JP5196934B2 - High fatigue life quenched and tempered steel pipe and method for manufacturing the same - Google Patents
High fatigue life quenched and tempered steel pipe and method for manufacturing the same Download PDFInfo
- Publication number
- JP5196934B2 JP5196934B2 JP2007251196A JP2007251196A JP5196934B2 JP 5196934 B2 JP5196934 B2 JP 5196934B2 JP 2007251196 A JP2007251196 A JP 2007251196A JP 2007251196 A JP2007251196 A JP 2007251196A JP 5196934 B2 JP5196934 B2 JP 5196934B2
- Authority
- JP
- Japan
- Prior art keywords
- steel pipe
- less
- fatigue life
- steel
- quenching
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 229910000831 Steel Inorganic materials 0.000 title claims description 104
- 239000010959 steel Substances 0.000 title claims description 104
- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 238000000034 method Methods 0.000 title description 23
- 238000005496 tempering Methods 0.000 claims description 32
- 238000010791 quenching Methods 0.000 claims description 30
- 230000000171 quenching effect Effects 0.000 claims description 30
- 239000000463 material Substances 0.000 claims description 28
- 239000000203 mixture Substances 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 7
- 229910052748 manganese Inorganic materials 0.000 claims description 6
- 229910052758 niobium Inorganic materials 0.000 claims description 6
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000012535 impurity Substances 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 229910052698 phosphorus Inorganic materials 0.000 claims description 3
- 229910052717 sulfur Inorganic materials 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 13
- 230000008569 process Effects 0.000 description 10
- 238000001816 cooling Methods 0.000 description 8
- 150000001247 metal acetylides Chemical class 0.000 description 8
- 239000003381 stabilizer Substances 0.000 description 8
- 229910001566 austenite Inorganic materials 0.000 description 7
- 238000005452 bending Methods 0.000 description 6
- 230000001105 regulatory effect Effects 0.000 description 6
- 230000009471 action Effects 0.000 description 5
- 230000001965 increasing effect Effects 0.000 description 4
- 229920006395 saturated elastomer Polymers 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000009661 fatigue test Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 238000003466 welding Methods 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- 239000005539 carbonized material Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000005121 nitriding Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000005097 cold rolling Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000005098 hot rolling Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 229910000734 martensite Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 238000005480 shot peening Methods 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Heat Treatment Of Articles (AREA)
Description
本発明は、焼入れおよび焼戻しの処理を施して得られる疲労特性に優れた鋼管であって、特に硬度を高めて高強度化を図るとともに微細な炭化物を析出させることで高疲労寿命化を図った、機械構造部材用焼入れ・焼戻し鋼管、およびその製造方法に関するものである。 The present invention is a steel pipe excellent in fatigue characteristics obtained by performing quenching and tempering treatment, and particularly intended to increase hardness and increase strength and to increase fatigue life by precipitating fine carbides. The present invention relates to a quenched / tempered steel pipe for machine structural members and a method for producing the same.
自動車をはじめ、各種機械構造物においては、高強度と疲労特性が要求される部材に焼入れ・焼戻しの処理を施した「鋼管」を使用することが多々ある。
一般に鋼材の疲労特性を向上させるためには、表面を硬化する、あるいは平滑化することが有効であるとされる。
特許文献１には、窒化処理により表面を硬化させて疲労特性を向上させる技術が開示されている。特許文献２には、鋼管内面を研削して平滑化するとともに脱炭層を除去して鋼管の疲労特性を向上させる技術が開示されている。
In various machine structures such as automobiles, “steel pipes” are often used in which quenching and tempering treatment is applied to members that require high strength and fatigue characteristics.
Generally, in order to improve the fatigue characteristics of steel materials, it is considered effective to harden or smooth the surface.
Patent Document 1 discloses a technique for improving fatigue characteristics by hardening a surface by nitriding treatment. Patent Document 2 discloses a technique for improving the fatigue characteristics of a steel pipe by grinding and smoothing the inner surface of the steel pipe and removing the decarburized layer.
昨今、機械構造物の各種部材には小型軽量化の要求が高まっている。鋼管で構成される高強度部材についても例外ではない。
鋼管部材を軽量化するには、肉厚の低減が最も有効である。しかし、薄肉化は強度や疲労寿命の面で不利となる。特に、鋼管は曲げ加工などにより所望の形状に加工される場合が多いが、曲げの外側では肉厚が薄くなり、耐久性の点で厳しい状況となる。したがって、薄肉化の要求に応えるには、鋼管自体の特性をレベルアップすること、すなわち、高強度を維持しながら疲労寿命を一層高レベルに引き上げることが望まれる。
Recently, there is an increasing demand for reducing the size and weight of various members of mechanical structures. High strength members made of steel pipe are no exception.
In order to reduce the weight of the steel pipe member, it is most effective to reduce the wall thickness. However, thinning is disadvantageous in terms of strength and fatigue life. In particular, the steel pipe is often processed into a desired shape by bending or the like, but the thickness is reduced outside the bending, and the situation is severe in terms of durability. Therefore, in order to meet the demand for thinning, it is desired to improve the characteristics of the steel pipe itself, that is, to raise the fatigue life to a higher level while maintaining high strength.
このように、高強度鋼管の耐久性を維持しながら薄肉化を図ることは必ずしも容易ではない。この問題を解決する手段として、例えば特殊元素の添加により鋼材自体の強度・疲労特性レベルを向上させる手法が考えられる。しかし、多くの機械構造物において、そのような素材コストの増加を招く手法は許容されない。また、特許文献１のように表面を窒化させる方法や特許文献２のように内面を研削する方法は、疲労特性の向上には有効であるが、工程の増加を伴い、現状の鋼管製造プロセスをそのまま適用できるものではない。特許文献２の手法ではさらに歩留低下の問題も生じる。 Thus, it is not always easy to reduce the thickness while maintaining the durability of the high-strength steel pipe. As a means for solving this problem, for example, a technique of improving the strength and fatigue property level of the steel material itself by adding a special element is conceivable. However, in many machine structures, such a method that causes an increase in material cost is not allowed. In addition, the method of nitriding the surface as in Patent Document 1 and the method of grinding the inner surface as in Patent Document 2 are effective in improving the fatigue characteristics. It cannot be applied as it is. The technique of Patent Document 2 also causes a problem of yield reduction.
