WO2000077270A1 - Highly cleaned steel - Google Patents

Highly cleaned steel Download PDF

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Publication number
WO2000077270A1
WO2000077270A1 PCT/JP2000/003975 JP0003975W WO0077270A1 WO 2000077270 A1 WO2000077270 A1 WO 2000077270A1 JP 0003975 W JP0003975 W JP 0003975W WO 0077270 A1 WO0077270 A1 WO 0077270A1
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WIPO (PCT)
Prior art keywords
composition
less
inclusions
steel
ratio
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PCT/JP2000/003975
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French (fr)
Japanese (ja)
Inventor
Wataru Yamada
Seiki Nishida
Satoshi Sugimaru
Shinjiro Ueyama
Hiroshi Yatabe
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Nippon Steel Corporation
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Publication date
Application filed by Nippon Steel Corporation filed Critical Nippon Steel Corporation
Priority to KR1020017002034A priority Critical patent/KR20010086358A/en
Priority to CA002340688A priority patent/CA2340688A1/en
Priority to BR0006880-2A priority patent/BR0006880A/en
Priority to EP00939092A priority patent/EP1127951A1/en
Publication of WO2000077270A1 publication Critical patent/WO2000077270A1/en

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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon

Definitions

  • the inventions described in Japanese Patent Publication No. 6-74484 and Japanese Patent Publication No. 6-74485 mentioned above add Si, Mn and other necessary constituent elements in the molten steel stage in order to soften the inclusions in the steel.
  • Complex deoxidation is performed by adding an alloy containing one or more of Ca, Mg and, if necessary, A1 to make the inclusion composition an inclusion of the composite composition.
  • the Ca and Mg alloys added in the molten steel stage are expensive, and it is preferable to reduce the amount of these expensive alloys because the manufacturing cost is reduced. Disclosure of the invention
  • An object of the present invention is to provide a high cleanliness steel having excellent cold workability and fatigue properties even with a small amount of Ca and Mg alloys used.
  • the first invention is, without the use of A1 to eliminate A 1 2 0 3 in the inclusions as much as possible, Si, Mn, and using one or both of Ca and Mg be invention to perform complex deoxidation
  • the summary is as follows.
  • the ratio of length (1) to width (d) of nonmetallic inclusions with a ratio of 1 Zd ⁇ 5 belonging to the following composition A1 is 20% or more in number ratio.
  • the cooling is characterized by being 80% or more in total belonging to the following composition A1 or B1, and the d of nonmetallic inclusions belonging to the following composition A1 with lZd ⁇ 5 is 40m or less.
  • composition of nonmetallic inclusions Si0 2, MnO, CaO, MgO, determined as 100 the sum of A 1 2 0 3. The same applies to the following inventions.
  • the average composition of the length (1) is, Si0 2: 30% or more, Mn0:. 8 to 65 Cold workability and fatigue, characterized in that d contains 40% or less of non-metallic inclusions where 1 / d ⁇ 5 contains one or both of Ca0: 40% or less and MgO: 12% or less. High cleanliness steel with excellent properties.
  • the average composition of non-metallic inclusions is determined by the average number of non-metallic inclusions whose composition is analyzed from one view of the L cross section of the rolled steel. The same applies to the following inventions.
  • a second invention is actively Ca0, MgO in inclusions, an invention for performing composite deoxidation to contain A 1 2 0 3, the place to Abstracts Oh following "3.
  • Composition A 2 SiO,: Over 75%
  • Composition B 2 Si0 2: 35 ⁇ 75%
  • Al 2 0 3 30% or less
  • Ca0 50% or less
  • Mg 0 containing one or both of 15% or less.
  • the steel composition in the present invention needs to contain 0.1% or more of S and Mn in order to control the inclusion composition, but there is no particular limitation on the other elements. It can be applied to carbon steel, high carbon and austenitic stainless steel. Specifically, it is as shown below.
  • inclusions of lZd ⁇ 5 were softened by compounding the inclusion composition.
  • Si 0 2 composition in inclusions is set to 60% or less to 75% or less. If Si0 2 exceeds this concentration, by the recognition of the Si0 2 inclusions of hard to occur.
  • the composition range of inclusions that are sufficiently soft and crushed by cold rolling or wire drawing to be finely dispersed and made harmless is B (B1, B2), and the inclusions having composition B the composition range of even Si0 2 concentration is high inclusions was a (a 1, a 2) .
  • composition of nonmetallic inclusions with 1 Z d ⁇ 5 20% or more of those belonging to composition A by composition, and 80% or more in total belonging to composition A or B.
  • composition A or B is not less than 80% in total, inclusions composition does not belong to B to A is, there, for example, CaO-based, MgO-based, A 1 2 0 3 based inclusions This is because the ratio of these hard inclusions exceeds 20%, which impairs the cold workability and fatigue properties of steel.
  • the reason why the ratio of the inclusions belonging to the composition A is set to 20% or more is that the inclusions in the composition A increase as the addition amount of the Ca and Mg alloys added in the molten steel decreases, but the inclusions in the composition A increase This is because if the amount of Ca and Mg alloys is reduced to the extent of not less than%, the cost reduction effect, which is the object of the present invention, can be achieved. If the content of the component A is 40% or more, a further cost reduction effect can be exhibited.
  • composition B The reasons for limiting the composition range of the composition B will be described for each of the first invention and the second invention.
  • Si0 In 2 is less than 20%, it occurred CaO or hard inclusions of the MgO-based, not can trigger sufficient miniaturization hot rolling and cold working co.
  • the inclusion composition in the present invention is a force that can be produced by producing an Mn-Silicate by deoxidation of Si and Mn and then adding an appropriate amount of an alloy containing Ca and Mg. It is important to point out that although ⁇ ⁇ tends to disappear with the addition of Ca and Mg alloys, by appropriately controlling the amount of these alloyed irons, M This is to prevent inclusions.
  • a 1 2 0 3 even when controlling the proper deoxidation methods A1 disuse and generates the most about 20%.
  • the inclusions containing A 1 2 0 3 This degree unlike the prior art in the composition of the present invention, rather than generating a hard Kola random or spinel Le, Al 2 0 3: 20% or less is acceptable.
  • the second invention in the composition B 2 the Si0 2: 35 ⁇ 75%, A1 2 0 3: 30% or less, Ca0: 50% or less, Mg0: reason for to include one or both of 15% or less of the following It is as follows.
  • Si, Ca, Mg be used to generate easily deoxidizing element hard inclusions such as Al, Ca0, MgO, Ri by the A 1 2 0 3 in the this coexist with Si0 2 in a range, very Can form soft inclusions.
  • Si0 In 2 is less than 35%, CaO, hard inclusions of the MgO or Al 2 0 3 system occurs, not both can trigger sufficient miniaturization hot rolling and cold working.
  • CaO exceeds 50%, MgO exceeds 15%, when A 1 2 0 3 exceeds 30%, respectively CaO-based, MgO-based, A 1 2 0 3 system, and hard intervention of these composite systems Things occur.
  • CaO is preferably at least 5% in order to reliably obtain the effect of softening inclusions by complex deoxidation.
  • the content of MgO is preferably 3% or more in order to surely obtain the effect of softening inclusions by complex deoxidation.
  • Major feature of the second invention may be thus positively Ca0, MgO, is contained Al 2 0 3, the prior art Kola random, harmful, such as spinel It is extremely excellent in production stability without producing any hard inclusions.
  • MnO, ⁇ is Ca, Mg, have a tendency to disappear by the addition of a strong deoxidizing element, such as A l, in particular as in the present invention, CaO, MgO, A 1 2 0 3
  • a 1 2 0 no 3 of the lower limit has been stipulated, but since the second invention to contain actively A 1 2 0 3, typically in inclusion composition B 2 is the A 1 2 0 3 Contains 5% or more.
  • the present invention As described above, according to the present invention, excellent cold workability and fatigue characteristics can be secured by controlling the composition and size of the inclusions.
  • the number of inclusions belonging to A 1 or A 2 at 1 Zd 5 is observed. In one visual field (5.5 mm ⁇ 11 mm), the number of inclusions is 1 / mm 2 or less, more preferably 0. . by the this to 5 / mm 2 or less, upon drawing Die life can be improved.
  • the composition of nonmetallic inclusions of 1 / d ⁇ 5 instead of specifying the composition of nonmetallic inclusions of 1 / d ⁇ 5 by the ratio of those in the A region and the ratio of those in the A or B region as described above, (3), (3) It can also be specified by the average composition of non-metallic inclusions with l Zd ⁇ 5 as in 6). Details are as follows. Here, the average composition of non-metallic inclusions is determined by the average number of non-metallic inclusions whose composition is analyzed in one view of the L cross section of the rolled steel. For one field of view, for example, a wire with a size of about 5.5 mm X 11 mm is appropriate.
  • the average composition of the length (1) the ratio is 1 / d ⁇ nonmetallic inclusions 5 of width (d) is, Si0 2: 30% or more, Mn0: in 8-65%, One or both of Ca0: 40% or less and Mg0: 12% or less, and d of nonmetallic inclusions with l Zd ⁇ 5 is 40 m or less.
  • Cost reduction effect 2 by the average composition Si0 is an object of the present invention when reducing Ca, and Mg alloy such that 30% or more can be exhibited. Presence of 8% or more of MnO prevents generation of hard inclusions. Order to Si0 2 of 30% or more, MnO upper limit is 65%.
  • CaO is preferably set to 5% or more in order to surely obtain the effect of softening inclusions by complex deoxidation.
  • MgO is preferably set to 3% or more in order to surely obtain the effect of softening inclusions by complex deoxidation. If the Si 0 2 60 percent, it is the this to exert even greater cost Bok reduction. In this case, Mn0 and CaO have an upper limit of 32%, and MgO has an upper limit of 30%.
  • the average composition of the length (1) the ratio is 1 Z d nonmetallic inclusions 5 of width (d) is, Si0 2: 43% or more, Al 2 0 3: 24% or less, Ca0: 40% or less, MgO: 12% or less, d of nonmetallic inclusions with l Z d ⁇ 5 is 40 / m or less.
  • CaO is preferably set to 5% or more in order to reliably obtain the effect of inclusion softening by complex deoxidation.
  • the content of MgO is preferably 3% or more in order to reliably obtain the effect of softening inclusions by complex deoxidation. If Si0 2 : more than 75%, further cost reduction effect can be exhibited.
  • CaO, MgO, the upper limit of A 1 2 0 3 is, Al 2 0 3, respectively: 17% or less, Ca0: 20% or less, MgO: determined as 15% or less.
