭化物の球状化率が８０％以上で、かつ硬さがＨｖ１００〜１８０であることを特徴とする加工性の優れた冷間鍛造用電縫鋼管であり、これらの電縫鋼管を製造する方法としては電縫鋼管を（ＡＣ1 点−１００℃）〜ＡＣ1 点に再加熱し、その温度で５〜１８０分保持した後、空冷することである。または、電縫溶接部の均一化を図るためにＡＣ3 点〜（ＡＣ3 点＋５０℃）に再加熱し、その後（ＡＣ1 点−１００℃）〜ＡＣ1 点未満の温度まで空冷し、その温度で５〜１８０分保持した後、空冷することを特徴とする加工性に優れた冷間鍛造用電縫鋼管とその製造方法である。
【０００６】
以下に本発明の加工性に優れた冷間鍛造用電縫鋼管とその製造方法について詳細に説明する。はじめに鋼の化学成分の限定理由について説明する。
Ｃはセメンタイト相を形成し、製品の強度確保に重要であり、Ｃは０．１０％以上必要である。一方、Ｃが０．５０％を越えるとセメンタイト量が過剰になり強度、硬さが著しく高くなる。したがって、Ｃは０．１０〜０．５０％とする。Ｓｉは脱酸剤として必須の成分であり、固溶強化あるいは焼き入れ性の増大効果を通じて製品の強度確保に重要な成分である。しかしながら、０．５０％を越えると高周波により電縫溶接したとき電縫溶接部に酸化反応生成物（微小粒状酸化物）が生成しやすくなる。また、熱延時に発生するスケ−ルによって鋼管の表面に凹凸が発生しやすくなる。一方、製品の強度確保の観点からＳｉは０．０１％以上必要である。したがって、Ｓｉは０．０１〜０．５０％とする。
【０００７】
Ｍｎは焼き入れ性の増大効果を通じて製品の強度確保に重要な成分である。しかし過剰に添加すると強度、硬さが著しく高くなるため、上限を２．０％とした。一方、Ｍｎの下限はＳ脆化防止のため０．１％とした。したがって、Ｍｎは０．１〜２．０％とする。
Ｓ、Ｐはいずれも冷間鍛造性に有害な元素である。いずれも０．０３％を越えると悪影響が顕著になるので、これ以下に限定した。
Ａｌは脱酸剤として作用するが、鋼中のＮと結合しオ−ステナイト結晶粒度の粗大化を抑制する。オ−ステナイト粒の粗大化抑制のためには０．０１％以上の添加を必要とする。一方、Ａｌが０．１０％を越えるとオ−ステナイト結晶粒粗大化抑制効果は飽和し、さらに冷間鍛造性が劣化する。したがって、Ａｌは０．０１〜０．１０％とする。
【０００８】
Ｎは固溶Ｎとして存在すると冷間鍛造中において、ひずみ時効を生じて冷間鍛造性を悪化させるため、極力低いことが望ましい。本発明においてはＡｌ等により固溶Ｎを窒化物として固定しているため、極端な低減は必要ないが、Ｎが過度に多いと窒化物として固定されない固溶Ｎの量が増加する恐れがある。したがって、Ｎは０．００３０％以下とする。
Ｃｒは焼き入れ性を向上し、強度ならびに靱性を高めると共に炭化物の形成を助長し耐摩耗性を向上させるのに有効である。この効果は０．０５％以上で顕著になるためこの値を下限とする。しかし、１．０％を越えると冷間鍛造性が劣化するとともに添加コストが上昇する。したがって、Ｃｒは０．０５〜１．０％とする。
【０００９】
Ｎｉは焼き入れ性を向上させる効果があるが、充分添加しなければ効果は顕著に現れず高価でもあるので下限を０．１％とした。一方、添加量が多くなると強度、硬さが高くなるので上限を２．０％とした。したがって、Ｎｉは０．１〜２．０％とする。
Ｃｕは強い固溶強化性を有し、焼き入れ性を向上させ少量の添加は切削性を向上させる作用があるが、０．１％より少ないと効果が認められない。一方、２．０％を越えると熱間加工性を著しく劣化させる。したがって、Ｃｕは０．１〜２．０％とする。
【００１０】
Ｍｏは炭化物を形成する元素であり、また焼き入れ性を向上させる元素で焼き入れ性および耐摩耗性向上のために添加する。しかし、０．０５％未満では焼き入れ性および耐摩耗性が不十分であり、１．０％を越えると冷間鍛造性が劣化する。したがって、Ｍｏは０．０５〜１．０％とする。
ＶはＡｌと同様にＮの固定に効果のある元素であり、その効果を得るには０．０３％以上必要である。しかし、過剰な添加はＶ炭窒化物の析出強化により冷間鍛造性を阻害する恐れがあるため０．２％を上限とした。したがって、Ｖは０．０３〜０．２％とする。
【００１１】
ＴｉはＶ、Ａｌと同様にＮの固定に効果のある元素であり、その効果を得るには０.０１％以上必要である。しかし、過剰な添加はＴｉ炭窒化物の析出強化により冷間鍛造性を阻害する恐れがあるため０．２％を上限とした。したがって、Ｔｉは０．０１〜０．２％とする。
ＮｂはＶ、Ｔｉ、Ａｌと同様にＮの固定に効果のある元素であり、その効果を得るには０．０１％以上必要である。しかし、過剰な添加はＮｂ炭窒化物の析出強化により冷間鍛造性を阻害する恐れがあるため０．２％を上限とした。したがって、Ｎｂは０．０１〜０．２％とする。
【００１２】
ＢはＮとの親和力が強く、Ａｌと同様に固溶Ｎの固定に効果がある元素である。しかし、過剰な添加はＢ炭窒化物を過剰に生成し冷間鍛造性を低下させるさせる恐れがあるため０．００１％を上限とした。したがって、Ｂは０．００１％以下とする。
Ｃａは、介在物の形態を調整し、冷間加工性を向上するのに有効である。Ｃａは多すぎると鋼中の介在物が増し逆に冷間加工性を劣化させる。したがって、Ｃａは０．０００２〜０．００２０％とする。
【００１３】
上記の組成を満足する鋼を熱処理により軟質化する理由は次の通りである。
熱処理法としては球状化焼鈍を用いる。球状化焼鈍を用いるのは変形能に有害な層状炭化物をなくし、球状炭化物とすることにより変形能を向上させるとともに軟質化することにより冷間鍛造性を良好にするためである。本発明では優れた冷間鍛造性を得るために硬さをＨｖ１００〜１８０を得るために組織中の炭化物の占める割合が面積率にして３０％以下、炭化物の球状化率が８０％以上と限定した。
【００１４】
