JP2819430B2 - Electrical resistance welded steel pipe for machine structure with excellent machinability - Google Patents
Electrical resistance welded steel pipe for machine structure with excellent machinabilityInfo
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- JP2819430B2 JP2819430B2 JP22372090A JP22372090A JP2819430B2 JP 2819430 B2 JP2819430 B2 JP 2819430B2 JP 22372090 A JP22372090 A JP 22372090A JP 22372090 A JP22372090 A JP 22372090A JP 2819430 B2 JP2819430 B2 JP 2819430B2
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- electric resistance
- steel pipe
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Description
【発明の詳細な説明】 （産業上の利用分野） 本発明は、被削性の良好な機械構造用電気抵抗溶接鋼
管に関するものである。Description: TECHNICAL FIELD The present invention relates to an electric resistance welded steel pipe for machine structures having good machinability.
（従来の技術） 切削加工技術の進展、自動車その他の機械生産量の増
大に伴い、被削性の優れた鋼材の必要性が大きくなって
いる。機械構造用鋼管についても、切削加工の自動化、
高能率化によって切屑処理性、切削仕上面の良好な材料
が望まれている。(Prior Art) With the progress of cutting technology and the increase in production of automobiles and other machines, the need for steel materials with excellent machinability has increased. Automation of cutting process for steel pipe for machine structure,
There is a demand for a material having good chip disposability and a good cut surface due to high efficiency.
一般に機械構造用鋼については、被削性を改善させる
ために、例えば、特開昭55−85658号公報、特開昭57−1
40853号公報や特開昭62−33747号公報に示されているよ
うなＳ系快削鋼、Pb快削鋼、Ca快削鋼およびこれらの複
合快削鋼が開発され、実用化されている。しかしなが
ら、被削性の良好な機械構造用鋼管を電気抵抗溶接によ
って製造しようとする際、これらの快削鋼の快削性元素
が生成する介在物は電気抵抗溶接性を劣化させ、溶接割
れ、超音波探傷試験時のUST不良などによる大幅な歩留
低下の原因となるため、電気抵抗溶接鋼管の材料として
従来の快削鋼を使用することはできない。なお、これら
の介在物による機械的性質の劣化を防ぐために、特公61
−16337号公報に示すようにsol.Alを制限し、S,Ca,Oの
量を特定しているものもあるが、電気抵抗溶接鋼管の素
材として用いる場合には、上記問題点を完全に解消する
ものではない。Generally, for steel for machine structural use, in order to improve machinability, for example, JP-A-55-85658, JP-A-57-1
S-type free-cutting steel, Pb free-cutting steel, Ca free-cutting steel, and composite free-cutting steels thereof as disclosed in 40853 and JP-A-62-33747 have been developed and put into practical use. . However, when attempting to manufacture a steel pipe for machine structure with good machinability by electric resistance welding, the inclusions generated by the free-cutting elements of these free-cutting steels deteriorate the electric resistance weldability, causing welding cracks, Conventional free-cutting steel cannot be used as a material for electric resistance welded steel pipes, because it causes a large decrease in yield due to UST failure during ultrasonic testing. In order to prevent the mechanical properties from being degraded by these inclusions,
Although sol.Al is limited and the amount of S, Ca, O is specified as shown in -16337 gazette, when used as a material for electric resistance welded steel pipe, the above problems are completely solved. It does not eliminate it.
（発明が解決しようとする課題） 被削性の優れた機械構造用電気抵抗溶接鋼管を製造す
るにあたって、快削性元素が生成する介在物は、電気抵
抗溶接性を著しく劣化させ、溶接割れ、UST不良などの
原因となるため、従来の快削鋼を電気抵抗溶接鋼管の素
材として使用することはできないという問題点がある。
本発明は、これらの問題点を解決し、機械構造用電縫鋼
管の被削性改善要求に応えることを目的としてなされた
ものである。(Problems to be Solved by the Invention) In producing electric resistance welded steel pipes for machine structures excellent in machinability, inclusions generated by free-cutting elements significantly deteriorate electric resistance weldability, and cause weld cracks, There is a problem that conventional free-cutting steel cannot be used as a material for electric resistance welded steel pipes because it causes UST defects and the like.
