JP2001131631A - Method of spheroidizing-annealing steel material in short time and steel material using this method - Google Patents

Method of spheroidizing-annealing steel material in short time and steel material using this method

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Publication number
JP2001131631A
JP2001131631A JP30846899A JP30846899A JP2001131631A JP 2001131631 A JP2001131631 A JP 2001131631A JP 30846899 A JP30846899 A JP 30846899A JP 30846899 A JP30846899 A JP 30846899A JP 2001131631 A JP2001131631 A JP 2001131631A
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JP
Japan
Prior art keywords
temperature
cooling
steel material
austenite
heating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
JP30846899A
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Japanese (ja)
Other versions
JP3870631B2 (en
Inventor
Takuya Atsumi
卓彌 厚見
Yoshio Yamazaki
義男 山崎
Toshiyuki Hoshino
俊幸 星野
Kenichi Amano
虔一 天野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
JFE Steel Corp
Original Assignee
Kawasaki Steel Corp
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Publication date
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Priority to JP30846899A priority Critical patent/JP3870631B2/en
Publication of JP2001131631A publication Critical patent/JP2001131631A/en
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Publication of JP3870631B2 publication Critical patent/JP3870631B2/en
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  • Heat Treatment Of Steel (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a short time spheroidizing-annealing method of a steel material, by which the treating time can remarkably be shortened in comparison with the conventional method and thus, this method is profitably used from the view point of the energy cost. SOLUTION: To a steel material for machine structural use containing 0.15-1.10 wt.% C, the spheroidizing-annealing treatment is applied as the follows. (1) The steel material is heated in the temperature range of (the developing temperature of austenite -50 deg.C)-(the developing temperature of austenite -5 deg.C) during the heating at <=0.01 deg.C/s heating rate. (2) After heating to the temperature range of (the forming temperature of the single phase of austenite -30 deg.C)-(the forming temperature of the single phase of austenite -5 deg.C) which is the maximum heating temperature, this steel material is immediately turned to cooling. (3) After cooling in the temperature range of (the forming temperature of ferrite +10 deg.C)-(the forming temperature of ferrite -40 deg.C) during cooling, at <=0.005 deg.C/s cooling rate, this steel material is air-cooled.

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、塑性加工や切削加
工などの機械加工を容易にし、また機械的性質を改善す
るために行う鋼中炭化物の球状化処理を短時間で行うこ
とができる、鋼材の短時間球状化焼なまし方法および同
法による鋼材に関するものである。
The present invention relates to a method for facilitating machining such as plastic working and cutting, and for performing spheroidizing treatment of carbides in steel in order to improve mechanical properties. The present invention relates to a method for annealing a steel material in a short time in a spheroidizing manner and a steel material produced by the method.

【0002】[0002]

【従来の技術】自動車および産業機械等に用いられる機
械部品には、従来から炭素鋼や合金鋼等のいわゆる機械
構造用鋼や軸受鋼が素材として汎用されている。これら
の機械部品は、通常、例えば捧鋼線材の場合、素材を球
状化焼なましし、切断後、冷間鍛造を施し、ついで切削
等の冷間加工を行うことによって製造されている。ここ
に、冷間加工は、加工精度、量産性およびコストの点で
優れているため多用されており、また球状化焼なまし
は、かかる冷間加工性を向上させるべく、鋼中の炭化物
を球状化させて変形抵抗を低下させる等の目的で実施さ
れる。なお、球状化焼なまし後の組織は、フェライト素
地に球状の炭化物が分散したものになっている。
2. Description of the Related Art Conventionally, so-called machine structural steel such as carbon steel and alloy steel and bearing steel have been widely used as materials for mechanical parts used in automobiles and industrial machines. These mechanical parts are usually manufactured, for example, in the case of a dedicated steel wire rod, by spheroidizing the raw material, cutting, performing cold forging, and then performing cold working such as cutting. Here, cold working is frequently used because it is excellent in terms of working accuracy, mass productivity and cost, and spheroidizing annealing is to reduce carbides in steel in order to improve such cold workability. This is performed for the purpose of reducing the deformation resistance by spheroidizing. The structure after the spheroidizing annealing is such that spherical carbides are dispersed in a ferrite base.