このように、低廉な手法で高強度鋼管の高強度を維持しながら疲労寿命のレベルアップを図ることは容易ではなく、現状においてそのような手法は確立されていない。
本発明は、このような現状に鑑み、素材コストおよび製造コストを従来材と同等に抑えながら、高強度化と一層の疲労寿命の向上を図った鋼管であって、特に自動車用中空スタビライザーの薄肉化に適した鋼管を提供しようというものである。
As described above, it is not easy to improve the fatigue life level while maintaining the high strength of the high-strength steel pipe by an inexpensive method, and such a method has not been established at present.
In view of the present situation, the present invention is a steel pipe that has improved strength and further improved fatigue life while suppressing the raw material cost and manufacturing cost to be the same as those of conventional materials, and in particular, the thin wall of a hollow stabilizer for automobiles The aim is to provide a steel pipe suitable for conversion.
発明者らは詳細な検討の結果、特殊な成分元素を添加したり、特殊な工程を採用したりしなくても、鋼管の高強度を維持しながら疲労寿命を顕著に改善することが可能であることを知見した。つまり、成分組成と焼入れ・焼戻し条件との組合せには、疲労寿命を顕著に向上させることのできる余地が残されていることがわかり、発明者らはそのような「解」を見出すことにより本発明を完成するに至った。 As a result of detailed studies, the inventors have been able to significantly improve fatigue life while maintaining the high strength of steel pipes without adding special component elements or adopting special processes. I found out that there was. In other words, the combination of the component composition and the quenching / tempering conditions leaves room for a significant improvement in fatigue life. The invention has been completed.
すなわち本発明では、質量％で、Ｃ：０.１〜０.４％、Ｓｉ：０.５〜１.５％、Ｍｎ：０.３〜２％、Ｐ：０.０２％以下、Ｓ：０.０１％以下、Ｃｒ：０.１〜２％、Ｔｉ：０.０１〜０.１％、Ｎｂ：０.０１〜０.１％、Ａｌ：０.０１〜０.１％、Ｂ：０.０００５〜０.０１％、Ｎ：０.００６％以下であり、必要に応じてさらにＮｉ：０.５％以下、Ｃａ：０.０２％以下、Ｍｏ：０.５％以下、Ｖ：０.５％以下の１種以上を含有し、残部Ｆｅおよび不可避的不純物からなる組成を有し、析出炭化物の平均粒径が０.５μｍ以下、鋼管長手方向に垂直な断面における肉厚中心部の硬さが４００ＨＶ以上である高疲労寿命焼入れ・焼戻し鋼管が提供される。この場合、例えば肉厚ｔが１〜７ｍｍ、管の外径Ｄが１０〜４５ｍｍであり、Ｄ／ｔ≧４を満たすものが好適な対象となる。 That is, in the present invention, by mass%, C: 0.1 to 0.4%, Si: 0.5 to 1.5%, Mn: 0.3 to 2%, P: 0.02% or less, S: 0.01% or less, Cr: 0.1~2%, Ti: 0.01~0.1%, Nb: 0.01~0.1%, Al: 0.01 ~0.1%, B: It is 0.0005 to 0.01%, N: 0.006% or less, and if necessary, Ni: 0.5% or less, Ca: 0.02% or less, Mo: 0.5% or less, V: Thickness center portion in a cross section perpendicular to the longitudinal direction of the steel pipe, containing one or more of 0.5% or less, having a composition composed of the balance Fe and inevitable impurities, and having an average particle size of precipitated carbide of 0.5 μm or less A high fatigue life quenched / tempered steel pipe having a hardness of 400 HV or higher is provided. In this case, for example, the wall thickness t is 1 to 7 mm, the outer diameter D of the tube is 10 to 45 mm, and a material satisfying D / t ≧ 4 is suitable.
また、このような鋼管の製造方法として、上記の成分組成を有する焼入れ前の素材鋼管に対して、９００〜１１００℃で１０〜６０秒保持した後急冷する焼入れ処理と、２８０〜３８０℃で１０〜６０分保持する焼戻し処理を施す高疲労寿命焼入れ・焼戻し鋼管の製造方法が提供される。ここで、素材鋼板として板厚ｔが１〜７ｍｍの焼鈍鋼板を用い、それを溶接造管することにより外径Ｄが１０〜４５ｍｍ、ただしＤ／ｔ≧４を満たす素材鋼管とすることが望ましい。 Moreover, as a manufacturing method of such a steel pipe, with respect to the raw steel pipe before quenching which has said component composition, it is the quenching process which hold | maintains at 900-1100 degreeC for 10 to 60 second, and then rapidly cools, and it is 10 at 280-380 degreeC. A method for producing a high fatigue life quenched / tempered steel pipe that is subjected to a tempering treatment that is held for ˜60 minutes is provided. Here, it is desirable to use an annealed steel sheet having a thickness t of 1 to 7 mm as the material steel sheet, and to make a material steel pipe satisfying D / t ≧ 4 with an outer diameter D of 10 to 45 mm by welding and pipe forming it. .
本発明に従えば、従来材と同等の安価な鋼を用いて、各種機械構造部材に用いる高強度鋼管の疲労寿命を顕著に向上させることが可能になった。この特性向上により、自動車用中空スタビライザーその他の機械構造用鋼管において、更なる耐久性の向上、あるいは部材の薄肉化が実現できる。また、本発明の鋼管の製造に際しては特殊な工程を付加する必要もない。したがって本発明は、自動車をはじめとする機械構造部材の高耐久性化あるいは軽量化に寄与し得るものである。 According to the present invention, it is possible to remarkably improve the fatigue life of high-strength steel pipes used for various mechanical structural members using inexpensive steel equivalent to conventional materials. By improving the characteristics, it is possible to further improve the durability or reduce the thickness of the member in a hollow stabilizer for automobiles and other steel pipes for machine structures. Moreover, it is not necessary to add a special process when manufacturing the steel pipe of the present invention. Therefore, the present invention can contribute to increasing the durability or weight of machine structural members including automobiles.
本発明では各元素の含有量を以下のように調整した鋼を使用する。なお、合金元素含有量の「％」は「質量％」を意味する。
Ｃは、機械構造用鋼疲労寿命鋼管に望まれる強度とばね性を確保するために、０.１％以上の含有が必要である。ただし、多量に含有させると靭性低下による脆性破壊が生じやすくなるとともに、粒界強度の低下による疲労寿命の低下が懸念される。また、造管時の加工性や溶接部の健全性が劣化する。このためＣ含有量は０.４％以下の範囲に規定される。
In the present invention, steel whose content of each element is adjusted as follows is used. Note that “%” of the alloy element content means “mass%”.