次に、電縫鋼管に造管後、軟質化処理のための熱処理条件について説明する。熱処理条件として、（ＡＣ1 点−１００℃）〜ＡＣ1 点に再加熱し、その温度で５〜１８０分保持した後、空冷する。まず、（ＡＣ1 点−１００℃）以上に限定したのは（ＡＣ1 点−１００℃）以下では炭化物の球状化が不十分で冷間加工性の向上が少ない。一方、ＡＣ1 点以上では一部がオ−ステナイト化され炭化物の一部が再固溶される。オ−ステナイトはその後の冷却によりフェライト＋パ−ライトに変態し冷間加工性が劣化する。以上のことから本熱処理での加熱温度を（ＡＣ1 点−１００℃）〜ＡＣ1 点とした。
【００１５】
加熱時間を５〜１８０分に保持した理由について説明する。加熱時間が５分以下では炭化物の球状化が不十分で冷間鍛造性の向上が少ない。一方、１８０分以上では炭化物の球状化が進行するが鋼の硬さの低下代は飽和してしまう。さらには熱処理時間が増すことで、製造コストが高くなる。以上のことから本熱処理での加熱時間を５分〜１８０分とした。
【００１６】
さらに冷間鍛造性を向上させるためには電縫溶接部と母材部の均一化が重要である。そのためには上記の熱処理前にＡＣ3 点〜（ＡＣ3 点＋５０℃）の温度に再加熱する。ＡＣ3 点以下では完全にオ−ステナイト化されないため組織の均一化が達成できない。一方、（ＡＣ3 点＋５０℃）以上ではオ−ステナイト粒径が大きくなり、軟質化にはよいが特定の強度、硬さが得られない。以上のことからＡＣ3 点〜（ＡＣ3 点＋５０℃）の温度の再加熱しその後、上記に記載した熱処理を行うことで電縫溶接部と母材部が均一化され、さらに冷間鍛造性は向上する。本発明のように特性の成分系と熱処理条件により優れた特性を有する加工性に優れた冷間鍛造用電縫鋼管が得られる。
【００１７】
【実施例】
表１に鋼板の化学成分を示す。表２に造管後の熱処理条件を示す。表３に本発明により製造された電縫鋼管および比較で製造された電縫鋼管の特性を示す。表３から明らかのように、本発明により製造された電縫鋼管は組織中の炭化物の占める割合が面積率にして３０％以下、炭化物の球状化率が８０％以上で、かつ硬さがＨｖ１００〜１８０である。本発明法により製造された電縫鋼管の硬さは熱処理前後で著しく低下している。
【００１８】
【表１】
【表２】
【表３】
【発明の効果】
本発明法により製造された電縫鋼管は、組織中の炭化物の占める割合が面積率にして３０％以下、炭化物の球状化率が８０％以上で、かつ硬さがＨｖ１００〜１８０と熱処理前後の硬さの低下が顕著である。今後、自動車および機械構造用部品のコスト削減の観点から安価で加工性の良好な冷間鍛造用電縫鋼管の要求がますます増える。したがって、本発明により製造された電縫鋼管の効果は極めて大きいものである。[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to an electric resistance welded steel pipe for automobiles and machine structures that requires excellent workability, and an electric resistance welded steel pipe for cold forging having excellent characteristics by a specific component and a manufacturing method and its manufacture. Regarding the method.
[0002]
[Prior art]
Conventionally, in cold forging, in order to lower the deformation resistance and improve cold forgeability, softening treatment has been performed, and cementite spheroidization annealing has been performed as one of the means. This spheroidizing annealing treatment is performed by a method of heating to a temperature of A 1 point or higher and then continuously cooling by ultra-slow cooling of about 10 ° C./h as seen in, for example, Japanese Patent Application Laid-Open No. 59-136421. ing. However, this is very disadvantageous industrially because the processing time becomes very long. On the other hand, or the cooling rate of continuous cooling for the purpose of shortening the annealing time or performed attempted so as to shorten the inter-coercive scheduled immediately below A 1 point, resulting in intensity, both increases the hardness of the softened The goal cannot be achieved.
[0003]
[Problems to be solved by the invention]