The present invention has been made to solve these problems and to meet the demand for improving machinability of ERW steel pipes for machine structures.
（課題を解決するための手段） 本発明の要旨とするところは下記の通りである。(Means for Solving the Problems) The gist of the present invention is as follows.
（１）重量％表示で、C:0.02〜0.60％、Si:0.4％以下、
Mn:0.20〜2.0％、P:0.030％以下、S:0.010％以下、sol.
Al:0.001〜0.005％、N:0.0040〜0.0100％、O:0.0060％
以下、Ca:0.002〜0.020％でかつCa％／（1.25×Ｏ％＋
0.625×Ｓ％）≧0.05、を含有し、残部鉄および不可避
的不純物からなり、電気抵抗溶接後に500℃以上の熱処
理を施すことを特徴とする被削性の優れた機械構造用電
気抵抗溶接鋼管。(1) In terms of% by weight, C: 0.02 to 0.60%, Si: 0.4% or less,
Mn: 0.20-2.0%, P: 0.030% or less, S: 0.010% or less, sol.
Al: 0.001-0.005%, N: 0.0040-0.0100%, O: 0.0060%
Hereinafter, Ca: 0.002 to 0.020% and Ca% / (1.25 × O% +
0.625 × S%) ≧ 0.05, the balance being iron and unavoidable impurities, and subjected to heat treatment at 500 ° C. or more after electric resistance welding. .
（２）重量％表示で、C:0.02〜0.60％、Si:0.4％以下、
Mn:0.20〜2.0％、P:0.030％以下、S:0.010％以下、Cr:
0.10〜1.50％、Mo:0.10〜0.60％、sol.Al:0.001〜0.005
％、N:0.0040〜0.0100％、O:0.0060％以下、Ca:0.002〜
0.020％でかつCa％／（1.25×Ｏ％＋0.625×Ｓ％）≧0.
05、を含有し、残部鉄および不可避的不純物からなり、
電気抵抗溶接後に500℃以上の熱処理を施すことを特徴
とする被削性の優れた機械構造用電気抵抗溶接鋼管。(2) In terms of% by weight, C: 0.02 to 0.60%, Si: 0.4% or less,
Mn: 0.20 to 2.0%, P: 0.030% or less, S: 0.010% or less, Cr:
0.10 to 1.50%, Mo: 0.10 to 0.60%, sol.Al: 0.001 to 0.005
%, N: 0.0040 to 0.0100%, O: 0.0060% or less, Ca: 0.002 to
0.020% and Ca% / (1.25 × O% + 0.625 × S%) ≧ 0.
05, containing iron and unavoidable impurities,
An electric resistance welded steel pipe for machine structure with excellent machinability, which is subjected to heat treatment at 500 ° C or higher after electric resistance welding.
ここで本発明は、切屑処理性の良好な電気抵抗溶接鋼
管を歩留良く製造することを可能とするためにＮを添加
し、さらに造管後に500℃以上の熱処理を施すことによ
り切屑処理性を向上させ、Ｓの添加量を通常の機械構造
用電気抵抗溶接鋼管のレベルとほぼ同等にまで軽減させ
たことを特徴としている。Here, the present invention adds N in order to make it possible to produce an electric resistance welded steel pipe having good chip disposability with a good yield, and further performs a heat treatment at 500 ° C. or more after the pipe making to improve the chip disposability. And the addition amount of S is reduced to substantially the same level as that of a normal electric resistance welded steel pipe for machine structures.
（作用） 以下に本発明の詳細を述べるとともに、前記のように
本発明の鋼の成分範囲を定めた理由について説明する。(Operation) The details of the present invention will be described below, and the reason for defining the component range of the steel of the present invention as described above will be described.
本発明は、切屑処理性の良好な機械構造用鋼管を電気
抵抗溶接により製造することを目的としたもので、N,S,
Ca,Oおよびsol.Alの量を特定することにより、快削成分
の介在物による電気抵抗溶接の際の溶接割れ、UST不良
などを原因とする歩留の大幅低下を抑制している。The present invention has an object to manufacture a steel pipe for machine structural use having good chip controllability by electric resistance welding.
By specifying the amounts of Ca, O, and sol. Al, the yield is significantly reduced due to welding cracks and UST defects during electric resistance welding due to inclusions of free-cutting components.
