JP2745848B2 - High-strength ERW steel pipe for automobiles with excellent fatigue properties - Google Patents
High-strength ERW steel pipe for automobiles with excellent fatigue propertiesInfo
- Publication number
- JP2745848B2 JP2745848B2 JP3059268A JP5926891A JP2745848B2 JP 2745848 B2 JP2745848 B2 JP 2745848B2 JP 3059268 A JP3059268 A JP 3059268A JP 5926891 A JP5926891 A JP 5926891A JP 2745848 B2 JP2745848 B2 JP 2745848B2
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- strength
- erw
- less
- fatigue
- 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.)
- Expired - Fee Related
Links
Description
【０００１】[0001]
【産業上の利用分野】本発明は、引張強さ70〜120kgf/m
m2の高強度を有し、しかも疲労特性に優れた自動車用高
強度電縫鋼管に関するものである。The present invention relates to a tensile strength of 70 to 120 kgf / m.
The present invention relates to a high-strength ERW steel pipe for automobiles having a high strength of m 2 and excellent in fatigue properties.
【０００２】[0002]
【従来の技術】近年、電縫鋼管製造技術の進展に伴い、
プロペラシャフト、インパクトバー等の自動車用構造部
材に対して、電縫鋼管の適用が著しい伸びを見せてい
る。しかし、その電縫鋼管には自動車用構造部材を軽量
化し、燃費の向上や高出力化を図るために薄肉および小
径化が要求されており、そのため、更なる高強度化が強
く望まれるようになってきているが、電縫鋼管の自動車
用構造部材としての使用を考えた場合、単に静的な強度
を向上させるだけでは不十分であり、荷重の繰り返しに
対する耐久性（以下、疲労特性という）も同時に向上さ
せる必要がある。ところが、自動車用構造部材としての
電縫鋼管は実車に装着される際に他の部材、例えば、プ
ロペラシャフトにヨークを溶接して使用されるが、プロ
ペラシャフトに使われる電縫鋼管を高強度化してもヨー
クを溶接した継手溶接部や電縫溶接部において前記疲労
特性に関連した幾つかの問題が生じる場合がある。2. Description of the Related Art In recent years, with the development of ERW steel pipe manufacturing technology,
The application of ERW steel pipes to structural members for automobiles such as propeller shafts and impact bars has shown remarkable growth. However, the electric resistance welded steel pipe is required to have a thinner wall and a smaller diameter in order to reduce the weight of structural members for automobiles, improve fuel efficiency and increase output, and as a result, it is strongly desired to further increase strength. However, considering the use of ERW steel pipes as structural members for automobiles, simply increasing the static strength is not enough, and the durability against repeated load (hereinafter referred to as fatigue property) is not enough. Need to be improved at the same time. However, ERW steel tubes as structural members for automobiles are used by welding other members, for example, a yoke to a propeller shaft when they are mounted on an actual vehicle. However, some problems related to the fatigue characteristics may occur in a joint weld or an electric resistance weld in which the yoke is welded.
【０００３】その一つは、変態強化や加工強化機構を利
用して高強度化した電縫鋼管の場合には、溶接時の入熱
によって溶接部近傍の熱影響部が軟化をきたし、引張強
度の増加に対応した疲労特性の向上が得られないという
問題である。One of the problems is that, in the case of an ERW steel pipe whose strength is enhanced by utilizing a transformation strengthening or processing strengthening mechanism, the heat-affected zone near the welded portion is softened by the heat input during welding, and the tensile strength is increased. The problem is that it is not possible to obtain an improvement in the fatigue characteristics corresponding to the increase in fatigue.
【０００４】特開平２−197525号公報に、このような熱
影響部の軟化を解消する一つの方法が提案されており、
NbとCr又はMoの１種以上を複合添加する成分設計とし、
この成分設計の鋼を熱間圧延して熱延鋼板とする際に、
熱間圧延の条件を適正に調整すると、継手溶接部の熱影
響部が軟化しにくい疲労特性に優れた自動車用高強度電
縫鋼管を得ることができると記載されている。しかしな
がら、この方法でも次に述べるようなもう一つの問題に
よる疲労特性の低下を解消することができない。即ち、
電縫鋼管の電縫溶接部およびその熱影響部に疲労亀裂が
発生し、疲労寿命を低下させるという問題である。この
疲労亀裂は従来の高強度電縫鋼管の全てに生ずるという
ものではなく、量産した場合にある確率で発生するもの
であるが、自動車の生産台数を考えた場合、こうした問
題はとうてい容認できるものではなく、工業上極めて重
要な問題となる。Japanese Patent Application Laid-Open No. Hei 2-197525 proposes one method for eliminating such softening of the heat-affected zone.