C is required to be contained in an amount of 0.1% or more in order to ensure the strength and springiness desired for the steel pipe for machine structural use. However, if contained in a large amount, brittle fracture due to a decrease in toughness tends to occur, and there is a concern about a decrease in fatigue life due to a decrease in grain boundary strength. Moreover, the workability at the time of pipe making and the soundness of a welding part deteriorate. For this reason, C content is prescribed | regulated to 0.4% or less of range.
Ｓｉは、焼入れ性および焼戻し軟化抵抗を高め、焼戻し後の強度を確保する上で有効な元素である。また、焼戻しの際にフィルム状の炭化物の生成を抑制し、平均粒径０.５μｍ以下の微細な炭化物を析出させることで粒界強度の低下を抑える作用を有する。高疲労寿命化には不可欠な元素であり、０.５％以上のＳｉ含有が必要である。ただし、Ｓｉ含有量が多すぎると粒界に粗大な炭化物が形成されやすくなり、逆に疲労寿命の低下を招く要因となる。このためＳｉ含有量は１.５％以下の範囲に規制される。 Si is an element effective in enhancing hardenability and temper softening resistance and ensuring strength after tempering. Moreover, it has the effect | action which suppresses the production | generation of a film-form carbide | carbonized_material in the case of tempering, and suppresses the fall of a grain boundary strength by depositing the fine carbide | carbonized_material with an average particle diameter of 0.5 micrometer or less. It is an indispensable element for increasing the fatigue life, and it is necessary to contain 0.5% or more of Si. However, if the Si content is too large, coarse carbides are likely to be formed at the grain boundaries, and conversely, this causes a reduction in fatigue life. For this reason, the Si content is restricted to a range of 1.5% or less.
Ｍｎは、焼入れ性および強度を確保する上で有効な元素であり、その効果を十分に得るためには０.３％以上含有させる必要がある。しかし、過剰に添加すると、炭素当量も高くなり、加工性および溶接部の健全性に悪影響を及ぼす。このためＭｎ含有量は２％以下の範囲に規定される。 Mn is an element effective in ensuring hardenability and strength. In order to sufficiently obtain the effect, it is necessary to contain 0.3% or more. However, if added in excess, the carbon equivalent also increases, which adversely affects workability and the soundness of the weld. For this reason, Mn content is prescribed | regulated to the range of 2% or less.
Ｐは、焼入れ時にオーステナイト粒界に偏析し、粒界強度の低下により、疲労寿命を低下させる。このためＰ含有量は０.０２％以下に制限される。 P segregates at the austenite grain boundaries during quenching and reduces the fatigue life due to a decrease in grain boundary strength. For this reason, the P content is limited to 0.02% or less.
Ｓは、鋼中でＭｎＳを形成し、これが亀裂の起点となって強度、靭性を低下させる要因になる。また、粒界に偏析し、疲労寿命低下に繋がる。このためＳ含有量は０.０１％以下に制限される。 S forms MnS in steel, which becomes a starting point of cracks and becomes a factor of reducing strength and toughness. Moreover, it segregates at the grain boundary, leading to a decrease in fatigue life. For this reason, the S content is limited to 0.01% or less.
Ｃｒは、Ｍｎと同様に焼入れ性の向上に有効であるとともに、焼戻し軟化抵抗を高めるため、少なくとも０.１％以上の含有が必要である。しかし、２％を超えると焼入れ・焼戻し後の組織が未溶解炭化物を多量に含むものとなり、この炭化物が亀裂を助長させる起点となって靭性や疲労寿命の低下を招く。このためＣｒ含有量は０.１〜２％に規定される。 Cr is effective for improving the hardenability like Mn, and at least 0.1% or more is required to increase the temper softening resistance. However, if it exceeds 2%, the structure after quenching and tempering contains a large amount of undissolved carbide, and this carbide serves as a starting point for promoting cracks, leading to a decrease in toughness and fatigue life. For this reason, Cr content is prescribed | regulated to 0.1 to 2%.
Ｔｉは、鋼中のＮをＴｉＮとして固定することにより、焼入れ性向上に有効な固溶Ｂの確保に寄与する。また、焼入れ時に旧オーステナイト粒径の粗大化を抑制し、疲労寿命を向上させる。これらの効果を十分に得るには０.０１％以上のＴｉ含有が必要となる。ただし、０.１％を超えてＴｉを添加しても旧オーステナイト粒径の粗大化抑制効果は飽和し、却って疲労破壊の起点となるＴｉ系介在物が増加する。このためＴｉ含有量は０.０１〜０.１％に規定される。 Ti contributes to securing solid solution B effective for improving hardenability by fixing N in steel as TiN. Further, the coarsening of the prior austenite grain size is suppressed during quenching, and the fatigue life is improved. In order to sufficiently obtain these effects, Ti content of 0.01% or more is required. However, even if Ti is added in excess of 0.1%, the effect of suppressing the coarsening of the prior austenite grain size is saturated, and on the contrary, Ti-based inclusions that become the starting point of fatigue fracture increase. For this reason, Ti content is prescribed | regulated to 0.01 to 0.1%.
Ｎｂは、炭窒化物を形成し、旧オーステナイト結晶粒の粗大化を抑制して靭性を向上させるとともに疲労寿命を向上させる作用がある。これらの効果を十分に得るためには０.０１％以上のＮｂ含有が必要である。ただし、０.１％を超えると上記効果は飽和し、不経済となる。このためＮｂ含有量は０.０１〜０.１％に規定される。 Nb forms carbonitrides and suppresses the coarsening of prior austenite crystal grains, thereby improving toughness and improving fatigue life. In order to sufficiently obtain these effects, Nb content of 0.01% or more is necessary. However, if it exceeds 0.1%, the above effect is saturated and uneconomical. For this reason, Nb content is prescribed | regulated to 0.01 to 0.1%.