Ｃは、機械的強度を確保するために必須であるため、
下限を0.02％とした。また、0.60％を超えると靭性およ
び被削性が劣化するうえ、製管のための電気抵抗溶接時
に、その熱影響によって著しく硬化し加工性を損なうの
で、その上限を0.60％とした。C is essential for ensuring mechanical strength,
The lower limit was set to 0.02%. Further, if it exceeds 0.60%, toughness and machinability are deteriorated, and at the time of electric resistance welding for pipe making, the material is significantly hardened due to its thermal effect and impairs workability. Therefore, the upper limit is set to 0.60%.
Siは、脱酸上鋼に含まれる元素であるが、過剰に添加
すると延性を低下させるほか、Siスケールの生成によっ
て被削材の表面性状を劣化させ、被削性も悪化させるた
め、その上限値を0.4％とした。Si is an element contained in the deoxidized upper steel, but if added excessively, it reduces ductility, and the formation of Si scale deteriorates the surface properties of the work material and deteriorates the machinability. The value was 0.4%.
Mnは、一般に鋼の強度、靭性を確保する上で不可欠な
元素であり、Ｓによる熱間脆性を回避する意味を併せ
て、下限を0.20％とした。しかしながら、過度の添加は
加工性・溶接性を劣化させるため、2.0％とした。Mn is generally an indispensable element for ensuring the strength and toughness of steel, and the lower limit is set to 0.20% in consideration of avoiding hot brittleness due to S. However, excessive addition deteriorates workability and weldability, so the content was set to 2.0%.
Ｐは、一般に鋼中に固溶して生地を脆化させることに
より被削性を向上させる元素であるが、この量が多いと
電気抵抗溶接性を劣化させる。従って、その上限を0.03
0％とした。P is an element that generally improves the machinability by forming a solid solution in steel to embrittle the material, but when this amount is large, the electric resistance weldability is deteriorated. Therefore, the upper limit is 0.03
0%.
Ｓは、切屑処理性を改善するために有効な元素である
が、Ｓ量の増大とともに、製管のための電気抵抗溶接の
際の溶接割れ、超音波探傷試験時のUST不良などによる
大幅な歩留低下の原因となるため、その上限値を0.010
％とした。S is an effective element for improving the chip disposability, but as the amount of S increases, significant cracks occur due to welding cracks during electric resistance welding for pipe making, UST defects during ultrasonic testing, etc. The upper limit is set to 0.010 to reduce the yield.
%.
sol.Alは一般に脱酸上含まれる元素であり、リムド鋼
ベースのものを考慮して下限値を0.001％とした。一
方、Alはアルミナクラスターの生成により鋼の被削性を
悪化させるうえ、後述のＮの効果を最大限に発揮させる
ためにはＮを固溶させておく必要があるため、その上限
を0.005％とした。sol.Al is an element generally included in deoxidation, and its lower limit is set to 0.001% in consideration of a rimmed steel base. On the other hand, Al deteriorates the machinability of steel due to the formation of alumina clusters, and it is necessary to dissolve N in order to maximize the effect of N described below, so the upper limit is 0.005%. And
Ｎは、被削性に対して有効な元素である。これは、切
削加工の際、切屑の温度が固溶Ｎによる青熱脆性温度領
域に達するため、切屑の分断性が良くなるというもので
あり、前述のsol.Alの量を前提とした場合、0.0040％以
上の添加でその作用を発揮する。しかしながら、0.0100
％を超えて添加すると溶接性を著しく劣化させることか
ら、その上限値を0.0100％とした。N is an element effective for machinability. This means that, during cutting, the temperature of the chips reaches the blue-hot brittleness temperature region due to solid solution N, so that the cutting ability of the chips is improved, and assuming the amount of sol.Al described above, It exerts its effect when 0.0040% or more is added. However, 0.0100
%, The weldability is remarkably deteriorated, so the upper limit was made 0.0100%.
Ｏは、前述のＳ量、sol.Alを前提とした場合、0.0060
％超の添加によって酸化物が増大し、超音波探傷試験時
のUST不良の要因となるうえ、Ca酸化物を生成すること
により、次に述べる硫化物MnSの形態を制御するためのC
aを少なくするため、その上限を0.0060％とした。O is 0.0060 assuming the aforementioned S amount and sol.Al.
