JP2001225105A - Method for manufacturing high-carbon chromium steel wire and structural parts of machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a high-carbon chromium steel wire having good spheroidized structure by single spheroidizing annealing without generating cracks in the inside and to provide the structural parts of a machine such as bearings and various types of shafts excellent in wear resistance and fatigue characteristics. SOLUTION: After finishing a wire containing >=0.7% C and >=0.5% Cr after hot rolling into a prescribed shape by performing elongation the total reduction of area of which is 30-80% at a temperature not higher than the transformation point Ac1, spheroidizing annealing is performed. Elongation the reduction of area of which is >=30% is performed to the resultant wire at a temperature not higher than the transformation point Ac1. When expressing the reduction of area of wire drawing by DR and the total reaction (%) of area obtained by adding the reduction of area of the elongation to that of the wire drawing by TR, the wire drawing is performed at the reduction of area which satisfies DR<=0.0011×TR2-0.3603×TR+21.701 and also the total reduction TR of area of <=80% and, after finishing the wire into the prescribed shape, the spheroiding annealing may be performed. In the structural parts of the machine, the steel wire which contains >=0.7% C and >=0.5% Cr and is manufactured by the above process is adopted as the base stock.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は高炭素クロム鋼線の
製造方法及び機械構造部品に関する。詳しくは、軸受や
各種のシャフトなど耐摩耗性や耐疲労特性に優れた機械
構造部品及びその素材となる高炭素クロム鋼線の製造方
法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high carbon chromium steel wire and a mechanical structural part. More specifically, the present invention relates to a mechanical structure component having excellent wear resistance and fatigue resistance characteristics, such as a bearing and various shafts, and a method for producing a high carbon chromium steel wire as a material thereof.

【０００２】[0002]

【従来の技術】従来、JIS G 4805で規格化されたＳＵＪ
１〜ＳＵＪ５を初めとする高炭素クロム鋼を母材とする
直径が５．０ｍｍ以下の鋼線は、図２に示す工程で製造
されてきた。つまり、熱間圧延された線材に球状化熱処
理（球状化焼鈍）が施され、次いで、穴ダイスを用いた
中間伸線加工（以下、穴ダイスを用いた伸線加工を単に
「伸線加工」という）と再度の球状化熱処理が行われた
後、仕上げ伸線加工が施されていた。2. Description of the Related Art Conventionally, SUJ standardized by JIS G 4805
Steel wires having a diameter of 5.0 mm or less and made of a high carbon chromium steel such as 1 to SUJ5 have been manufactured by the process shown in FIG. That is, the hot-rolled wire is subjected to a spheroidizing heat treatment (spheroidizing annealing), and then the intermediate wire drawing using a hole die (hereinafter, wire drawing using a hole die is simply referred to as “wire drawing”). After that, the spheroidizing heat treatment was performed again, and the finish wire drawing was performed.

【０００３】これは、高炭素クロム鋼を母材とする熱間
圧延線材には、硬くて脆い初析セメンタイト（つまり、
旧オーステナイト粒界に沿うセメンタイト）が析出して
いるため、熱間圧延組織のままで伸線加工を行うと、後
述の図３で詳しく述べるように旧オーステナイト粒界間
に微細なクラックが発生し、そのクラックを起点に伸線
加工時に断線を生じたり、断線を生じないまでも鋼線に
は内部欠陥が残ってしまうからである。[0003] This is because a hard and brittle proeutectoid cementite (that is, a hot rolled wire made of high carbon chromium steel as a base material)
(Cementite along the old austenite grain boundaries) precipitates, and if wire drawing is performed with the hot-rolled structure, fine cracks are generated between the old austenite grain boundaries as described in detail in FIG. This is because the cracks are used as starting points to cause disconnection during wire drawing, or internal defects remain in the steel wire even if no disconnection occurs.

【０００４】しかしながら、上記の従来法は、繰り返し
の球状化焼鈍を必要とするので、工程が複雑になり処理
時間も長くなって、コスト面で不利であった。加えて、
長時間の熱処理（焼鈍処理）のために、線材の表面には
脱炭や厚いスケールが生成する場合もあった。更に、高
炭素クロム鋼線は、軸受や各種のシャフトなど耐摩耗性
や耐疲労特性が要求される構造部品の素材として用いら
れるため、表面疵の発生を避ける必要があるが、工程が
多い場合には、工程間の搬送時に疵が発生することがあ
り、品質管理面での問題もあった。However, the above-mentioned conventional method requires repeated spheroidizing annealing, which complicates the process and increases the processing time, which is disadvantageous in cost. in addition,
Due to the long-term heat treatment (annealing treatment), decarburization and thick scale were sometimes formed on the surface of the wire. Furthermore, high carbon chromium steel wire is used as a material for structural parts such as bearings and various shafts that require wear resistance and fatigue resistance, so it is necessary to avoid surface flaws. In some cases, flaws may occur during transportation between processes, and there is also a problem in quality control.

【０００５】一方、最近では軸受メーカーで部品加工の
前に仕上げ伸線加工を行うことも試みられており、した
がって、軸受メーカーに納入する前の寸法精度として、
従来の鋼線のような仕上げ加工精度が必ずしも要求され
ない場合が生じている。又、球状化熱処理後に表面潤滑
した鋼線を軸受メーカーでそのまま部品に加工すること
も試みられるようになっている。On the other hand, recently, a bearing maker has also attempted to perform finish wire drawing before processing a part. Therefore, the dimensional accuracy before delivery to a bearing maker is as follows.
There have been cases where finishing accuracy is not always required as in conventional steel wires. In addition, bearing manufacturers have attempted to directly process steel wires whose surface has been lubricated after spheroidizing heat treatment into parts as they are.