In order to improve workability as an electric-welded steel pipe for cold forging, it is effective to make the electric-welded steel pipe soft by heat treatment after it is formed. The present invention provides an electric-welded steel pipe for cold forging excellent in workability and a method for producing the same.
[0004]
[Means for Solving the Problems]
The gist of the invention is weight%, C: 0.10 to 0.50%, Si: 0.01 to 0.50%, Mn: 0.1 to 2.0%, S: 0.00. 03% or less, P: 0.03% or less, Al: 0.01 to 0.10%, N: 0.0030% or less, and if necessary, Cr: 0.05 to 1.0%, Ni : 0.1-2.0%, Cu: 0.1-2.0%, Mo: 0.05-1.0%, V: 0.03-0.2%, Ti: 0.01-0 .2%, Nb: 0.01 to 0.2%, B: 0.001% or less, Ca: 0.0002 to 0.0020%, or one or two or more types, with the balance from iron and inevitable impurities The proportion of carbides in the structure is 30% or less in terms of area ratio, the spheroidization rate of carbides is 80% or more, and the hardness is Hv 100 to 180. An excellent electric resistance welded steel pipe for cold forging in coatability, these as a method for producing an electric resistance welded steel pipe is reheated electric resistance welded steel pipe (AC 1 point -100 ° C.) to Ac 1 point, at that temperature After holding for 5 to 180 minutes, air cooling. Or, reheated to AC 3 point ~ (AC 3 point + 50 ° C.) in order to achieve uniform electric resistance welding unit, air-cooled to thereafter (AC 1 point -100 ° C.) to Ac less than 1 point temperature, the It is air-cooled after holding at temperature for 5 to 180 minutes.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The feature of the present invention is that the proportion of carbide in the structure is 30% or less in terms of area ratio, the spheroidization rate of this carbide is 80% or more, and the hardness is Hv 100 to 180. excellent an electric resistance welded steel pipe for forging cold, the electric resistance welded steel pipe as a method for producing these electric resistance welded steel pipe (AC 1 point -100 ° C.) was reheated to to Ac 1 point, at temperature 5 to 180 It is air cooling after holding for a minute. Or, reheated to AC 3 point ~ (AC 3 point + 50 ° C.) in order to achieve uniform electric resistance welding unit, air-cooled to thereafter (AC 1 point -100 ° C.) to Ac less than 1 point temperature, the It is an electric-welded steel pipe for cold forging excellent in workability, characterized in that it is air-cooled after being held at temperature for 5 to 180 minutes, and a method for producing the same.