  • the present invention achieves good results in applications requiring the same severe cold workability and fatigue characteristics as in the past.
  • tire cords have been used in some applications with a large diameter, and the cold workability of the tire cord has been reduced as compared with the conventional one.
  • the life of the wire drawing dies can be manufactured without being affected even if the inclusion level of the steel material is slightly reduced due to improved lubrication. In such applications, the high cleanliness steel of the present invention is particularly effective.
  • One example is carbon steel and low alloy carbon steel wire rods, which are drawn after hot rolling and used for wires, springs, etc. Especially 0.3mm0 or less Wires and hard wires are effective in preventing breakage during wire drawing and burning, and springs are effective in improving fatigue strength.
  • Si and Mn are necessary for deoxidation and inclusion composition control, and if less than 0.1%, there is no effect.
  • the steel which is effective as a steel strengthening element, becomes brittle when the Si content exceeds 1.5% and the Mn content exceeds 1.5%.
  • B is an element that improves the hardenability of steel.
  • its addition is a force that can increase the strength of the steel.
  • the upper limit is set to 0.01% in order to increase precipitates and impair the toughness of the steel. Also, if the amount is too small, there is no effect. Therefore, the lower limit of the amount is set to 0.01%.
  • Mo is an element that improves the hardenability of steel.
  • the addition of Mo can increase the strength of the steel.
  • the addition of an excessive amount hardens the steel excessively and makes working difficult, so the Mo addition range was set to 0.05 to 1.0%.
  • Co improves ductility by the effect of suppressing the formation of proeutectoid cementite in hypereutectoid steel.
  • P and S not only deteriorate the drawability but also the ductility after drawing, so that the content of P and S is preferably 0.02% or less.
  • Another application is austenitic stainless steel. Hot-rolled and then cold-rolled and used as an ultra-thin leaf spring of 0.3 or less, it is effective in improving the fatigue strength of the spring.
  • the composition of steel used in this application is as follows: C: 0.15% or less, Si: 0.1 to 1%, Mn: 0.1 to 2%, Cr: 16 to 20%, N 3.5 to 22% Be represented.
  • Another application is low carbon steel sheet for deep drawing. Hot rolling and cold rolling are performed to make a thin plate of 1.2 mm or less. After annealing and skim pass, deep drawing is performed. It is effective in preventing surface flaws and improving deep drawability.
  • the components of steel materials applied for this purpose are represented by C: 0.12% or less, Si: 0.3% or less, and Mn: 0.50% or less.
  • the wire was subjected to wire drawing, and the die life and wire breaking rate during wire drawing were evaluated. Tables 1 and 2 also show the evaluation results. Since the longer the die life, the better the average die life of the current process material (which is longer than the die life standard) because the longer the dice life, the better the die life, and the X less than the average life of the current process material. In addition, the lower the disconnection rate, the better the lower the average disconnection rate of the current process material (the disconnection rate is less than the allowable disconnection standard), and the higher the disconnection rate of the current process material, X.

Abstract

A highly cleaned steel being excellent in cold forming property and fatigue characteristics, characterized in that, in the L cross section of a rolled steel, with respect to non-metal inclusions having a ratio of length (l) to width (d), l/d, of 5 or less, those having the composition A1 described below account for 20 number % or more, the sum of those having the composition A1 or B1 account for 80 number % or more, and non-metal inclusions having a l/d of 5 or less and the composition A1 have a d of 40 νm or less, composition A1: SiO2: 60 % or more, composition B1: SiO2: 20 to 60 %, MnO: 10 to 80 %, and further 50 % or less of CaO and/or 15 % or less of MgO are contained. The highly cleaned steel being excellent in cold forming property and fatigue characteristics can be produced by use of a reduced amount of an alloy containing Ca and/or Mg.

Description

明 細 書 高清浄度鋼 技術分野  Description High cleanliness steel Technical field
本発明は、 冷間加工性および疲労特性の優れた高清浄度鋼、 特に 超高張力線、 極細線、 高強度ばね、 極薄板ばねにおいて優れた性能 を有する高清浄度鋼に関する。 背景技術  The present invention relates to a high cleanliness steel having excellent cold workability and fatigue properties, and particularly to a high cleanliness steel having excellent performance in ultra-high tension wires, extra fine wires, high strength springs, and ultra thin leaf springs. Background art
薄板ばねやタイヤコ一 ドのように冷間圧延や伸線など強度の冷間 加工を受ける鋼や、 弁ばねのように高い疲労強度を必要とする鋼に おいては、 硬質の非金属介在物は有害であり、 これらの硬質介在物 を起点と して破壊が起ることはよ く知られている。 この対策と して 介在物を軟質化するこ とにより熱間圧延および冷間圧延又は伸線に より延伸させ、 介在物を小型化させるこ とが可能である。 例えば、 特公昭 54— 7252号公報では、 介在物をスぺサタイ トを主成分と し、 Al 203 /Si 20+ A1203 十 MnO 二 0.15〜 0.40とする ことが示されてい るが、 こ こに示された介在物はコラ ンダムを初晶とする領域にまた がっているため、 実際の製造においては極めて硬質で有害なコラ ン ダムの発生を防止するこ とが困難であり、 十分な効果が得られない Hard non-metallic inclusions are used for steel that undergoes high-strength cold working such as cold rolling or wire drawing, such as thin leaf springs and tire cords, and steel that requires high fatigue strength, such as valve springs. Is harmful and it is well known that fracture originates from these hard inclusions. As a countermeasure, by softening the inclusions, the inclusions can be drawn by hot rolling, cold rolling or wire drawing, and the inclusions can be reduced in size. For example, in JP-B-54-7252, inclusions composed mainly of scan Bae Satai DOO, have been shown to the Al 2 0 3 / Si 2 0+ A1 2 0 3 tens MnO two .15-.40 However, since the inclusions shown here extend over the area where the primary crystal originates in Kolandam, it is difficult to prevent the occurrence of extremely hard and harmful Korandam in actual production. Is not enough effect
また、 特公平 6 — 74484 号公報においては、 圧延鋼材の L断面に おいて、 長さ （ 1 ) と幅 （ d ) の比が l Z d ≤ 5 の非金属介在物の 平均的組成が、 Si02 ： 20〜60%、 Mn0:10~80%に、 Ca0:50%以下、 Mg0:15%以下の一方又は両方を含む鋼が開示されている。 更に、 特 公平 6 — 74485 号公報においては、 圧延鋼材の L断面において、 長 さ （ 1 ) と幅 （d) の比が 1 Z d≤ 5 の非金属介在物の平均的組成 が、 Si02 ： 35〜75%、 Al 203 :30 %以下、 Ca0:50%以下、 Mg0:25%以 下からなる鋼が開示されている。 これら公報に記載の発明により、 鋼中の介在物は熱間圧延でよ く 延伸するも、 熱間圧延で十分に伸延 しない 1 Z d ≤ 5 の非金属介在物も冷間圧延又は伸線で破砕し微細 に分散するこ とにより、 冷間加工性および疲労特性の優れた高清浄 度鋼を得るこ とができる。 In Japanese Patent Publication No. 74484/1994, the average composition of non-metallic inclusions with a ratio of length (1) to width (d) of l Z d ≤ 5 in the L section of rolled steel is Si0 2: 20~60%, Mn0: in 10 ~ 80%, Ca0: 50 % or less, Mg0: steel is disclosed that includes one or both of 15% or less. Furthermore, in Japanese Patent Publication No. 6-74485, in the L section of rolled steel, Averaged composition ratio of (1) and width (d) non-metallic inclusions of 1 Z d≤ 5 is, Si0 2: 35~75%, Al 2 0 3: 30% or less, Ca0: 50% or less A steel consisting of less than 25% Mg0 is disclosed. According to the inventions described in these publications, inclusions in steel are stretched well by hot rolling, but are not sufficiently stretched by hot rolling.Non-metallic inclusions with 1 Z d ≤ 5 are also cold-rolled or drawn. By crushing and finely dispersing, high clean steel with excellent cold workability and fatigue properties can be obtained.
上記特公平 6 - 74484 号公報、 特公平 6 - 74485 号公報に記載の 発明は、 鋼中の介在物を軟質化するため、 溶鋼段階で Si， Mn、 その 他必要成分元素を添加した後、 Ca， Mg, 更に必要により A1の 1 種又 は 2種以上を含む合金を添加する ことによって複合脱酸を行い、 介 在物組成を複合組成の介在物と している。 溶鋼段階で添加する Ca， Mg合金は高価であり、 これら高価な合金の使用量を低減できれば製 造コス 卜が削減されるため好適である。 発明の開示  The inventions described in Japanese Patent Publication No. 6-74484 and Japanese Patent Publication No. 6-74485 mentioned above add Si, Mn and other necessary constituent elements in the molten steel stage in order to soften the inclusions in the steel. Complex deoxidation is performed by adding an alloy containing one or more of Ca, Mg and, if necessary, A1 to make the inclusion composition an inclusion of the composite composition. The Ca and Mg alloys added in the molten steel stage are expensive, and it is preferable to reduce the amount of these expensive alloys because the manufacturing cost is reduced. Disclosure of the invention
本発明は、 Ca， Mg合金の使用量が少なく ても冷間加工性および疲 労特性の優れている高清浄度鋼を提供するこ とを目的とする。  An object of the present invention is to provide a high cleanliness steel having excellent cold workability and fatigue properties even with a small amount of Ca and Mg alloys used.
第 1 の発明は、 介在物中の A 1203を極力排除するために A1を使用 せず、 Si， Mn、 及び Caと Mgの一方又は両方を用いて複合脱酸を行う 発明であり、 その要旨とすると ころは以下のとおりである。 The first invention is, without the use of A1 to eliminate A 1 2 0 3 in the inclusions as much as possible, Si, Mn, and using one or both of Ca and Mg be invention to perform complex deoxidation The summary is as follows.
( 1 ) 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 Zd≤ 5 の非金属介在物の組成が下記組成 A 1 に属する ものが個数 比で 20%以上、 下記組成 A 1 又は B 1 に属する ものが合計で 80%以 上であり、 かつ l Zd≤ 5 で下記組成 A 1 に属する非金属介在物の dが 40 m以下であるこ とを特徴とする冷間加工性及び疲労特性の 優れた高清浄度鋼。 組成 A 1 ： Si02 ： 60%超 (1) In the L section of the rolled steel, the ratio of length (1) to width (d) of nonmetallic inclusions with a ratio of 1 Zd ≤ 5 belonging to the following composition A1 is 20% or more in number ratio. The cooling is characterized by being 80% or more in total belonging to the following composition A1 or B1, and the d of nonmetallic inclusions belonging to the following composition A1 with lZd≤5 is 40m or less. High cleanliness steel with excellent workability and fatigue properties. Composition A 1: Si0 2: 60% more than
組成 B 1 ： Si02 ： 20〜60%、 Mn0:10〜80%に、 Ca0:50%以下、 MgO: 15%以下の一方又は両方を含む。 Composition B 1: Si0 2: 20~60% , Mn0: to 10~80%, Ca0: 50% or less, MgO: includes one or both of 15% or less.