【０００６】[0006]

【発明が解決しようとする課題】本発明は、上記現状に
鑑みなされたもので、１回の球状化熱処理（球状化焼
鈍）で、鋼線内部にクラックを生ずることなく、従来の
２回の球状化焼鈍を行った場合と同等の球状化組織を有
するJIS G 4805のＳＵＪ１〜ＳＵＪ５を初めとする高炭
素クロム鋼を母材とする鋼線の製造方法、及び、当該方
法で製造された高炭素クロム鋼線を素材とする軸受や各
種のシャフトなど耐摩耗性や耐疲労特性に優れた機械構
造部品を提供することにある。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has been achieved by a conventional spheroidizing heat treatment (spheroidizing annealing) without causing cracks inside the steel wire. A method of manufacturing a steel wire based on a high carbon chromium steel such as SUJ1 to SUJ5 of JIS G 4805 having a spheroidized structure equivalent to the case of performing spheroidized annealing, and a high-temperature steel manufactured by the method. It is an object of the present invention to provide a mechanical structure component having excellent wear resistance and fatigue resistance characteristics, such as bearings and various shafts made of carbon chrome steel wire.

【０００７】[0007]

【課題を解決するための手段】本発明の要旨は、下記
（１）、（２）に示す高炭素クロム鋼線の製造方法及び
（３）に示す機械構造部品にある。SUMMARY OF THE INVENTION The gist of the present invention resides in a method for producing a high carbon chromium steel wire as shown in the following (1) and (2) and a mechanical structural part as shown in (3).

【０００８】（１）質量％で、Ｃ：０．７％以上、Ｃ
ｒ：０．５％以上を含有する熱間圧延後の線材に、Ａc₁
変態点以下の温度で総減面率３０〜８０％の延伸加工を
行って所定の形状に仕上げた後、球状化焼鈍することを
特徴とする高炭素クロム鋼線の製造方法。(1) By mass%, C: 0.7% or more, C
r: 0.5% or more of the hot-rolled wire rod contains Ac ₁
A method for producing a high-carbon chromium steel wire, comprising performing a stretching process at a temperature equal to or lower than a transformation point and a total area reduction of 30 to 80% to finish a predetermined shape, and then performing spheroidizing annealing.

【０００９】（２）質量％で、Ｃ：０．７％以上、Ｃ
ｒ：０．５％以上を含有する熱間圧延後の線材に、Ａc₁
変態点以下の温度で減面率３０％以上の延伸加工を行
い、次いで、下記 (1)式を満たすとともに延伸加工と合
わせた総減面率が８０％以下となる減面率で伸線加工を
行って所定の形状に仕上げた後、球状化焼鈍することを
特徴とする高炭素クロム鋼線の製造方法。(2) In mass%, C: 0.7% or more, C
r: 0.5% or more of the hot-rolled wire rod contains Ac ₁
Stretching is performed at a temperature below the transformation point with a reduction of area of 30% or more. And performing a spheroidizing annealing after finishing to a predetermined shape by carrying out the above method.

【００１０】 ＤＲ≦０．００１１×ＴＲ² −０．３６０３×ＴＲ＋２１．７０１・・・(1) ここで、ＤＲは伸線加工の減面率（％）、ＴＲは延伸加
工と伸線加工を合わせた総減面率（％）を指す。DR ≦ 0.0011 × TR ² −0.3603 × TR + 21.701 (1) Here, DR is a reduction ratio (%) of the wire drawing, and TR is a drawing and a wire drawing. Refers to the total reduction of area (%).

【００１１】（３）上記（１）又は（２）に記載の方法
で製造された鋼線を素材とする機械構造部品。(3) A machine structural part made of a steel wire produced by the method according to (1) or (2).

【００１２】なお、「線材」とは、棒状に熱間圧延され
た鋼で、コイル状に巻かれた鋼材を指し、所謂「バーイ
ンコイル」を含むものである。The term "wire" refers to steel that has been hot-rolled into a rod and refers to a steel material that is wound into a coil and includes a so-called "burn-in coil."

【００１３】「延伸加工」とは、ローラダイスを用いた
引き抜き加工、所謂「２ロール圧延機」、「３ロール圧
延機」や「４ロール圧延機」を用いた圧延加工を指し、
通常の穴ダイスを用いた伸線加工を除いたものである。The term “stretching” refers to drawing using a roller die, ie, rolling using a so-called “two-roll rolling mill”, “three-roll rolling mill”, or “four-roll mill”.
This excludes wire drawing using a normal hole die.

【００１４】本発明者らは、球状化焼鈍の回数を減らし
ても従来と同等の球状化組織を高炭素クロム鋼線に付与
でき、しかも旧オーステナイト粒界間に内部欠陥（クラ
ック）を残さない加工方法について調査・研究を重ね
た。その結果、下記の知見を得た。[0014] The present inventors can provide a high carbon chromium steel wire with the same spheroidized structure as before even if the number of times of spheroidizing annealing is reduced, and do not leave internal defects (cracks) between the prior austenite grain boundaries. Investigated and researched on processing methods. As a result, the following findings were obtained.