[0006]
The electric forging steel pipe for cold forging excellent in workability of the present invention and the manufacturing method thereof will be described in detail below. First, the reasons for limiting the chemical composition of steel will be described.
C forms a cementite phase and is important for securing the strength of the product, and C needs to be 0.10% or more. On the other hand, when C exceeds 0.50%, the amount of cementite becomes excessive and the strength and hardness are remarkably increased. Therefore, C is set to 0.10 to 0.50%. Si is an essential component as a deoxidizer, and is an important component for securing the strength of the product through the effect of solid solution strengthening or hardenability. However, if it exceeds 0.50%, an oxidation reaction product (fine particulate oxide) tends to be generated in the ERW weld when high frequency welding is performed. In addition, irregularities are likely to occur on the surface of the steel pipe due to the scale generated during hot rolling. On the other hand, 0.01% or more of Si is necessary from the viewpoint of securing the strength of the product. Therefore, Si is made 0.01 to 0.50%.
[0007]
Mn is an important component for securing the strength of the product through the effect of increasing hardenability. However, when added excessively, the strength and hardness are remarkably increased, so the upper limit was made 2.0%. On the other hand, the lower limit of Mn is set to 0.1% to prevent S embrittlement. Therefore, Mn is set to 0.1 to 2.0%.
S and P are both elements harmful to the cold forgeability. In any case, if it exceeds 0.03%, the adverse effect becomes remarkable, so it was limited to this.
Al acts as a deoxidizer, but combines with N in the steel to suppress coarsening of the austenite grain size. In order to suppress coarsening of austenite grains, addition of 0.01% or more is required. On the other hand, if Al exceeds 0.10%, the effect of suppressing austenite grain coarsening is saturated, and cold forgeability deteriorates. Therefore, Al is set to 0.01 to 0.10%.
[0008]
If N is present as solute N, it is desirable that it be as low as possible because it causes strain aging and deteriorates cold forgeability during cold forging. In the present invention, since solid solution N is fixed as nitride by Al or the like, an extreme reduction is not necessary, but if N is excessively large, the amount of solid solution N that is not fixed as nitride may increase. . Therefore, N is set to 0.0030% or less.
Cr is effective for improving the hardenability, increasing the strength and toughness, promoting the formation of carbides, and improving the wear resistance. Since this effect becomes significant at 0.05% or more, this value is set as the lower limit. However, if it exceeds 1.0%, the cold forgeability deteriorates and the addition cost increases. Therefore, Cr is made 0.05 to 1.0%.
[0009]
Ni has the effect of improving the hardenability, but if it is not added sufficiently, the effect does not appear remarkably and is expensive, so the lower limit was made 0.1%. On the other hand, the strength and hardness increase as the amount added increases, so the upper limit was made 2.0%. Therefore, Ni is made 0.1 to 2.0%.
Cu has a strong solid solution strengthening property and improves the hardenability, and the addition of a small amount has the effect of improving the machinability, but if it is less than 0.1%, the effect is not recognized. On the other hand, when it exceeds 2.0%, hot workability is remarkably deteriorated. Therefore, Cu is made 0.1 to 2.0%.
[0010]
Mo is an element that forms carbides, and is an element that improves hardenability and is added to improve hardenability and wear resistance. However, if it is less than 0.05%, the hardenability and wear resistance are insufficient, and if it exceeds 1.0%, the cold forgeability deteriorates. Therefore, Mo is set to 0.05 to 1.0%.