% Increases the oxide content, causing UST failure during ultrasonic testing. In addition, the formation of Ca oxide allows the formation of the following sulfide MnS to control the form of MnS:
In order to reduce a, the upper limit was made 0.0060%.
Caは、0.002％以上の添加によって、硫化物MnSの形態
を制御し靭性を向上させる効果を有しているほか、酸化
物生成により工具寿命、切削抵抗を良好とする。一方、
0.020％を超えて添加すると大型介在物となり、靭性、
電気抵抗溶接性に悪影響を及ぼす。このため添加量の範
囲を0.002〜0.020％に制限した。When Ca is added in an amount of 0.002% or more, Ca has the effect of controlling the form of sulfide MnS and improving toughness, and also improves tool life and cutting resistance due to oxide formation. on the other hand,
If added over 0.020%, it becomes a large inclusion, toughness,
Has a bad effect on electric resistance weldability. For this reason, the range of the amount added was limited to 0.002 to 0.020%.
さらに、Ca％／（1.25×Ｏ％＋0.625×Ｓ％）を0.05
以上とすることで、製管のための電気抵抗溶接の際のUS
T不良の原因となるMnSの展伸を抑える効果を発揮させる
ことができる。なお、上式の分母は、CaがCaSとしてＳ
と有効に結びつき、硫化物の多くを楕円状化してMnSの
展伸を抑制し、さらにCa,Alが有効に結びついて低融点
酸化物CaO・Al2O3を生成するために必要なCa量を表して
いる。Furthermore, Ca% / (1.25 × O% + 0.625 × S%) is 0.05%.
With the above, the US in electric resistance welding for pipe making
The effect of suppressing the spread of MnS that causes T failure can be exerted. Note that the denominator of the above equation is S when Ca is CaS.
And the amount of Ca required to form a low-melting oxide CaO.Al 2 O 3 by effectively binding MnS by making many of the sulfides elliptical and suppressing the expansion of MnS Is represented.
また、本発明は、機械構造用鋼管の耐食性を考慮し
て、0.10％以上のCr,Mo等の合金元素を加えた場合にも
有効であり、炭素鋼をはじめ、各種の合金鋼に対しても
適用し得る。但し、これらの元素についても、多量添加
は機械構造用合金鋼としての被削性を低下させるので、
その上限値をそれぞれ1.50％、0.60％とした。さらに、
必要に応じて、結晶粒を細粒化し靭性を向上させるため
に、Nb,W等を含有させることも可能である。また、本発
明にREM（希土類元素）を含有させることにより、機械
的性質を改善させることも可能である。In addition, the present invention is also effective when adding alloy elements such as Cr and Mo in an amount of 0.10% or more in consideration of the corrosion resistance of steel pipes for machine structures, and is applicable to various alloy steels including carbon steel. May also be applied. However, also for these elements, the addition of a large amount lowers the machinability as alloy steel for machine structural use.
The upper limits were 1.50% and 0.60%, respectively. further,
If necessary, Nb, W, and the like can be contained in order to refine crystal grains and improve toughness. Further, by including REM (rare earth element) in the present invention, it is also possible to improve the mechanical properties.
なお、本発明においては、電気抵抗溶接後の熱処理が
必須である。これは、電気抵抗溶接鋼管の製管のための
管成形による冷間加工により加工硬化し、切屑処理性を
劣化させ、本発明における範囲のS,Nの添加のみでは十
分な切屑処理性を確保することができないためであり、
管全体の500℃以上の焼きなまし処理を行う必要があ
る。また、この熱処理は、通常、電気抵抗溶接後に組織
の改善と軟化を目的として実施される、Ac3点以上の温
度での管全体の焼きならし処理により代用することも可
能である。In the present invention, heat treatment after electric resistance welding is essential. This is work hardened by cold working by pipe forming for the production of electric resistance welded steel pipe, deteriorating chip disposability, ensuring sufficient chip disposability only by adding S and N in the range of the present invention. Because they cannot
It is necessary to perform annealing at 500 ° C or higher for the entire tube. This heat treatment can be replaced by a normalizing treatment of the entire pipe at a temperature of 3 or more Ac, which is usually performed for the purpose of improving and softening the structure after electric resistance welding.