【００１５】（ａ）図３に示すように、伸線加工の場
合、被加工材１には伸線方向（長手方向）に垂直な方向
の圧縮応力Ｃと長手方向の大きな引張応力Ｔが働き、相
当応力は被加工材１の内部にまで浸透しない。なお、相
当応力とはすべての応力が合成されたものをいう。した
がって、被加工材１、つまり、初析セメンタイトが存在
する高炭素クロム鋼の線材を熱間圧延組織のままで、穴
ダイス２を用いて伸線加工すれば、低い加工度、例え
ば、３０％にも満たない減面率で、旧オーステナイト粒
界間に微細なクラック３が発生する。このため、伸線加
工を続けるとそのクラック３を起点に断線を生じたり、
断線を生じないまでも鋼線には内部欠陥が残ってしま
う。なお、図３には伸線加工前後の組織を模式的に示し
た。 （ｂ）延伸加工はロールやローラーダイスによって被加
工材１をその半径方向に圧縮する加工であるため、伸線
加工に比べて被加工材１を内奥まで均一に塑性変形させ
ることができる。つまり、延伸加工では、相当応力を被
加工材１の内奥まで浸透させることができる。例えば、
図１に示すように、ロール４を用いた延伸加工の場合、
被加工材１には垂直方向の圧縮応力Ｃに加えて長手方向
にも圧縮応力Ｃが働くので、相当応力は被加工材１の内
奥にまで浸透する。ローラーダイスを用いた延伸加工の
場合、被加工材１には伸線方向（長手方向）に垂直な方
向の圧縮応力Ｃと長手方向の引張応力Ｔが働くが、中心
部での長手方向の引張応力Ｔは僅かなものであるため相
当応力は被加工材１の内奥にまで浸透する。このため、
被加工材１、つまり、初析セメンタイトが存在する高炭
素クロム鋼の線材を、熱間圧延組織のままで加工しても
旧オーステナイト粒界間に微細なクラックが発生するこ
とがない。なお、図１にも延伸加工前後の組織を模式的
に示した。(A) As shown in FIG. 3, in the case of wire drawing, a compressive stress C in the direction perpendicular to the drawing direction (longitudinal direction) and a large tensile stress T in the longitudinal direction act on the workpiece 1. The equivalent stress does not penetrate into the workpiece 1. Note that the equivalent stress refers to a stress obtained by combining all stresses. Therefore, if the workpiece 1, that is, the wire rod of high carbon chromium steel having proeutectoid cementite, is drawn using the hole die 2 while maintaining the hot-rolled structure, a low workability, for example, 30% Fine cracks 3 occur between the prior austenite grain boundaries at a reduction in area of less than 10%. For this reason, if the wire drawing is continued, a break may occur starting from the crack 3 or
Even if no break occurs, the steel wire will have internal defects. FIG. 3 schematically shows the structures before and after the wire drawing. (B) Since the stretching process is a process of compressing the workpiece 1 in the radial direction by a roll or a roller die, the workpiece 1 can be more uniformly plastically deformed to the inner side as compared with the wire drawing. That is, in the stretching process, the equivalent stress can be penetrated deep into the workpiece 1. For example,
As shown in FIG. 1, in the case of stretching using a roll 4,
Since the compressive stress C acts on the workpiece 1 in the longitudinal direction in addition to the compressive stress C in the vertical direction, the equivalent stress penetrates deep into the workpiece 1. In the case of stretching using a roller die, a compressive stress C and a longitudinal tensile stress T in a direction perpendicular to the drawing direction (longitudinal direction) act on the workpiece 1, but a tensile force in a longitudinal direction at a central portion. Since the stress T is slight, the equivalent stress penetrates deep into the workpiece 1. For this reason,
Even if the work material 1, that is, the wire rod of high carbon chromium steel in which proeutectoid cementite is present, is processed with the hot rolled structure, fine cracks do not occur between the prior austenite grain boundaries. FIG. 1 also schematically shows the structures before and after the stretching process.

【００１６】（ｃ）高炭素クロム鋼を母材とする熱間圧
延線材のミクロ組織は、パーライトを主体とするもので
あり、これを単に球状化焼鈍しても粒径の細かい炭化物
からなる球状化組織しか得られない。しかし、上記の組
織を有する高炭素クロム鋼の線材に、Ａc₁変態点以下の
温度で総減面率３０〜８０％の延伸加工を施せば、パー
ライト組織中のセメンタイトが破砕され、更に、加工歪
が導入される。したがって、高炭素クロム鋼の線材に上
記の延伸加工を施してから球状化焼鈍を行えば、その加
熱過程でセメンタイトの固溶が促進されるとともに、冷
却の初期段階に析出した微細な炭化物を核にして炭化物
が凝集する。このため、１回の球状化焼鈍で、仕上げ加
工前に、従来法のように２回の球状化焼鈍を施した場合
と同等の球状化組織（つまり、比較的大きな炭化物から
なり、球状化率も同程度の組織）とすることができる。
更に、上記（ｂ）で述べたように鋼線内部にクラックが
生じることはない。(C) The microstructure of a hot-rolled wire made of a high-carbon chromium steel as a base material is mainly made of pearlite, and a spheroid consisting of a carbide having a small particle size is obtained simply by spheroidizing and annealing the wire. You can only get a chemical structure. However, the wire of high-carbon chromium steel having the above structure, if Hodokose the stretching of the total area reduction rate of 30% to 80% at a temperature below the Ac ₁ transformation point, cementite pearlite tissue is crushed, further processed Distortion is introduced. Therefore, if the wire rod of high carbon chromium steel is subjected to the above-mentioned stretching process and then subjected to spheroidizing annealing, solid solution of cementite is promoted in the heating process and fine carbides precipitated in the initial stage of cooling are nucleated. And the carbides aggregate. Therefore, one spheroidizing annealing has the same spheroidizing structure (that is, made of a relatively large carbide, and a spheroidizing rate equal to that obtained by performing the spheroidizing annealing twice as in the conventional method before the finishing process. Organization of the same degree).
Further, as described in the above (b), no crack is generated inside the steel wire.

【００１７】（ｄ）パーライトを主体とする高炭素クロ
ム鋼を母材とする熱間圧延線材に、Ａc₁変態点以下の温
度で減面率３０％以上の延伸加工を行い、次いで、前記
(1)式を満たすとともに延伸加工と合わせた総減面率が
８０％以下となる減面率で伸線加工を行った場合にも、
鋼線内部にクラックを生じさせることなく、パーライト
組織中のセメンタイトの破砕と加工歪の導入が行える。
したがって、高炭素クロム鋼の線材に上記の延伸加工と
伸線加工を施してから球状化焼鈍を行えば、その加熱過
程でセメンタイトの固溶が促進されるとともに、冷却の
初期段階に析出した微細な炭化物を核にして炭化物が凝
集する。このため、１回の球状化焼鈍で、仕上げ加工前
に、従来法のように２回の球状化焼鈍を施した場合と同
等の球状化組織とすることができる。(D) The hot-rolled wire mainly composed of pearlite-based high carbon chromium steel is stretched at a temperature not higher than the Ac ₁ transformation point to have a surface reduction rate of 30% or more.
Even when wire drawing is performed at a reduction ratio that satisfies the expression (1) and the total reduction ratio combined with the stretching process is 80% or less,
Cementite in the pearlite structure can be crushed and processing strain can be introduced without causing cracks inside the steel wire.
Therefore, if the wire rod of high carbon chromium steel is subjected to the above-described drawing and drawing, and then subjected to spheroidizing annealing, the solid solution of cementite is promoted in the heating process, and the fine precipitates precipitated in the initial stage of cooling. The carbides are aggregated with the fine carbides as nuclei. Therefore, a single spheroidizing annealing can provide a spheroidized structure equivalent to a case where two spheroidizing annealings are performed as in the conventional method before the finishing process.