Nb and one or more of Cr or Mo are added as a component design,
When hot rolling steel with this composition design into a hot rolled steel sheet,
It is described that by appropriately adjusting the conditions of hot rolling, it is possible to obtain a high-strength ERW steel pipe for automobiles having excellent fatigue characteristics in which the heat-affected zone of the welded joint is less likely to soften. However, even with this method, deterioration in fatigue characteristics due to another problem described below cannot be solved. That is,
The problem is that fatigue cracks occur in the ERW welded portion of the ERW steel pipe and the heat-affected zone thereof, thereby reducing the fatigue life. This fatigue crack does not occur in all conventional high-strength ERW pipes, but occurs at a certain probability in mass production. Rather, it is a very important industrial issue.
【０００５】[0005]
【発明が解決しようとする課題】本発明の課題は、上記
のような自動車用高強度電縫鋼管における問題を解消す
ることにあり、詳しくは、工業的規模で安定に量産する
ことができる電縫鋼管であって、電縫溶接部および継手
溶接部ともに十分な疲労特性を有し、引張強度が70〜12
0kgf/mm2の高強度を具備した自動車用高強度電縫鋼管を
提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in high-strength ERW steel tubes for automobiles, and more specifically, to achieve stable mass production on an industrial scale. A sewn steel pipe, which has sufficient fatigue characteristics in both the electric resistance welded part and the joint welded part, and has a tensile strength of 70 to 12
An object of the present invention is to provide a high-strength ERW steel pipe for automobiles having a high strength of 0 kgf / mm 2 .
【０００６】[0006]
【課題を解決するための手段】本発明者らは、上記課題
を達成すべく数多くの実験を繰り返しながら研究を重ね
た結果、素材鋼の成分、特にNb、MoおよびTiのそれぞれ
の含有量を適正に調整することによって、非常に優れた
疲労特性を有する信頼性の高い高強度電縫鋼管が得られ
ることを見出した。Means for Solving the Problems The inventors of the present invention have repeatedly conducted many experiments in order to achieve the above object, and as a result, have found that the content of the material steel, particularly the respective contents of Nb, Mo and Ti, have been reduced. It has been found that by properly adjusting, a highly reliable high-strength ERW pipe having very excellent fatigue characteristics can be obtained.
【０００７】即ち、Nb含有量を0.01〜0.10％、Mo含有量
を0.05〜0.8 ％の範囲にそれぞれ調整すると、極めて微
細で熱的に安定した組織が得られ、継手溶接部の軟化に
よる強度低下が抑制されること、これに加えて、Ti含有
量を0.005 〜0.04％の範囲に調整すると、継手溶接部の
疲労特性が更に向上するとともに、電縫溶接部の靭性が
改善されるので、電縫溶接部の疲労特性も格段に向上す
るのである。特に、微量Tiの添加は従来解決できなかっ
た電縫溶接部に疲労亀裂が発生し、疲労寿命が低下する
問題に対して、極めて有効である。That is, when the Nb content is adjusted to 0.01 to 0.10% and the Mo content is adjusted to 0.05 to 0.8%, an extremely fine and thermally stable structure is obtained, and the strength is reduced by the softening of the joint weld. In addition, if the Ti content is adjusted in the range of 0.005 to 0.04%, the fatigue properties of the joint weld are further improved, and the toughness of the ERW weld is improved. The fatigue characteristics of the seam weld are also significantly improved. In particular, the addition of a small amount of Ti is extremely effective against the problem that fatigue cracks occur in the ERW weld, which has not been able to be solved conventionally, and the fatigue life is reduced.
【０００８】本発明は、上記知見に基づいてなされたも
のであって、その要旨は下記の化学組成を有する電縫鋼
管にある。[0008] The present invention has been made based on the above findings, and a gist of the invention resides in an electric resistance welded steel pipe having the following chemical composition.
【０００９】 重量％で、Ｃ：０．０６〜０．３０
％、Ｓｉ：１．０％以下、Ｍｎ：２．０％以下、Ｍｏ：
０．０５〜０．８％、Ｎｂ：０．０１〜０．１０％、Ｔ
ｉ：０．００５〜０．０４％、Ｓｏｌ．Ａｌ：０．００
５〜０．０５％を含有し、残部はＦｅおよび不可避不純
物からなり、不純物のＰ、ＳおよびＮの含有量が、Ｐ：
０．０１８％以下、Ｓ：０．００５％以下、Ｎ：０．０
０８％以下であることを特徴とする疲労特性に優れた自
動車用高強度電縫鋼管。In weight%, C: 0.06-0.30
%, Si: 1.0% or less, Mn: 2.0% or less, Mo:
0.05 to 0.8%, Nb: 0.01 to 0.10%, T
i: 0.005 to 0.04%, Sol. Al: 0.00
5 to 0.05%, the balance being Fe and unavoidable impurities, and the contents of impurities P, S and N are as follows :
0.018% or less , S: 0.005% or less, N: 0.0
A high strength electric resistance welded steel pipe for automobiles having excellent fatigue properties, characterized by being at most 08%.