Ａｌは、脱酸に有効な元素であるが、焼入れ時のオーステナイト結晶粒の粗大化抑制にも有効である。トータルＡｌ（Ｔ.Ａｌ）として０.０１％以上のＡｌ含有量を確保することが望ましい。ただし、過剰のＡｌ含有は電縫溶接部の靭性および疲労寿命に悪影響を及ぼす。したがってＡｌ含有量（Ｔ.Ａｌ）は０.１％以下に制限され、０.０５％以下とすることがより好ましい。 Al is an element effective for deoxidation, but is also effective for suppressing coarsening of austenite crystal grains during quenching. It is desirable to ensure an Al content of 0.01% or more as total Al (T.Al). However, excessive Al content adversely affects the toughness and fatigue life of ERW welds. Therefore, the Al content (T.Al) is limited to 0.1% or less, and more preferably 0.05% or less.
Ｂは、微量の添加で焼入れ性を高める作用がある。また、焼入れ・焼戻し後の旧オーステナイト粒界を強化して脆性破壊を抑制し、靭性を向上させる作用を有する。これらの作用を十分に発揮させるためには０.０００５％以上のＢ含有が必要である。ただし、０.０１％を超えるとこれらの作用は飽和する。このためＢ含有量は０.０００５〜０.０１％に規定される。０.００２〜０.０１％の範囲とすることがより好ましい。 B has the effect of enhancing the hardenability by adding a small amount. Moreover, it has the effect | action which strengthens the prior austenite grain boundary after hardening and tempering, suppresses a brittle fracture, and improves toughness. In order to fully exhibit these actions, it is necessary to contain 0.0005% or more of B. However, when the content exceeds 0.01%, these effects are saturated. For this reason, B content is prescribed | regulated to 0.0005 to 0.01%. A range of 0.002 to 0.01% is more preferable.
Ｎは、ＢＮの形成によってＢを消費し、前記のＢ添加の作用を引き出す上でマイナスの要因となる。このためＮ含有量はできるだけ低い方が望ましい。種々検討の結果、Ｎ含有量は０.０１％まで許容されるが、０.００６％以下とすることがより好ましい。 N consumes B due to the formation of BN, and becomes a negative factor in drawing out the effect of the addition of B. For this reason, it is desirable that the N content be as low as possible. As a result of various studies, the N content is allowed to be 0.01%, but is more preferably 0.006% or less.
Ｎｉは、炭窒化物を形成し、焼入れ性、靭性および疲労寿命の向上に有効であるため、必要に応じて添加することができる。０.１％以上の含有量を確保することが一層効果的である。ただし、０.５％を超えると上記作用は飽和し、不経済となる。このためＮｉを添加する場合は０.５％以下の範囲で行う。 Ni forms a carbonitride and is effective in improving hardenability, toughness, and fatigue life, and can be added as necessary. It is more effective to ensure a content of 0.1% or more. However, if it exceeds 0.5%, the above action is saturated and uneconomical. For this reason, when adding Ni, it carries out in 0.5% or less of range.
Ｃａは、ＭｎＳ系介在物の形態を球状化する作用があり、それによって鋼材の異方性が軽減される。このため、必要に応じてＣａを添加することができ、その含有量を０.００１％以上とすることが一層効果的である。しかし、多量に添加するとＣａ系介在物が増加して疲労特性に悪影響を及ぼすので、Ｃａを添加する場合は０.０２％以下の範囲で行う。 Ca has the effect | action which spheroidizes the form of a MnS type inclusion, and, thereby, the anisotropy of steel materials is reduced. For this reason, Ca can be added as needed, and it is more effective to make the content 0.001% or more. However, when Ca is added in a large amount, Ca-based inclusions increase and adversely affect the fatigue characteristics. Therefore, when Ca is added, it is performed within a range of 0.02% or less.
Ｍｏは、焼入れ性と焼戻し軟化抵抗の向上に有効な元素であり、Ｍｎ、Ｃｒの過剰な添加による靭性劣化を抑えるために補助的に添加することができる。Ｍｏを添加する場合は０.１％以上の含有量を確保することが一層効果的である。ただしＭｏは高価な元素であり多量添加は経済性を損なう。このため、Ｍｏ添加は０.５％以下の範囲で行う必要がある。 Mo is an element effective for improving the hardenability and temper softening resistance, and can be supplementarily added in order to suppress toughness deterioration due to excessive addition of Mn and Cr. When adding Mo, it is more effective to secure a content of 0.1% or more. However, Mo is an expensive element, and adding a large amount impairs economic efficiency. For this reason, it is necessary to add Mo in the range of 0.5% or less.
Ｖは、焼入れ時に結晶粒を微細化する作用があり、靭性向上に有効であるため、必要に応じて添加される。０.１％以上の含有量を確保することが一層効果的である。ただしＶも高価な元素であり、多量添加は経済性を損なうので、Ｖを添加する場合は０.５％以下の範囲で行う。 V has the effect of refining crystal grains during quenching and is effective in improving toughness, and therefore is added as necessary. It is more effective to ensure a content of 0.1% or more. However, V is also an expensive element, and the addition of a large amount impairs economic efficiency.
以上の化学組成を有する素材鋼管に対して、本発明で規定する焼入れ処理と焼戻し処理を施すことによって、高強度を維持しながら疲労寿命を顕著に改善した鋼管を得ることができる。 By subjecting the material steel pipe having the above chemical composition to the quenching treatment and the tempering treatment specified in the present invention, a steel pipe having a significantly improved fatigue life while maintaining high strength can be obtained.
鋼管を製造するには、ビレットからシームレス鋼管を得る方法を採用することもできるが、熱延鋼板あるいは冷延鋼板を焼鈍した「素材鋼板」を製造し、これを高周波溶接などにより溶接造管して鋼管とする方法が大量生産には適している。造管に供する「素材鋼板」は、造管時の変形および造管後に行われる曲げ加工に耐えられるよう、十分に軟化された焼鈍鋼板であることが望ましい。すなわち、焼きが入らないよう、Ａｃ1点未満の温度域で軟化焼鈍された素材鋼板を用いて造管することが望ましい。なお、本発明の対象鋼の場合、焼鈍後の組織は概ね「フェライト＋１.５〜６体積％炭化物」となる。 In order to manufacture steel pipes, a method of obtaining seamless steel pipes from billets can be adopted. The steel pipe method is suitable for mass production. It is desirable that the “material steel plate” used for pipe making is an annealed steel plate that has been sufficiently softened to withstand deformation during pipe making and bending work performed after pipe making. That is, it is desirable to make a pipe using a raw steel plate softened and annealed in a temperature range less than Ac 1 point so as not to be baked. In the case of the target steel of the present invention, the structure after annealing is generally “ferrite + 1.5-6% by volume carbide”.