【0003】しかしながら、かような球状化焼なまし方
法については、高温でしかも約10〜30時間程度の長時間
加熱を必要とする点が、従来から問題視されてきた。こ
の問題の解決策として、例えば特公平6−2898号公報に
は、図2(a), (b)に示すようなヒートパターンが開示さ
れているが、依然として長時間かつ数回の繰り返し熱サ
イクルを必要とするものであり、エネルギーコストおよ
び温度制御の点で大きな問題を残していた。また、特開
平4−362123号公報には、図3に示すようなヒートパタ
ーンが開示されているが、このヒートパターンでは、上
記したエネルギーコストの点は改善されるにしても、炭
化物の球状化という点では依然として問題が残ってい
た。
However, such a spheroidizing annealing method has conventionally been regarded as a problem in that it requires high temperature and a long heating time of about 10 to 30 hours. As a solution to this problem, for example, Japanese Patent Publication No. 6-2898 discloses a heat pattern as shown in FIGS. 2 (a) and 2 (b). And there remains a major problem in terms of energy cost and temperature control. Japanese Unexamined Patent Publication No. 4-362123 discloses a heat pattern as shown in FIG. 3. In this heat pattern, even if the above-mentioned energy cost is improved, spheroidization of carbides is performed. In that respect, problems remained.

【0004】その他、特開平4−333527号公報には、2
段階の保定処理後、徐冷することからなる球状化焼鈍方
法が開示されているが、この方法も、基本的に2度にわ
たる長時間の保定処理を必要とする不利があるだけでな
く、球状化炭化物の核を作るためにMnやCr等のセメンタ
イト安定化元素が不可欠であることから、合金コストの
面でも問題があった。
[0004] In addition, JP-A-4-333527 discloses that
A spheroidizing annealing method comprising slow cooling after the stage of holding treatment is disclosed. However, this method also has a disadvantage that basically requires two times of long-term holding treatment, Since cementite stabilizing elements such as Mn and Cr are indispensable for forming nuclei of carbides, there is a problem in terms of alloy cost.

【0005】[0005]

【発明が解決しようとする課題】本発明は、上記の問題
を有利に解決するもので、短時間で効果的な炭化物の球
状化を達成することができる、鋼材の短時間球状化焼な
まし方法を、この方法に従い処理して得た鋼材と共に提
案することを目的とする。
DISCLOSURE OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and provides a short-time spheroidizing annealing of a steel material that can achieve effective carbide spheroidization in a short time. It is an object of the invention to propose a method together with the steel obtained by processing according to this method.

【0006】[0006]

【課題を解決するための手段】さて、発明者らは、上記
の目的を達成するために、鋼材の球状化焼なまし条件に
関して調査研究を重ねた結果、球状化焼なまし時間の短
縮化には、鋼材の変態挙動、炭素の拡散速度および徐冷
前の未溶解炭化物の個数が大きな影響を及ぼしているこ
との知見を得た。本発明は、上記の知見に立脚するもの
である。
Means for Solving the Problems In order to achieve the above object, the present inventors have conducted repeated studies on the conditions for spheroidizing annealing of steel materials, and have found that the time required for spheroidizing annealing is reduced. It was found that the transformation behavior of the steel material, the diffusion rate of carbon, and the number of undissolved carbides before slow cooling had a significant effect. The present invention is based on the above findings.

【0007】すなわち、本発明は、C:0.15〜1.10mass
%を含有する機械構造用の鋼材に対して、球状化焼なま
しを施すに際し、(1) 加熱途中の、(オーステナイトが
出現する温度−50℃)〜 (オーステナイトが出現する温
度−5℃)の温度範囲を0.01℃/s 以下の速度で加熱
し、(2) 最高加熱温度である(オーステナイト単相にな
る温度−30℃)〜(オーステナイト単相になる温度−5
℃)の温度範囲まで加熱した後、直ちに冷却に転じ、
(3) 冷却途中の、(フェライトが出現する温度+10℃)
〜(フェライトが出現する温度−40℃)の温度範囲を
0.005℃/s 以下の速度で冷却した後、空冷することを
特徴とする鋼材の短時間球状化焼なまし方法である。
That is, the present invention provides a method for preparing C: 0.15 to 1.10 mass
% Of steel for machine structural use containing (%), (1) During heating, (temperature at which austenite appears -50 ° C) to (temperature at which austenite appears -5 ° C) Is heated at a rate of 0.01 ° C./s or less.
℃), then immediately cool down,
(3) During cooling (temperature at which ferrite appears + 10 ° C)
~ (Temperature at which ferrite appears -40 ℃)
This is a short-time spheroidizing annealing method for steel, which is cooled at a rate of 0.005 ° C / s or less and then air-cooled.