【００１０】 上記１に記載の成分に加えてさら
に、重量％で、Ｃｒ：０．５％未満、Ｎｉ：３．０％以
下、Ｃｕ：１．０％以下、Ｖ：０．１０％以下および
Ｂ：０．０００５〜０．００２０％のうちの１種以上を
含有することを特徴とする疲労特性に優れた自動車用高
強度電縫鋼管。[0010] In addition to the components described in the above 1, further by weight : Cr: less than 0.5% , Ni: 3.0% or less, Cu: 1.0% or less, V: 0.10% or less, B: A high-strength ERW steel pipe for automobiles having excellent fatigue properties, characterized by containing one or more of 0.0005 to 0.0020%.
【００１１】[0011]
【作用】以下に、本発明における電縫鋼管の化学組成を
上記のように限定する理由を説明する。なお、成分含有
量の「％」は「重量％」を意味する。The reason for limiting the chemical composition of the electric resistance welded steel pipe in the present invention as described above will be described below. In addition, “%” of the component content means “% by weight”.
【００１２】Ｃ：Ｃは自動車用高強度電縫鋼管として必
要な高強度を確保するために添加する成分である。しか
し、その含有量が0.06％より少ないと引張強度が70kgf/
mm2 を下回り、0.30％より多いと継手溶接部および電縫
溶接部の靱性が低下し、疲労特性の向上が得られないの
で、その含有量を0.06〜0.30％とした。C: C is a component added to secure a high strength required for a high strength electric resistance welded steel pipe for an automobile. However, if the content is less than 0.06%, the tensile strength is 70 kgf /
below the mm 2, it reduces the toughness of greater than 0.30% and the joint weld part and electric resistance welding unit, because the improvement of fatigue characteristics can not be obtained, and the content thereof from 0.06 to .30%.
【００１３】Si：Siは脱酸作用のほか、鋼の強度を高め
る作用を有しており、所望の高強度を確保する上から必
要な成分であるが、その含有量が1.0％を超えると母材
(電縫鋼管) 、継手溶接部および電縫溶接部の靱性に悪
影響が現れるとともに、電縫溶接部に溶接欠陥が発生し
やすくなり、疲労特性の向上が得られないので、その含
有量を 1.0％以下とした。Si: Si has an effect of increasing the strength of steel in addition to a deoxidizing effect, and is a necessary component for securing a desired high strength. Base material
(ERW pipes), the toughness of joint welds and ERW welds is adversely affected, and welding defects are likely to occur in ERW welds, and improvement in fatigue properties cannot be obtained. % Or less.
【００１４】Mn：Mnも所望の高強度を得るために添加す
る成分であり、また、Mnには組織を微細化して疲労特性
を向上させる効果がある。しかし、 2.0％を超えて含有
すると電縫溶接部に欠陥が発生しやすくなり、かえって
疲労強度が低下するので、その含有量を 2.0％以下とし
た。Mn: Mn is also a component added to obtain a desired high strength, and Mn has the effect of making the structure finer and improving the fatigue characteristics. However, if the content exceeds 2.0%, defects are likely to occur in the ERW weld, and the fatigue strength is rather reduced. Therefore, the content is set to 2.0% or less.
【００１５】Mo：Moも固溶強化を通して鋼管を高強度化
するとともに、継手溶接部の熱影響部（ＨＡＺ部）の軟
化を抑制して、疲労特性を向上させる作用を有してい
る。しかし、その含有量が0.05％未満では所望の効果が
得られず、 0.8％を超えると母材部、継手溶接部および
電縫溶接部の靱性が低下し、疲労特性の向上が見られな
いので、その含有量を0.05〜0.8 ％とした。Mo: Mo also has the effect of increasing the strength of the steel pipe through solid solution strengthening and also suppressing the softening of the heat-affected zone (HAZ portion) of the joint weld and improving the fatigue properties. However, if the content is less than 0.05%, the desired effect cannot be obtained, and if it exceeds 0.8%, the toughness of the base material, the joint weld, and the ERW weld decreases, and no improvement in the fatigue properties is observed. , The content of which is 0.05-0.8%.