造管後の鋼管は、焼入れ処理に供する前の軟質な段階で必要に応じて所望形状の部材鋼管に成形加工される。ここでは、必要に応じて成形加工された、焼入れ処理前の鋼管を「素材鋼管」と呼んでいる。発明者らの研究の結果、上記の化学組成を有する素材鋼管に対して焼入れ処理および焼戻し処理を施す際、その焼戻し処理を低温域で行うことにより、疲労寿命の顕著な向上が実現できることがわかった。 The steel pipe after pipe forming is formed into a member steel pipe having a desired shape as needed at a soft stage before being subjected to quenching. Here, the steel pipe before being quenched and formed as necessary is called a “material steel pipe”. As a result of the inventors' research, it has been found that when the steel pipe having the above chemical composition is subjected to quenching and tempering treatment, the fatigue life can be significantly improved by performing the tempering treatment in a low temperature region. It was.
具体的には、上記組成範囲の素材鋼管に「９００〜１１００℃×１０〜６０秒保持、急冷」の焼入れ処理を施し、次いで「２８０〜３８０℃×１０〜６０分保持」の焼戻し処理を施すことにより、鋼管長手方向に対して垂直な断面（以下「Ｃ断面」ということがある）における肉厚中心部の硬さが４００ＨＶ以上の強度レベルを維持しながら、疲労寿命を顕著に改善することができる。焼入れ処理時の「急冷」は、マルテンサイト変態が起こるに足る冷却速度であるが、例えば水中に浸漬する「水冷」が採用できる。 Specifically, the material steel pipe having the above composition range is subjected to a quenching process of “holding at 900 to 1100 ° C. × 10 to 60 seconds, rapid cooling”, and then subjected to a tempering process of “holding at 280 to 380 ° C. × 10 to 60 minutes”. In this way, the fatigue life can be remarkably improved while maintaining the strength level of the thickness center of the cross section perpendicular to the longitudinal direction of the steel pipe (hereinafter sometimes referred to as “C cross section”) at 400 HV or higher. Can do. “Rapid cooling” at the time of quenching is a cooling rate sufficient to cause martensitic transformation, and for example, “water cooling” immersed in water can be adopted.
高強度が要求される中空スタビライザー等の用途では、Ｃ断面における肉厚中心部の硬さが４００ＨＶ以上の強度レベルのものを使用することが望ましいが、前記組成範囲の素材鋼管に、上記の焼入れ・焼戻し処理を施すことにより、このような高強度も同時に維持することができる。なお、硬さを評価するＣ断面としては、部材への成形加工（例えば曲げ加工）により断面形状が大きく変化した箇所以外の部分を選ぶ。具体的には、Ｃ断面内における肉厚の最大値をｔmax、最小値をｔminとするとき、（ｔmax−ｔmin）／ｔmaxの値が０.２以下である部分を選択して硬さを測定すればよい。 In applications such as hollow stabilizers where high strength is required, it is desirable to use a material having a strength level of 400 HV or more in the thickness center in the C cross section. -By applying tempering treatment, such high strength can be maintained at the same time. In addition, as C cross-section which evaluates hardness, parts other than the location where the cross-sectional shape changed greatly by the shaping | molding process (for example, bending process) to a member are selected. Specifically, when the maximum value of the wall thickness in the C cross section is t max and the minimum value is t min , the part where the value of (t max −t min ) / t max is 0.2 or less is selected. And measure the hardness.
また、発明者らの詳細な検討によれば、鋼管部材において粗大な析出炭化物が存在すると、たとえ強度レベルが高くても、優れた疲労寿命を安定して実現することは難しいことがわかった。具体的には析出炭化物の平均粒径が０.５μｍ以下に抑えられていることが重要である。 Further, according to detailed studies by the inventors, it has been found that if coarse precipitated carbides exist in the steel pipe member, it is difficult to stably realize an excellent fatigue life even if the strength level is high. Specifically, it is important that the average particle size of the precipitated carbide is suppressed to 0.5 μm or less.
本発明で対象とする鋼管のなかでも、肉厚ｔが１〜７ｍｍ好ましくは１〜５ｍｍ、管の外径Ｄが１０〜４５ｍｍ、Ｄ／ｔが４以上である鋼管は、中空スタビライザー用鋼管として適しており、同様の鋼種からなる従来の中空スタビライザーと同等以上の高強度・高疲労特性を、一層軽量化した鋼管において実現するものである。 Among the steel pipes targeted in the present invention, a steel pipe having a wall thickness t of 1 to 7 mm, preferably 1 to 5 mm, an outer diameter D of the pipe of 10 to 45 mm, and D / t of 4 or more is used as a steel pipe for a hollow stabilizer. It is suitable, and realizes high strength and high fatigue characteristics equivalent to or higher than those of conventional hollow stabilizers made of the same steel type in a steel pipe that is further reduced in weight.
表１に示す鋼を溶製し、スラブを１２５０℃で６０分加熱したのち抽出して、熱間圧延（粗圧延および仕上げ圧延）を行い、５３０℃で巻き取った。熱間圧延後の板厚は５.６ｍｍまたは８ｍｍとした。得られた熱延鋼板を酸洗し、板厚５.６ｍｍの熱延鋼板からは「熱延まま」の材料、および、その後、水素雰囲気中６９０℃×１８時間保持の焼鈍を施した「熱延・焼鈍材」を得た。また板厚８ｍｍの熱延鋼板からは、その後３０％の冷間圧延と、水素雰囲気中６９０℃×１８時間保持の焼鈍を施した板厚５.６ｍｍの「冷延・焼鈍材」を得た。上記焼鈍温度は再結晶温度以上Ａｃ1点以下に相当する。これら「熱延まま」の鋼板、「熱延・焼鈍材」、および「冷延・焼鈍材」を素材鋼板と呼ぶ。 The steel shown in Table 1 was melted, the slab was heated at 1250 ° C. for 60 minutes, extracted, hot rolled (rough rolling and finish rolling), and wound at 530 ° C. The plate thickness after hot rolling was 5.6 mm or 8 mm. The obtained hot-rolled steel sheet was pickled, and from a hot-rolled steel sheet having a thickness of 5.6 mm, a “hot-rolled” material, and then annealed in a hydrogen atmosphere at 690 ° C. for 18 hours. Obtained "rolled and annealed material". Further, from a hot-rolled steel sheet having a thickness of 8 mm, a “cold-rolled / annealed material” having a thickness of 5.6 mm obtained after 30% cold rolling and annealing in a hydrogen atmosphere at 690 ° C. for 18 hours was obtained. . The annealing temperature corresponds to the recrystallization temperature or higher and the Ac 1 point or lower. These “hot rolled” steel plates, “hot rolled / annealed materials”, and “cold rolled / annealed materials” are called raw steel plates.