【0008】また、本発明は、球状化焼なまし処理を施
して得た、C:0.15〜1.10mass%を含有する機械構造用
の鋼材であって、該球状化焼なましが、(1) 加熱途中
の、(オーステナイトが出現する温度−50℃)〜 (オー
ステナイトが出現する温度−5℃)の温度範囲を0.01℃
/s 以下の速度で加熱し、(2) 最高加熱温度である(オ
ーステナイト単相になる温度−30℃)〜(オーステナイ
ト単相になる温度−5℃)の温度範囲まで加熱した後、
直ちに冷却に転じ、(3) 冷却途中の、(フェライトが出
現する温度+10℃)〜(フェライトが出現する温度−40
℃)の温度範囲を 0.005℃/s 以下の速度で冷却した
後、空冷する工程からなることを特徴とする鋼材であ
る。
The present invention also relates to a steel material for machine structure containing C: 0.15 to 1.10 mass% obtained by performing a spheroidizing annealing treatment, wherein the spheroidizing annealing is (1) ) During heating, the temperature range of (temperature at which austenite appears -50 ° C) to (temperature at which austenite appears -5 ° C) is 0.01 ° C.
/ S at a rate of not more than (2) After heating to the maximum heating temperature (temperature at which austenite becomes single phase -30 ° C) ~ (temperature at which austenitic single phase becomes -5 ° C),
(3) During cooling, (temperature at which ferrite appears + 10 ° C) ~ (temperature at which ferrite appears -40
(° C) at a rate of 0.005 ° C / s or less, followed by air cooling.

【0009】[0009]

【発明の実施の形態】以下、本発明の解明経緯について
説明する。さて、発明者らは、Cを0.15〜1.10mass%含
有する鋼材の球状化焼なまし条件に関して調査したとこ
ろ、球状化焼なまし時間を短縮すると、球状化焼なまし
後のミクロ組織には、棒状や層状の炭化物が増加する
か、あるいは球状化程度は問題ないものの細かな炭化物
が数多く存在するため、いずれも硬さが従来材と比べて
上昇し、冷間加工性が低下することが判明した。また、
さらなる調査により、球状化程度と冷間加工性は、鋼材
の変態挙動、炭素の拡散速度および徐冷前の未溶解炭化
物の個数に強く影響されることが判明した。
DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the invention will be described below. By the way, the present inventors have investigated the spheroidizing annealing conditions of steel containing 0.15 to 1.10 mass% of C. When the spheroidizing annealing time is shortened, the microstructure after the spheroidizing annealing is reduced. However, although the number of rod-shaped or layered carbides increases, or the degree of spheroidization is not a problem, there are many fine carbides, so that the hardness increases compared to conventional materials and the cold workability decreases. found. Also,
Further investigations revealed that the degree of spheroidization and cold workability were strongly affected by the transformation behavior of the steel, the diffusion rate of carbon, and the number of undissolved carbides before slow cooling.

【0010】上記の結果に基づき、球状化焼なまし時間
を短縮したとしても従来材と同等の冷間加工性を得るた
めの要件を解明すべく、球状化焼なまし条件を種々変化
させて、得られた鋼材の冷間加工性について調査したと
ころ、以下に述べるような3つの要件を満足させること
が肝要であることが究明された。
On the basis of the above results, various conditions of the spheroidizing annealing were used to clarify the requirements for obtaining the same cold workability as the conventional material even if the spheroidizing annealing time was shortened. Investigating the cold workability of the obtained steel material, it was found that it was important to satisfy the following three requirements.