V, like Al, is an element effective in fixing N, and 0.03% or more is necessary to obtain the effect. However, excessive addition may impair the cold forgeability due to precipitation strengthening of V carbonitride, so the upper limit was made 0.2%. Therefore, V is 0.03 to 0.2%.
[0011]
Ti, like V and Al, is an element effective in fixing N, and 0.01% or more is necessary to obtain the effect. However, excessive addition may impair the cold forgeability due to precipitation strengthening of Ti carbonitride, so the upper limit was made 0.2%. Therefore, Ti is set to 0.01 to 0.2%.
Nb is an element that is effective in fixing N like V, Ti, and Al, and needs to be 0.01% or more to obtain the effect. However, excessive addition may impair the cold forgeability due to precipitation strengthening of Nb carbonitride, so the upper limit was made 0.2%. Therefore, Nb is set to 0.01 to 0.2%.
[0012]
B is an element that has a strong affinity for N and is effective in fixing solute N as with Al. However, excessive addition may cause excessive formation of B carbonitride and lower the cold forgeability, so 0.001% was made the upper limit. Therefore, B is 0.001% or less.
Ca is effective in adjusting the form of inclusions and improving cold workability. When there is too much Ca, inclusions in the steel increase and conversely the cold workability deteriorates. Therefore, Ca is 0.0002 to 0.0020%.
[0013]
The reason why the steel satisfying the above composition is softened by heat treatment is as follows.
Spheroidizing annealing is used as the heat treatment method. The reason why the spheroidizing annealing is used is to eliminate the layered carbide harmful to the deformability and improve the cold forgeability by improving the deformability and softening by using the spherical carbide. In the present invention, in order to obtain excellent cold forgeability, in order to obtain a hardness of Hv 100 to 180, the proportion of carbide in the structure is limited to 30% or less in terms of area ratio, and the spheroidization rate of carbide is limited to 80% or more. did.
[0014]
Next, heat treatment conditions for softening treatment will be described after forming the ERW steel pipe. As heat treatment conditions, and reheated to (1 point -100 ° C. AC) to Ac 1 point, after holding 5 to 180 minutes at that temperature and air cooling. First, the reason why it is limited to (AC 1 point-100 ° C.) or more is that (AC 1 point-100 ° C.) or less, the carbide is insufficiently spheroidized and the cold workability is hardly improved. On the other hand, at AC 1 or more, a part is austenitized and a part of the carbide is re-dissolved. Austenite is transformed into ferrite + pearlite by subsequent cooling, and the cold workability deteriorates. The heating temperature in this heat treatment (AC 1 point -100 ° C.) to Ac 1 point from the above.
[0015]
The reason why the heating time is kept at 5 to 180 minutes will be described. When the heating time is 5 minutes or less, the spheroidization of the carbide is insufficient and the cold forgeability is not improved. On the other hand, in 180 minutes or more, the spheroidization of carbide proceeds, but the decrease in the hardness of the steel is saturated. Furthermore, the manufacturing cost increases due to the increase in the heat treatment time. From the above, the heating time in this heat treatment was set to 5 minutes to 180 minutes.
[0016]
Furthermore, in order to improve cold forgeability, it is important to make the ERW weld and the base metal uniform. For this purpose, reheating is performed to a temperature of AC 3 point to (AC 3 point + 50 ° C.) before the heat treatment. When AC is 3 points or less, it is not completely austenitic, so that the structure cannot be made uniform. On the other hand, at (AC 3 point + 50 ° C.) or more, the austenite particle size becomes large and it is good for softening, but specific strength and hardness cannot be obtained. From the above, AC 3 point to (AC 3 point + 50 ° C) is reheated, and then the heat treatment described above is performed to make the ERW weld and base material uniform, and further, cold forgeability. Will improve. As in the present invention, it is possible to obtain an electric-welded steel pipe for cold forging with excellent workability having excellent characteristics due to the characteristic component system and heat treatment conditions.
[0017]
【Example】
Table 1 shows the chemical components of the steel sheet. Table 2 shows the heat treatment conditions after pipe making. Table 3 shows the characteristics of the ERW steel pipe manufactured according to the present invention and the ERW steel pipe manufactured by comparison. As is apparent from Table 3, the ratio of carbide in the structure is 30% or less, the spheroidization rate of carbide is 80% or more, and the hardness is Hv100. ~ 180. The hardness of the ERW steel pipe manufactured by the method of the present invention is remarkably reduced before and after the heat treatment.