【００１６】Nb：Nbは主に析出物を生成することによっ
て、強度上昇をもたらすと同時に組織を微細化して母材
の靱性を向上させる効果がある。また、Nbには継手溶接
部のＨＡＺ部の軟化を抑制し、電縫溶接部およびＨＡＺ
部の靱性を向上させ、疲労強度を増加させる効果もあ
る。しかし、これらの効果はその含有量が0.01％未満で
は期待できず、0.10％を超えると逆に電縫溶接部の靱性
が低下するので、その含有量を0.01〜0.10％とした。Nb: Nb mainly produces precipitates, thereby increasing the strength and at the same time, has the effect of refining the structure and improving the toughness of the base material. In addition, Nb suppresses the softening of the HAZ portion of the joint welded portion, and the electric resistance welded portion and the HAZ
It also has the effect of improving the toughness of the part and increasing the fatigue strength. However, these effects cannot be expected if the content is less than 0.01%, and if it exceeds 0.10%, on the contrary, the toughness of the electric resistance welded portion is reduced. Therefore, the content is set to 0.01 to 0.10%.
【００１７】Ti：Tiは母材と電縫溶接部および継手溶接
部の組織の微細化を促進するとともに、電縫溶接部の靱
性を改善して疲労強度特性を向上させるのに必要な成分
である。Ti: Ti is a component required to promote the refinement of the microstructure of the base metal, the ERW weld and the joint weld, and to improve the toughness of the ERW weld to improve the fatigue strength characteristics. is there.
【００１８】しかし、その含有量が 0.005％未満では所
望の効果が得られず、0.04％を超えるとかえって疲労強
度が低下するので、その含有量を0.005 〜0.04％とし
た。However, if the content is less than 0.005%, the desired effect cannot be obtained, and if it exceeds 0.04%, the fatigue strength is rather reduced. Therefore, the content is made 0.005 to 0.04%.
【００１９】Sol.Al：Alは鋼の脱酸および組織の微細化
に有効な成分であるが、その含有量がSol.Al量で 0.005
％より少ないとこれらの効果が十分に得られず、0.05％
を超えると電縫溶接部の靱性および疲労特性に悪影響を
及ぼすので、その含有量を0.005 〜0.05％とした。Sol.Al: Al is an effective component for deoxidizing steel and refining the structure, but its content is 0.005 in terms of Sol.Al content.
%, These effects are not sufficiently obtained, and 0.05%
If the content exceeds 0.005%, the toughness and fatigue properties of the ERW weld are adversely affected, so the content was made 0.005 to 0.05%.
【００２０】Cr、Ni、Cu、ＶおよびＢ：Cr、Ni、Cu、Ｖ
およびＢはいずれも鋼管の強度、靱性あるいは疲労特性
を改善する作用を有しているので、これらの特性を更に
改善したい場合には、上記の成分に加えて、１種又は２
種以上を添加してもよい。これらの成分の含有量を特定
の範囲に限定した理由は下記の通りである。Cr, Ni, Cu, V and B: Cr, Ni, Cu, V
And B all have the effect of improving the strength, toughness or fatigue properties of the steel pipe. Therefore, in order to further improve these properties, in addition to the above components, one or two kinds of
Seeds or more may be added. The reasons for limiting the contents of these components to specific ranges are as follows.
【００２１】Ｃｒ：Ｃｒは鋼管の強度および耐食性を向
上させるとともに、継手溶接部の軟化を抑制する作用を
有しているが、０．５％以上含有させると母材および電
縫溶接部の靱性が低下する他に、電縫溶接部に溶接欠陥
が発生しやすくなるので、その含有量は０．５％未満と
するのがよい。Cr: Cr has the effect of improving the strength and corrosion resistance of the steel pipe and suppressing the softening of the welded joint. However, if it is contained in an amount of 0.5% or more , the toughness of the base metal and the ERW welded part is improved. In addition to the decrease in the content, it is easy for welding defects to occur in the electric resistance welded portion. Therefore, the content is preferably less than 0.5% .
【００２２】Ni：Niは鋼管の強度、靱性および耐食性を
向上させる作用を有しているが、高価な元素であり、ま
た 3.0％を超えると電縫溶接部の靱性劣化を招くので、
その含有量は 3.0％以下とするのがよい。Ni: Ni has the effect of improving the strength, toughness and corrosion resistance of the steel pipe, but is an expensive element, and if it exceeds 3.0%, the toughness of the ERW weld is deteriorated.
Its content should be less than 3.0%.
【００２３】Cu：Cuは鋼管の強度および耐食性を向上さ
せる作用を有しているが、 1.0％を超えると熱間加工性
が低下し、しかも電縫溶接部の靱性も低下するので、そ
の含有量は 1.0％以下とするのがよい。Cu: Cu has the effect of improving the strength and corrosion resistance of the steel pipe. However, if it exceeds 1.0%, the hot workability is reduced and the toughness of the ERW weld is also reduced. The amount should be less than 1.0%.
【００２４】Ｖ：Ｖは析出物を生成して鋼管の強度を高
め、且つ継手溶接部の軟化抵抗も高める作用を有してい
るが、0.10％を超えると母材および電縫溶接部の靱性が
低下するので、その含有量は0.10％以下とするのがよ
い。V: V has the effect of forming precipitates to increase the strength of the steel pipe and also increase the softening resistance of the welded joint, but if it exceeds 0.10%, the toughness of the base metal and the electric resistance welded joint is increased. Therefore, its content is preferably 0.10% or less.
【００２５】Ｂ：Ｂは鋼管の強度を高める作用を有して
いるが、0.0005％未満では所望の強度上昇が望めず、0.
0020％を超えると母材、電縫溶接部および継手溶接部の
靱性低下が顕著になるので、その含有量は0.0005〜0.00
20％とするのがよい。B: B has the effect of increasing the strength of the steel pipe, but if it is less than 0.0005%, a desired increase in strength cannot be expected, and B is not sufficient.
If the content exceeds 0020%, the toughness of the base metal, the electric resistance welded portion and the joint welded portion becomes remarkable, so the content is 0.0005 to 0.00
20% is good.
【００２６】本発明の電縫鋼管は、上記成分の他、残部
はFeおよび不可避不純物である。不純物として代表的な
元素はＰ、ＳおよびＮであり、これらの成分は靭性や疲
労特性を損ねるので、その含有量は下記のように限定す
る。In the ERW steel pipe of the present invention, in addition to the above components, the balance is Fe and unavoidable impurities. Typical elements as impurities are P, S, and N. Since these components impair toughness and fatigue characteristics, their contents are limited as follows.
【００２７】Ｐ：Ｐは鋼中で偏析して母材、継手溶接部
および電縫溶接部の靱性を低下させるので、その含有量
を０．０１８％以下に抑える。P: Since P segregates in the steel and lowers the toughness of the base metal, the joint weld and the electric resistance weld, its content is suppressed to 0.018% or less .
【００２８】Ｓ：ＳはMnやFe等と結合して非金属介在物
を生成し、疲労特性を低下させるので、その含有量を
0.005％以下に抑える。S: S combines with Mn, Fe, etc. to form non-metallic inclusions and lowers fatigue characteristics.
Keep it below 0.005%.
【００２９】Ｎ：Ｎは母材および溶接部の靱性を著しく
損ねるとともに疲労特性も低下させるので、その含有量
を 0.008％以下に抑える。N: N significantly impairs the toughness of the base metal and the weld and also reduces the fatigue properties, so its content is suppressed to 0.008% or less.
【００３０】本発明の電縫鋼管は、上記化学組成を有す
る素材鋼を熱間圧延して鋼帯とし、これを通常の工程で
電縫鋼管とすることにより得られる。前記通常の工程と
は、鋼帯を管状に成形した後、高周波電流により相対向
するエッジ部を加熱して溶融させ、スクイズロールによ
り加圧圧接して製管する工程をいう。The electric resistance welded steel pipe of the present invention is obtained by hot rolling material steel having the above-mentioned chemical composition into a steel strip, which is made into an electric resistance welded steel pipe in a usual process. The normal process is a process of forming a steel strip into a tubular shape, heating and melting opposing edge portions by high-frequency current, and pressing and pressing with a squeeze roll to form a tube.
【００３１】[0031]
【実施例】表１に示す成分組成を有する鋼を溶製し、鋼
片に鋳造したのち熱間圧延して板厚 1.6mmの熱延鋼板と
した。次いで、通常の電縫鋼管製造工程により外径65mm
の電縫鋼管に製管した。表２にこれらの電縫鋼管の機械
的性質を示す。EXAMPLE A steel having the composition shown in Table 1 was melted, cast into a billet, and then hot-rolled into a hot-rolled steel sheet having a thickness of 1.6 mm. Then, the outer diameter of 65 mm by the normal ERW steel pipe manufacturing process
Of ERW steel pipe. Table 2 shows the mechanical properties of these ERW steel pipes.
【００３２】次いで、これらの電縫鋼管を短管に切断
し、それぞれの短管の両端に別途準備した接続体を溶接
し、継手モデル体を作製した。継手モデル体は、図１に
示すように鋼管１の両端（図では一端側のみを示す）
に、鋼管との接合側２を内ぐりにより径65.5mm×肉厚2.
1mm のリング状断面に加工した炭素鋼 (Ｓ55Ｃ) の接続
体３を、摩擦圧力：５kgf/mm2 、アプセット圧力：10kg
f/mm2 、アプセット時間：５秒、加熱寄代： 2.5mm、軸
回転数：1800rpm の条件の摩擦溶接法にて溶接し、鋼管
毎にそれぞれ２体づつ作製した。なお、鋼管側に疲労損
傷が生じさせるために、この実施例では接続体の内ぐり
部の肉厚を鋼管の肉厚より 0.5mm厚くした。Next, these ERW steel pipes were cut into short pipes, and separately prepared connecting bodies were welded to both ends of each short pipe to produce a joint model body. As shown in FIG. 1, the joint model body has both ends of the steel pipe 1 (only one end is shown in the figure).
Then, the inner diameter of the joint side 2 with the steel pipe is 65.5 mm x wall thickness 2.
A carbon steel (S55C) connector 3 machined into a 1 mm ring-shaped cross section was rubbed with a friction pressure of 5 kgf / mm 2 and an upset pressure of 10 kg.
f / mm 2 , upset time: 5 seconds, heat allowance: 2.5 mm, shaft rotation speed: 1800 rpm Welded by a friction welding method under the conditions of 2 pieces for each steel pipe. In addition, in order to cause fatigue damage on the steel pipe side, in this example, the thickness of the inner bore of the connection body was set to be 0.5 mm thicker than the thickness of the steel pipe.
【００３３】こうして作製したそれぞれの継手モデル体
に対して、トルク振幅180kgf・m の繰り返しねじり荷重
を負荷する疲労試験を行い、ねじり疲労寿命を調査し
た。調査は各鋼管毎に作製した２体の継手モデル体に対
して行い、疲労寿命が短いものの結果を同じく表２に示
す。Each of the joint model bodies thus produced was subjected to a fatigue test in which a repeated torsional load having a torque amplitude of 180 kgf · m was applied, and the torsional fatigue life was examined. The investigation was carried out on two joint model bodies produced for each steel pipe, and the results are shown in Table 2 for those having a short fatigue life.
【００３４】[0034]
【表１】 [Table 1]
【００３５】[0035]
【表２】 [Table 2]
【００３６】表２において、No.A1 〜A13 は本発明例の
電縫鋼管、No.B1 〜B10 は化学組成が本発明で規定する
範囲外である比較例の電縫鋼管、No.C1 は化学組成が特
開平２−197525号公報に記載されている化学組成に相当
する比較例の電縫鋼管である。In Table 2, Nos. A1 to A13 are ERW steel pipes of the present invention, Nos. B1 to B10 are ERW steel pipes of comparative examples whose chemical compositions are outside the range specified in the present invention, and No. C1 is It is an electric resistance welded steel pipe of a comparative example whose chemical composition corresponds to the chemical composition described in JP-A-2-197525.
【００３７】同一引張強度レベレで、本発明例の電縫鋼
管と比較例の電縫鋼管とを比較すると、 1) 引張強度が70kgf/mm2 級の電縫鋼管では、本発明例
（Ａ１，Ａ12）は比較例（Ｂ２、Ｂ９）に比べ疲労寿命
が長い。これは両者ともに摩擦溶接による継手溶接部に
疲労亀裂が生じたが、本発明例の電縫鋼管においてその
部分の硬度低下が抑制されたことが原因である。When the ERW steel pipe of the present invention example and the ERW steel pipe of the comparative example are compared at the same tensile strength level, 1) In the ERW steel pipe having a tensile strength of 70 kgf / mm 2 class, the example of the present invention (A1, A12) has a longer fatigue life than the comparative examples (B2, B9). This is due to the fact that fatigue cracking occurred in the joint welded portion by friction welding in both cases, but the decrease in hardness at that portion was suppressed in the ERW steel pipe of the present invention.
【００３８】2) 引張強度が80kgf/mm2 級の電縫鋼管で
は、本発明例（Ａ２，Ａ４，Ａ６，Ａ７，Ａ10，Ａ11)
は比較例（Ｂ４，Ｂ５，Ｂ10，Ｃ１）に比べ疲労寿命が
長い。Ｂ４の比較例との差異の原因は上記1)と同じく、
継手溶接部の硬度低下が本発明例において少ないことに
よる。また、Ｂ５，Ｂ10，Ｃ１の比較鋼の疲労寿命が極
端に短いのは、電縫溶接部に疲労亀裂が生じたためであ
る。2) In the case of an electric resistance welded steel pipe having a tensile strength of 80 kgf / mm 2 class, the present invention example (A2, A4, A6, A7, A10, A11)
Has a longer fatigue life than the comparative examples (B4, B5, B10, C1). The cause of the difference from the comparative example of B4 is the same as in 1) above,
This is because the decrease in the hardness of the welded joint is small in the examples of the present invention. The reason why the fatigue life of the comparative steels B5, B10 and C1 is extremely short is that a fatigue crack has occurred in the ERW weld.
【００３９】3) 引張強度が90kgf/mm2 超級の電縫鋼管
では、本発明例（Ａ３，Ａ５，Ａ８，Ａ９，Ａ13）は比
較例（Ｂ１，Ｂ３，Ｂ６，Ｂ７，Ｂ８）に比べ疲労寿命
が極端に長い。この原因は両者で亀裂発生部位が異なっ
ており、本発明例の電縫鋼管では継手溶接部、比較鋼の
電縫鋼管では電縫溶接部にそれぞれ亀裂が発生している
ことによる。このような差異は電縫溶接部の靱性の相違
に起因しており、本発明例の電縫鋼管は溶接部の靱性が
高いことにより、優れた疲労特性が得られている。3) In an ERW steel pipe having a tensile strength of more than 90 kgf / mm 2 , the inventive example (A3, A5, A8, A9, A13) has a higher fatigue strength than the comparative examples (B1, B3, B6, B7, B8). Life is extremely long. The reason for this is that the crack initiation site is different between the two, and that the ERW steel pipe according to the present invention has a crack at the joint weld and the ERW steel pipe of the comparative steel has the crack at the ERW weld. Such a difference is caused by a difference in toughness of the ERW weld. The ERW steel pipe of the present invention has excellent fatigue properties due to the high toughness of the weld.
【００４０】[0040]
【発明の効果】以上説明したように、本発明の電縫鋼管
は、高強度であり、しかも、電縫溶接部および他の部材
との継手溶接部の疲労特性に優れている。また、この電
縫鋼管は従来と全く同じ工程で製造することができるの
で、製造コストが嵩むこともない。As described above, the electric resistance welded steel pipe of the present invention has high strength and is excellent in the fatigue characteristics of the electric resistance welded portion and the joint welded portion with other members. Further, since the electric resistance welded steel pipe can be manufactured in exactly the same process as the conventional one, the manufacturing cost does not increase.
【図１】図１ねじり疲労寿命の測定で使用した継手モデ
ル体とする前の鋼管の両端に摩擦圧接した接続体の形状
を示す断面図である。FIG. 1 is a cross-sectional view showing the shape of a connection body that has been friction-welded to both ends of a steel pipe before forming a joint model body used in the measurement of torsional fatigue life.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 外山 和男 大阪府大阪市中央区北浜４丁目５番33号 住友金属工業株式会社内 (56)参考文献 特開 昭59−38356（ＪＰ，Ａ) 特開 平２−197525（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazuo Toyama 4-5-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. (56) References JP-A-59-38356 (JP, A) Kaihei 2-197525 (JP, A)
Claims (2)
ｉ：１．０％以下、Ｍｎ：２．０％以下、Ｍｏ：０．０
５〜０．８％、Ｎｂ：０．０１〜０．１０％、Ｔｉ：
０．００５〜０．０４％、Ｓｏｌ．Ａｌ：０．００５〜
０．０５％を含有し、残部はＦｅおよび不可避不純物か
らなり、不純物のＰ、ＳおよびＮの含有量が、Ｐ：０．
０１８％以下、Ｓ：０．００５％以下、Ｎ：０．００８
％以下であることを特徴とする疲労特性に優れた自動車
用高強度電縫鋼管。(1) C: 0.06 to 0.30% by weight, S
i: 1.0% or less, Mn: 2.0% or less, Mo: 0.0
5 to 0.8%, Nb: 0.01 to 0.10%, Ti:
0.005 to 0.04%, Sol. Al: 0.005 to
0.05%, with the balance being Fe and unavoidable impurities, where the contents of impurities P, S and N are P: 0.
018% or less , S: 0.005% or less, N: 0.008
% High-strength ERW steel pipe for automobiles having excellent fatigue properties, characterized in that it is not more than 0.1%.
量％で、Ｃｒ：０．５％未満、Ｎｉ：３．０％以下、Ｃ
ｕ：１．０％以下、Ｖ：０．１０％以下およびＢ：０．
０００５〜０．００２０％のうちの１種以上を含有する
ことを特徴とする疲労特性に優れた自動車用高強度電縫
鋼管。2. The composition according to claim 1, further comprising, in terms of% by weight, Cr: less than 0.5% , Ni: 3.0% or less, C:
u: 1.0% or less, V: 0.10% or less and B: 0.