【0011】(1) 加熱途中の、(オーステナイトが出現
する温度−50℃)〜 (オーステナイトが出現する温度−
5℃)の温度範囲を0.01℃/s 以下の速度で加熱するこ
とこの要件は、本発明の重要な要件である。熱処理時間
を短縮するためには、加熱速度を大きくすることが有効
な手段である。しかしながら、加熱速度を大きくした場
合、球状化焼なまし後の組織は、その後の冷却条件を如
何に変化させても、従来と比較して非常に細かな炭化物
が数多く見られ、硬さが従来材と比較して高くなり、冷
間加工性の低下が免れ得ない。この理由は、微細な炭化
物の分散により鋼が強化されるからである。従って、最
終的に得られるミクロ組織から微細な炭化物を除くた
め、加熱過程において、細かな炭化物を母相に溶解させ
る必要がある。
(1) During heating, (temperature at which austenite appears-50 ° C) ~ (temperature at which austenite appears-
5 ° C.) at a rate of 0.01 ° C./s or less. This requirement is an important requirement of the present invention. In order to shorten the heat treatment time, it is effective to increase the heating rate. However, when the heating rate is increased, the structure after spheroidizing annealing shows a lot of very fine carbides compared to the conventional one, no matter how the subsequent cooling conditions are changed. It is higher than the material, and the reduction in cold workability cannot be avoided. This is because the dispersion of fine carbides strengthens the steel. Therefore, in order to remove fine carbides from the finally obtained microstructure, it is necessary to dissolve the fine carbides in the matrix during the heating process.

【0012】そこで、種々の温度範囲で加熱速度を変化
させて、最終的に得られる炭化物の粒度分布を調査した
ところ、オーステナイトが出現する温度直下に保持する
ことが最も有効であることが分かった。オーステナイト
が出現する温度以上では、炭素の拡散速度が急激に低下
し、細かな炭化物の母相への溶解が非常に遅くなるた
め、短時間化の点からオーステナイトが出現する温度よ
り低い温度が望ましいことも判明した。ここに、炭化物
の溶解は、温度範囲と加熱速度とで決定されるが、実操
業と細かな炭化物の溶解状況調査から、(オーステナイ
トが出現する温度−50℃)〜(オーステナイトが出現す
る温度−5℃)の最適温度範囲では、0.01℃/s 以下の
速度で加熱することが最も望ましく、この速度より大き
くなると微細な炭化物の溶解は不十分であった。従っ
て、上記の温度範囲および冷却速度に限定した。
[0012] Thus, when the heating rate was changed in various temperature ranges and the particle size distribution of the finally obtained carbide was investigated, it was found that it was most effective to maintain the temperature just below the temperature at which austenite appeared. . Above the temperature at which austenite appears, the diffusion rate of carbon sharply decreases and the dissolution of fine carbides into the matrix becomes very slow, so a temperature lower than the temperature at which austenite appears is desirable from the viewpoint of shortening the time. It turned out that. Here, the dissolution of the carbide is determined by the temperature range and the heating rate. From actual operation and a detailed investigation of the dissolution state of the carbide, from the temperature at which austenite appears-50 ° C) to the temperature at which austenite appears- In the optimum temperature range (5 ° C.), it is most desirable to heat at a rate of 0.01 ° C./s or less. Above this rate, the dissolution of fine carbides was insufficient. Therefore, it was limited to the above temperature range and cooling rate.

【0013】(2) 最高加熱温度である(オーステナイト
単相になる温度−30℃)〜(オーステナイト単相になる
温度−5℃)の温度範囲まで加熱した後、直ちに冷却に
転じること最高加熱温度を、上記の範囲に規定した理由
は、球状化焼なまし時間の短縮を指向する場合、上記の
温度範囲外では高すぎても低すぎても球状化は不十分と
なったからである。その理由は、温度が高すぎる場合
は、炭化物のほとんどが固溶してしまい、球状炭化物の
核生成サイトの密度が減少し、結果として冷却時に再生
パーライトが生じるためであり、一方温度が低すぎる場
合は、層状パーライトが固溶せずに残存したためであ
る。また、短時間化のために最高加熱温度まで加熱後
は、保持せずに、直ちに冷却に移ることができ、従来の
ように保持する必要はないことも判明した。
(2) After heating to the maximum heating temperature range of (austenite single phase -30 ° C.) to (austenitic single phase -5 ° C.), immediately start cooling. The reason why spheroidization is specified in the above range is that when the spheroidizing annealing time is intended to be shortened, spheroidization becomes insufficient if the temperature is too high or too low outside the above temperature range. The reason is that if the temperature is too high, most of the carbides will form a solid solution, the density of the nucleation sites of the spherical carbides will decrease, and as a result regenerated pearlite will be generated during cooling, while the temperature is too low In this case, the layered perlite remained without being dissolved. In addition, after heating up to the maximum heating temperature for the purpose of shortening the time, cooling can be immediately started without holding, and it has been found that it is not necessary to hold as in the conventional case.