ただし、 非金属介在物の組成は、 Si02， MnO, CaO, MgO, A 1203の和 を 100と して求める。 以下の発明においても同様である。 However, the composition of nonmetallic inclusions, Si0 2, MnO, CaO, MgO, determined as 100 the sum of A 1 2 0 3. The same applies to the following inventions.
( 2 ) 長さ （ 1 ) と幅 （d) の比が l Zd≤ 5 の非金属介在物の組 成が上記組成 A 1 に属する ものの個数が 1 個/龍2 以下であること を特徴とする上記 （ 1 ) に記載の冷間加工性及び疲労特性の優れた 高清浄度鋼。 (2) The composition of non-metallic inclusions with a ratio of length (1) to width (d) of l Zd ≤ 5 belongs to the above composition A 1 is 1 piece / dragon 2 or less. A high cleanliness steel having excellent cold workability and fatigue properties according to the above (1).
( 3 ) 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 Z d ≤ 5 の非金属介在物の平均組成が、 Si02 ： 30%以上、 Mn0: 8〜 65%に、 Ca0:40%以下、 MgO： 12%以下の一方又は両方を含み、 1 / d ≤ 5 の非金属介在物の dが 40 m以下であるこ とを特徵とする冷 間加工性および疲労特性の優れた高清浄度鋼。 (3) In the L cross-section of rolled steel, the average composition of the length (1) the ratio is 1 Z d ≤ nonmetallic inclusions 5 of width (d) is, Si0 2: 30% or more, Mn0:. 8 to 65 Cold workability and fatigue, characterized in that d contains 40% or less of non-metallic inclusions where 1 / d ≤ 5 contains one or both of Ca0: 40% or less and MgO: 12% or less. High cleanliness steel with excellent properties.
ただし、 非金属介在物の平均組成は、 圧延鋼材の L断面 1 視野で組 成を分析した非金属介在物の個数平均によって求める。 以下の発明 においても同じである。 However, the average composition of non-metallic inclusions is determined by the average number of non-metallic inclusions whose composition is analyzed from one view of the L cross section of the rolled steel. The same applies to the following inventions.
第 2 の発明は、 介在物に積極的に Ca0， MgO, A 1203を含有させる 複合脱酸を行う発明であり、 その要旨とするところは以下のとおり あ《3。 A second invention is actively Ca0, MgO in inclusions, an invention for performing composite deoxidation to contain A 1 2 0 3, the place to Abstracts Oh following "3.
( 4 ) 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 Z d 5 の非金属介在物の組成が下記組成 A 2 に属する ものが個数 比で 20%以上、 下記組成 A 2 又は B 2 に属する ものが合計で 80%以 上であり、 かつ 1 / d ^ 5 で下記組成 A 2 に属する非金属介在物の dが 40/ m以下であるこ とを特徴とする冷間加工性及び疲労特性の 優れた高清浄度鋼。  (4) In the L section of the rolled steel, the ratio of length (1) to width (d) of non-metallic inclusions with a ratio of 1 Zd5 belonging to the following composition A2 is 20% or more in number ratio. The composition belonging to the following composition A2 or B2 is 80% or more in total, and the d of nonmetallic inclusions belonging to the following composition A2 of 1 / d ^ 5 is 40 / m or less. High cleanliness steel with excellent cold workability and fatigue properties.
組成 A 2 ： SiO, ： 75%超 組成 B 2 ： Si02 ： 35〜75%、 Al 203 : 30 %以下に、 Ca0:50%以下、 Mg 0:15%以下の一方又は両方を含む。 Composition A 2: SiO,: Over 75% Composition B 2: Si0 2: 35~75% , Al 2 0 3: 30% or less, Ca0: 50% or less, Mg 0: containing one or both of 15% or less.
( 5 ) 長さ （ 1 ) と幅 （ d ) の比が 1 Z d ≤ 5 の非金属介在物の組 成が上記組成 A 2 に属する ものの個数が 1 個 Zmm2 以下であること を特徴とする上記 （ 4 ) に記載の冷間加工性及び疲労特性の優れた 高清浄度鋼。 (5) and wherein the set configuration of length (1) the ratio is 1 Z d ≤ nonmetallic inclusions 5 of width (d) is the number of those belonging to the above composition A 2 is one ZMM 2 below A high cleanliness steel having excellent cold workability and fatigue properties according to the above (4).
( 6 ) 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 Z d ≤ 5 の非金属介在物の平均組成が、 Si02 43%以上、 A 1203 24 %以下に、 CaO 40%以下、 MgO 12%以下の一方又は両方を含み、 1 Zd≤ 5 の非金属介在物の dが 40 m以下であるこ とを特徴とする 冷間加工性および疲労特性の優れた高清浄度鋼。 (6) in the L cross-section of rolled steel, the average composition of the length (1) the ratio is 1 Z d ≤ nonmetallic inclusions 5 of width (d) is, Si0 2 43% or more, A 1 2 0 3 24 % Or less, containing one or both of CaO 40% or less and MgO 12% or less, characterized in that d of non-metallic inclusions with 1 Zd ≤ 5 is 40 m or less. Excellent high cleanliness steel.
本発明における鋼組成は、 介在物組成を制御するために Sし Mnを 0.1%以上含むことを必要とするが、 その他の元素については特に 制限はなく 、 必要に応じて合金元素を加えた低炭素鋼、 高炭素およ びオーステナイ ト系ステンレス鋼などに適用することができる。 具 体的には下記に示すとおりである。  The steel composition in the present invention needs to contain 0.1% or more of S and Mn in order to control the inclusion composition, but there is no particular limitation on the other elements. It can be applied to carbon steel, high carbon and austenitic stainless steel. Specifically, it is as shown below.
( 7 ) 質量％で、 C :0.4〜1.2 %、 Si :0.1〜1.5 %、 Mn:0.1〜1.5 %を含むこ とを特徴とする上記 （ 1 ) 〜 ( 6 ) のいずれかに記載の 冷間加工性および疲労特性の優れた高清浄度鋼。  (7) The refrigeration system according to any one of (1) to (6) above, which contains C: 0.4 to 1.2%, Si: 0.1 to 1.5%, and Mn: 0.1 to 1.5% by mass. High cleanliness steel with excellent workability and fatigue properties.
( 8 ) 質量％で、 C :0.4〜1.2 %、 Si :0.1〜し 5 %、 Mn:0.1-1.5 %に加えて、 Cr ： 0.05- 1.0 %、 Ni ： 0.05〜1.0 %、 Cu： 0.05〜1. 0 %、 B :0.001-0.01%, Ti :0.001〜0.2 %、 V :0.001〜0.2 %、 Nb:0.001〜0.2 %、 Mo： 0.05-1.0 %、 Co:0.1〜 2 %の 1 種又は 2 種以上を含むこ とを特徴とする上記 （ 1 ) 〜 （ 6 ) のいずれかに記 載の冷間加工性および疲労特性の優れた高清浄度鋼。 発明を実施するための最良の形態 熱間圧延鋼材においては、 低融点の介在物は圧延温度において鋼 材より も軟化するために長手方向に延伸する。 従って圧延後の鋼材 の L断面において、 介在物の長さ （ 1 ) と幅 （ d ) の比 l Z dを測 定するこ とにより、 軟質化の程度を判定するこ とができる。 1 d が大き く 、 具体的には 1 / d 〉 5 になる介在物は伸延性が大き く 、 圧延で伸延されるために無害である。 一方、 l Z dの小さい介在物 であっても、 その後の冷間圧延又は伸線加工により砕かれ、 微細に 分散され無害化される介在物と、 そのまま残存して有害となる介在 物とがあるため、 1 ノ dのみで介在物の良否判定をするこ とはでき ない。 (8) In mass%, C: 0.4-1.2%, Si: 0.1--5%, Mn: 0.1-1.5%, Cr: 0.05-1.0%, Ni: 0.05-1.0%, Cu: 0.05- 1.0%, B: 0.001-0.01%, Ti: 0.001-0.2%, V: 0.001-0.2%, Nb: 0.001-0.2%, Mo: 0.05-1.0%, Co: 0.1-2%, or A high cleanliness steel having excellent cold workability and fatigue properties according to any one of the above (1) to (6), characterized by containing two or more types. BEST MODE FOR CARRYING OUT THE INVENTION In hot-rolled steel, inclusions with a low melting point elongate in the longitudinal direction because they become softer than steel at the rolling temperature. Therefore, the degree of softening can be determined by measuring the ratio lZd of the length (1) to the width (d) of the inclusions in the L section of the rolled steel material. Inclusions where 1 d is large, specifically 1 / d> 5, have high ductility and are harmless because they are elongated by rolling. On the other hand, even for inclusions with a small lZd, inclusions that are crushed and finely dispersed and rendered harmless by subsequent cold rolling or wire drawing, and inclusions that remain harmful as they remain are Therefore, it is not possible to judge the quality of inclusions using only 1 d.
前記の従来技術においては、 介在物組成を複合化するこ とによつ て l Z d ^ 5の介在物を軟質化した。 こ こにおいて、 介在物中の Si 02組成は 60%以下乃至 75%以下と している。 Si02がこの濃度を超え ると、 硬質の Si02系介在物が発生するとの認識による。 In the above prior art, inclusions of lZd ^ 5 were softened by compounding the inclusion composition. In here, Si 0 2 composition in inclusions is set to 60% or less to 75% or less. If Si0 2 exceeds this concentration, by the recognition of the Si0 2 inclusions of hard to occur.