【００１８】なお、「球状化率」とは、顕微鏡観察した
時、「その視野における炭化物（セメンタイト）に対し
ての（短径）／（長径）の比が０．５以上である炭化物
の割合（％）」を意味する。The "spheroidization ratio" is defined as the ratio of a carbide having a (minor axis) / (major axis) ratio of 0.5 or more to carbide (cementite) in the visual field when observed under a microscope. (%) ".

【００１９】本発明は、上記の知見に基づいて完成され
たものである。The present invention has been completed based on the above findings.

【００２０】[0020]

【発明の実施の形態】以下、本発明の各要件について詳
しく説明する。なお、化学成分の含有量の「％」は「質
量％」を意味する。 （Ａ）線材の化学組成 本発明が対象とする高炭素クロム鋼線は、所定の形状に
加工された後、最終工程で焼入れ焼戻しなどの熱処理が
施されて、所望の特性（硬さ、耐摩耗性、耐疲労特性な
ど）が付与される。この最終製品（機械構造部品）にお
ける特性の付与のために鋼線に加工する線材の化学成分
としてＣ量、Ｃｒ量のみを下記の範囲に限定する。DESCRIPTION OF THE PREFERRED EMBODIMENTS Each requirement of the present invention will be described in detail below. In addition, “%” of the content of the chemical component means “% by mass”. (A) Chemical composition of wire rod The high-carbon chromium steel wire targeted by the present invention is processed into a predetermined shape, and then subjected to a heat treatment such as quenching and tempering in the final step to obtain desired properties (hardness, resistance to heat). Wear resistance, fatigue resistance, etc.). Only the C content and the Cr content are limited to the following ranges as chemical components of a wire rod processed into a steel wire in order to impart properties to the final product (machine structural component).

【００２１】Ｃ：０．７％以上 Ｃは、硬さを確保して耐摩耗性を得るのに有効な元素で
ある。しかし、その含有量が０．７％未満では充分な硬
さが得られない。Ｃの含有量の上限は特に規定しなくて
もよい。しかし、Ｃの含有量が多すぎると鋼材が硬質化
し、室温近傍で延伸加工、又は、延伸加工と伸線加工を
組み合わせた加工を行う場合、加工性の低下を招く場合
があり、特に、Ｃ含有量が１．３％を超えると、前記加
工時の加工性が大きく低下する場合があるので、Ｃの含
有量の上限は１．３％とすることが好ましい。なお、Ｃ
含有量の上限は１．１％とすることが一層好ましい。 Ｃｒ：０．８％以上 Ｃｒは、鋼の焼入れ性を高めて強度、靱性、耐摩耗性を
高める作用がある。しかし、その含有量が０．８％未満
では添加効果に乏しい。Ｃｒの含有量の上限は特に規定
しなくても良い。しかし、多量のＣｒを含有させても前
記の効果が飽和してコストが嵩むし、転動疲労特性が低
下する場合があるので、Ｃｒの含有量の上限は１．７％
とすることが好ましい。なお、Ｃｒ含有量の上限は１．
６％とすることが一層好ましい。C: 0.7% or more C is an element effective for securing hardness and obtaining wear resistance. However, if the content is less than 0.7%, sufficient hardness cannot be obtained. The upper limit of the C content need not be particularly defined. However, if the content of C is too large, the steel material becomes hard, and when performing stretching at or near room temperature, or when performing a combination of the stretching and the wire drawing, the workability may be reduced. If the content exceeds 1.3%, the workability at the time of the above-mentioned processing may be greatly reduced. Therefore, the upper limit of the content of C is preferably set to 1.3%. Note that C
The upper limit of the content is more preferably 1.1%. Cr: 0.8% or more Cr has the effect of increasing the hardenability of steel to increase strength, toughness, and wear resistance. However, if the content is less than 0.8%, the effect of addition is poor. The upper limit of the Cr content need not be particularly defined. However, even if a large amount of Cr is contained, the above effect is saturated and the cost is increased, and the rolling fatigue characteristics may be reduced. Therefore, the upper limit of the Cr content is 1.7%.
It is preferable that The upper limit of the Cr content is 1.
More preferably, it is 6%.

【００２２】本発明が対象とする高炭素クロム鋼線のＣ
及びＣｒ以外の他の化学成分の組成に関しては、特別な
限定を加える必要はない。最終製品（機械構造部品）に
おいて要求される特性の付与が可能な成分範囲でありさ
えすれば良い。The carbon content of the high carbon chromium steel wire to which the present invention is applied
There is no particular limitation on the composition of chemical components other than Cr and Cr. What is necessary is just to be a component range capable of imparting the characteristics required in the final product (machine structural component).

【００２３】具体的には、例えば、ＣとＣｒ以外の元素
としてＳｉ：０〜１．０％、Ｍｎ：０〜１．０％、Ｃ
ｕ：０〜０．５％、Ｎｉ：０〜０．５％、Ｍｏ：０〜
１．０％、Ｗ：０〜１．０％、Ｖ：０〜０．４％、Ｎ
ｂ：０〜０．０５％、Ｂ：０〜０．００５％を含有し、
残部がＦｅと不可避不純物からなり、不純物としてのＰ
が０．０５％以下、Ｓが０．０３％以下、Ｔｉが０．０
１％のものであれば良い。Specifically, for example, as elements other than C and Cr, Si: 0 to 1.0%, Mn: 0 to 1.0%, C:
u: 0 to 0.5%, Ni: 0 to 0.5%, Mo: 0
1.0%, W: 0 to 1.0%, V: 0 to 0.4%, N
b: 0 to 0.05%, B: 0 to 0.005%,
The balance consists of Fe and unavoidable impurities, and P
Is 0.05% or less, S is 0.03% or less, and Ti is 0.0% or less.
What is necessary is just 1%.