【0014】(3) 冷却途中の、(フェライトが出現する
温度+10℃)〜(フェライトが出現する温度−40℃)の
温度範囲を0.005 ℃/s 以下の速度で冷却し、その後空
冷することこの要件は、本発明において特に重要な要件
である。すなわち、球状化を促進するには、冷却中に、
未溶解炭化物の周辺に、オーステナイトとフェライトの
固溶差の炭素を析出させる必要がある。そのためには、
徐冷温度範囲および冷却速度の選定が重要である。そこ
で、徐冷温度範囲と冷却速度を種々に変化させて球状化
の程度を調べたところ、安定的に球状化した炭化物を得
るためには(フェライトが出現する温度+10℃)から、
変態が完了する温度である(フェライトが出現する温度
−40℃)までの範囲を、0.005 ℃/s 以下の速度で冷却
する必要であることが判明した。
(3) During cooling, a temperature range of (temperature at which ferrite appears + 10 ° C.) to (temperature at which ferrite appears −40 ° C.) is cooled at a rate of 0.005 ° C./s or less, and then air-cooled. The requirements are particularly important requirements in the present invention. That is, to promote spheroidization, during cooling,
It is necessary to deposit carbon having a solid solution difference between austenite and ferrite around the undissolved carbide. for that purpose,
It is important to select the slow cooling temperature range and cooling rate. Therefore, the degree of spheroidization was examined by changing the annealing temperature range and the cooling rate in various ways. In order to obtain a stable spheroidized carbide (the temperature at which ferrite appears + 10 ° C),
It was found that it was necessary to cool at a rate of 0.005 ° C./s or less up to the temperature at which the transformation was completed (the temperature at which ferrite appeared—40 ° C.).

【0015】ここに、徐冷開始温度を(フェライトが出
現する温度+10℃)としたのは、この開始温度とするこ
とにより短時間化の点から変態開始までの潜伏時間が短
く、全体の徐冷時間を短くできるからである。また、冷
却速度が速すぎる場合、あるいは徐冷の温度範囲下限が
(フェライトが出現する温度−40℃)より高い場合に
は、相状のパーライトが出現し硬さが高くなり、冷間加
工性の低下を招く。また、徐冷開始温度である(フェラ
イトが出現する温度+10℃)より高い温度で徐冷を開始
した場合には、冷間加工性はほとんど同等ではあるが、
球状化焼なまし時間の短縮効果が不十分となる。従っ
て、上記の温度範囲および冷却速度に限定した。
The reason for setting the slow cooling start temperature to (temperature at which ferrite appears + 10 ° C.) is that by setting this start temperature, the incubation time from the point of shortening to the start of transformation is short, and the whole slow cooling is started. This is because the cooling time can be shortened. If the cooling rate is too high, or if the lower limit of the temperature range for slow cooling is higher than (temperature at which ferrite appears −40 ° C.), phase-like pearlite appears and the hardness increases, and the cold workability increases. Causes a decrease in In addition, when slow cooling is started at a temperature higher than the slow cooling start temperature (temperature at which ferrite appears + 10 ° C), the cold workability is almost the same,
The effect of shortening the spheroidizing annealing time becomes insufficient. Therefore, it was limited to the above temperature range and cooling rate.