前記素材鋼板について、造管後に行われる焼入れ・焼戻し処理を模擬した熱処理を実施して、硬さ、炭化物の平均粒径、および疲労特性をシミュレートした。
焼入れ処理は「８００〜１２００℃×１０〜６０秒保持→水冷」の条件で行った。
焼戻し処理は「２００〜４２０℃×１０〜６０分保持→空冷」の条件で行った。
硬さは、Ｃ断面（圧延方向に垂直な断面）の肉厚中心部についてマイクロビッカース硬度計を用いて測定した。
炭化物の平均粒径は、ＴＥＭ（透過型電子顕微鏡）により観察される炭化物を観察視野内からランダムに合計３０個選択して各炭化物の長径を測定し、その平均値を算出することによって求めた。
疲労特性は、ＪＩＳＺ２２７５に準拠して最大曲げ応力を７５０Ｎ・ｍｍ-2とする金属平板の平面曲げ疲れ試験を実施した。この試験による破断寿命が５万回以上であれば、従来の中空スタビライザー材と比較して疲労寿命が大幅に向上していると認められるので、ここでは、破断寿命が５万回以上のものを○（合格）、それ未満のものを×（不合格）と評価した。
結果を表２に示す。
The raw steel plate was subjected to a heat treatment simulating a quenching / tempering process performed after pipe making to simulate hardness, average grain size of carbides, and fatigue characteristics.
The quenching process was performed under the conditions of “800 to 1200 ° C. × 10 to 60 seconds hold → water cooling”.
The tempering treatment was performed under the conditions of “200 to 420 ° C. × 10 to 60 minutes holding → air cooling”.
Hardness was measured using a micro Vickers hardness meter at the thickness center of the C cross section (cross section perpendicular to the rolling direction).
The average particle size of the carbide was determined by selecting a total of 30 carbides observed by a TEM (transmission electron microscope) from the observation field, measuring the major axis of each carbide, and calculating the average value. .
As for the fatigue characteristics, a plane bending fatigue test was performed on a metal flat plate having a maximum bending stress of 750 N · mm −2 in accordance with JISZ2275. If the rupture life in this test is 50,000 times or more, it is recognized that the fatigue life is significantly improved compared to the conventional hollow stabilizer material. ○ (pass), less than that was evaluated as x (fail).
The results are shown in Table 2.
表２からわかるように、比較例であるＮｏ.１（鋼Ａ）、２４（鋼Ｐ）、２５（鋼Ｑ）はそれぞれＣ、Ｂ、Ｍｎ含有量が本発明規定範囲より低いものである。これらは焼入れ性が低下したことにより焼戻し後の硬さが不十分となり、疲労寿命は改善されなかった。Ｎｏ.１１（鋼Ｅ）はＭｎ含有量が高すぎることにより残留オーステナイト相が増加して、焼入れ硬さの低下に伴って焼戻し後の硬さが低くなり、疲労寿命に劣った。また、Ｎｏ.２８（鋼Ｔ）はＳｉ含有量が低く、焼戻し硬さが不十分であるとともに、Ｎｂ無添加であったために、粒界に０.５μｍを超える粗大な析出炭化物が形成され、その結果、粒界強度が低下して疲労寿命に劣った。Ｎｏ.２（鋼Ｂ）、３（鋼Ｃ）、１５（鋼Ｇ）はそれぞれＣ、Ｓｉ、Ｃｒ含有量が高過ぎるもの、またＮｏ.１８（鋼Ｊ）はＴｉおよびＮｂを添加していないものである。これらはいずれも粒界に０.５μｍを超える粗大な析出炭化物が形成され、その結果、粒界強度が低下して疲労寿命に劣った。Ｎｏ.１７（鋼Ｉ）はＴｉ、Ｎｂが本発明範囲を超えているものである。Ｔｉ、Ｎｂの粗大な炭化物が生成し、それが疲労破壊の起点となって、疲労寿命が低下した。Ｎｏ.７〜１０は本発明規定範囲の組成を有するＤ鋼を用いたものであるが、焼入れ・焼戻し条件が本発明の規定を外れたものである。すなわち、Ｎｏ.７は焼入れ温度が低過ぎたことにより溶体化が不十分となり、焼戻し後の硬さが低く、疲労寿命にも劣った。Ｎｏ.８は焼入れ温度が高過ぎたことにより粗大な析出炭化物が形成され、疲労寿命が短くなった。Ｎｏ.９は焼戻し温度が低過ぎ、またＮｏ.１０は焼戻し温度が高過ぎたことにより、これらはいずれも焼戻し後の硬さが本発明規定範囲となり、疲労寿命が短くなった。 As can be seen from Table 2, Nos. 1 (steel A), 24 (steel P), and 25 (steel Q), which are comparative examples, have C, B, and Mn contents lower than the specified range of the present invention. Since the hardenability deteriorated, the hardness after tempering became insufficient, and the fatigue life was not improved. In No. 11 (steel E), the retained austenite phase increased due to the Mn content being too high, the hardness after tempering decreased with a decrease in the quenching hardness, and the fatigue life was inferior. In addition, No. 28 (steel T) has a low Si content, an insufficient tempering hardness, and because Nb was not added, coarse precipitate carbide exceeding 0.5 μm was formed at the grain boundary. As a result, the grain boundary strength decreased and the fatigue life was inferior. No. 2 (steel B), 3 (steel C) and 15 (steel G) have too high contents of C, Si and Cr, respectively, and No. 18 (steel J) does not contain Ti and Nb. Is. In each of these, coarse precipitated carbides exceeding 0.5 μm were formed at the grain boundaries. As a result, the grain boundary strength was reduced and the fatigue life was inferior. No. 17 (steel I) has Ti and Nb exceeding the scope of the present invention. Coarse carbides of Ti and Nb were generated, which became the starting point of fatigue failure, and the fatigue life was reduced. Nos. 7 to 10 use D steel having a composition within the scope of the present invention, but the quenching and tempering conditions deviate from the provisions of the present invention. That is, in No. 7, the solution temperature was insufficient because the quenching temperature was too low, the hardness after tempering was low, and the fatigue life was also inferior. In No. 8, when the quenching temperature was too high, coarse precipitated carbides were formed, and the fatigue life was shortened. In No. 9, the tempering temperature was too low, and in No. 10, the tempering temperature was too high. Therefore, the hardness after tempering was within the range specified by the present invention, and the fatigue life was shortened.