【００２４】なお、最終製品における特性向上を目的
に、ＣとＣｒ以外の上記した元素を追加含有させる場
合、各元素の含有量はそれぞれ、Ｓｉ：０．１〜１．０
％、Ｍｎ：０．１〜１．０％、Ｃｕ：０．０５〜０．５
％、Ｎｉ：０．０５〜０．５％、Ｍｏ：０．０５〜１．
０％、Ｗ：０．０５〜１．０％、Ｖ：０．０５〜０．４
％、Ｎｂ：０．００２〜０．０５％、Ｂ：０．０００３
〜０．００５％とすることが好ましい。不純物としての
Ｐ、Ｓ、Ｔｉの含有量は、Ｐが０．０２％以下、Ｓが
０．０１５％以下、Ｔｉが０．００５％以下とすること
が好ましい。 （Ｂ）熱間圧延後の線材の加工 本発明においては、高炭素クロム鋼の線材に、Ａc₁変態
点以下の温度で総減面率３０〜８０％の延伸加工を行う
か、減面率３０％以上の延伸加工を行い、次いで、前記
(1)式を満たすとともに延伸加工と合わせた総減面率が
８０％以下となる減面率で伸線加工を行う必要がある。When the above-mentioned elements other than C and Cr are additionally contained for the purpose of improving the characteristics of the final product, the content of each element is set to 0.1 to 1.0, respectively.
%, Mn: 0.1 to 1.0%, Cu: 0.05 to 0.5
%, Ni: 0.05-0.5%, Mo: 0.05-1.
0%, W: 0.05 to 1.0%, V: 0.05 to 0.4
%, Nb: 0.002 to 0.05%, B: 0.0003
It is preferable to set it to 0.005%. The contents of P, S, and Ti as impurities are preferably such that P is 0.02% or less, S is 0.015% or less, and Ti is 0.005% or less. (B) Processing of Wire after Hot Rolling In the present invention, a high carbon chromium steel wire is stretched at a temperature not higher than the Ac ₁ transformation point to a total area reduction of 30 to 80%, or Perform a stretching process of 30% or more, and then,
It is necessary to perform the wire drawing at a reduction ratio that satisfies the expression (1) and the total reduction ratio combined with the stretching process is 80% or less.

【００２５】上記した加工の温度と延伸加工における下
限の減面率（３０％）の両方ともが満足されない場合に
は、パーライト組織中のセメンタイトが破砕され難い
し、加工歪も導入され難い。特に、線材を加工する際の
温度がＡc₁変態点を超えるような高い温度である場合に
は、パーライト組織中のセメンタイトの一部はオーステ
ナイト中に固溶するし、導入された加工歪も解放されて
しまう。したがって、高炭素クロム鋼の線材を加工した
後で球状化焼鈍を行っても、所望の球状化組織、つま
り、従来法のように２回の球状化焼鈍を施した場合と同
等の球状化組織が得られない。したがって、線材を加工
する際の温度をＡc₁変態点以下とし、延伸加工における
下限の減面率を３０％とした。なお、線材を加工する際
の温度の下限は特に規定しなくてもよい。室温で加工し
てもよい。When neither the above-mentioned processing temperature nor the lowering area reduction rate (30%) in the stretching processing is satisfied, cementite in the pearlite structure is hard to be crushed, and processing strain is hardly introduced. In particular, when the temperature at which the wire is processed is high enough to exceed the Ac ₁ transformation point, part of the cementite in the pearlite structure becomes a solid solution in austenite and the introduced processing strain is released. Will be done. Therefore, even if spheroidizing annealing is performed after processing a wire rod of high carbon chromium steel, a desired spheroidizing structure, that is, a spheroidizing structure equivalent to the case of performing spheroidizing annealing twice as in the conventional method is obtained. Can not be obtained. Therefore, the temperature at the time of processing the wire was set to the Ac ₁ transformation point or lower, and the lower limit of area reduction in the stretching process was set to 30%. The lower limit of the temperature at which the wire is processed does not have to be particularly defined. It may be processed at room temperature.

【００２６】高炭素クロム鋼の線材に、Ａc₁変態点以下
の温度で延伸加工だけを施す場合、延伸加工の総減面率
が８０％を超えると鋼線内部にクラックが生じる場合が
あるので、延伸加工の総減面率は８０％以下とする必要
がある。高炭素クロム鋼の線材に、Ａc₁変態点以下の温
度で延伸加工と伸線加工を合わせて施す場合、先ず減面
率３０％以上で延伸加工してから伸線加工する必要があ
るのは、減面率３０％未満の延伸加工に続けて伸線加工
を行うと、鋼線内部にクラックが生じる場合があるため
である。In the case where a wire rod of high carbon chromium steel is subjected to only drawing at a temperature not higher than the Ac ₁ transformation point, cracks may occur inside the steel wire if the total area reduction of the drawing exceeds 80%. In addition, the total area reduction rate of the stretching process needs to be 80% or less. When a wire rod of high carbon chromium steel is subjected to stretching and drawing at a temperature below the Ac ₁ transformation point, it is necessary to first draw at a surface reduction rate of 30% or more and then draw. This is because, if the wire drawing is performed subsequent to the drawing with the area reduction rate of less than 30%, cracks may be generated inside the steel wire.

【００２７】一方、減面率３０％以上の延伸加工に続け
て伸線加工を行う場合に、延伸加工と伸線加工を合わせ
た総減面率が８０％を超えると、同様に鋼線内部にクラ
ックが生じる場合がある。On the other hand, when the wire drawing is performed subsequent to the drawing with the reduction of area of 30% or more, if the total reduction in area of the combined drawing and drawing exceeds 80%, the inside of the steel wire is similarly reduced. Cracks may occur.

【００２８】減面率３０％以上の延伸加工に続けて伸線
加工を行う場合、延伸加工と伸線加工を合わせた総減面
率ＴＲが８０％以下であっても、伸線加工の減面率ＤＲ
が前記 (1)式を満たさなければ、図４に示すように鋼線
の内部にクラックが発生してしまう。なお、図４は、通
常の方法で製造したＳＵＪ２鋼（JIS G 4805(1990)）の
５．５ｍｍ線材を用いて減面率を種々変化させて延伸加
工と伸線加工を行い、伸線加工の減面率ＤＲと、延伸加
工と伸線加工とを合わせた減面率ＴＲとが鋼線の内部ク
ラックの発生に及ぼす影響を調査した結果を整理した一
例である。In the case where wire drawing is performed subsequent to drawing with a surface reduction rate of 30% or more, even if the total area reduction rate TR of the combined drawing and wire drawing is 80% or less, the reduction in wire drawing is not required. Area ratio DR
If the above expression (1) is not satisfied, cracks occur inside the steel wire as shown in FIG. FIG. 4 shows a drawing process and a drawing process using a 5.5 mm wire made of SUJ2 steel (JIS G 4805 (1990)) manufactured by an ordinary method while varying the area reduction rate in various ways. 5 is an example in which the results obtained by examining the effects of the reduction in area DR of the steel sheet and the reduction in area TR obtained by combining the drawing and the wire drawing on the occurrence of internal cracks in the steel wire are arranged.