【0016】なお、上記(l) および(3) に示した温度域
以外では、加熱速度および冷却速度を大幅に増加させて
も球状化程度に特に影響を及ぼさないので、球状化焼な
まし時間の短縮化のためには、急加熱および急冷却処理
とすることが有利である。ただし、加熱および冷却速度
を大きくすると、設備コストが上昇するだけでなく、操
作が複雑になり、メンテナンス等種々の問題が出てくる
ため、例えば1℃/s 以下程度が現実的である。
In the temperature ranges other than those shown in the above (1) and (3), even if the heating rate and the cooling rate are greatly increased, the degree of spheroidization is not particularly affected. In order to shorten the time, it is advantageous to perform rapid heating and rapid cooling. However, increasing the heating and cooling rates not only increases the equipment cost, but also complicates the operation and causes various problems such as maintenance, so that a temperature of, for example, about 1 ° C./s or less is practical.

【0017】図1に、上述したような、本発明に従う球
状化処理の好適ヒートパターンを例示する。
FIG. 1 illustrates a preferred heat pattern of the spheroidizing treatment according to the present invention as described above.

【0018】次に、本発明で対象とする素材について述
べると、本発明は、Cを0.15〜1.10mass%含有していれ
ば、従来公知の機械構造用鋼の全てに対して適用するこ
とができる。ここに、C量を0.15〜1.10mass%の範囲に
限定した理由は次のとおりである。Cは、固溶して基地
を強化し、機械部品として十分な強度および耐摩耗性を
得る上で有用な元素であるが、含有量が0.15mass%未満
では、冷間加工性の点から球状化焼なましの必要がな
く、一方1.10mass%を超えると母材の靱性が著しく劣化
するため、C量は0.15〜1.10mass%の範囲に限定した。
Next, the material to be treated in the present invention will be described. If the present invention contains 0.15 to 1.10 mass% of C, the present invention can be applied to all conventionally known steels for machine structural use. it can. Here, the reason why the amount of C is limited to the range of 0.15 to 1.10 mass% is as follows. C is a useful element for forming a solid solution to strengthen the matrix and obtaining sufficient strength and wear resistance as a mechanical part. However, if the content is less than 0.15 mass%, it is spherical from the viewpoint of cold workability. There is no need for chemical annealing. On the other hand, if it exceeds 1.10 mass%, the toughness of the base material is significantly deteriorated.

【0019】なお、従来は、球状化炭化物の核を作るた
めに、MnやCr等のセメンタイト安定化元素の添加が不可
欠であったが、本発明では、上記(1) の徐熱処理によっ
て炭化物の数を適切に調整できるので、かような元素の
添加は特に必要としない。従って、Mn,Crはそれぞれ、
Mn<0.25mass%, Cr<0.1 mass%であっても良い。
Conventionally, the addition of a cementite stabilizing element such as Mn or Cr has been indispensable in order to form a nucleus of a spheroidized carbide. Since the number can be appropriately adjusted, addition of such an element is not particularly required. Therefore, Mn and Cr are
Mn <0.25 mass% and Cr <0.1 mass% may be satisfied.

【0020】なお、本発明を適用して好適な鋼種を例示
すると次のとおりである。 ・JIS G 4051 機械構造用炭素鋼鋼材 特にS45C〜S55C
(C≧0.45wt%)。 ・JIS G 4105 クロムモリブデン鋼鋼材 特にSCM435〜
SCM445(C≧0.35wt%)。 ・JIS G 4805 高炭素クロム軸受鋼鋼材 特に SUJ 2
(軸受鋼代表)。
The following are examples of suitable steel types to which the present invention is applied.・ JIS G 4051 Carbon steel for machine structure, especially S45C ~ S55C
(C ≧ 0.45 wt%).・ JIS G 4105 Chrome molybdenum steel, especially SCM435 ~
SCM445 (C ≧ 0.35 wt%).・ JIS G 4805 High carbon chromium bearing steel, especially SUJ 2
(Bearing steel representative).