本発明者らの検討の結果、 たとえ l Z d≤ 5の介在物の組成が高 S ί 02であっても、 この介在物の大きさが小さければその後の冷間圧 延又は伸線加工においても悪影響を及ぼさないこ とを見出した。 Si 02系介在物は硬質とはいっても CaO系、 MgO系、 A1203系の介在物 に比較すると軟質であり、 その大きさを 40〃 mに抑えさえすれ ば鋼材の冷間加工性および疲労特性は十分良好に保たれるのである 。 l Z d ^ 5で組成が高 Si02の介在物の大きさは、 d≤20〃 mとす ることがより好ま しい。 Results of study of the present inventors, if l Z d≤ the composition of inclusions 5 is a high S ί 0 2, subsequent cold rolling or wire drawing when the small size of the inclusions Have no adverse effect. Si 0 2 inclusions are CaO system also entered a hard, MgO-based, is soft as compared with the A1 2 0 3 based inclusions, steel cold working if only suppress the magnitude 40〃 m The properties and fatigue properties are kept good enough. l Z d ^ size of 5 the composition is high Si0 2 inclusions, D≤20〃 m and be Rukoto more preferred arbitrariness.
本発明においては、 十分に軟質で冷間圧延又は伸線加工により砕 かれ微細に分散され無害化される介在物の組成範囲を B ( B 1 , B 2 ) と し、 組成 Bの介在物より も Si02濃度が高い介在物の組成範囲 を A ( A 1 , A 2 ) と した。 In the present invention, the composition range of inclusions that are sufficiently soft and crushed by cold rolling or wire drawing to be finely dispersed and made harmless is B (B1, B2), and the inclusions having composition B the composition range of even Si0 2 concentration is high inclusions was a (a 1, a 2) .
第 1 の発明、 第 2 の発明と も、 1 Z d≤ 5の非金属介在物の組成 が組成 Aに属する ものが個数比で 20%以上、 組成 A又は Bに属する ものが合計で 80%以上とする。 In both the first and second inventions, the composition of nonmetallic inclusions with 1 Z d ≤ 5 20% or more of those belonging to composition A by composition, and 80% or more in total belonging to composition A or B.
組成 A又は Bに属する ものが合計で 80%以上と したのは、 Aにも Bにも属しない組成の介在物は、 例えば CaO系、 MgO系、 A 1203系 の介在物であっても硬質であり、 これら硬質介在物の比率が 20%を 超えると鋼材の冷間加工性および疲労特性を損なうからである。 The belonging to composition A or B is not less than 80% in total, inclusions composition does not belong to B to A is, there, for example, CaO-based, MgO-based, A 1 2 0 3 based inclusions This is because the ratio of these hard inclusions exceeds 20%, which impairs the cold workability and fatigue properties of steel.
また、 組成 Aに属する ものが 20%以上と したのは、 溶鋼において 添加する Ca， Mg合金添加量を低減していく と組成 Aに属する介在物 が増大するが、 組成 Aに属する ものが 20%以上となる程度にまで Ca ， Mg合金を削減すれば本発明の目的であるコス ト削減効果が発揮で きるからである。 組成 Aに属する ものを 40%以上とすれば、 より一 層のコス ト削減効果を発揮するこ とができる。  In addition, the reason why the ratio of the inclusions belonging to the composition A is set to 20% or more is that the inclusions in the composition A increase as the addition amount of the Ca and Mg alloys added in the molten steel decreases, but the inclusions in the composition A increase This is because if the amount of Ca and Mg alloys is reduced to the extent of not less than%, the cost reduction effect, which is the object of the present invention, can be achieved. If the content of the component A is 40% or more, a further cost reduction effect can be exhibited.
組成 Bの組成範囲の限定理由を第 1 の発明、 第 2 の発明それぞれ について述べる。  The reasons for limiting the composition range of the composition B will be described for each of the first invention and the second invention.
第 1 の発明において組成 B 1 を Si02 ： 20〜60%、 Mn0:10〜80%に 、 Ca0:50%以下、 Mg0:15%以下の一方又は両方を含むと した理由は 下記のとおりである。 The first composition B 1 in the invention of the Si0 2: 20~60%, Mn0: to 10~80%, Ca0: 50% or less, Mg0: reason for to include one or both of 15% or less was as follows is there.
Si02が 20%未満では、 CaO又は MgO系の硬質介在物が発生し、 共 に熱間圧延および冷間加工で十分小型化させるこ とができない。 Si 02 : 60%超は組成 A 1 の領域であり、 従来硬質介在物が発生すると して忌避されていた領域である。 本発明における介在物組成は、 Si ， Mn脱酸により Mn- Si l icateを生成せしめた後、 Ca, Mgを含む合金 を適量添加するこ とにより製造するこ とができる力 <、 本発明におい て重要な点は、 ΜπΟは Ca， Mg合金の添加により消滅する傾向を有す るけれども、 これら合金鉄の添加量を適正に制御するこ とにより M ηθを 10〜80%存在せしめ、 もって硬質介在物の発生を防止する点で ある。 CaOが 50%を超えると CaO系の硬質介在物が発生し、 MgOが 15%を超えると MgO系の硬質介在物が発生し、 共に、 目的を達成で きない。 CaOは複合脱酸による介在物軟質化の効果を確実に得るた め、 好ま し く は 5 %以上とする。 同じく 、 MgOは複合脱酸による介 在物軟質化の効果を確実に得るため、 好ま し く は 3 %以上とする。 Si0 In 2 is less than 20%, it occurred CaO or hard inclusions of the MgO-based, not can trigger sufficient miniaturization hot rolling and cold working co. Si 0 2: 60% more than is the region of the composition A 1, a conventional hard inclusions have been repellent as a generating region. The inclusion composition in the present invention is a force that can be produced by producing an Mn-Silicate by deoxidation of Si and Mn and then adding an appropriate amount of an alloy containing Ca and Mg. It is important to point out that although 傾向 πΟ tends to disappear with the addition of Ca and Mg alloys, by appropriately controlling the amount of these alloyed irons, M This is to prevent inclusions. When CaO exceeds 50%, CaO-based hard inclusions are generated, and MgO If it exceeds 15%, MgO-based hard inclusions are generated, and both cannot achieve the purpose. CaO is preferably set to 5% or more to ensure the effect of softening inclusions by complex deoxidation. Similarly, MgO is preferably at least 3% in order to surely obtain the effect of softening inclusions by complex deoxidation.
また、 A 1203については極力排除することが硬質な介在物の生成 を防止するために望ま しいが、 第 1 の発明では A1を使用 しない。 し かし、 A1不使用で適正に脱酸方法を制御した場合にも A 1203は 20% 程度以下は生成する ものである。 本発明の介在物組成では従来技術 と異なり この程度の A 1203の含有では、 硬質のコラ ンダムやスピネ ルを生成することはなく 、 Al 203 :20 %以下は許容される。 Further, arbitrary desired to prevent the formation of A 1 2 0 3 as much as possible it is hard inclusions to eliminate about is, in the first invention does not use A1. However, A 1 2 0 3 even when controlling the proper deoxidation methods A1 disuse and generates the most about 20%. The inclusions containing A 1 2 0 3 This degree unlike the prior art in the composition of the present invention, rather than generating a hard Kola random or spinel Le, Al 2 0 3: 20% or less is acceptable.
第 2 の発明において組成 B 2 を Si02 ： 35〜75%、 A1203 :30 %以下 に、 Ca0:50%以下、 Mg0:15%以下の一方又は両方を含むと した理由 は下記のとおりである。 The second invention in the composition B 2 the Si0 2: 35~75%, A1 2 0 3: 30% or less, Ca0: 50% or less, Mg0: reason for to include one or both of 15% or less of the following It is as follows.
Si, Ca, Mg, Alなどの硬質介在物を生成しやすい脱酸元素を使用 しても、 Ca0， MgO, A 1203を一定範囲の Si02と共存させる こ とによ り、 極めて軟質な介在物となすこ とができる。 Si02が 35%未満では 、 CaO, MgOあるいは Al 203系の硬質介在物が発生し、 共に熱間圧延 および冷間加工で十分小型化させる こ とができない。 Si02 ： 75%超 は組成 A 2 の領域であり、 従来硬質介在物が発生すると して忌避さ れていた領域である。 また、 CaOが 50%を超え、 MgOが 15%を超え 、 A 1203が 30%を超えると、 それぞれ CaO系、 MgO系、 A 1203系、 およびこれらの複合系の硬質介在物が発生する。 CaOは複合脱酸に よる介在物軟質化の効果を確実に得るためには 5 %以上とするこ と が好ま しい。 同じ く 、 MgOは複合脱酸による介在物軟質化の効果を 確実に得るためには 3 %以上とするこ とが好ま しい。 Si, Ca, Mg, be used to generate easily deoxidizing element hard inclusions such as Al, Ca0, MgO, Ri by the A 1 2 0 3 in the this coexist with Si0 2 in a range, very Can form soft inclusions. Si0 In 2 is less than 35%, CaO, hard inclusions of the MgO or Al 2 0 3 system occurs, not both can trigger sufficient miniaturization hot rolling and cold working. Si0 2: 75% greater is the area of the composition A 2, a conventional hard inclusions have been repellent as a generating region. Further, CaO exceeds 50%, MgO exceeds 15%, when A 1 2 0 3 exceeds 30%, respectively CaO-based, MgO-based, A 1 2 0 3 system, and hard intervention of these composite systems Things occur. CaO is preferably at least 5% in order to reliably obtain the effect of softening inclusions by complex deoxidation. Similarly, the content of MgO is preferably 3% or more in order to surely obtain the effect of softening inclusions by complex deoxidation.
第 2の発明の大きな特徴は、 このように積極的に Ca0， MgO, Al 2 03を含有させても、 従来技術のコラ ンダム、 スピネルのような有害 な硬質介在物を生成することな く 、 極めて製造安定性に優れている こ とである。 MnOについて特に規定しないのは、 ΜπΟは Ca， Mg, A l のような強力な脱酸元素の添加により消滅する傾向を有し、 特に本 発明のように、 CaO， MgO, A 1 2 0 3の含有量を比較的多く した場合に は通常 20 %以下になる。 また、 MnOは介在物を軟質化させるのに有 効な成分であり、 これを含有しても本発明の効果を妨げるこ とはあ りえないため、 MnOについては特に規定しない。 A 1 2 0 3の下限を規 定していないが、 第 2 の発明では積極的に A 1 2 0 3を含有させるため 、 組成 B 2 の介在物中には通常は A 1 2 0 3が 5 %以上含まれる。 Major feature of the second invention may be thus positively Ca0, MgO, is contained Al 2 0 3, the prior art Kola random, harmful, such as spinel It is extremely excellent in production stability without producing any hard inclusions. Particularly not defined for MnO, ΜπΟ is Ca, Mg, have a tendency to disappear by the addition of a strong deoxidizing element, such as A l, in particular as in the present invention, CaO, MgO, A 1 2 0 3 When the content of is relatively high, it is usually less than 20%. Further, MnO is an effective component for softening the inclusions, and even if it is contained, the effect of the present invention cannot be hindered, so that MnO is not particularly defined. A 1 2 0 no 3 of the lower limit has been stipulated, but since the second invention to contain actively A 1 2 0 3, typically in inclusion composition B 2 is the A 1 2 0 3 Contains 5% or more.
本発明においては、 1 / d ≤ 5 で組成が A 1 又は A 2 に属する介 在物の大きさを d ^ 40 mに抑えるこ とが重要なボイ ン トである。 組成が A 1 又は A 2 に属する介在物は組成が B 1 、 B 2 に属する介 在物に比較してやや硬質であるにもかかわらず、 d ≤ 40 mとする こ とにより、 介在物軟質化の効果を損なう ことがない。  In the present invention, it is an important point to keep the size of the inclusions belonging to A 1 or A 2 with d / 40 when the ratio is 1 / d ≦ 5. Inclusions belonging to the composition A 1 or A 2 are softer by setting d ≤ 40 m even though the composition is slightly harder than the inclusions belonging to B 1 and B 2. It does not impair the effect of
dが 40 /z mを超える大きな介在物は、 脱酸後の溶鋼中に形成され る一次脱酸生成物が主体である。 本発明のように、 1 7 d ≤ 5 とな る介在物の組成が組成 Bを主体とするよう に Ca、 又は Mgを含めた複 合脱酸を行う場合、 上記一次脱酸生成物は結果と して軟質化され、 d > 40〃 mとなる大きな介在物はすべて 1 / dが 5 を越える展延さ れた介在物となる。 本発明においては、 このよう にして 1 / d 5 で組成が A 1 又は A 2 に属する介在物の大きさを d 40 mに抑え るこ とができた。  Large inclusions with d exceeding 40 / zm are mainly primary deoxidation products formed in the molten steel after deoxidation. As in the present invention, when performing the complex deoxidation including Ca or Mg so that the composition of the inclusions satisfying 17 d ≤ 5 is mainly composed of composition B, the primary deoxidation product results As a result, all large inclusions that are softened and have d> 40 m are extended inclusions where 1 / d exceeds 5. In the present invention, the size of the inclusions belonging to 1 / d5 and having the composition belonging to A1 or A2 could be suppressed to d40 m in this way.
本発明は、 以上のよう に介在物の組成と大きさを制御するこ とに よつて優れた冷間加工性および疲労特性を確保するこ とができた。 本発明においては更に、 1 Z d 5 で組成が A 1 又は A 2 に属する 介在物個数を観察 1 視野（5. 5mm x 1 1 mm) において 1 個/ mm 2 以下、 より好ま し く は 0. 5個 / mm 2 以下とする こ とにより、 伸線加工時に おけるダイス寿命を向上するこ とができる。 As described above, according to the present invention, excellent cold workability and fatigue characteristics can be secured by controlling the composition and size of the inclusions. In the present invention, the number of inclusions belonging to A 1 or A 2 at 1 Zd 5 is observed. In one visual field (5.5 mm × 11 mm), the number of inclusions is 1 / mm 2 or less, more preferably 0. . by the this to 5 / mm 2 or less, upon drawing Die life can be improved.
本発明は、 以上のように 1 / d ≤ 5 の非金属介在物の組成が A領 域にある ものの比率と A又は B領域にある ものの比率で特定する代 りに、 上記 （ 3 ) 、 （ 6 ) のよ う に l Zd≤ 5 の非金属介在物の平 均組成で特定するこ と もできる。 詳し く は下記のとおりである。 こ こで、 非金属介在物の平均組成は圧延鋼材の L断面 1 視野で組成を 分析した非金属介在物の個数平均によって求める。 1 視野は、 例え ば線材であれば 5.5mm X 11mm程度の大きさの視野が適切である。 第 1 の発明においては、 長さ （ 1 ) と幅 （ d ) の比が 1 / d ≤ 5 の非金属介在物の平均組成が、 Si02 ： 30%以上、 Mn0: 8〜65%に、 Ca0:40%以下、 Mg0:12%以下の一方又は両方を含み、 l Zd≤ 5 の 非金属介在物の dが 40 m以下である。 平均組成で Si02が 30%以上 となるように Ca， Mg合金を削減すれば本発明の目的であるコス ト削 減効果が発揮できる。 MnOを 8 %以上存在せしめ、 もって硬質介在 物の発生を防止する。 Si02を 30%以上とするため、 MnOは上限が 65 %となる。 CaOが 40%を超えると CaO系の硬質介在物が発生し、 M g0が 12%を超えると MgO系の硬質介在物が発生し、 共に、 目的を達 成できない。 1 Z d 5 の非金属介在物の dが 40 m以下である理 由は前述のとおりである。 According to the present invention, instead of specifying the composition of nonmetallic inclusions of 1 / d ≤ 5 by the ratio of those in the A region and the ratio of those in the A or B region as described above, (3), (3) It can also be specified by the average composition of non-metallic inclusions with l Zd ≤ 5 as in 6). Details are as follows. Here, the average composition of non-metallic inclusions is determined by the average number of non-metallic inclusions whose composition is analyzed in one view of the L cross section of the rolled steel. For one field of view, for example, a wire with a size of about 5.5 mm X 11 mm is appropriate. In the first invention, the average composition of the length (1) the ratio is 1 / d ≤ nonmetallic inclusions 5 of width (d) is, Si0 2: 30% or more, Mn0: in 8-65%, One or both of Ca0: 40% or less and Mg0: 12% or less, and d of nonmetallic inclusions with l Zd ≤ 5 is 40 m or less. Cost reduction effect 2 by the average composition Si0 is an object of the present invention when reducing Ca, and Mg alloy such that 30% or more can be exhibited. Presence of 8% or more of MnO prevents generation of hard inclusions. Order to Si0 2 of 30% or more, MnO upper limit is 65%. When CaO exceeds 40%, CaO-based hard inclusions are generated, and when Mg0 exceeds 12%, MgO-based hard inclusions are generated, and both cannot achieve the purpose. The reason why the d of the nonmetallic inclusion of 1 Z d 5 is 40 m or less is as described above.
CaOは複合脱酸による介在物軟質化の効果を確実に得るためには 5 %以上とすると好ま しい。 同じ く 、 MgOは複合脱酸による介在物 軟質化の効果を確実に得るためには 3 %以上とすると好ま しい。 Si 02を 60%超とすれば、 より一層のコス 卜削減効果を発揮する こ とが できる。 この場合、 Mn0， CaOは上限が 32%、 MgOは上限が 30%とな る。 CaO is preferably set to 5% or more in order to surely obtain the effect of softening inclusions by complex deoxidation. Similarly, MgO is preferably set to 3% or more in order to surely obtain the effect of softening inclusions by complex deoxidation. If the Si 0 2 60 percent, it is the this to exert even greater cost Bok reduction. In this case, Mn0 and CaO have an upper limit of 32%, and MgO has an upper limit of 30%.
第 2 の発明においては、 長さ （ 1 ) と幅 （ d ) の比が 1 Z d 5 の非金属介在物の平均組成が、 Si02 ： 43%以上、 Al 203 :24%以下、 Ca0:40%以下、 MgO: 12%以下からなり、 l Z d ≤ 5 の非金属介在物 の dが 40 / m以下である。 平均組成で Si02が 43%以上となるように Ca, Mg合金を削減すれば本発明の目的であるコス ト削減効果が発揮 できる。 CaOが 40%を超え、 MgOが 12%を超え、 A 1203が 24%を超 えると、 それぞれ CaO系、 MgO系、 A 1203系、 およびこれらの複合 系の硬質介在物が発生し、 共に、 目的を達成できない。 l Z d ≤ 5 の非金属介在物の dが 40 m以下である理由は前述のとおりである o In the second invention, the average composition of the length (1) the ratio is 1 Z d nonmetallic inclusions 5 of width (d) is, Si0 2: 43% or more, Al 2 0 3: 24% or less, Ca0: 40% or less, MgO: 12% or less, d of nonmetallic inclusions with l Z d ≤ 5 is 40 / m or less. Ca as 2 by the average composition Si0 becomes 43% or more, cost reduction is an object of the present invention when reducing the Mg alloy can be exhibited. CaO exceeds 40%, MgO exceeds 12%, when A 1 2 0 3 is obtain ultra 24%, respectively CaO-based, MgO-based, A 1 2 0 3 system, and hard inclusions of these composite systems Occur, and both cannot achieve their goals. The reason why d of nonmetallic inclusions with l Z d ≤ 5 is 40 m or less is as described above.
CaOは複合脱酸による介在物軟質化の効果を確実に得るためには 5 %以上とすることが好ま しい。 同じ く 、 MgOは複合脱酸による介 在物軟質化の効果を確実に得るためには 3 %以上とするこ とが好ま しい。 Si02 : 75%超とすれば、 より一層のコス ト削減効果を発揮す ることができる。 この場合、 CaO, MgO, A 1203の上限が、 それぞれ Al 203 :17%以下、 Ca0:20%以下、 MgO: 15%以下と定まる。 CaO is preferably set to 5% or more in order to reliably obtain the effect of inclusion softening by complex deoxidation. Similarly, the content of MgO is preferably 3% or more in order to reliably obtain the effect of softening inclusions by complex deoxidation. If Si0 2 : more than 75%, further cost reduction effect can be exhibited. In this case, CaO, MgO, the upper limit of A 1 2 0 3 is, Al 2 0 3, respectively: 17% or less, Ca0: 20% or less, MgO: determined as 15% or less.
本発明は、 以上のように従来と同様の厳しい冷間加工性および疲 労特性を要求される用途において良好な成績を収める。 さ らに、 最 近はタイヤコ一 ドにおいて用途によっては太径のコ一ドが用いられ 、 冷間加工性についても従来に比較して緩和される ものがある。 ま た、 伸線ダイスの寿命については、 潤滑の改善などにより鋼材の介 在物レベルが若干低下しても影響を受けないで製造を行う ことが可 能になってきている。 このような用途において、 本発明の高清浄度 鋼は特に効果を発揮する。  As described above, the present invention achieves good results in applications requiring the same severe cold workability and fatigue characteristics as in the past. In addition, recently, tire cords have been used in some applications with a large diameter, and the cold workability of the tire cord has been reduced as compared with the conventional one. In addition, the life of the wire drawing dies can be manufactured without being affected even if the inclusion level of the steel material is slightly reduced due to improved lubrication. In such applications, the high cleanliness steel of the present invention is particularly effective.
次に鋼成分について述べる。 本発明は介在物の特性を規定する も のであるから、 鋼成分については特に限定する必要はないが、 利用 分野を具体的に挙げるならば次の分野を挙げるこ とができる。  Next, steel components will be described. Since the present invention defines the properties of the inclusions, it is not necessary to particularly limit the steel composition, but the following fields can be mentioned if the fields of application are specifically mentioned.
1 例と して炭素鋼および低合金炭素鋼線材があり、 熱間圧延後伸 線され、 ワイヤ、 ばね等に用いられる。 特に 0.3min0以下の極細軟 線、 硬線においては、 伸線時および燃り線時の断線防止に効果があ り、 ばねにおいては疲労強度の向上に効果がある。 One example is carbon steel and low alloy carbon steel wire rods, which are drawn after hot rolling and used for wires, springs, etc. Especially 0.3mm0 or less Wires and hard wires are effective in preventing breakage during wire drawing and burning, and springs are effective in improving fatigue strength.
これらの用途に適用される鋼材の成分と しては、 質量％で、 c :o The components of steel materials applicable to these applications are as follows:
.6〜1.2 %、 S 0. 1〜し 5 %、 Mn:0. 1〜し 5 %を含み、 必要に応じ て Cr： 0.05〜0.5 %、 Ni ： 0.05〜 0 %、 Cu： 0.05〜し 0 %、 B :0 .001〜0.01%、 Ti :0.001〜0.2 %、 V :0.001〜0.2 %、 Nb:0.001〜 0.2 % Mo : 0.05〜1.0 %、 Co:0. 1〜 2 %の 1 種又は 2種以上を含 むものである。 .6 ~ 1.2%, S 0.1 ~ 5%, Mn: 0.1 ~ 5%, Cr: 0.05 ~ 0.5%, Ni: 0.05 ~ 0%, Cu: 0.05 ~ 0%, B: 0.001 to 0.01%, Ti: 0.001 to 0.2%, V: 0.001 to 0.2%, Nb: 0.001 to 0.2% Mo: 0.05 to 1.0%, Co: 0.1 to 2% Or two or more types are included.
Cは鋼を強化するのに経済的かつ有効な強化元素であり、 硬鋼線 と して必要な強度を得るためには 0.4%以上が必要である。 しかし 、 1.2%を超えると鋼の延性が低下し脆化し、 二次加工が困難とな るため 1.2%以下と した。  C is an economical and effective strengthening element for strengthening steel, and requires 0.4% or more to obtain the required strength as hard steel wire. However, if it exceeds 1.2%, the ductility of the steel decreases and becomes brittle, making secondary processing difficult, so the content was made 1.2% or less.
一方、 Siと Mnは脱酸と介在物組成コ ン ト ロールのために必要であ り、 0.1%未満では効果がない。 また鋼の強化元素と しても有効で ある力 Siが 1.5%、 Mnが 1.5%を超えると鋼が脆化する。  On the other hand, Si and Mn are necessary for deoxidation and inclusion composition control, and if less than 0.1%, there is no effect. In addition, the steel, which is effective as a steel strengthening element, becomes brittle when the Si content exceeds 1.5% and the Mn content exceeds 1.5%.
Crを 0.05〜1.0 %と したのは、 Crはパーライ トラメ ラを微細にし 、 鋼の強度を上げる効果があるため、 この効果を得るために必要な 量が 0.05%であり、 それ以上の添加が望ま しい。 しかし、 1.0%を 超えて添加した場合、 延性を阻害するため上限を 1.0%と した。  The reason why the content of Cr is set to 0.05 to 1.0% is that Cr has the effect of making the pearlite lamella finer and increasing the strength of the steel. Therefore, the amount required to obtain this effect is 0.05%, and further addition is necessary. Desirable. However, if added in excess of 1.0%, the upper limit was set to 1.0% because ductility was impaired.
Niも Crと同様の効果によって鋼を強化するため、 その効果を発揮 する 0.05%以上の添加が望ま し く 、 延性の低下を招かない 1.0%以 下とする。  Since Ni also strengthens steel by the same effect as Cr, it is desirable to add 0.05% or more, which exerts the effect, and to 1.0% or less, which does not cause a decrease in ductility.
Cuはワ イ ヤのスケール特性および腐蝕疲労特性を向上させる効果 があるため、 効果を発揮する 0.05%以上の添加が望ま しいが、 上限 は延性の低下を招かない 1.0%以下とする。  Since Cu has the effect of improving the scale properties and corrosion fatigue properties of the wire, it is desirable to add 0.05% or more, which exerts the effect, but the upper limit is set to 1.0% or less, which does not cause a decrease in ductility.
Bは鋼の焼き入れ性を向上させる元素である。 本発明の場合、 そ の添加により鋼の強度を高める こ とができる力く、 過度の添加は Bの 析出物を増加させ、 鋼の靱性を損なうためその上限を 0.01%とする 。 また添加量が少なすぎると効果がないため、 添加量の下限を 0.0 01%とする。 B is an element that improves the hardenability of steel. In the case of the present invention, its addition is a force that can increase the strength of the steel, The upper limit is set to 0.01% in order to increase precipitates and impair the toughness of the steel. Also, if the amount is too small, there is no effect. Therefore, the lower limit of the amount is set to 0.01%.
Ti， Nb, Vは析出強化により線材の強度を高める効果がある。 い ずれも 0.001%未満では効果がなく 、 0.2%を超えると析出脆化を 引き起こすため、 その含有量を 0.2%以下とする。 また、 これらの 元素はパテ ンティ ングの際の y粒サイズを小さ く する効果にも添加 することが有効である。  Ti, Nb, and V have the effect of increasing the strength of the wire by precipitation strengthening. In any case, if the content is less than 0.001%, there is no effect, and if it exceeds 0.2%, precipitation embrittlement is caused, so the content is made 0.2% or less. It is also effective to add these elements to the effect of reducing the y grain size during patterning.
Moは鋼の焼き入れ性を向上させる元素である。 本発明の場合、 そ の添加により鋼の強度を高めるこ とができる力 過度の量の添加は 鋼を過剰に硬化させ、 加工を困難とするため、 Mo添加範囲は 0.05〜 1.0 %と した。 Coは過共析鋼の初析セメ ンタイ 卜の生成を抑制する 効果により延性を向上する。  Mo is an element that improves the hardenability of steel. In the case of the present invention, the addition of Mo can increase the strength of the steel. The addition of an excessive amount hardens the steel excessively and makes working difficult, so the Mo addition range was set to 0.05 to 1.0%. Co improves ductility by the effect of suppressing the formation of proeutectoid cementite in hypereutectoid steel.
さ らに、 高炭素鋼においては、 P , Sは伸線加工性を劣化させる のみならず伸線加工後の延性を劣化させるため、 Pと Sの含有量は 0.02%以下が望ま しい。  Furthermore, in high-carbon steels, P and S not only deteriorate the drawability but also the ductility after drawing, so that the content of P and S is preferably 0.02% or less.
他の利用分野と してはオーステナイ ト系ステンレス鋼がある。 熱 間圧延後冷間圧延され 0.3 以下の極薄板ばねと して用いられるが 、 ばねの疲労強度の向上に効果がある。 この用途に適用される鋼材 の成分は、 C : 0. 15%以下、 Si :0. 1〜 1 %、 Mn:0. 1〜 2 %、 Cr ： 16 〜20%、 N 3.5~22%に代表される。  Another application is austenitic stainless steel. Hot-rolled and then cold-rolled and used as an ultra-thin leaf spring of 0.3 or less, it is effective in improving the fatigue strength of the spring. The composition of steel used in this application is as follows: C: 0.15% or less, Si: 0.1 to 1%, Mn: 0.1 to 2%, Cr: 16 to 20%, N 3.5 to 22% Be represented.
他の利用分野と して深絞り加工用の低炭素鋼板がある。 熱間圧延 後冷間圧延され 1.2mm以下の薄板とされ、 焼鈍、 スキ ンパス後、 深 絞り加工されるが、 表面疵防止および深絞り加工性の向上に効果が ある。 この用途に適用される鋼材の成分は、 C ： 0. 12%以下、 Si :0 .3%以下、 Mn： 0.50%以下に代表される。 実施例 Another application is low carbon steel sheet for deep drawing. Hot rolling and cold rolling are performed to make a thin plate of 1.2 mm or less. After annealing and skim pass, deep drawing is performed. It is effective in preventing surface flaws and improving deep drawability. The components of steel materials applied for this purpose are represented by C: 0.12% or less, Si: 0.3% or less, and Mn: 0.50% or less. Example
(実施例 1 )  (Example 1)
250ト ン転炉で溶製された溶鋼に出鋼時に S i， Mn、 その他必要成 分元素を添加した後、 Ca， Mgの 1 種又は 2種を含む合金を添加し、 表 1 、 表 2 に示す組成の鋼を製造した。 これを 80 %以上の熱間圧延 により線材と し、 L断面の非金属介在物を調査した。 本実施例にお いて、 L断面非金属介在物の個数および組成の調査は、 直径 5. 5mm の線材の 1 コイルから 0. 5 mの長さのサンプルを切り出し、 長さ方 向の任意の 10力所から長さ l lmmの小サンプルを切り出し、 それぞれ 、 長さ方向の中心線を通る縦断面を光学顕微鏡により全面観察する ことによって ί亍った。  After the addition of Si, Mn, and other necessary constituent elements during tapping to molten steel produced in a 250-ton converter, an alloy containing one or two of Ca and Mg was added. A steel having the composition shown in Fig. 2 was produced. This was made into a wire by hot rolling of 80% or more, and nonmetallic inclusions in the L section were investigated. In this example, the number and composition of the non-metallic inclusions in the L section were investigated by cutting out a 0.5 m long sample from one coil of a 5.5 mm diameter wire rod, A small sample having a length of l lmm was cut out from 10 places, and each was observed by observing the entire longitudinal section passing through the center line in the longitudinal direction with an optical microscope.
更に該線材を伸線加工し、 伸線加工時のダイス寿命と断線率の評 価を行った。 評価結果を同じ く 表 1 、 表 2 に示す。 ダイス寿命は、 長いほどよいため現行工程材の平均ダイス寿命 （ダイス寿命基準よ り長い寿命となる） を越したものを〇、 現行工程材の平均寿命に満 たないものを X と した。 また断線率は、 低い程良いため現行工程材 の平均断線率 （断線許容基準より少ない断線率となる） よ り低いも のを〇、 現行工程材の平均断線率を上回る ものを X と した。 Further, the wire was subjected to wire drawing, and the die life and wire breaking rate during wire drawing were evaluated. Tables 1 and 2 also show the evaluation results. Since the longer the die life, the better the average die life of the current process material (which is longer than the die life standard) because the longer the dice life, the better the die life, and the X less than the average life of the current process material. In addition, the lower the disconnection rate, the better the lower the average disconnection rate of the current process material (the disconnection rate is less than the allowable disconnection standard), and the higher the disconnection rate of the current process material, X.
表 1 table 1
Figure imgf000016_0001
Figure imgf000016_0001
*1 \ d≤5(D H )fil¾A 1に属するもの及 «£A 1又は B 1に属するも 脾 i2 l/d≤5 3l A 1に属する I  * 1 \ d≤5 (D H) fil belongs to A1 and «£ A 1 or B 1 but belongs to spleen i2 l / d≤5 3l A 1 I
i3 l/d≤5 l ΙΑ 1に属する非 介 mm2 i3 l / d≤5 l 非 1 non-intervening mm 2
表 2 Table 2
Figure imgf000017_0001
Figure imgf000017_0001
*1 l/d≤5£¾ m 職 A 1に属するもの及 D¾ A 1又は B 1 { するも 脾 *2 l/d≤5Ti ΙΑ 1に属する  * 1 l / d≤5 £ ¾ m Occupation belonging to A 1 and D¾ A 1 or B 1 {脾 spleen * 2 l / d≤5Ti ΙΑ 1
« l/d≤5T¾ ZA 1に属する非 m m ( 画2) «L / d≤5T¾ Non-mm belonging to ZA 1 (Picture 2 )
表 3 Table 3
Figure imgf000018_0002
Figure imgf000018_0002
iの  i
Iの  I
！の
Figure imgf000018_0001
! of
Figure imgf000018_0001
表 4 Table 4
Figure imgf000019_0002
Figure imgf000019_0002
Iの  I
Iの  I
Iの
Figure imgf000019_0001
I
Figure imgf000019_0001
表 3 、 表 4 には、 表 1 、 表 2 に示す各線材の L断面における 1 / d≤ 5 の非金属介在物の平均組成を示す。 表中、 左側は l Zd≤ 5 の全非金属介在物の平均組成、 中央は l Zd≤ 5 の非金属介在物の う ち組成 A 1 に属する非金属介在物の平均組成、 右側は 1 Zd≤ 5 の非金属介在物のう ち組成 B 1 に属する非金属介在物の平均組成で の 。 Tables 3 and 4 show the average composition of non-metallic inclusions of 1 / d≤5 in the L section of each wire shown in Tables 1 and 2. In the table, the left side is the average composition of all non-metallic inclusions with l Zd ≤ 5, the center is the average composition of non-metallic inclusions belonging to composition A1 among non-metallic inclusions with l Zd ≤ 5, and the right side is 1 Zd The average composition of the nonmetallic inclusions belonging to composition B1 among the nonmetallic inclusions with ≤5.
表 1 、 表 3 の No. 1 〜 21が本発明例であり、 いずれのパラメ ータ も 本発明の範囲内であり、 断線率、 ダイス寿命と も良好な成績を得る ことができた。  Nos. 1 to 21 in Tables 1 and 3 are examples of the present invention, and all parameters were within the scope of the present invention, and good results were obtained with respect to the disconnection rate and the die life.
表 2、 表 4 の No.22〜29が比較例である。 Να22は 1 Z d ≤ 5 で組成 A 1 に属する非金属介在物の dが 40 mを超えており、 断線率が不 良であった。 No.23は組成 A 1 、 A 1 又は B 1 に属する介在物の比率 が共に不足であり、 ダイス寿命が不良であった。 No.24は Siが高めで あって結果と して組成 A 1 又は B 1 に属する非金属介在物の比率が 不足であり、 ダイス寿命が不良であった。 Να25は Μπが高めであって 結果と して組成 A 1 又は B 1 に属する非金属介在物の比率が不足で あり、 ダイス寿命が不良であった。 No.26は Siが低めであって結果と して組成 A 1 に属する介在物の比率が不足であり、 断線率が不良で あった。 No.27は断線率は良好で本発明の効果を有している ものの、 Mnが低めであって結果と して介在物個数が請求項 2 の範囲から外れ ており、 ダイス寿命が不良であった。 No.28は介在物個数が請求項 2 の範囲から外れており、 ダイ ス寿命が不良であった。 No.29は 1 Z d Nos. 22 to 29 in Tables 2 and 4 are comparative examples. Να22 was 1 Z d ≤ 5, the d of nonmetallic inclusions belonging to composition A1 exceeded 40 m, and the disconnection rate was poor. In No. 23, the ratio of inclusions belonging to the composition A1, A1 or B1 was insufficient, and the die life was poor. In No. 24, the ratio of nonmetallic inclusions belonging to the composition A 1 or B 1 was insufficient as a result of high Si, and the die life was poor. As for Να25, Μπ was higher, and as a result, the ratio of nonmetallic inclusions belonging to composition A 1 or B 1 was insufficient, and the die life was poor. In No. 26, the content of inclusions belonging to the composition A 1 was insufficient as a result of low Si, and the disconnection rate was poor. No. 27 has a good disconnection rate and has the effect of the present invention, but has a low Mn and consequently the number of inclusions is out of the range of claim 2, and the die life is poor. Was. In No. 28, the number of inclusions was out of the scope of Claim 2, and the die life was poor. No.29 is 1 Z d
≤ 5 で組成 A 1 に属する非金属介在物の dが 40 z mを超えており、 断線率が不良であった。 When ≤ 5, the d of nonmetallic inclusions belonging to composition A1 exceeded 40 zm, and the disconnection rate was poor.
表 1 、 表 2 に示した本発明例 No. 2 と比較例 No.23について、 直径 5 For Example No. 2 of the present invention and Comparative Example No. 23 shown in Tables 1 and 2, the diameter was 5
.5mmの熱間圧延線材を伸線加工により 1.6mmのワイヤと し 950°Cで ァ化処理した後、 560°Cの鉛浴に浸漬して最終パテンティ ングを行 ないパーライ ト組織のワイヤと した。 このワイヤを連続伸線加工で 直径 0. 3匪と しハンター疲労試験により疲労特性を比較した。 A .5mm hot-rolled wire is converted to a 1.6mm wire by wire drawing, and then subjected to heat treatment at 950 ° C. Then, the wire is immersed in a 560 ° C lead bath for final patenting. There was no perlite-structured wire. This wire was made to have a diameter of 0.3 by continuous drawing and the fatigue characteristics were compared by a hunter fatigue test.
表 5 に直径 0. 3mmのワイヤの引張強さ、 及びこのワイヤにおいて ハ ンター疲労試験を行なった結果を疲労限応力と して示す。 表 5 に 示すように、 引張強さは本発明例と比較例とで差はなく 、 ほぼ同一 強度において本発明例は比較例に比べ高い疲労限応力を示す。  Table 5 shows the tensile strength of a 0.3 mm diameter wire and the results of a Hunter fatigue test performed on this wire as fatigue limit stress. As shown in Table 5, there is no difference in tensile strength between the present invention example and the comparative example, and the present invention example shows higher fatigue limit stress than the comparative example at almost the same strength.
表 5  Table 5
Figure imgf000021_0001
Figure imgf000021_0001
(実施例 2 ) (Example 2)
250 ト ン転炉で溶製された溶鋼に出鋼時に S i , Mn、 その他必要成 分元素を添加した後、 C a, g, A 1を含む合金を添加し、 表 6 、 表 7 に示す組成の鋼を製造した。 これを 80 %以上の熱間圧延により線材 と した。 L断面の介在物調査、 伸線加工と伸線加工時の品質評価に ついては、 上記実施例 1 と同様である。 実施例 1 と異なる点は、 A 1 を積極的に添加している点、 及び常に Caと Mgの両方を添加している 点である。 After adding Si, Mn, and other necessary constituent elements to the molten steel melted in a 250-ton converter at the time of tapping, an alloy containing Ca, g, and A1 was added.Table 6 and Table 7 show the results. A steel having the composition shown was produced. This was made into a wire by hot rolling of 80% or more. The investigation of inclusions in the L section, wire drawing and quality evaluation during wire drawing are the same as in Example 1 above. The difference from Example 1 is that A 1 is actively added, and both Ca and Mg are always added.
表 6 Table 6
Figure imgf000022_0002
Figure imgf000022_0002
*1  * 1
*2  * 2
ネ 3
Figure imgf000022_0001
Ne 3
Figure imgf000022_0001
表 7 Table 7
Figure imgf000023_0002
Figure imgf000023_0002
n n
Figure imgf000023_0001
Figure imgf000023_0001
表 8 Table 8
Figure imgf000024_0002
Figure imgf000024_0002
Iの  I
の  of
Iの
Figure imgf000024_0001
I
Figure imgf000024_0001
表 9 Table 9
Figure imgf000025_0002
Figure imgf000025_0002
Iの  I
iの  i
1の
Figure imgf000025_0001
One
Figure imgf000025_0001
表 8、 表 9 には、 表 6 、 表 7 に示す各線材の L断面における 1 d≤ 5 の非金属介在物の平均組成を示す。 表中、 左側は l Zd ^ 5 の全非金属介在物の平均組成、 中央は 1 Zd≤ 5 の非金属介在物の うち組成 A 2 に属する非金属介在物の平均組成、 右側は l ,d≤ 5 の非金属介在物のうち組成 B 2 に属する非金属介在物の平均組成で め な o Tables 8 and 9 show the average composition of non-metallic inclusions of 1 d ≤ 5 in the L section of each wire shown in Tables 6 and 7. In the table, the left side is the average composition of all non-metallic inclusions of l Zd ^ 5, the center is the average composition of non-metallic inclusions belonging to composition A2 among the non-metallic inclusions of 1 Zd ≤ 5, and the right side is l, d Average composition of non-metallic inclusions belonging to composition B 2 among non-metallic inclusions ≤ 5
表 6 、 表 8 に示す No.31〜51が本発明例であり、 いずれのパラメ一 タ も本発明の範囲内であり、 断線率、 ダイス寿命と も良好な成績を 得ることができた。  Nos. 31 to 51 shown in Tables 6 and 8 are examples of the present invention, and all the parameters were within the scope of the present invention, and good results were obtained with respect to the disconnection rate and the die life.
表 7 、 表 9 に示す Να52〜59が比較例である。 52は 1 ノ d ≤ 5で 組成 A 2 に属する非金属介在物の dが 40 mを超えており、 断線率 が不良であった。 No.53は組成 A 2又は B 2 に属する介在物の比率が 不足であり、 ダイス寿命が不良であった。 No.54は S iが高めであって 結果と して組成 A 2、 A 2又は B 2 に属する非金属介在物の比率が 共に不足であり、 ダイス寿命が不良であった。 No.55は Mnが高めであ つて結果と して組成 A 2又は B 2 に属する非金属介在物の比率が不 足であり、 ダイス寿命が不良であった。 Να56は Siが低めであって結 果と して組成 A 2 に属する介在物の比率が不足であり、 断線率が不 良であつた。 No.57は Mnが低めであつて結果と して 1 / d ≤ 5で組成 A 2 に属する非金属介在物の dが 40/ mを超えており、 さ らに介在 物個数が請求項 5 の範囲から外れており、 ダイス寿命が不良であつ た。 No.58は介在物個数が請求項 5 の範囲から外れており、 ダイス寿 命が不良であった。 No.59は 1 / d ≤ 5 で組成 A 2 に属する非金属介 在物の dが 40 z mを超えており、 断線率が不良であった。 産業上の利用可能性  Να52 to 59 shown in Tables 7 and 9 are comparative examples. 52 was 1 d ≤ 5 and the d of nonmetallic inclusions belonging to composition A2 exceeded 40 m, and the disconnection rate was poor. In No. 53, the ratio of inclusions belonging to composition A 2 or B 2 was insufficient, and the die life was poor. No. 54 had a higher Si, and as a result, the ratio of nonmetallic inclusions belonging to the composition A2, A2, or B2 was insufficient, and the die life was poor. In No. 55, the Mn was high, and as a result, the ratio of nonmetallic inclusions belonging to the composition A2 or B2 was insufficient, and the die life was poor. Να56 had a low Si content, resulting in an insufficient ratio of inclusions belonging to composition A 2, resulting in poor disconnection rate. In No. 57, the Mn was low, and as a result, d of nonmetallic inclusions belonging to composition A2 exceeded 1 / d ≤ 5 and the number of inclusions was more than 40 / m. And the die life was poor. In No. 58, the number of inclusions was out of the range of claim 5, and the die life was poor. In No.59, 1 / d ≤ 5, the d of nonmetallic inclusions belonging to composition A2 exceeded 40 zm, and the disconnection rate was poor. Industrial applicability
本発明は冷間加工性および疲労特性に優れており、 極薄板ばね、 極細線、 高強度ばね用鋼と して優れた性能を有すると同時に、 高価 な C a合金、 Mg合金の添加量が少なくてすむので、 低コス トで製造で きるという優れた効果を有する ものである。 The present invention is excellent in cold workability and fatigue properties, Excellent performance as ultra-fine wire and high-strength spring steel, and at the same time, it has the excellent effect of being able to be manufactured at low cost because the addition of expensive Ca alloy and Mg alloy is small. It is.

Claims

請 求 の 範 囲 The scope of the claims
1 . 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 / d≤ 5 の非金属介在物の組成が下記組成 A 1 に属する ものが個数 比で 20%以上、 下記組成 A 1 又は B 1 に属する ものが合計で 80%以 上であり、 かつ l Zd≤ 5で下記組成 A 1 に属する非金属介在物の dが 40;/ m以下であることを特徴とする冷間加工性及び疲労特性の 優れた高清浄度鋼。 1. In the L section of the rolled steel material, the ratio of length (1) to width (d) of non-metallic inclusions whose ratio of 1 / d≤5 belongs to the following composition A1 is 20% or more in number ratio. The composition belonging to the following composition A1 or B1 is 80% or more in total, and the d of nonmetallic inclusions belonging to the following composition A1 with lZd≤5 is 40; / m or less. High cleanliness steel with excellent cold workability and fatigue properties.
組成 A 1 ： Si02 ： 60%超 Composition A 1: Si0 2: 60% more than
組成 B 1 ： Si02 ： 20~60%、 Mn0:10〜80%に、 Ca0:50%以下、 MgO: 15%以下の一方又は両方を含む。 Composition B 1: Si0 2: 20 ~ 60%, Mn0: to 10~80%, Ca0: 50% or less, MgO: includes one or both of 15% or less.
ただし、 非金属介在物の組成は、 Si02, MnO, CaO, MgO, A 1203の和 を 100と して求める。 However, the composition of nonmetallic inclusions, Si0 2, MnO, CaO, MgO, determined as 100 the sum of A 1 2 0 3.
2. 長さ （ 1 ) と幅 （ d ) の比が 1 Z d ≤ 5 の非金属介在物の組 成が上記組成 A 1 に属する ものの個数が 1 個 Zmm2 以下であること を特徴とする請求項 1 に記載の冷間加工性及び疲労特性の優れた高 清浄度鋼。 2. The composition of non-metallic inclusions whose ratio of length (1) to width (d) is 1 Z d ≤ 5 belongs to the above composition A 1, and the number of non-metallic inclusions is 1 Zmm 2 or less The high-cleanliness steel according to claim 1 having excellent cold workability and fatigue properties.
3. 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 Z d ≤ 5 の非金属介在物の平均組成が、 Si02 ： 30%以上、 MnO: 8 〜 65%に、 Ca0:40%以下、 MgO： 12%以下の一方又は両方を含み、 1 d ≤ 5 の非金属介在物の dが 40 m以下であるこ とを特徴とする冷 間加工性および疲労特性の優れた高清浄度鋼。 3. In L cross-section of rolled steel, the average composition of the length (1) the ratio is 1 Z d ≤ nonmetallic inclusions 5 of width (d) is, Si0 2: 30% or more, MnO: 8 ~ 65% In addition, it contains one or both of Ca0: 40% or less and MgO: 12% or less, and the d of nonmetallic inclusions with 1 d ≤ 5 is 40 m or less. Excellent high cleanliness steel.
ただし、 非金属介在物の平均組成は、 圧延鋼材の L断面 1 視野で組 成を分析した非金属介在物の個数平均によって求める。 However, the average composition of non-metallic inclusions is determined by the average number of non-metallic inclusions whose composition is analyzed from one view of the L cross section of the rolled steel.
4. 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が 1 4. In the L section of rolled steel, the ratio of length (1) to width (d) is 1
/ ά≤ 5 の非金属介在物の組成が下記組成 A 2 に属する ものが個数 比で 20%以上、 下記組成 A 2 又は B 2 に属する ものが合計で 80%以 上であり、 かつ l / d ≤ 5で下記組成 A 2に属する非金属介在物の dが 40; m以下であることを特徴とする冷間加工性及び疲労特性の 優れた高清浄度鋼。 / The composition of nonmetallic inclusions with ά≤5 belonging to the following composition A2 is 20% or more in number ratio, and those belonging to the following composition A2 or B2 are 80% or more in total A high cleanliness steel having excellent cold workability and fatigue properties, characterized in that l and d ≤ 5 and d of nonmetallic inclusions belonging to the following composition A2 is 40; m or less.
組成 A 2 ： Si02 ： 75%超 Composition A 2: Si0 2: 75% more than
組成 B 2 ： Si02： 35〜75%、 A1203： 30%以下に、 Ca0:50%以下、 Mg 0:15%以下の一方又は両方を含む。 Composition B 2: Si0 2: 35~75% , A1 2 0 3: 30% or less, Ca0: 50% or less, Mg 0: containing one or both of 15% or less.
5. 長さ （ 1 ) と幅 （ d ) の比が 1 d ≤ 5の非金属介在物の組 成が上記組成 A 2 に属するものの個数が 1個ノ廳 2 以下であること を特徴とする請求項 4 に記載の冷間加工性及び疲労特性の優れた高 清浄度鋼。 5. set configuration of length (1) the ratio is non-metallic inclusions of 1 d ≤ 5 the width (d) is characterized in that the number of belonging to the above composition A 2 is 1 Kono廳2 or less The high cleanliness steel according to claim 4, which is excellent in cold workability and fatigue properties.
6. 圧延鋼材の L断面において、 長さ （ 1 ) と幅 （ d ) の比が I / d≤ 5の非金属介在物の平均組成が、 Si02 ： 43%以上、 Al 203 : 24 %以下に、 Ca0:40%以下、 Mg0:12%以下の一方又は両方を含み、 1 Z d ≤ 5の非金属介在物の dが 40 / m以下であることを特徴とする 冷間加工性および疲労特性の優れた高清浄度鋼。 6. In L cross-section of rolled steel, the ratio of length (1) and width (d) is the average composition of non-metallic inclusions of I / d≤ 5, Si0 2: 43% or more, Al 2 0 3: 24 % Or less, Ca0: 40% or less, Mg0: 12% or less, or both, and the d of non-metallic inclusions with 1 Z d ≤ 5 is 40 / m or less. High cleanliness steel with excellent fatigue and fatigue properties.
7. 質量％で、 C :0.4〜1.2 %、 Si :0.1〜 5 %、 Mn:0.1〜1.5 %を含むことを特徴とする請求項 1乃至 6のいずれかに記載の冷間 加工性および疲労特性の優れた高清浄度鋼。  7. The cold workability and fatigue according to any one of claims 1 to 6, wherein C: 0.4 to 1.2%, Si: 0.1 to 5%, and Mn: 0.1 to 1.5% by mass%. High cleanliness steel with excellent properties.
8. 質量％で、 C :0.4〜し 2 %、 Si:0.1〜l, 5 %、 Mn:0.1~1.5 %に加えて、 Cr： 0.05〜 0 %、 Ni ： 0.05〜し 0 %、 Cu： 0.05〜し 0 B :0.001-0.01% , Ti:0.001〜0.2 %、 V :0.001〜0.2 %、 Nb:0.001〜0.2 %、 Mo： 0.05〜1.0 %、 Co:0.1〜 2 %の 1 種又は 2 種以上を含むことを特徴とする請求項 1 乃至 6のいずれかに記載の 冷間加工性および疲労特性の優れた高清浄度鋼。  8. In mass%, C: 0.4 ~ 2%, Si: 0.1 ~ 1, 5%, Mn: 0.1 ~ 1.5%, Cr: 0.05 ~ 0%, Ni: 0.05 ~ 0%, Cu: 0.05 or less 0 B: 0.001-0.01%, Ti: 0.001 to 0.2%, V: 0.001 to 0.2%, Nb: 0.001 to 0.2%, Mo: 0.05 to 1.0%, Co: 0.1 to 2%, or 2 The high-cleanliness steel having excellent cold workability and fatigue properties according to any one of claims 1 to 6, wherein the steel includes at least one kind.
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