【００２９】上記の理由から、本発明においては、熱間
圧延した高炭素クロム鋼の線材に対して、Ａc₁変態点以
下の温度で総減面率３０〜８０％の延伸加工を行うか、
減面率３０％以上の延伸加工を行い、次いで、前記 (1)
式を満たすとともに延伸加工と合わせた総減面率が８０
％以下となる減面率で伸線加工を行うように規定した。 （Ｃ）球状化焼鈍 前記（Ａ）項の化学組成を有し（Ｂ）項の加工を受けた
鋼線は次に球状化焼鈍される。この球状化焼鈍の方法は
特に限定されるものでなく、通常の条件で行われるもの
でよい。For the above reasons, in the present invention, the hot-rolled high carbon chromium steel wire is stretched at a temperature not higher than the Ac ₁ transformation point to a total area reduction of 30 to 80%,
Stretching is performed with a surface reduction rate of 30% or more, and then (1)
Satisfies the formula and the total area reduction rate combined with the stretching process is 80
% Is specified so that wire drawing is performed with a reduction in area of not more than%. (C) Spheroidizing Annealing The steel wire having the chemical composition of the above item (A) and subjected to the processing of the item (B) is then subjected to spheroidizing annealing. The method of spheroidizing annealing is not particularly limited, and may be performed under ordinary conditions.

【００３０】本発明が対象とする高炭素クロム鋼線は、
例えば、前記（Ａ）項の化学組成を有する鋼を通常の方
法で溶製して鋼片に加工した後、通常の方法で熱間圧延
して線材に加工し、この線材に、（Ｂ）項の加工、
（Ｃ）項の球状化焼鈍を施して製造される。このように
して製造された鋼線は、例えば通常の方法で脱スケール
や潤滑の処理を受けた後、所定形状に加工され、更に、
最終工程としての焼入れ焼戻しなどの熱処理を受けて、
所望の特性を有する機械構造部品に仕上げられる。The high carbon chromium steel wire targeted by the present invention is:
For example, after the steel having the chemical composition of the above item (A) is melted by a usual method and processed into a billet, it is hot-rolled by a normal method to be processed into a wire, and the wire (B) Term processing,
It is manufactured by performing spheroidizing annealing described in (C). The steel wire thus manufactured is processed into a predetermined shape, for example, after being subjected to descaling and lubrication processing by a usual method, and further,
After heat treatment such as quenching and tempering as the final process,
Finished into mechanical structural parts with desired properties.

【００３１】以下、実施例により本発明を詳しく説明す
る。Hereinafter, the present invention will be described in detail with reference to examples.

【００３２】[0032]

【実施例】表１に示す化学組成のＳＵＪ２鋼（JIS G 48
05(1990)）を供試鋼として直径５．５ｍｍの線材を熱間
圧延した。[Example] SUJ2 steel (JIS G 48) having the chemical composition shown in Table 1
05 (1990)) as a test steel, a wire rod having a diameter of 5.5 mm was hot-rolled.

【００３３】[0033]

【表１】 [Table 1]

【００３４】上記の直径５．５ｍｍの線材に機械的なデ
スケーリング（メカニカルデスケーリング）処理を施
し、次いで、室温で３ロール圧延機を用いた通常の延伸
加工（圧延加工）を行った。一方、前記の直径５．５ｍ
ｍの線材に通常の酸洗によるデスケーリングを行ってか
ら潤滑処理して室温で伸線加工することも行った。表２
に、前記の延伸加工、伸線加工におけるパススケジュー
ルの詳細を示す。なお、表２に示した減面率は直径５．
５ｍｍからの総減面率であり、減面率３０％以上は延伸
加工と伸線加工とで同じパススケジュールとした。The above-mentioned wire having a diameter of 5.5 mm was subjected to a mechanical descaling (mechanical descaling) treatment, and then was subjected to a normal stretching process (rolling process) at room temperature using a three-roll rolling mill. On the other hand, the above-mentioned diameter 5.5m
m was subjected to descaling by ordinary pickling, followed by lubrication and wire drawing at room temperature. Table 2
The details of the pass schedule in the above-mentioned drawing and wire drawing are shown below. In addition, the area reduction rate shown in Table 2 is 5 mm in diameter.
It is the total area reduction rate from 5 mm, and when the area reduction rate is 30% or more, the same pass schedule was used for the stretching and the wire drawing.

【００３５】[0035]

【表２】 [Table 2]

【００３６】表２の各パス毎にサンプルを採取し、鋼線
の長手方向縦断面（鋼線の加工方向に平行に、その中心
線を通って切断した面）を顕微鏡観察するとともに、試
料数を２０以上とした引張試験を行って、鋼線の内部欠
陥（クラック）発生の有無を調査した。なお、表２には
この内部欠陥の発生の有無も併せて示した。A sample was taken for each pass shown in Table 2, and a longitudinal section of the steel wire in a longitudinal direction (a plane cut parallel to the processing direction of the steel wire and cut through the center line) was observed under a microscope. Was set to 20 or more, and the occurrence of internal defects (cracks) in the steel wire was investigated. Table 2 also shows whether or not this internal defect has occurred.

【００３７】表２において、伸線加工では減面率３０％
で内部欠陥が認められるが、延伸加工の場合には減面率
８０％の加工でも内部欠陥が認められない。つまり、延
伸加工することで、ＳＵＪ２のような高炭素クロム鋼の
線材を旧オーステナイト粒界間に微細なクラックを発生
させることなくサイズダウンできることが明らかであ
る。次いで、前記の減面率で３０〜８０％の延伸加工を
施した鋼線に、図５に示すヒートパターンで球状化焼鈍
ＳＡ１を施し、球状化焼鈍後の球状化率及び平均炭化物
粒径を調査した。In Table 2, in wire drawing, the area reduction rate is 30%.
, Internal defects are recognized, but in the case of stretching, no internal defects are recognized even when the area is reduced by 80%. In other words, it is clear that the size of a wire rod of a high carbon chromium steel such as SUJ2 can be reduced by stretching without causing fine cracks between the prior austenite grain boundaries. Next, spheroidizing annealing SA1 is applied to the steel wire that has been subjected to the drawing process at a reduced area ratio of 30 to 80% by the heat pattern shown in FIG. 5, and the spheroidizing rate and the average carbide particle size after the spheroidizing annealing are determined. investigated.