[0018]
[Table 1]
[Table 2]
[Table 3]
【The invention's effect】
The ratio of the proportion of carbide in the structure produced by the method of the present invention to the area ratio is 30% or less, the spheroidization ratio of carbide is 80% or more, and the hardness is Hv 100 to 180, before and after heat treatment. The decrease in hardness is remarkable. In the future, there will be an increasing demand for ERW steel pipes for cold forging, which are cheap and have good workability, from the viewpoint of cost reduction of automobile and machine structural parts. Therefore, the effect of the electric resistance welded steel pipe manufactured according to the present invention is extremely great.
Claims (3)
Ｃ ：０．１０〜０．５０％、
Ｓｉ：０．０１〜０．５０％、
Ｍｎ：０．１〜２．０％、
Ｓ ：０．０３％以下
Ｐ ：０．０３％以下、
Ａｌ：０．０１〜０．１０％、
Ｎ ：０．００３０％以下に、
さらに必要に応じて
Ｃｒ：０．０５〜１．０％、
Ｎｉ：０．１〜２．０％、
Ｃｕ：０．１〜２．０％、
Ｍｏ：０．０５〜１．０％、
Ｖ：０．０３〜０．２％、
Ｔｉ：０．０１〜０．２％、
Ｎｂ：０．０１〜０．２％、
Ｂ：０．００１％以下、
Ｃａ：０．０００２〜０．００２０％のうち一種または二種以上含有し、残部が鉄および不可避不純物からなり組織中の炭化物の占める割合が面積率にして３０％以下、炭化物の球状化率が８０％以上で、かつ硬さがＨｖ１００〜１８０であることを特徴とする加工性に優れた冷間鍛造用電縫鋼管。% By weight
C: 0.10 to 0.50%,
Si: 0.01 to 0.50%,
Mn: 0.1 to 2.0%,
S: 0.03% or less P: 0.03% or less,
Al: 0.01 to 0.10%,
N: 0.0030% or less,
If necessary, Cr: 0.05-1.0%
Ni: 0.1 to 2.0%,
Cu: 0.1 to 2.0%,
Mo: 0.05-1.0%,
V: 0.03-0.2%,
Ti: 0.01-0.2%
Nb: 0.01-0.2%
B: 0.001% or less,
Ca: One or two or more of Ca: 0.0002 to 0.0020%, the balance being iron and inevitable impurities, and the proportion of carbide in the structure is 30% or less in terms of area ratio, and the spheroidization rate of carbide is An electric-welded steel pipe for cold forging excellent in workability, characterized by being 80% or more and having a hardness of Hv 100 to 180.
Ｃ ：０．１０〜０．５０％、
Ｓｉ：０．０１〜０．５０％、
Ｍｎ：０．１〜２．０％、
Ｓ ：０．０３％以下、
Ｐ ：０．０３％以下、
Ａｌ：０．０１〜０．１０％、
Ｎ ：０．００３０％以下に、
さらに必要に応じて
Ｃｒ：０．０５〜１．０％、
Ｎｉ：０．１〜２．０％、
Ｃｕ：０．１〜２．０％、
Ｍｏ：０．０５〜１．０％、
Ｖ：０．０３〜０．２％、
Ｔｉ：０．０１〜０．２％、
Ｎｂ：０．０１〜０．２％、
Ｂ：０．００１％以下、
Ｃａ：０．０００２〜０．００２０のうち一種または二種以上含有し、残部が鉄および不可避不純物からなる電縫鋼管を熱処理するに際し、（ＡＣ1 点−１００℃）〜ＡＣ1 点に再加熱し、その温度で５〜１８０分保持した後、空冷することを特徴とする加工性に優れた冷間鍛造用電縫鋼管の製造方法。% By weight
C: 0.10 to 0.50%,
Si: 0.01 to 0.50%,
Mn: 0.1 to 2.0%,
S: 0.03% or less,
P: 0.03% or less,
Al: 0.01 to 0.10%,
N: 0.0030% or less,
If necessary, Cr: 0.05-1.0%
Ni: 0.1 to 2.0%,
Cu: 0.1 to 2.0%,
Mo: 0.05-1.0%,
V: 0.03-0.2%,
Ti: 0.01-0.2%
Nb: 0.01-0.2%
B: 0.001% or less,
Ca: containing one or two or more of 0.0002 to 0.0020, when heat-treating the electric resistance welded steel pipe balance of iron and inevitable impurities, reheated to (AC 1 point -100 ° C.) to Ac 1 point A method for producing an electric-welded steel pipe for cold forging excellent in workability, characterized by holding the temperature for 5 to 180 minutes and then air-cooling.