【0021】[0021]

【実施例】表1に示す種々の成分組成になる鋼を、転炉
で溶製し、連続鋳造法で鋼片としたのち、20mmφの棒鋼
に圧延した。ついで、この棒鋼に対し、表2に示す種々
の条件下で球状化焼なましを施したのち、各素材から15
mmφ×22.5mm高さの冷間加工性試験片を切り出し、各条
件下での冷間加工性について調査した。得られた結果を
表2に併記する。なお、変形抵抗については、圧縮率:
60%の条件で拘束圧縮変形を行った時の変形抵抗により
評価した。また、変形能については、各圧縮率でn=5
の拘束圧縮変形を行い、割れの発生が認められた最低の
圧縮率を割れ限界圧縮率として評価した。
EXAMPLES Steel having various component compositions shown in Table 1 was melted in a converter, made into a billet by a continuous casting method, and then rolled into a 20 mmφ bar. Next, the steel bars were subjected to spheroidizing annealing under various conditions shown in Table 2, and then each material was subjected to spheroidizing annealing.
A cold workability test specimen having a height of mmφ × 22.5 mm was cut out, and the cold workability under each condition was investigated. The obtained results are also shown in Table 2. In addition, about deformation resistance, compression ratio:
Evaluation was made based on the deformation resistance when restrained compression deformation was performed under the condition of 60%. As for the deformability, n = 5 at each compression ratio.
Was subjected to constrained compression deformation, and the lowest compression rate at which cracking was observed was evaluated as the crack limit compression rate.

【0022】[0022]

【表1】 [Table 1]

【0023】[0023]

【表2】 [Table 2]

【0024】表2から明らかなように、本発明に従って
球状化焼なましを実施した場合は、処理時間が大幅に低
減できたにもかかわらず、従来と同等の冷間加工性(変
形抵抗および変形能)が得られている。これに対して、
比較例(No.11〜20)はいずれも、球状化焼なまし条件が
本発明の適正範囲から外れているため、変形抵抗あるい
は変形能の著しい低下を招いている。
As is evident from Table 2, when spheroidizing annealing was performed according to the present invention, the cold workability (deformation resistance and deformation resistance) were the same as in the prior art, although the processing time was greatly reduced. Deformability) is obtained. On the contrary,
In all of the comparative examples (Nos. 11 to 20), since the spheroidizing annealing conditions are out of the proper range of the present invention, the deformation resistance or the deformability is significantly reduced.

【0025】[0025]

【発明の効果】かくして、本発明によれば、短時間で効
果的な炭化物の球状化を達成することができ、従来に比
べ、所要時間ならびにエネルギーコストを大幅に低減で
きる点において、産業上極めて有用である。
As described above, according to the present invention, effective spheroidization of carbides can be achieved in a short time, and the required time and energy cost can be greatly reduced as compared with the conventional one. Useful.

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

【図1】 本発明に従う球状化熱処理の好適ヒートパタ
ーンである。
FIG. 1 is a preferred heat pattern of a spheroidizing heat treatment according to the present invention.

【図2】 特公平6−2898号公報に開示のヒートパター
ンである。
FIG. 2 is a heat pattern disclosed in Japanese Patent Publication No. 6-2898.

【図3】 特開平4−362123号公報に開示のヒートパタ
ーンである。
FIG. 3 is a heat pattern disclosed in JP-A-4-362123.

───────────────────────────────────────────────────── フロントページの続き (72)発明者 星野 俊幸 岡山県倉敷市水島川崎通1丁目(番地な し) 川崎製鉄株式会社水島製鉄所内 (72)発明者 天野 虔一 岡山県倉敷市水島川崎通1丁目(番地な し) 川崎製鉄株式会社水島製鉄所内 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiyuki Hoshino 1-chome, Mizushima-Kawasaki-dori, Kurashiki-shi, Okayama Pref. 1-chome (without address) Inside Kawasaki Steel Corporation Mizushima Works

Claims (2)