一方、このような電気抵抗溶接鋼管においては、製管
後に所定の外径に仕上げることを目的として冷間引抜き
を実施する場合がある。この際、減面率が大きく、材料
の加工硬化が大きくなると考えられる場合には、前述と
同様の理由で、加工後に仕上熱処理を実施する必要があ
る。On the other hand, in such an electric resistance welded steel pipe, cold drawing may be performed in order to finish the pipe to a predetermined outer diameter after pipe production. At this time, when it is considered that the surface reduction rate is large and the work hardening of the material is increased, it is necessary to perform a finishing heat treatment after the processing for the same reason as described above.
本発明に従い前記の化学成分で構成された鋼は、転
炉、電気炉などで溶製され、造塊−分塊あるいは連続鋳
造の工程を経て熱間圧延される。この後に、必要に応じ
て冷間圧延を施され、管成形−電気抵抗溶接された後、
所定の熱処理を受け、機械構造用鋼管として使用に供さ
れる。According to the present invention, steel composed of the above chemical components is melted in a converter, an electric furnace, or the like, and hot-rolled through a process of ingot-bulking or continuous casting. After this, cold rolling is performed as necessary, and tube forming-after electric resistance welding,
After undergoing a predetermined heat treatment, it is used as a steel pipe for machine structure.
（実施例） 第１表は、本発明を実施するにあたって使用に供した
鋼の化学組成を示したものである。第１表に示した成分
の鋼を溶製、連続鋳造、熱間圧延を行った後、電気抵抗
溶接を行い、φ50.8×t5.0mmの電気抵抗溶接鋼管を製造
した。また、製管後の全ての管について、超音波探傷
（UST）を実施した。この際のUSTの歩留値と実用試験結
果について第２表に示す。さらに、製管後、熱処理を行
ない、旋盤によって切削試験を実施した。その結果も併
せて第２表に示す。これらの結果をまとめて模式的に第
１図に示す。(Example) Table 1 shows the chemical composition of steel used for carrying out the present invention. After the steel having the components shown in Table 1 was melted, continuously cast, and hot rolled, electric resistance welding was performed to produce an electric resistance welded steel pipe of φ50.8 × t5.0 mm. In addition, ultrasonic inspection (UST) was performed on all the tubes after the tube production. Table 2 shows the UST yield values and practical test results at this time. Further, after pipe production, heat treatment was performed, and a cutting test was performed using a lathe. The results are also shown in Table 2. FIG. 1 schematically shows these results.
なお、切削試験は、回転数300〜800RPM,送り0.10〜0.
50mm/rev.,切削速度50〜200mm/min.,切込み1.5mmの切削
条件で超硬工具を用いて実施し、切屑を採取した。ここ
で、切屑処理性指数は、切屑長さ50mm以下が得られる条
件数の全条件数に対する百分率で示した。The cutting test was performed at a rotational speed of 300 to 800 RPM and a feed of 0.10 to 0.
Cutting was performed using a carbide tool under cutting conditions of 50 mm / rev., A cutting speed of 50 to 200 mm / min., And a cutting depth of 1.5 mm, and chips were collected. Here, the chip disposability index was shown as a percentage of the number of conditions for obtaining a chip length of 50 mm or less with respect to the total number of conditions.
第２表および第１図より、Ｓレベルの低い従来の機械
構造用電気抵抗溶接鋼管は、UST時の歩留は良好である
が、切屑処理性が劣ること、Ｓレベルの高い従来の快削
鋼を素材とした場合には切屑処理性は良好であるが、US
T時の歩留が著しく劣ることが分かる。さらに、S,N,Ca,
O,およびsol.Alの量を、本発明で示した範囲に特定し、
製管後に500℃以上の熱処理を実施することにより、UST
時の歩留を通常の電気抵抗溶接管製管時と比べてほとん
ど低下させることなく、切屑処理性の良好な溶接鋼管を
製造することが可能であることが分かる。According to Table 2 and FIG. 1, the conventional electric resistance welded steel pipe for machine structure with a low S level has a good yield at the time of UST, but has a poor chip controllability and a conventional free cutting with a high S level. When steel is used as the material, chip handling is good, but US
It can be seen that the yield at T is significantly inferior. Furthermore, S, N, Ca,
O, and the amount of sol.Al are specified in the range shown in the present invention,
By performing heat treatment at 500 ℃ or more after pipe making, UST
It can be seen that it is possible to manufacture a welded steel pipe having good chip disposability without substantially lowering the yield at the time of pipe production compared with the case of ordinary electric resistance welding pipe production.