Ｃ ：０．１０〜０．５０％、
Ｓｉ：０．０１〜０．５０％、
Ｍｎ：０．１〜２．０％、
Ｓ ：０．０３％以下、
Ｐ ：０．０３％以下、
Ａｌ：０．０１〜０．１０％、
Ｎ ：０．００３０％以下に、
さらに必要に応じて
Ｃｒ：０．０５〜１．０％、
Ｎｉ：０．１〜２．０％、
Ｃｕ：０．１〜２．０％、
Ｍｏ：０．０５〜１．０％、
Ｖ：０．０３〜０．２％、
Ｔｉ：０．０１〜０．２％、
Ｎｂ：０．０１〜０．２％、
Ｂ：０．００１％以下、
Ｃａ：０．０００２〜０．００２０％のうち一種または二種以上含有し、残部が鉄および不可避不純物からなる電縫鋼管を熱処理するに際し、ＡＣ3 点〜（ＡＣ3 点＋５０℃）に再加熱し、その後（ＡＣ1 点−１００℃）〜ＡＣ1 点未満の温度まで空冷し、その温度で５〜１８０分保持した後、空冷することを特徴とする加工性に優れた冷間鍛造用電縫鋼管の製造方法。% By weight
C: 0.10 to 0.50%,
Si: 0.01 to 0.50%,
Mn: 0.1 to 2.0%,
S: 0.03% or less,
P: 0.03% or less,
Al: 0.01 to 0.10%,
N: 0.0030% or less,
If necessary, Cr: 0.05-1.0%
Ni: 0.1 to 2.0%,
Cu: 0.1 to 2.0%,
Mo: 0.05-1.0%,
V: 0.03-0.2%,
Ti: 0.01-0.2%
Nb: 0.01-0.2%
B: 0.001% or less,
Ca: One or two or more of 0.0002 to 0.0020% contained, and when heat-treating an ERW steel pipe consisting of iron and inevitable impurities, reheating from AC 3 point to (AC 3 point + 50 ° C.) and thereafter (AC 1 point -100 ° C.) air-cooled to a temperature of ~AC less than 1 point, its was held 5 to 180 minutes at a temperature, excellent cold forging electroconductive workability, characterized by cooling Manufacturing method of sewn steel pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31315999A JP3999915B2 (en) | 1999-11-04 | 1999-11-04 | ERW steel pipe for cold forging with excellent workability and its manufacturing method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP31315999A JP3999915B2 (en) | 1999-11-04 | 1999-11-04 | ERW steel pipe for cold forging with excellent workability and its manufacturing method |
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| Publication Number | Publication Date |
|---|---|
| JP2001131702A JP2001131702A (en) | 2001-05-15 |
| JP3999915B2 true JP3999915B2 (en) | 2007-10-31 |
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| JP4486516B2 (en) * | 2004-05-21 | 2010-06-23 | 新日本製鐵株式会社 | ERW steel pipe excellent in cold workability and hardenability and its manufacturing method |
| WO2018139672A1 (en) * | 2017-01-30 | 2018-08-02 | 新日鐵住金株式会社 | Steel pipe for underbody components of automobiles, and underbody component of automobiles |
| WO2018139671A1 (en) * | 2017-01-30 | 2018-08-02 | 新日鐵住金株式会社 | Steel pipe for underbody components of automobiles, and underbody component of automobiles |
| CN118613600A (en) * | 2022-02-10 | 2024-09-06 | 日本制铁株式会社 | Electric welded steel pipe for automobile parts and method for manufacturing automobile parts |
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