これに対し、化学組成および焼入れ・焼戻し条件を本発明で規定する条件とした本発明例のものは、４００ＨＶ以上の強度レベルを示すとともに、析出炭化物の平均粒径が０.５μｍ以下であり、疲労寿命は５万回を超えて極めて良好であった。ここでは、「板材」を用いて焼入れ・焼戻し後の特性を調べたが、「管材」においても高強度化および高疲労寿命化に及ぼす焼入れ・焼戻し条件の影響は同様の傾向となる。すなわち、本発明で規定する組成の素材鋼管に対して本発明で規定する焼入れ・焼戻し処理を採用すると、強度および疲労特性が顕著に向上し、中空スタビライザーをはじめとする種々の機械構造部材において疲労寿命の顕著な改善が可能になる。 In contrast, the examples of the present invention in which the chemical composition and quenching / tempering conditions are defined in the present invention show a strength level of 400 HV or higher, and the average particle size of the precipitated carbide is 0.5 μm or less, The fatigue life was very good over 50,000 times. Here, the properties after quenching and tempering were investigated using “plate material”, but the effect of quenching and tempering conditions on the increase in strength and the fatigue life of “tube material” has the same tendency. That is, when the quenching and tempering treatment specified in the present invention is adopted for the material steel pipe having the composition specified in the present invention, the strength and fatigue characteristics are remarkably improved, and fatigue in various mechanical structural members including a hollow stabilizer is improved. A significant improvement in lifetime is possible.
次に、表１の鋼Ｄ、鋼Ｅ、鋼Ｇを用いて、実施例１と同様の工程で作った冷延焼鈍鋼板を素材鋼板として、高周波溶接にて造管し、外径３０ｍｍの３種類の鋼管ａ、ｂ、ｃを製造した。ただし鋼管ａおよびｂは肉厚３ｍｍ、鋼管ｃは肉厚５ｍｍとした。溶接造管後の鋼管（素材鋼管）を長さ１ｍに切断し、「９５０〜１０５０℃（表３に記載の温度）×３０秒保持→水中へ急冷」の焼入れ処理と、「３４０℃×４５分保持→空冷」の焼戻し処理を施した。その後、鋼管の外表面にショットピーニングを行った。焼入れ・焼戻し後の各鋼管（部材鋼管）について、Ｃ断面の肉厚中心部の硬さを実施例１と同様の要領で測定した。 Next, using the steel D, steel E, and steel G shown in Table 1, a cold-rolled annealed steel plate made in the same process as in Example 1 was used as a material steel plate, and was piped by high-frequency welding. Various types of steel pipes a, b and c were produced. However, the steel pipes a and b were 3 mm thick, and the steel pipe c was 5 mm thick. A steel pipe (material steel pipe) after welded pipe forming is cut into a length of 1 m, and a quenching treatment of “950 to 1050 ° C. (temperature shown in Table 3) × 30 seconds holding → cooling rapidly into water” and “340 ° C. × 45 A tempering treatment of “minute retention → air cooling” was performed. Thereafter, shot peening was performed on the outer surface of the steel pipe. About each steel pipe (member steel pipe) after hardening and tempering, the hardness of the thickness center part of C cross section was measured in the same way as Example 1.
また、上記鋼管から長さ１ｍの直管を切り出し、この鋼管の両端部１００ｍｍを掴み、円周方向にねじり応力を付与させる方法で疲労試験を行った。その際、各鋼管の長手方向中央位置の外表面に歪みゲージを貼付し、ねじり応力が７００Ｎ・ｍｍ-2となる条件で疲労試験を実施した。この試験による破断寿命が７万回以上であれば、従来の中空スタビライザー材と比較して疲労寿命が大幅に向上していると認められるので、ここでは、破断寿命が７万回以上のものを○（合格）、それ未満のものを×（不合格）と評価した。
結果を表３に示す。
Further, a straight pipe having a length of 1 m was cut out from the steel pipe, and a fatigue test was performed by a method of grasping both ends 100 mm of the steel pipe and applying a torsional stress in the circumferential direction. At that time, a strain gauge was affixed to the outer surface of the center position in the longitudinal direction of each steel pipe, and a fatigue test was performed under the condition that the torsional stress was 700 N · mm −2 . If the fracture life in this test is 70,000 times or more, it is recognized that the fatigue life is significantly improved compared to the conventional hollow stabilizer material. ○ (pass), less than that was evaluated as x (fail).
The results are shown in Table 3.
表３からわかるように、本発明の鋼管ａは４００ＨＶ以上の高強度化が達成されるとともに、析出炭化物粒径の平均値も０.５μｍ以下であり、薄肉化されているにも関わらず、肉厚の厚い鋼管ｃ（Ｃｒが高いもの）より優れた疲労特性を示した。鋼管ｂ（Ｍｎが高いもの）は薄肉化した状態では疲労特性の向上が不十分であった。 As can be seen from Table 3, the steel pipe a of the present invention achieves an increase in strength of 400 HV or more, and the average value of the precipitated carbide particle diameter is 0.5 μm or less, and despite being thinned, Fatigue characteristics superior to those of thick steel pipe c (high in Cr) were exhibited. When the steel pipe b (having a high Mn) was thinned, the fatigue characteristics were not sufficiently improved.