【特許請求の範囲】[Claims] 【請求項1】 C:0.15〜1.10mass%を含有する機械構
造用の鋼材に対して、球状化焼なましを施すに際し、
(1) 加熱途中の、(オーステナイトが出現する温度−50
℃)〜 (オーステナイトが出現する温度−5℃)の温度
範囲を0.01℃/s 以下の速度で加熱し、(2) 最高加熱温
度である(オーステナイト単相になる温度−30℃)〜
(オーステナイト単相になる温度−5℃)の温度範囲ま
で加熱した後、直ちに冷却に転じ、(3) 冷却途中の、
(フェライトが出現する温度+10℃)〜(フェライトが
出現する温度−40℃)の温度範囲を 0.005℃/s 以下の
速度で冷却した後、空冷することを特徴とする鋼材の短
時間球状化焼なまし方法。
When spheroidizing annealing is performed on a steel material for a machine structure containing C: 0.15 to 1.10 mass%,
(1) During heating, (the temperature at which austenite appears -50
(° C) ~ (Temperature at which austenite appears -5 ° C) is heated at a rate of 0.01 ° C / s or less. (2) Maximum heating temperature (temperature at which austenite becomes single phase -30 ° C) ~
After heating to the temperature range (temperature at which austenite becomes a single phase -5 ° C), immediately start cooling, and (3) during cooling,
Short-time spheroidizing sintering of steel characterized by cooling at a rate of 0.005 ° C / s or less in the temperature range of (temperature at which ferrite appears + 10 ° C) to (temperature at which ferrite appears -40 ° C) Annealing method.
【請求項2】 球状化焼なまし処理を施して得た、C:
0.15〜1.10mass%を含有する機械構造用の鋼材であっ
て、該球状化焼なましが、(1) 加熱途中の、(オーステ
ナイトが出現する温度−50℃)〜 (オーステナイトが出
現する温度−5℃)の温度範囲を0.01℃/s 以下の速度
で加熱し、(2) 最高加熱温度である(オーステナイト単
相になる温度−30℃)〜(オーステナイト単相になる温
度−5℃)の温度範囲まで加熱した後、直ちに冷却に転
じ、(3) 冷却途中の、(フェライトが出現する温度+10
℃)〜(フェライトが出現する温度−40℃)の温度範囲
を 0.005℃/s 以下の速度で冷却した後、空冷する工程
からなることを特徴とする鋼材。
2. A spheroidizing annealing treatment, C:
A steel material for a mechanical structure containing 0.15 to 1.10 mass%, wherein the spheroidizing annealing is carried out in the following manner: (1) During heating, (temperature at which austenite appears-50 ° C) ~ (temperature at which austenite appears- (5 ° C) at a rate of 0.01 ° C / s or less, and (2) the maximum heating temperature (temperature at which austenitic single phase becomes -30 ° C) to (temperature at which austenitic single phase becomes -5 ° C) After heating to the temperature range, it immediately starts cooling. (3) During cooling, (temperature at which ferrite appears +10
A steel material characterized by comprising a step of cooling at a rate of 0.005 ° C / s or less in a temperature range of (° C) to (temperature at which ferrite appears -40 ° C) and then air cooling.
JP30846899A 1999-10-29 1999-10-29 Method for short-time spheroidizing annealing of steel and steel by the same method Expired - Fee Related JP3870631B2 (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007077432A (en) * 2005-09-13 2007-03-29 Sanyo Special Steel Co Ltd Method for producing ball screw or one-way clutch component
JP2008088448A (en) * 2006-09-29 2008-04-17 Sanyo Special Steel Co Ltd Method for annealing low-carbon steel containing cr
JP2014177692A (en) * 2013-03-15 2014-09-25 Kobe Steel Ltd Method of producing steel material excellent in cold workability and grindability
CN114182070A (en) * 2021-12-02 2022-03-15 南京钢铁股份有限公司 Spheroidizing annealing method for carbon tool steel roller bottom type annealing furnace for automobile

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007077432A (en) * 2005-09-13 2007-03-29 Sanyo Special Steel Co Ltd Method for producing ball screw or one-way clutch component
JP4569961B2 (en) * 2005-09-13 2010-10-27 山陽特殊製鋼株式会社 Manufacturing method of parts for ball screw or one-way clutch
JP2008088448A (en) * 2006-09-29 2008-04-17 Sanyo Special Steel Co Ltd Method for annealing low-carbon steel containing cr
JP2014177692A (en) * 2013-03-15 2014-09-25 Kobe Steel Ltd Method of producing steel material excellent in cold workability and grindability
CN114182070A (en) * 2021-12-02 2022-03-15 南京钢铁股份有限公司 Spheroidizing annealing method for carbon tool steel roller bottom type annealing furnace for automobile

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