A high-strength electric resistance welded steel tube for automobiles having excellent fatigue properties, characterized by containing at least one of 0005 to 0.0020%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3059268A JP2745848B2 (en) | 1991-03-25 | 1991-03-25 | High-strength ERW steel pipe for automobiles with excellent fatigue properties |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3059268A JP2745848B2 (en) | 1991-03-25 | 1991-03-25 | High-strength ERW steel pipe for automobiles with excellent fatigue properties |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0551692A JPH0551692A (en) | 1993-03-02 |
| JP2745848B2 true JP2745848B2 (en) | 1998-04-28 |
Family
ID=13108458
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3059268A Expired - Fee Related JP2745848B2 (en) | 1991-03-25 | 1991-03-25 | High-strength ERW steel pipe for automobiles with excellent fatigue properties |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2745848B2 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19824613A1 (en) | 1998-06-02 | 1999-12-09 | Dornier Gmbh Lindauer | Process for monitoring the weft release and stopping process on winding machines for looms |
| DE60224262T2 (en) | 2001-03-07 | 2008-12-11 | Nippon Steel Corp. | ELECTRO-WELDED STEEL TUBE FOR HOLLOW STABILIZER |
| JP4133220B2 (en) * | 2002-10-30 | 2008-08-13 | 新日本製鐵株式会社 | Manufacturing method of high-strength propeller shaft with excellent durability |
| JP4443910B2 (en) | 2003-12-12 | 2010-03-31 | Ｊｆｅスチール株式会社 | Steel materials for automobile structural members and manufacturing method thereof |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5938356A (en) * | 1982-08-25 | 1984-03-02 | Daido Steel Co Ltd | Electric welded pipe |
| JPH0742499B2 (en) * | 1989-01-24 | 1995-05-10 | 新日本製鐵株式会社 | Method for manufacturing high strength electric resistance welded steel pipe for automobiles in which heat-affected zone is hard to soften |
-
1991
- 1991-03-25 JP JP3059268A patent/JP2745848B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0551692A (en) | 1993-03-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4780189B2 (en) | Austenitic heat-resistant alloy | |
| JP4631986B1 (en) | Ni-based alloy product and manufacturing method thereof | |
| JP4761993B2 (en) | Manufacturing method of ferritic stainless steel welded pipe for spinning | |
| JP5273266B2 (en) | Double pipe and welded structure using the same | |
| JP3322097B2 (en) | High strength, high corrosion resistant ferritic steel welding material with excellent weldability | |
| JP2745848B2 (en) | High-strength ERW steel pipe for automobiles with excellent fatigue properties | |
| JP4377869B2 (en) | Boiler steel excellent in ERW weldability and ERW boiler steel pipe using the same | |
| JP2622530B2 (en) | Welding material for austenitic steel with excellent high-temperature strength | |
| JP3552517B2 (en) | Method for welding high Cr ferritic heat resistant steel and method for manufacturing welded steel pipe | |
| JP2000204442A (en) | High strength electric resistance welded steel pipe excellent in toughness of electric resistance weld zone | |
| JP3265591B2 (en) | High-strength ERW steel pipe for automobiles with excellent weld toughness | |
| JP5000472B2 (en) | Ferritic stainless steel welded pipe excellent in pipe expansion workability and manufacturing method thereof | |
| JP4608818B2 (en) | Ferritic stainless steel with excellent secondary work brittleness resistance and high temperature fatigue properties of welds | |
| JP2001140040A (en) | Low carbon ferrite-martensite duplex stainless welded steel pipe excellent in sulfide stress cracking resistance | |
| JP3937369B2 (en) | Processing method of ferritic stainless steel pipe | |
| JP2594265B2 (en) | TIG welding wire for 9Cr-Mo steel | |
| JP2000084614A (en) | Production of high strength resistance welded steel tube for automobile excellent in toughness | |
| JPH10280102A (en) | Seamless pipe made of ferritic stainless steel for bellows and bellows using the same | |
| JP2019130591A (en) | Weld joint | |
| JPH07171679A (en) | Welded joint for structural steel excellent in fatigue resistance | |
| JP7376779B2 (en) | Welded joints and auto parts | |
| JP2622516B2 (en) | Welding material for heat resistant steel with excellent creep strength | |
| JP2005271015A (en) | Friction welding method of steel tube and aluminum alloy hollow member | |
| JPH108924A (en) | Manufacture of valve for large diesel engine | |
| JP2004249360A (en) | Steel tube combined body of excellent fatigue strength, and working method therefor |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110213 Year of fee payment: 13 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110213 Year of fee payment: 13 |
|
| LAPS | Cancellation because of no payment of annual fees |