【００３８】又、直径５．５ｍｍの線材に機械的なデス
ケーリング（メカニカルデスケーリング）処理を施し、
次いで、６００℃で３ロール圧延機を用いた通常の温間
延伸加工（圧延加工）を行った後、この鋼線に、上記の
球状化焼鈍ＳＡ１を施し、球状化焼鈍後の球状化率と平
均炭化物粒径とを調査した。Further, mechanical descaling (mechanical descaling) processing is performed on the wire rod having a diameter of 5.5 mm.
Next, after performing normal warm drawing (rolling) using a three-roll rolling mill at 600 ° C., the steel wire is subjected to the above-described spheroidizing annealing SA1, and the spheroidizing rate after the spheroidizing annealing is determined. The average carbide particle size was investigated.

【００３９】比較のために、従来法と同様に２回の球状
化焼鈍を施した場合の球状化率と平均炭化物粒径も調査
した。すなわち、直径５．５ｍｍの線材に図６に示すヒ
ートパターンで球状化焼鈍ＳＡ２を行い、次いで、通常
の方法で酸洗・潤滑処理した後、減面率で３０〜８０％
の伸線加工を施し、更に、図７に示すヒートパターンで
球状化焼鈍ＳＡ３を行い、球状化焼鈍後の球状化率及び
平均炭化物粒径を調査した。For comparison, the spheroidization ratio and the average carbide particle size when spheroidizing annealing was performed twice as in the conventional method were also investigated. That is, spheroidizing annealing SA2 is performed on a wire having a diameter of 5.5 mm by the heat pattern shown in FIG. 6, and then pickling and lubricating are performed by a normal method, and then a surface reduction rate of 30 to 80%
, And further, spheroidizing annealing SA3 was performed according to the heat pattern shown in FIG. 7, and the spheroidizing rate after spheroidizing annealing and the average carbide particle size were examined.

【００４０】表３に、球状化率及び平均炭化物粒径の調
査結果を示す。なお、表３には、直径５．５ｍｍの線材
をそのまま図４に示すヒートパターンで球状化焼鈍した
場合の球状化率と平均炭化物粒径及び硬さも併記した。Table 3 shows the results of the investigation on the spheroidization ratio and the average carbide particle size. Table 3 also shows the spheroidization rate, the average carbide particle size, and the hardness when the wire having a diameter of 5.5 mm was directly subjected to spheroidizing annealing using the heat pattern shown in FIG.

【００４１】[0041]

【表３】 [Table 3]

【００４２】表３から、本発明に係る方法で処理された
鋼線が、従来法と同様に２回の球状化焼鈍を施した鋼線
と同等の球状化組織（つまり、同等の平均炭化物粒径と
同等の球状化率）を有する。なお、本実施例における球
状化焼鈍はバッチ処理としたが、この球状化焼鈍は、例
えば、所定の形状に仕上げた後にループレイヤを取り付
け、鋼線をリング状に展開した後、連続的に焼鈍処理す
る方法で行っても良い。表２に示した３０〜８０％の減
面率で延伸加工した鋼線を、更に室温で伸線加工するこ
とも行った。表４に、延伸加工及び伸線加工におけるパ
ススケジュールの詳細を示す。なお、表４に示した総減
面率ＴＲは延伸加工と伸線加工を合わせた直径５．５ｍ
ｍからの減面率であり、伸線加工の減面率ＤＲは、延伸
加工した鋼線から伸線加工した場合の減面率を示す。な
お、総減面率ＴＲに占める伸線加工の減面率ＤＲの割合
を括弧内に併せて示した。表４の各条件毎にサンプルを
採取し、鋼線の長手方向縦断面を顕微鏡観察するととも
に、試料数を２０以上とした引張試験を行って、鋼線の
内部欠陥（クラック）発生の有無を調査した。なお、表
４にはこの内部欠陥の発生の有無も併せて示した。表４
において内部に欠陥（クラック）のない鋼線について
は、前記図５に示すヒートパターンで球状化焼鈍ＳＡ１
を施し、球状化焼鈍後の球状化率及び平均炭化物粒径も
調査した。From Table 3, it can be seen that the steel wire treated by the method according to the present invention has a spheroidized structure equivalent to a steel wire subjected to twice spheroidizing annealing in the same manner as in the conventional method (that is, an equivalent average carbide grain size). (Spheroidization rate equivalent to the diameter). In addition, although the spheroidizing annealing in the present example was a batch process, the spheroidizing annealing is performed, for example, after finishing to a predetermined shape, attaching a loop layer, expanding a steel wire into a ring shape, and continuously annealing. The processing may be performed. The steel wire drawn at a reduction in area of 30 to 80% shown in Table 2 was further drawn at room temperature. Table 4 shows details of the pass schedule in the stretching and the wire drawing. The total area reduction rate TR shown in Table 4 is 5.5 m in diameter obtained by combining the stretching and the wire drawing.
m, and the area reduction rate DR of wire drawing indicates the area reduction rate when wire drawing is performed from a drawn steel wire. The ratio of the wire-drawing reduction ratio DR to the total reduction ratio TR is also shown in parentheses. A sample was taken for each condition in Table 4, and the longitudinal section of the steel wire in the longitudinal direction was observed under a microscope, and a tensile test was performed with the number of samples being 20 or more to determine whether or not internal defects (cracks) occurred in the steel wire. investigated. Table 4 also shows the presence / absence of this internal defect. Table 4
As for the steel wire having no defect (crack) inside, the spheroidized annealing SA1 was obtained using the heat pattern shown in FIG.
, And the spheroidization rate after spheroidizing annealing and the average carbide particle size were also investigated.

【００４３】[0043]

【表４】 [Table 4]

【００４４】表４から、延伸加工と伸線加工の両方を本
発明で規定する条件で施された鋼線には内部欠陥が認め
られず、しかも、従来法と同様に２回の球状化焼鈍を施
した鋼線（表３参照）と同等の球状化組織を有すること
が明らかである。As can be seen from Table 4, no internal defects were observed in the steel wire subjected to both the drawing and the wire drawing under the conditions specified in the present invention, and two rounds of spheroidizing annealing were performed as in the conventional method. It is apparent that the steel wire has a spheroidized structure equivalent to that of the steel wire subjected to (see Table 3).

【００４５】[0045]

【発明の効果】本発明の方法によれば、高炭素クロム鋼
線の内部にクラックを生ずることなく、球状化熱処理
（球状化焼鈍）を１回に削減することができる。本発明
の機械構造部品の素材となる高炭素クロム鋼線は、本発
明の方法によって比較的容易に低コストで製造できる。According to the method of the present invention, the spheroidizing heat treatment (spheroidizing annealing) can be reduced to one without causing cracks inside the high carbon chromium steel wire. The high carbon chromium steel wire used as the material of the mechanical structural component of the present invention can be relatively easily manufactured at low cost by the method of the present invention.

【図面の簡単な説明】[Brief description of the drawings]

【図１】初析セメンタイトが存在する高炭素クロム鋼の
線材を熱間圧延組織のままで延伸加工した場合の応力状
況と加工後の組織状況を模式的に示す図である。BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram schematically showing a stress state when a high-carbon chromium steel wire having proeutectoid cementite is stretched while maintaining a hot-rolled structure, and a structure state after the processing.

【図２】高炭素クロム鋼線の従来の製造方法を示す図で
ある。FIG. 2 is a view showing a conventional method for manufacturing a high carbon chromium steel wire.

【図３】初析セメンタイトが存在する高炭素クロム鋼の
線材を熱間圧延組織のままで伸線加工した場合の応力状
況、加工後の組織状況及び旧オーステナイト粒界間に微
細なクラックが発生する状況を模式的に示す図である。Fig. 3 Stress in the case of high carbon chromium steel wire with proeutectoid cementite drawn in hot-rolled structure, microstructure after processing and micro-cracks between former austenite grain boundaries It is a figure which shows the situation which performs.

【図４】通常の方法で製造したＳＵＪ２鋼（JIS G 4805
(1990)）の５．５ｍｍ線材を用いて、減面率を種々変化
させて延伸加工と伸線加工を行った場合に、伸線加工の
減面率ＤＲと、延伸加工と伸線加工とを合わせた総減面
率ＴＲとが鋼線の内部クラックの発生に及ぼす影響を調
査した結果の一例を示す図である。FIG. 4 SUJ2 steel (JIS G 4805) manufactured by a normal method
(1990)), when the drawing process and the drawing process were performed by changing the area reduction rate variously using the 5.5 mm wire rod, the reduction ratio DR of the drawing process, the drawing process and the wire drawing process, FIG. 9 is a diagram illustrating an example of a result of an investigation on an influence of a total area reduction rate TR, which is combined with the above, on the occurrence of internal cracks in a steel wire.

【図５】実施例で行った球状化焼鈍ＳＡ１のヒートパタ
ーンを示す図である。FIG. 5 is a view showing a heat pattern of spheroidizing annealing SA1 performed in an example.

【図６】実施例で行った球状化焼鈍ＳＡ２のヒートパタ
ーンを示す図である。FIG. 6 is a view showing a heat pattern of spheroidizing annealing SA2 performed in the example.

【図７】実施例で行った球状化焼鈍ＳＡ３のヒートパタ
ーンを示す図である。FIG. 7 is a view showing a heat pattern of spheroidized annealing SA3 performed in the example.

【符号の説明】[Explanation of symbols]

１：被加工材、 ２：穴ダイス、 ３：クラック、 ４：ロール、 Ｓ：剪断応力、 Ｃ：圧縮応力 1: work material, 2: hole die, 3: crack, 4: roll, S: shear stress, C: compressive stress

Claims (3)

【特許請求の範囲】[Claims] 【請求項１】質量％で、Ｃ：０．７％以上、Ｃｒ：０．
５％以上を含有する熱間圧延後の線材に、Ａc₁変態点以
下の温度で総減面率３０〜８０％の延伸加工を行って所
定の形状に仕上げた後、球状化焼鈍することを特徴とす
る高炭素クロム鋼線の製造方法。(1) In mass%, C: 0.7% or more, Cr: 0.
The wire rod after hot rolling containing 5% or more, was finished into a predetermined shape by performing the drawing processing of the whole cross sectional reduction ratio 30% to 80% at a temperature below the Ac ₁ transformation point, to annealing spheroidizing Characteristic method for producing high carbon chrome steel wire. 【請求項２】質量％で、Ｃ：０．７％以上、Ｃｒ：０．
５％以上を含有する熱間圧延後の線材に、Ａc₁変態点以
下の温度で減面率３０％以上の延伸加工を行い、次い
で、下記 (1)式を満たすとともに延伸加工と合わせた総
減面率が８０％以下となる減面率で伸線加工を行って所
定の形状に仕上げた後、球状化焼鈍することを特徴とす
る高炭素クロム鋼線の製造方法。 ＤＲ≦０．００１１×ＴＲ² −０．３６０３×ＴＲ＋２１．７０１・・・(1) ここで、ＤＲは伸線加工の減面率（％）、ＴＲは延伸加
工と伸線加工を合わせた総減面率（％）を指す。2. C .: 0.7% or more and Cr: 0.
The hot-rolled wire containing 5% or more is stretched at a temperature not higher than the Ac ₁ transformation point to have a reduction in area of 30% or more. A method for producing a high carbon chromium steel wire, comprising drawing a wire to a predetermined shape by performing wire drawing at a surface reduction rate of 80% or less and then performing spheroidizing annealing. DR ≦ 0.0011 × TR ² −0.3603 × TR + 21.701 (1) Here, DR is the area reduction rate (%) of the wire drawing, and TR is the total of the drawing and the wire drawing. Indicates the area reduction rate (%). 【請求項３】請求項１又は２に記載の方法で製造された
鋼線を素材とする機械構造部品。3. A machine structural part made of a steel wire produced by the method according to claim 1.