（発明の効果） 以上の実施例からも分かるように、N,S,Ca,Oおよびso
l.Alの量を、本発明で示した範囲に特定し、製管後に熱
処理を実施することにより、UST時の歩留の低下はほと
んどない。本発明により、被削性の優れた機械構造用電
気抵抗溶接鋼管を製造することが可能となった。 (Effect of the Invention) As can be seen from the above embodiments, N, S, Ca, O and so
By specifying the amount of l.Al within the range shown in the present invention and performing heat treatment after pipe production, there is almost no decrease in the yield during UST. ADVANTAGE OF THE INVENTION By this invention, it became possible to manufacture the electrical resistance welded steel pipe for machine structures excellent in machinability.
第１図は本発明の効果について模式的に示したものであ
る。FIG. 1 schematically shows the effect of the present invention.
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 平３−177539（ＪＰ，Ａ) 特開 平３−177540（ＪＰ，Ａ) 特開 平３−226545（ＪＰ，Ａ) (58)調査した分野(Int.Cl.6，ＤＢ名) C22C 38/00 - 38/60 C21D 9/08────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-3-17739 (JP, A) JP-A 3-177540 (JP, A) JP-A 3-226545 (JP, A) (58) Field (Int.Cl. 6 , DB name) C22C 38/00-38/60 C21D 9/08
Claims (2)
抵抗溶接後に500℃以上の熱処理を施すことを特徴とす
る被削性の優れた機械構造用電気抵抗溶接鋼管。[Claim 1] C: 0.02 to 0.60%, Si: 0.4% or less, Mn: 0.20 to 2.0%, P: 0.030% or less, S: 0.010% or less, sol.Al: 0.001 to 0.005% by weight%, N: 0.0040-0.0100%, O: 0.0060% or less, Ca: 0.002-0.020% and Ca% / (1.25 × O% + 0.625 × S%) ≧ 0.05, containing from the balance iron and inevitable impurities An electric resistance welded steel pipe for machine structures with excellent machinability, which is subjected to heat treatment at 500 ° C or higher after electric resistance welding.
抵抗溶接後に500℃以上の熱処理を施すことを特徴とす
る被削性の優れた機械構造用電気抵抗溶接鋼管。2. In% by weight, C: 0.02 to 0.60%, Si: 0.4% or less, Mn: 0.20 to 2.0%, P: 0.030% or less, S: 0.010% or less, Cr: 0.10 to 1.50%, Mo: 0.10 ~ 0.60%, sol.Al:0.001~0.005%, N: 0.0040 ~ 0.0100%, O: 0.0060% or less, Ca: 0.002 ~ 0.020% and Ca% / (1.25 × O% + 0.625 × S%) An electric resistance welded steel pipe for machine structure excellent in machinability, characterized by containing ≧ 0.05, the balance being iron and unavoidable impurities, and being subjected to heat treatment at 500 ° C. or more after electric resistance welding.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22372090A JP2819430B2 (en) | 1990-08-24 | 1990-08-24 | Electrical resistance welded steel pipe for machine structure with excellent machinability |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP22372090A JP2819430B2 (en) | 1990-08-24 | 1990-08-24 | Electrical resistance welded steel pipe for machine structure with excellent machinability |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04107241A JPH04107241A (en) | 1992-04-08 |
| JP2819430B2 true JP2819430B2 (en) | 1998-10-30 |
Family
ID=16802623
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP22372090A Expired - Fee Related JP2819430B2 (en) | 1990-08-24 | 1990-08-24 | Electrical resistance welded steel pipe for machine structure with excellent machinability |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2819430B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0681078A (en) * | 1992-07-09 | 1994-03-22 | Sumitomo Metal Ind Ltd | Low yield ratio high strength steel and its production |
-
1990
- 1990-08-24 JP JP22372090A patent/JP2819430B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH04107241A (en) | 1992-04-08 |
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