Claims (6)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007251196A JP5196934B2 (en) | 2007-09-27 | 2007-09-27 | High fatigue life quenched and tempered steel pipe and method for manufacturing the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2007251196A JP5196934B2 (en) | 2007-09-27 | 2007-09-27 | High fatigue life quenched and tempered steel pipe and method for manufacturing the same |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2009079280A JP2009079280A (en) | 2009-04-16 |
| JP5196934B2 true JP5196934B2 (en) | 2013-05-15 |
Family
ID=40654257
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2007251196A Active JP5196934B2 (en) | 2007-09-27 | 2007-09-27 | High fatigue life quenched and tempered steel pipe and method for manufacturing the same |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP5196934B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20190125396A (en) | 2017-04-07 | 2019-11-06 | 제이에프이 스틸 가부시키가이샤 | Steel member, hot rolled sheet steel for said steel member, and these manufacturing methods |
| KR20190125397A (en) | 2017-04-07 | 2019-11-06 | 제이에프이 스틸 가부시키가이샤 | Steel member, hot rolled sheet steel for said steel member, and these manufacturing methods |
| US10487382B2 (en) | 2016-09-09 | 2019-11-26 | Hyundai Motor Company | High strength special steel |
| US10487380B2 (en) | 2016-08-17 | 2019-11-26 | Hyundai Motor Company | High-strength special steel |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5142792B2 (en) * | 2008-04-01 | 2013-02-13 | 日新製鋼株式会社 | High fatigue life quenched and tempered steel pipe and method for manufacturing the same |
| KR101706839B1 (en) * | 2012-05-25 | 2017-02-14 | 신닛테츠스미킨 카부시키카이샤 | Hollow stabilizer, and steel pipe for hollow stabilizers and method for production thereof |
| JP6282571B2 (en) * | 2014-10-31 | 2018-02-21 | 株式会社神戸製鋼所 | Manufacturing method of high strength hollow spring steel |
| JP2016125119A (en) * | 2015-01-07 | 2016-07-11 | 株式会社神戸製鋼所 | Hollow seamless steel pipe for spring |
| JP2016125118A (en) * | 2015-01-07 | 2016-07-11 | 株式会社神戸製鋼所 | Hollow seamless steel pipe for spring |
| US20180265952A1 (en) * | 2015-01-07 | 2018-09-20 | Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel, Ltd.) | Hollow seamless steel pipe for spring |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006291252A (en) * | 2005-04-07 | 2006-10-26 | Nisshin Steel Co Ltd | Material steel plate with excellent fatigue characteristic for quenched-and-tempered steel tube, and steel tube |
-
2007
- 2007-09-27 JP JP2007251196A patent/JP5196934B2/en active Active
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10487380B2 (en) | 2016-08-17 | 2019-11-26 | Hyundai Motor Company | High-strength special steel |
| US10487382B2 (en) | 2016-09-09 | 2019-11-26 | Hyundai Motor Company | High strength special steel |
| KR20190125396A (en) | 2017-04-07 | 2019-11-06 | 제이에프이 스틸 가부시키가이샤 | Steel member, hot rolled sheet steel for said steel member, and these manufacturing methods |
| KR20190125397A (en) | 2017-04-07 | 2019-11-06 | 제이에프이 스틸 가부시키가이샤 | Steel member, hot rolled sheet steel for said steel member, and these manufacturing methods |
| US11313008B2 (en) | 2017-04-07 | 2022-04-26 | Jfe Steel Corporation | Steel member and production method therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2009079280A (en) | 2009-04-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5196934B2 (en) | High fatigue life quenched and tempered steel pipe and method for manufacturing the same | |
| JP6465249B2 (en) | ERW steel pipe for high-strength thin-walled hollow stabilizer and method for manufacturing the same | |
| JP4486516B2 (en) | ERW steel pipe excellent in cold workability and hardenability and its manufacturing method | |
| JP6017341B2 (en) | High strength cold-rolled steel sheet with excellent bendability | |
| JP5973903B2 (en) | High strength spring steel wire excellent in hydrogen embrittlement resistance, method for producing the same, and high strength spring | |
| JP6027302B2 (en) | High strength tempered spring steel | |
| JP6332473B2 (en) | High-strength hollow stabilizer ERW steel pipe, high-strength hollow stabilizer ERW steel pipe manufacturing method, high-strength hollow stabilizer, and high-strength hollow stabilizer manufacturing method | |
| WO2005056856A1 (en) | Steel product for structural member of automobile and method for production thereof | |
| JP6232324B2 (en) | Stabilizer steel and stabilizer with high strength and excellent corrosion resistance, and method for producing the same | |
| JP2013181208A (en) | High strength hot-rolled steel sheet having excellent elongation, hole expansibility and fatigue characteristics, and method for producing the same | |
| JP5499559B2 (en) | High tensile steel material for automobile undercarriage members having excellent formability and torsional fatigue resistance and method for producing the same | |
| JP5142792B2 (en) | High fatigue life quenched and tempered steel pipe and method for manufacturing the same | |
| US9540704B2 (en) | Method of making quenched and tempered steel pipe with high fatigue life | |
| JP6796472B2 (en) | Hollow member and its manufacturing method | |
| JP5125601B2 (en) | High tensile welded steel pipe for automobile structural members and method for manufacturing the same | |
| JP5499560B2 (en) | High tensile steel material for automobile undercarriage members having excellent formability and torsional fatigue resistance and method for producing the same | |
| JP2012237052A (en) | Case-hardened steel excellent in cold forgeability and suppressing ability of crystal grain coarsening, and method for manufacturing the same | |
| JP2006291252A (en) | Material steel plate with excellent fatigue characteristic for quenched-and-tempered steel tube, and steel tube | |
| CN113631735B (en) | Electric welded steel pipe for hollow stabilizer, and method for producing same | |
| JP2013072104A (en) | Steel excellent in toughness and wear resistance | |
| JP5734050B2 (en) | Medium carbon steel with excellent rolling fatigue properties and induction hardenability | |
| JP2005350736A (en) | High-strength steel having superior corrosion resistance and fatigue characteristics for spring, and manufacturing method therefor | |
| JP5512231B2 (en) | ERW steel pipe for drive shaft with excellent static torsional strength and method for manufacturing the same | |
| CN114555850A (en) | Shock absorber spring |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20100903 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20110516 |
|
| A711 | Notification of change in applicant |
Free format text: JAPANESE INTERMEDIATE CODE: A711 Effective date: 20110516 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A821 Effective date: 20110516 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20120809 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20120918 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20121108 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20130205 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20130205 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20160215 Year of fee payment: 3 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 5196934 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| S111 | Request for change of ownership or part of ownership |
Free format text: JAPANESE INTERMEDIATE CODE: R313115 |
|
| R350 | Written notification of registration of transfer |
Free format text: JAPANESE INTERMEDIATE CODE: R350 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
|
| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |