JP2007131907A - Steel for induction hardening with excellent cold workability, and its manufacturing method - Google Patents
Steel for induction hardening with excellent cold workability, and its manufacturing method Download PDFInfo
- Publication number
- JP2007131907A JP2007131907A JP2005325480A JP2005325480A JP2007131907A JP 2007131907 A JP2007131907 A JP 2007131907A JP 2005325480 A JP2005325480 A JP 2005325480A JP 2005325480 A JP2005325480 A JP 2005325480A JP 2007131907 A JP2007131907 A JP 2007131907A
- Authority
- JP
- Japan
- Prior art keywords
- less
- ratio
- steel
- spheroidizing annealing
- hardness
- 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
Links
Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
Abstract
Description
自動車や各種産業機械の分野にて冷間加工を実施しその後高周波焼入れ処理により表面に硬さの高い硬化層を付与する部品に使用される冷間加工性に優れた高周波焼入れ用鋼に関する。 The present invention relates to a steel for induction hardening that is excellent in cold workability and is used for parts that are cold worked in the field of automobiles and various industrial machines and then give a hardened layer with high hardness to the surface by induction hardening.
従来、自動車や各種産業機械に使用される部品、例えば等速ジョイント部品、各種シャフト、各種ギヤ、クランクシャフト、ハブユニット、軸受部品などの製造において、炭素を概ね０．３％以上含む鋼を高周波焼入れすることで表面に硬さの高い硬化層を形成して疲労強度や耐摩耗性などを付与させた部品を製造する方法が使用されている。 Conventionally, in the production of parts used in automobiles and various industrial machines, such as constant velocity joint parts, various shafts, various gears, crankshafts, hub units, bearing parts, etc., steel containing approximately 0.3% or more of carbon is high frequency. A method of manufacturing a part in which a hardened layer having a high hardness is formed on the surface by quenching to impart fatigue strength, wear resistance, or the like is used.
この高周波焼入れによる部品の製造方法は、鋼材表面を硬化する最も一般的な方法である浸炭焼入れ方法に比べ、熱処理時間自体が短縮できることやインラインでの熱処理が可能であることなどのメリットが得られるため、靭性を大きく要求されない比較的形状の簡単な部品においては、高周波焼入れを用いた部品の製造が行われている。 Compared to the carburizing and quenching method, which is the most common method for hardening the steel surface, this method of producing parts by induction hardening provides advantages such as shorter heat treatment time and in-line heat treatment. For this reason, for parts having relatively simple shapes that do not require great toughness, parts are manufactured using induction hardening.
この高周波焼入れに使用される鋼（以下、「高周波焼入れ用鋼」と称す。）については、要求される硬さレベルに合わせて含有される炭素量が選択される。しかし、一般的には質量％で炭素量０．４５〜０．５５％の中炭素量の鋼が用いられている。炭素量が０．４５％未満では焼入れ後の硬さが５８ＨＲＣ以下となり、特に転動疲労特性や耐摩砕性を必要とする部品においては十分な特性が得られない。また、炭素量が０．５５％を超えると、焼入れ後の硬さは十分得られるものの、部品を加工する際に成形性が劣るといった問題や、被削性が劣るといった問題がある。特に冷間加工により部品を成形する際には、炭素量が多いと素材硬さが高くなり、変形抵抗が上がり、金型寿命が劣化し、かつ、冷間加工時に割れが発生するといった問題がある。例えば、軸受のレースのような加工率の低い単純な形状の部品においては、０．６％を超える高炭素量の鋼であっても、冷間加工により部品を成形している。しかし、例えば、等速ジョイントに使われるアウターレースのような冷間加工により最終製品に近い形状まで加工する高加工度の部品においては、冷間加工により金型寿命が低下し、かつ、被加工材に割れが発生するという問題がある。そこで、炭素量０．６％以下の高周波焼入れ用鋼が使用されることが一般的である。 For the steel used for this induction hardening (hereinafter referred to as “steel for induction hardening”), the amount of carbon contained is selected according to the required hardness level. However, generally, steel with a medium carbon content by mass% and a carbon content of 0.45 to 0.55% is used. If the carbon content is less than 0.45%, the hardness after quenching is 58 HRC or less, and sufficient characteristics cannot be obtained particularly in parts that require rolling fatigue characteristics and abrasion resistance. On the other hand, if the carbon content exceeds 0.55%, the hardness after quenching can be sufficiently obtained, but there are problems that the formability is inferior when parts are processed, and the machinability is inferior. In particular, when forming parts by cold working, there is a problem that if the amount of carbon is large, the material hardness increases, the deformation resistance increases, the mold life deteriorates, and cracks occur during cold working. is there. For example, in a simple-shaped part with a low processing rate, such as a bearing race, even if the steel has a high carbon content exceeding 0.6%, the part is formed by cold working. However, for example, in the case of high workability parts that are processed to a shape close to the final product by cold working such as outer races used in constant velocity joints, the die life is reduced by cold working and the workpiece is processed. There is a problem that the material cracks. Therefore, it is common to use steel for induction hardening with a carbon content of 0.6% or less.
転動疲労特性や耐摩耗性などの特性で見れば、炭素量を向上させることにより高周波焼入れ後の硬さが向上し、その結果、部品の機能が大きく向上するため、高炭素量の鋼で冷間加工性に優れる高周波焼入れ用鋼が求められていた。 In terms of characteristics such as rolling fatigue and wear resistance, increasing the carbon content improves the hardness after induction hardening, and as a result, the function of the parts is greatly improved. There has been a demand for a steel for induction hardening that is excellent in cold workability.
ここで冷間加工性について説明すると、最近の金型用材の進歩やＶＣなどの形成による硬化処理（ＴＤ処理）やダイヤモンド状炭素膜形成（ＤＬＣ）処理などの各種の表面処理により、過酷な条件下においても使用可能な金型が開発されており、炭素量の増量により変形抵抗が上がることによる冷間加工性の低下は比較的重視されなくなってきている。しかしながら、被加工材の冷間加工時の割れについては、金型の性能が上がっても向上するわけではなく、むしろ金型の性能向上により過酷な冷間加工が行われる今日では、この冷間加工時の割れ発生をいかに抑制するかが重要となってきている。 Here, cold workability will be explained. Due to various surface treatments such as recent advances in mold materials and hardening treatment (TD treatment) and diamond-like carbon film formation (DLC) treatment due to the formation of VC, severe conditions Molds that can be used below are also being developed, and the reduction of cold workability due to an increase in deformation resistance due to an increase in the amount of carbon has become less important. However, cracks during cold working of workpieces do not improve even if the performance of the mold is improved, but rather today, cold working is performed by improving the performance of the mold. It has become important to suppress cracking during processing.
冷間加工を行うに当たり冷間加工の前の熱処理において、一般的には球状化焼きなましが用いられる。この球状化焼きなましは、ミクロ組織をフェライトと球状化セメンタイトの組織として硬さを低下させ、冷間加工時の割れ発生を低減する熱処理である。 In performing the cold working, spheroidizing annealing is generally used in the heat treatment before the cold working. This spheroidizing annealing is a heat treatment that reduces the hardness by using a microstructure as a structure of ferrite and spheroidized cementite, and reduces the occurrence of cracks during cold working.
一般的には、この球状化焼きなましを施すことで冷間加工性が向上すると言われているが、今回のような高炭素の鋼の場合、同じような硬さの鋼材であっても冷間加工時に割れが発生するものとしないものがあり、実際のところ素材硬さと冷間加工時の割れ自体には必ずしも相関があるわけではない。 In general, it is said that cold workability is improved by applying this spheroidizing annealing. However, in the case of high carbon steel such as this time, even if the steel material has the same hardness, Some cracks may or may not occur during processing, and in fact, there is not necessarily a correlation between the hardness of the material and the crack itself during cold processing.
例えば、冷間加工時の割れを抑制するに当たり、ＡＳＴＭ法に順じて測定したＡｌ2Ｏ3、ＴｉＮ等の硬質介在物量を制御することが有効であると述べられている（特許文献１参照。）が、ここに述べられている鋼材を用いても加工度の大きな冷間加工においては割れ発生が避けられない場合がある。 For example, when suppressing cracking during cold working, it is possible to control the hard amount of inclusions Al 2 O 3, TiN or the like as measured sequentially applies the ASTM method is stated to be effective (see Patent Document 1 )), However, cracking may be unavoidable in cold work with a high degree of work even if the steel materials described here are used.
また、例えば、球状化焼きなまし後の炭化物粒径や炭化物間の距離などを規定することにより冷間加工性が向上すると述べられている（特許文献２参照、あるいは、特許文献３参照。）が、これらの文献に述べられている鋼材を用いても、加工度の大きな冷間加工においては割れ発生が避けられない場合があるのが実態である。 Further, for example, it is stated that the cold workability is improved by defining the carbide particle diameter after spheroidizing annealing, the distance between carbides, and the like (see Patent Document 2 or Patent Document 3). Even if the steel materials described in these documents are used, the occurrence of cracks may be unavoidable in cold working with a large workability.
そこで、出願人は、高炭素鋼としながらも球状化焼きなまし後の高加工率の冷間加工をしても割れを発生し難く、高周波焼入れ後の硬さを確保した高炭素含有鋼を開発した（例えば、特許文献４参照。）。しかし、このものは限界据込率を６５％以上とするものであった。 Therefore, the applicant has developed a high-carbon steel that is hard to crack even if it is made of high-carbon steel but is cold-worked at a high processing rate after spheroidizing annealing and has secured hardness after induction hardening. (For example, refer to Patent Document 4). However, this had a limit upsetting rate of 65% or more.
一般に炭素鋼や合金鋼において、冷間加工後に高周波焼入れする場合、冷間加工性を考慮して炭素量を０．５５質量％以下に抑えるのが通常である。しかし、このものはその後の高周波焼入れにおいて硬さが低くなる問題がある。一方、炭素量が０．５５質量％を超える高炭素含有鋼では、冷間加工において割れが発生する問題がある。そこで発明者らは鋭意研究して上記の先願の高炭素含有鋼を開発したが、さらに研究し、球状化焼きなましを行う前組織を初析フェライトがない状態とするとともに、さらに鋼成分において、ＡｌとＮのバランスを図り、かつ、フェライト強化元素を低減することで、炭素量が０．６０％以上の高炭素含有鋼において、球状化焼きなまし後の硬さが低く、従って限界据込率が７０％以上と先願の発明に比してより高くしながらも、割れを生ずることなく容易に冷間加工でき、その後の高周波焼入れで先願の発明に劣らない十分な硬さが得られる鋼及び鋼の製造方法を見出した。 In general, in carbon steel or alloy steel, when induction hardening is performed after cold working, the carbon content is usually suppressed to 0.55% by mass or less in consideration of cold workability. However, this has a problem that the hardness is lowered in the subsequent induction hardening. On the other hand, in the high carbon content steel in which the carbon content exceeds 0.55% by mass, there is a problem that cracking occurs in cold working. Therefore, the inventors have intensively researched and developed the high-carbon steel of the above-mentioned prior application, but further researched and made the structure before the spheroidizing annealing free of proeutectoid ferrite, and further in the steel component, By balancing Al and N and reducing ferrite strengthening elements, high carbon content steel with a carbon content of 0.60% or more has low hardness after spheroidizing annealing, so the limit upsetting rate is low. Steel that is 70% or higher and higher than the invention of the prior application, but can be easily cold worked without causing cracks, and can be sufficiently hardened not to be inferior to the invention of the prior application by subsequent induction hardening. And the manufacturing method of steel was discovered.
そこで、本発明が解決しようとする課題は、炭素量が０．６０％以上の高炭素含有鋼において、球状化焼きなまし後の硬さが低く、限界据込率が７０％以上において割れを生ずることなく容易に冷間加工でき、その後の高周波焼入れで十分な６２ＨＲＣ以上の硬さが得られる鋼及び鋼の製造方法を提供することである。 Therefore, the problem to be solved by the present invention is that, in a high carbon content steel having a carbon content of 0.60% or more, the hardness after spheroidizing annealing is low, and cracking occurs when the limit upsetting rate is 70% or more. It is an object of the present invention to provide a steel and a method for producing the steel which can be easily cold worked and can obtain a hardness of 62 HRC or more sufficient by subsequent induction hardening.
上記の課題を解決するための本発明の、第１の手段は、鋼成分が、質量％で、Ｃ：０．６０〜０．８０％、Ｓｉ：０．０３〜０．２０％、Ｍｎ：０．１５〜０．８０％、Ｐ：０．３０％以下、Ｓ：０．０１５％以下、Ａｌ：０．０２０〜０．０５０％、Ｎ：０．０１００％以下、Ｏ：０．００１５％以下、かつ、ＡｌとＮは式：Ａｌ＞２．５Ｎを満足し、残部Ｆｅ及び不可避不純物からなるもので、球状化焼きなまし前のミクロ組織中の初析フェライト面積率が２％以下で、球状化焼きなまし後の硬さが８５ＨＲＢ以下で、かつ球状化焼きなまし後のミクロ組織中の球状化炭化物比率が８０％以上で、その後の高周波焼入れにおいて６２ＨＲＣ（≒７４０ＨＶ）以上の硬さを確保可能とした冷間加工性に優れた高周波焼入れ用鋼である。 The first means of the present invention for solving the above-mentioned problems is that the steel component is mass%, C: 0.60 to 0.80%, Si: 0.03 to 0.20%, Mn: 0.15 to 0.80%, P: 0.30% or less, S: 0.015% or less, Al: 0.020 to 0.050%, N: 0.0100% or less, O: 0.0015% In the following, Al and N satisfy the formula: Al> 2.5N, and consist of the balance Fe and inevitable impurities, the proeutectoid ferrite area ratio in the microstructure before spheroidizing annealing is 2% or less, and spherical The hardness after chemical annealing is 85HRB or less, and the ratio of spheroidized carbide in the microstructure after spheroidizing annealing is 80% or more, and it is possible to ensure a hardness of 62HRC (≈740HV) or more in the subsequent induction hardening. Induction hardening steel with excellent cold workability.
第２の手段は、鋼成分が、上記の第１の手段の鋼成分に加えて、さらに焼入性を向上させる元素として、質量％で、Ｎｉ：０．０７〜１．０％、Ｃｒ：０．１５〜０．８％、Ｍｏ：０．０２〜０．２０％、Ｂ：０．０００５〜０．００３０％から選択した１種又は２種以上を含有し、残部Ｆｅ及び不可避不純物からなるもので、球状化焼きなまし前のミクロ組織中の初析フェライト面積率が２％以下で、球状化焼きなまし後の硬さが８５ＨＲＢ以下で、かつ球状化焼きなまし後のミクロ組織中の球状化炭化物比率が８０％以上とし、その後の高周波焼入れにおいて６２ＨＲＣ以上の硬さを確保可能とした冷間加工性に優れた高周波焼入れ用鋼である。この場合、上記の鋼成分は、さらにその成分範囲を減縮している。 The second means is that, in addition to the steel component of the first means described above, the steel component is an element that further improves the hardenability in terms of mass%, Ni: 0.07 to 1.0%, Cr: Contains one or more selected from 0.15 to 0.8%, Mo: 0.02 to 0.20%, B: 0.0005 to 0.0030%, and consists of the remainder Fe and inevitable impurities In the microstructure before spheroidizing annealing, the pro-eutectoid ferrite area ratio is 2% or less, the hardness after spheroidizing annealing is 85 HRB or less, and the ratio of spheroidized carbide in the microstructure after spheroidizing annealing is It is a steel for induction hardening excellent in cold workability, which is 80% or more and can secure a hardness of 62 HRC or more in the subsequent induction hardening. In this case, the steel component further reduces its component range.
第３の手段は、鋼成分が、上記の第１又は第２の手段の鋼成分に加えて、さらに冷間加工性を向上させる元素として、質量％で、Ｔｉ：０．０２〜０．０５％，Ｖ：０．０１〜０．１０％から選択した１種又は２種を含有し、残部Ｆｅ及び不可避不純物からなるもので、球状化焼きなまし前のミクロ組織中の初析フェライト面積率が２％以下で、球状化焼きなまし後の硬さが８５ＨＲＢ以下で、かつ球状化焼きなまし後のミクロ組織中の球状化炭化物比率が８０％以上で、その後の高周波焼入れにおいて６２ＨＲＣ以上の硬さを確保可能とした冷間加工性に優れた高周波焼入れ用鋼である。 The third means is that, in addition to the steel component of the first or second means described above, the steel component is an element that further improves the cold workability in terms of mass%, and Ti: 0.02 to 0.05. %, V: Contains one or two selected from 0.01 to 0.10%, consists of the balance Fe and inevitable impurities, and has a pro-eutectoid ferrite area ratio of 2 in the microstructure before spheroidizing annealing. %, The hardness after spheroidizing annealing is 85 HRB or less, and the spheroidizing carbide ratio in the microstructure after spheroidizing annealing is 80% or more, and it is possible to secure a hardness of 62 HRC or more in the subsequent induction hardening. Induction hardening steel with excellent cold workability.
第４の手段は、鋼成分が、上記の第１〜３のいずれか１項の手段の鋼成分に加えて、さらに被削性を向上させる元素として、質量％で、Ｐｂ：０．００１〜０．３０％，Ｓｅ：０．００１〜０．３０％、Ｔｅ：０．００１〜０．３０％，Ｂｉ：０．００１〜０．３０％から選択したいずれか１種又は２種以上を含有し、残部Ｆｅ及び不可避不純物からなるもので、球状化焼きなまし前のミクロ組織中の初析フェライト面積率が２％以下で、球状化焼きなまし後の硬さが８５ＨＲＢ以下で、かつ球状化焼きなまし後のミクロ組織中の球状化炭化物比率が８０％以上で、その後の高周波焼入れにおいて６２ＨＲＣ以上の硬さを確保可能とした冷間加工性に優れた高周波焼入れ用鋼である。 In the fourth means, the steel component is added in addition to the steel component of any one of the above first to third means as an element that further improves the machinability, and is Pb: 0.001 to 0.001. Contains any one or more selected from 0.30%, Se: 0.001 to 0.30%, Te: 0.001 to 0.30%, Bi: 0.001 to 0.30% And the residual Fe and inevitable impurities, the proeutectoid ferrite area ratio in the microstructure before spheroidizing annealing is 2% or less, the hardness after spheroidizing annealing is 85 HRB or less, and after spheroidizing annealing It is a steel for induction hardening with excellent cold workability in which the ratio of spheroidized carbide in the microstructure is 80% or more and the hardness of 62 HRC or more can be secured in the subsequent induction hardening.
上記の第１〜４の手段において、球状化炭化物比率とは、被検面積０．１ｍｍ2中の（長径／短径）の比が２以下である炭化物の個数Ａを被検面積０．１ｍｍ2炭化物の総個数Ｂで除した個数比Ａ／Ｂを百分率で示す値である。 In the first to fourth means described above, the spheroidized carbide ratio means the number A of carbides having a (major axis / minor axis) ratio of 2 or less in the test area of 0.1 mm 2 and the test area of 0.1 mm. This is a value indicating the number ratio A / B divided by the total number B of 2 carbides as a percentage.
第５の手段は、上記の第１〜４のいずれか１項の手段の鋼成分からなる鋼を溶製し、熱間鍛造により鍛伸して７００℃〜５００℃までの平均冷却速度を０．２℃／秒〜１０℃／秒として冷却することでミクロ組織中の初析フェライトの面積率を２％以下に抑える。次いで球状化焼きなまし時の加熱保持温度を７２０〜７８０℃とし、かつ６５０℃までの徐冷速度を３０℃／Ｈｒ以下として冷却することにより球状化焼きなまし処理をすることを特徴とする冷間加工性に優れた高周波焼入れ用鋼の製造方法である。 5th means melts the steel which consists of the steel component of said means of any one of said 1st-4th, forges by hot forging, and sets the average cooling rate to 700 to 500 degreeC to 0. .The area ratio of pro-eutectoid ferrite in the microstructure is suppressed to 2% or less by cooling at 2 ° C./second to 10 ° C./second. Next, cold workability is characterized in that spheroidizing annealing is performed by cooling at a heating holding temperature of 720 to 780 ° C. during spheroidizing annealing and a slow cooling rate to 650 ° C. of 30 ° C./Hr or less. It is an excellent method for producing steel for induction hardening.
上記の手段における鋼成分の限定理由を以下に説明する。なお、％は質量％を示す。 The reasons for limiting the steel components in the above means will be described below. In addition,% shows the mass%.
Ｃ：０．６０〜０．８０％
Ｃは、０．６０％未満では、初析フェライト面積率が多くなり、冷間加工時に局所的な変形を促進させ、割れ発生の原因となる。しかし、０．８０％を超えると、熱間加工後の冷却において網状の炭化物が析出し、冷間加工時の割れ発生に原因となる。そこでＣは０．６０〜０．８０％とする。
C: 0.60 to 0.80%
If C is less than 0.60%, the pro-eutectoid ferrite area ratio increases, which promotes local deformation during cold working and causes cracking. However, if it exceeds 0.80%, a net-like carbide precipitates during cooling after hot working, which causes cracking during cold working. Therefore, C is set to 0.60 to 0.80%.
Ｓｉ：０．０３〜０．２０％
Ｓｉは、脱酸に必要な元素で、脱酸には０．０３％以上は必要ある。一方、フェライト強化元素であるため、球状化焼なまし後の硬さを上昇させる。このため、０．２０％を超えると、フェライトの硬さの上昇を招き、冷間加工時に変形抵抗の上昇と割れ発生を促進する。そこでＳｉは０．０３〜０．２０％とする。
Si: 0.03-0.20%
Si is an element necessary for deoxidation, and 0.03% or more is necessary for deoxidation. On the other hand, since it is a ferrite strengthening element, it increases the hardness after spheroidizing annealing. For this reason, if it exceeds 0.20%, an increase in the hardness of the ferrite is caused, and an increase in deformation resistance and cracking are promoted during cold working. Therefore, Si is made 0.03 to 0.20%.
Ｍｎ：０．１５〜０．８０％（好ましくは、Ｍｎ：０．１５〜０．５０％）
Ｍｎは、脱酸に必要な元素で、脱酸には０．１５％以上は必要である。一方、フェライト強化元素であるため、球状化焼なまし後の硬さを上昇させる。このため、０．８０％を超えると、フェライトの硬さの上昇を招き、冷間加工時に変形抵抗の上昇と割れ発生を促進する。しかし、より好ましくは上限を０．５０％とする。
Mn: 0.15-0.80% (preferably, Mn: 0.15-0.50%)
Mn is an element necessary for deoxidation, and 0.15% or more is necessary for deoxidation. On the other hand, since it is a ferrite strengthening element, it increases the hardness after spheroidizing annealing. For this reason, if it exceeds 0.80%, the hardness of the ferrite is increased, and an increase in deformation resistance and cracking are promoted during cold working. However, more preferably, the upper limit is 0.50%.
Ｐ：０．３０％以下
Ｐは、結晶粒界に偏在し強度を低下させるため、低い方が望ましいが、０．３０％以下であれば許容できる。そこで、Ｐは０．３０％以下とする。
P: 0.30% or less P is unevenly distributed at the grain boundaries and lowers the strength. Therefore, a lower value is desirable, but 0.30% or less is acceptable. Therefore, P is set to 0.30% or less.
Ｓ：０．０１５％以下（好ましくは、Ｓ：０．００５％以下）
Ｓは、Ｍｎと結合してＭｎＳを形成する元素であり、形成されたＭｎＳは被削性を向上させる効果を有する。しかし、ＭｎＳは冷間加工時の割れ発生の原因となり得るため、Ｓは０．０１５％以下とする。好ましくは、Ｓ：０．００５％以下とする。
S: 0.015% or less (preferably, S: 0.005% or less)
S is an element that combines with Mn to form MnS, and the formed MnS has an effect of improving machinability. However, since MnS can cause cracks during cold working, S is set to 0.015% or less. Preferably, S: 0.005% or less.
Ａｌ：０．０２０〜０．０５０％
Ａｌは、脱酸に必要な元素であると同時に、鋼中の固溶Ｎを固着することにより冷間加工時の変形抵抗増大を抑制する。その効果を発揮させるには０．０２０％以上の添加が必要である。しかし、Ａｌが０．０５０％を超えると、Ａｌの再酸化による大きな酸化物系介在物が残存し冷間加工時の割れ発生の原因となる。そこでＡｌは０．０２０〜０．０５０％とする。
Al: 0.020 to 0.050%
Al is an element necessary for deoxidation and, at the same time, suppresses an increase in deformation resistance during cold working by fixing solute N in steel. In order to exert the effect, 0.020% or more must be added. However, if Al exceeds 0.050%, large oxide inclusions remain due to re-oxidation of Al, causing cracking during cold working. Therefore, Al is made 0.020 to 0.050%.
Ｎ：０．０１００％以下（好ましくは、Ｎ：０．００８０％以下）
Ｎは、フェライト中に固溶した場合に歪時効を生じ、冷間加工時の変形抵抗の増大を招くため、極力低減することが望ましい。Ａｌとの兼ね合いから０．０１００％までは許容できる。そこでＮは０．０１００％以下とする。好ましくは、Ａｌ＞２．５Ｎの関係からＮ：０．００８０％以下とする。
N: 0.0100% or less (preferably N: 0.0080% or less)
N is desirable to reduce N as much as possible because it causes strain aging when dissolved in ferrite and causes an increase in deformation resistance during cold working. From the balance with Al, 0.0100% is acceptable. Therefore, N is set to 0.0100% or less. Preferably, N: 0.0080% or less from the relationship of Al> 2.5N.
Ｏ：０．００１５％以下（好ましくはＯ：０．００１０％以下）
Ｏは、冷間加工時に割れの発生の起点となりうる酸化物を形成するため、低減することが望ましい。そこでＯは０．００１５％以下とする。好ましくはＯ：０．００１０％以下とする。
O: 0.0015% or less (preferably O: 0.0010% or less)
Since O forms an oxide that can become a starting point of cracking during cold working, it is desirable to reduce O. Therefore, O is set to 0.0015% or less. Preferably, O: 0.0010% or less.
Ａｌ＞２．５Ｎとする理由
鋼成分のＡｌとＮは、式Ａｌ＞２．５Ｎを満足しない場合、固溶Ｎによる歪時効硬化が生じ、冷間加工時の変形抵抗の増大を招く。そこでＡｌ＞２．５Ｎとする。
Reasons for Al> 2.5N When the steel components Al and N do not satisfy the formula Al> 2.5N, strain age hardening occurs due to solute N, which leads to an increase in deformation resistance during cold working. Therefore, Al> 2.5N is set.
球状化焼鈍後の硬さを８５ＨＲＢ以下とする理由
球状化焼鈍後の硬さが８５ＨＲＢを超えると、冷間加工時の変形抵抗が高くなり、成形が困難になり、金型などを損傷させる。そこで球状化焼鈍後の硬さを８５ＨＲＢ以下とする。
The reason why the hardness after spheroidizing annealing is 85 HRB or less When the hardness after spheroidizing annealing exceeds 85 HRB, deformation resistance during cold working becomes high, forming becomes difficult, and the mold is damaged. Therefore, the hardness after spheroidizing annealing is set to 85 HRB or less.
Ｎｉ：０．０７〜１．０％
Ｎｉは、焼入れ性を向上させる元素であるが、０．０７％未満ではその効果は認められない。一方、１．０％を超えると球状化焼きなまし後の硬さを上昇させる。そこでＮｉは０．０７〜１．０％とする。
Ni: 0.07 to 1.0%
Ni is an element that improves the hardenability, but its effect is not recognized if it is less than 0.07%. On the other hand, if it exceeds 1.0%, the hardness after spheroidizing annealing is increased. Therefore, Ni is set to 0.07 to 1.0%.
Ｃｒ：０．１５〜０．８％
Ｃｒは、焼入れ性を向上させ、球状化焼きなまし時の炭化物の球状化を促進させる元素であるが、０．１５％未満ではその効果は認められない。一方０．８％を超えると、球状化焼きなまし後の硬さを上昇させる。そこでＣｒは０．１５〜０．８％とする。
Cr: 0.15-0.8%
Cr is an element that improves the hardenability and promotes the spheroidization of carbides during spheroidizing annealing, but its effect is not observed at less than 0.15%. On the other hand, if it exceeds 0.8%, the hardness after spheroidizing annealing is increased. Therefore, Cr is made 0.15 to 0.8%.
Ｍｏ：０．０２〜０．２０％
Ｍｏは、焼入れ性を向上させ、球状化焼きなまし時の炭化物の球状化を促進させる元素であるが、０．０２％未満ではその効果が認められない。一方、０．２０％を超えると、球状化焼きなまし後の硬さを上昇させる。そこでＭｏは０．０２〜０．２０％とする。
Mo: 0.02 to 0.20%
Mo is an element that improves the hardenability and promotes the spheroidization of the carbide during spheroidizing annealing, but its effect is not observed at less than 0.02%. On the other hand, if it exceeds 0.20%, the hardness after spheroidizing annealing is increased. Therefore, Mo is made 0.02 to 0.20%.
Ｂ：０．０００５〜０．００３０％
Ｂは、焼入れ性を向上させる元素であるが、０．０００５％未満では焼入れ性向上の効果がない。一方、０．００３０％を超えると焼入性向上の効果は飽和し、靱性が低下する。そこでＢは０．０００５〜０．００３０％とする。
B: 0.0005 to 0.0030%
B is an element that improves hardenability, but if it is less than 0.0005%, there is no effect of improving hardenability. On the other hand, if it exceeds 0.0030%, the effect of improving hardenability is saturated and toughness is lowered. Therefore, B is set to 0.0005 to 0.0030%.
なお、これらのＮｉ、Ｃｒ、Ｍｏ及びＢは選択的に１種又は２種以上を添加することができる。 In addition, these Ni, Cr, Mo, and B can selectively add 1 type (s) or 2 or more types.
Ｔｉ：０．０２〜０．０５％
Ｔｉは、固溶Ｎを固着して、冷間加工時の変形抵抗の上昇を抑制するが、０．０２％未満では、その効果はなく、０．０５％を超えると、被削性を低下させる。そこでＴｉは０．０２〜０．０５％とする。
Ti: 0.02 to 0.05%
Ti fixes solute N and suppresses an increase in deformation resistance during cold working, but if it is less than 0.02%, there is no effect, and if it exceeds 0.05%, the machinability decreases. Let Therefore, Ti is set to 0.02 to 0.05%.
Ｖ：０．０１〜０．１０％
Ｖは、固溶Ｎを固着して、冷間加工時の変形抵抗の上昇を抑制するが、０．０１％未満ではその効果はなく、０．１０％を超えると、被削性を低下させる。そこで、Ｖは０．０１〜０．１０％とする。
なお、Ｔｉ、Ｖは選択的に１種又は２種を添加することができる。
V: 0.01-0.10%
V fixes solute N and suppresses an increase in deformation resistance during cold working, but if it is less than 0.01%, there is no effect, and if it exceeds 0.10%, machinability is reduced. . Therefore, V is set to 0.01 to 0.10%.
In addition, Ti and V can selectively add 1 type or 2 types.
Ｐｂ：０．００１〜０．３０％、Ｓｅ：０．００１〜０．３０％、Ｔｅ：０．００１〜０．３０％、Ｂｉ：０．００１〜０．３０％
Ｐｂ、Ｓｅ、Ｓｅ、Ｂｉは選択的に適応できる元素である。これらは０．００１未満では被削性向上の効果がない。一方、０．３０％を超えると巨大なＰｂ、Ｓｅ、Ｔｅ、Ｂｉが介在物となって存在して冷間加工性を低下させる。そこで、これらはＰｂが０．００１〜０．３０％、Ｓｅが０．００１〜０．３０％、Ｓｅが０．００１〜０．３０％、Ｂｉが０．００１〜０．３０％の範囲で１種または２種以上を選択的に適応する。
Pb: 0.001 to 0.30%, Se: 0.001 to 0.30%, Te: 0.001 to 0.30%, Bi: 0.001 to 0.30%
Pb, Se, Se, and Bi are elements that can be selectively applied. If these are less than 0.001, there is no effect of improving machinability. On the other hand, if it exceeds 0.30%, huge Pb, Se, Te, Bi exist as inclusions, and cold workability is lowered. Therefore, in the range where Pb is 0.001 to 0.30%, Se is 0.001 to 0.30%, Se is 0.001 to 0.30%, and Bi is 0.001 to 0.30%. One type or two or more types are selectively applied.
さらに第５の手段で、熱間加工終了後の７００℃から５００℃まで平均冷却速度を０．２℃／秒〜１０℃／秒として冷却した後、放冷する理由は、７００℃から５００℃まで平均冷却速度が０．２℃秒未満では、初析のフェライトが多く生成し、球状化焼きなまし後にも球状化セメンタイトの存在しないフェライトの領域が残って冷間加工時の割れ発生の原因となる。一方、１０℃／秒を超えると、初析フェライトは生成しないもののベイナイト組織が顕著に現れ、球状化焼きなまし後に球状化セメンタイトが微細に分散するため、硬さが下がらず、冷間加工時の割れ発生の原因となる。そこで熱間加工後の冷却速度を０．２℃／秒〜１０℃／秒とした。 Furthermore, after cooling at an average cooling rate of 0.2 ° C./second to 10 ° C./second from 700 ° C. to 500 ° C. after completion of hot working, the reason for cooling is 700 ° C. to 500 ° C. When the average cooling rate is less than 0.2 ° C., a large amount of pro-eutectoid ferrite is formed, and even after spheroidizing annealing, a ferrite region in which spheroidizing cementite does not exist remains and causes cracking during cold working. . On the other hand, when it exceeds 10 ° C./second, a pro-eutectoid ferrite is not generated, but a bainite structure appears prominently, and since spheroidized cementite is finely dispersed after spheroidizing annealing, the hardness does not decrease and cracks during cold working Causes the occurrence. Therefore, the cooling rate after hot working was set to 0.2 ° C./second to 10 ° C./second.
さらに熱間加工終了後の球状化焼きなまし時の加熱保持温度を７２０℃〜７８０℃とする理由を説明すると、熱間加工終了後の加熱保持温度が７２０℃未満では、オーステナイト化が充分でなくセメンタイトの球状化が不充分となり、冷間加工時の割れを招く。しかし、７８０℃を超えると、セメンタイトの固溶化が進み、その後の冷却で層状のセメンタイトが現れ、冷間加工時の割れを招く。そこで熱間加工終了後の加熱保持温度は７２０℃〜７８０℃とする。 Furthermore, the reason why the heating and holding temperature at the time of spheroidizing annealing after the end of hot working is 720 ° C. to 780 ° C. will be explained. If the heating and holding temperature after the end of hot working is less than 720 ° C., austenitization is not sufficient and cementite is not obtained. Spheroidization becomes insufficient, causing cracks during cold working. However, when the temperature exceeds 780 ° C., cementite is solidified, and the subsequent cooling causes layered cementite to appear, leading to cracks during cold working. Therefore, the heating and holding temperature after the hot working is set to 720 ° C to 780 ° C.
さらに、６５０℃までの徐冷速度を３０℃／Ｈｒ以下とする理由は、６５０℃までの徐冷速度が３０℃／Ｈｒを超えると、加熱時に固溶したセメンタイトが層状に析出し冷間加工時の割れを招く。そこで６５０℃までの徐冷速度を３０℃／Ｈｒとする。 Furthermore, the reason for setting the slow cooling rate to 650 ° C. to 30 ° C./Hr or less is that when the slow cooling rate to 650 ° C. exceeds 30 ° C./Hr, cementite solid-dissolved during heating precipitates in a layer form and is cold worked. Incurs time cracking. Therefore, the slow cooling rate to 650 ° C. is set to 30 ° C./Hr.
本発明の鋼は、その製造において、球状化焼きなましを行う前組織を初析フェライトの面積率を２％以下の状態とし、さらにＡｌとＮのバランスを図り、フェライト強化元素であるＳｉ、Ｍｎを低減することで、得られた鋼は球状化焼きなまし後は硬さが低く、かつ、均一な球状化組織を有し、炭素含有量が０．６％以上の高炭素鋼あるいは高炭素合金鋼でありながら、球状化焼きなまし後に、高加工率の冷間加工を施しても割れを発生することなく、冷間加工性に優れ、高周波焼入れ後に６２ＨＲＣ以上の硬さの高周波焼入れ溶鋼を確保できる。さらに上記の鋼の鋼成分を基本成分とし、さらに、この基本成分に対応した請求項２〜４に規定する鋼成分を加えることで、それぞれ焼入性や、冷間加工性や、被削性を一層良好とした高周波焼入れ用鋼であり、本発明は優れた効果を奏するものである。 In the production of the steel of the present invention, in the production, the structure before spheroidizing annealing is set so that the area ratio of pro-eutectoid ferrite is 2% or less, and the balance of Al and N is further improved. By reducing, the steel obtained is a high carbon steel or high carbon alloy steel having a low hardness after spheroidizing annealing, a uniform spheroidizing structure, and a carbon content of 0.6% or more. However, after spheroidizing annealing, even if cold working at a high working rate is performed, cracking does not occur, and cold workability is excellent. After induction hardening, induction-hardened molten steel having a hardness of 62 HRC or more can be secured. Furthermore, the steel components of the above steel are used as basic components, and furthermore, by adding the steel components specified in claims 2 to 4 corresponding to these basic components, the hardenability, cold workability, and machinability are respectively added. This is a steel for induction hardening that has a better quality, and the present invention exhibits excellent effects.
以下に本発明の最良の実施の形態を表及び図面を参照して説明する。 The best mode for carrying out the present invention will be described below with reference to the tables and drawings.
表１に示す成分からなる、本発明の成分の鋼材であるＮｏ．１〜１２と、比較成分の鋼材であるＮｏ．１３〜２２の組成範囲からなる供試材の鋼を１００ｋｇ真空溶解炉で溶製し、鋼塊に鋳造し、これらの鋼塊を１１００℃に加熱して熱間鍛造によりφ２０ｍｍの棒鋼材に鍛伸して放冷した。なお、表１において各成分の数値に付したアステリスクマークは不可避的な不純物を示す。 No. 1, which is a steel material of the present invention composed of the components shown in Table 1. 1-12 and No. 1 which is a steel material for comparison. Steel of the test material having a composition range of 13 to 22 was melted in a 100 kg vacuum melting furnace, cast into steel ingots, these steel ingots were heated to 1100 ° C. and forged into steel bars with a diameter of 20 mm by hot forging. It was allowed to cool. In Table 1, the asterisk marks attached to the numerical values of the components indicate inevitable impurities.
得られたφ２０ｍｍの棒鋼材について、（１）初析フェライト面積率を棒鋼材の直径の１／４の部分について画像解析により測定した。さらに、表２に示す球状化焼きなまし条件の加熱保持温度に加熱し、次いで６５０℃までの冷却速度を表２に示す速度として冷却することで球状化焼きなまし処理をした。この球状化焼なまし処理を実施した後、さらに（２）この球状化焼きなましを行った棒鋼材の直径の１／４の部分における球状化焼きなまし後の硬さをロックウェル硬さ試験機により測定した。さらに、（３）球状化焼きなましを行った棒鋼材の直径の１／４の部分についての球状化焼きなまし後の、炭化物の総数と長径／短径の値が２以下の大きさの炭化物の数を、画像解析により測定して球状化炭化物比率を計算し、その球状化炭化物比率を表２において球状化比率（％）として示した。なお、上記の測定の被検面積は０．１ｍｍ2とした。 With respect to the obtained steel bar having a diameter of 20 mm, (1) the proeutectoid ferrite area ratio was measured by image analysis for a quarter of the diameter of the steel bar. Furthermore, the spheroidizing annealing treatment was performed by heating to the heating and holding temperature under the spheroidizing annealing conditions shown in Table 2, and then cooling the cooling rate to 650 ° C. as the speed shown in Table 2. After carrying out this spheroidizing annealing treatment, (2) the hardness after spheroidizing annealing at a quarter of the diameter of the steel bar subjected to this spheroidizing annealing was measured with a Rockwell hardness tester. did. Further, (3) the total number of carbides and the number of carbides having a major axis / minor axis value of 2 or less after spheroidizing annealing on a quarter of the diameter of the steel bar subjected to spheroidizing annealing. The ratio of the spheroidized carbide was measured by image analysis, and the ratio of the spheroidized carbide was shown in Table 2 as the spheroidized ratio (%). The test area for the above measurement was 0.1 mm 2 .
さらに（４）球状化焼きなましを行った棒鋼材の直径の１／４の部分より、径φ１４、高さ２１ｍｍの円筒形の試験片を各２個ずつ作製し、これらの試験片を冷間にて６０％据込み加工を実施し、６０％据込み時の変形抵抗を測定することで冷間据込み試験による変形抵抗を調査した。この調査した測定結果を６０％据込み時の変形抵抗として表２に示した。 Further, (4) two cylindrical test pieces each having a diameter of φ14 and a height of 21 mm were prepared from a quarter of the diameter of the steel bar subjected to spheroidizing annealing. 60% upsetting was performed, and the deformation resistance at the time of 60% upsetting was measured to investigate the deformation resistance by the cold upsetting test. The measured measurement results are shown in Table 2 as deformation resistance at 60% upsetting.
さらに（５）球状化焼きなましを行った棒鋼材の直径の１／４の部分より、径φ１４、高さ２１ｍｍの円筒形の試験片を各５個ずつ作製し、これらの試験片を冷間にて据込み加工を実施し冷間据込み試験による限界据込み率を調査した。据込み加工した試験片の表面に１０倍の拡大鏡で見える割れが発生した時点を、その試験片の割れ発生とし、その時点の据込み加工率の平均値を限界据込み率として表２に示した。 Furthermore, (5) five cylindrical test pieces each having a diameter of φ14 and a height of 21 mm were prepared from a quarter of the diameter of the steel bar subjected to spheroidizing annealing. Then, the upsetting process was carried out and the limit upsetting rate was investigated by the cold upsetting test. Table 2 shows the time when cracks that can be seen with a 10x magnifier on the surface of the upsetting specimen were generated, and the average upsetting ratio at that time was the limit upsetting ratio. Indicated.
さらに、（６）上記のφ２０ｍｍの棒鋼材から径３ｍｍで長さ１０ｍｍの試験片を作製し、これらの試験片を高周波誘導加熱により１５０℃／ｓｅｃにて９００℃まで加熱し、５秒間保持した後に、Ｎ2ガスにて５０℃／ｓｅｃの冷却速度で室温まで冷却して焼入れし、次いで１５０℃、９０分の焼戻しをした後、ビッカース硬さ試験機により、高周波焼入れ焼戻し後の硬さを測定した。この高周波焼入れ焼戻し後の硬さを表２において焼入れ硬さ（ＨＶ）として示した。 Further, (6) Test pieces having a diameter of 3 mm and a length of 10 mm were prepared from the above bar steel material of φ20 mm, and these test pieces were heated to 900 ° C. at 150 ° C./sec by high frequency induction heating and held for 5 seconds. Later, after cooling to room temperature with N 2 gas at a cooling rate of 50 ° C./sec and then tempering at 150 ° C. for 90 minutes, the hardness after induction hardening and tempering was measured with a Vickers hardness tester. It was measured. The hardness after induction hardening and tempering is shown in Table 2 as quenching hardness (HV).
この表２示す結果から、この６０％据込み時の変形抵抗が１１００ＭＰａを基準とし、１１００ＭＰａ以下のものを冷間加工時の変形抵抗に優れるものとした。さらに、この冷間加工時の割れに強い基準を限界据込み率７０％とし、７０％以上のものを冷間加工時の割れに対して強いものとした。さらに、冷間加工時の割れに強い基準は限界据込み率７０％以上とした。本発明の鋼成分を有する鋼の球状化焼きなましを実施したものは、冷間加工性時の変形抵抗に優れ、割れに対しても強いことがわかる。 From the results shown in Table 2, the deformation resistance at the time of upsetting of 60% is based on 1100 MPa, and those having a resistance of 1100 MPa or less are excellent in deformation resistance during cold working. Furthermore, the standard that is strong against cracking during cold working was set to a limit upsetting rate of 70%, and those with 70% or more were made strong against cracking during cold working. Furthermore, the strong standard for cracking during cold working was a limit upsetting rate of 70% or more. It can be seen that the steel having the steel component of the present invention subjected to spheroidizing annealing is excellent in deformation resistance during cold workability and strong against cracking.
一方、図１に鋼成分のＣ量と限界据込み率の関係を示し、図２に球状化比率と限界据込み率の関係を示す。図１において、本発明に規定する鋼成分のＣ量を有し、かつ、本発明の熱処理条件を満たしたものでは、限界据込み率をみると、限界据込み率はいずれも７４％を超えている。これに対し、本発明に規定する鋼成分のＣ量を有していても、本発明の熱処理条件を満たさないものでは、限界据込み率は６８％、６９％、７０％、７１％である。 On the other hand, FIG. 1 shows the relationship between the C content of the steel component and the limit upsetting rate, and FIG. 2 shows the relationship between the spheroidization ratio and the limit upsetting rate. In FIG. 1, in the case of having the C amount of the steel component specified in the present invention and satisfying the heat treatment conditions of the present invention, the limit upsetting rate exceeds 74% in all cases. ing. On the other hand, even if it has the C amount of the steel component specified in the present invention, the limit upsetting ratio is 68%, 69%, 70%, 71% when the heat treatment conditions of the present invention are not satisfied. .
さらに、図２において球状化比率をみると、本発明のＣ量を有し、かつ、本発明の熱処理条件を満たしたものでは、球状化比率はいずれも８０％を超えているが、本発明に規定する鋼成分のＣ量を有していても、本発明の熱処理条件を満たさないものでは、球状化比率は８０％未満のものもある。これに対し、炭素含有量が本発明の範囲から外れるものは、限界据込率は約６８％に中心があり、球状化率は約７０％に中心があり、これらは、本発明に比して共に低い値である。以上の結果から、鋼成分のＣ量が本発明における０．６０％〜０．８０％の範囲において限界据込率が優れることが分かる。また、図２から限界据込み率は球状化比率が高いほど優れることがいえる。 Further, when the spheroidization ratio is seen in FIG. 2, the spheroidization ratio exceeds 80% in the case of having the C amount of the present invention and satisfying the heat treatment conditions of the present invention. Even if it has the C content of the steel component specified in the above, the spheroidization ratio may be less than 80% if it does not satisfy the heat treatment conditions of the present invention. On the other hand, those whose carbon content is outside the scope of the present invention have a limit upsetting rate centered at about 68% and a spheroidization rate centered at about 70%, which is in comparison with the present invention. Both are low values. From the above results, it can be seen that the critical upsetting ratio is excellent when the C content of the steel component is in the range of 0.60% to 0.80% in the present invention. Moreover, it can be said from FIG. 2 that the limit upsetting rate is better as the spheroidization ratio is higher.
Claims (5)
なお、球状化炭化物比率は、被検面積０．１ｍｍ2中の（長径／短径）の比が２以下である炭化物の個数Ａを被検面積０．１ｍｍ2炭化物の総個数Ｂで除した個数比Ａ／Ｂを百分率で示す値である。 In mass%, C: 0.60 to 0.80%, Si: 0.03 to 0.20%, Mn: 0.15 to 0.80%, P: 0.30% or less, S: 0.015 %: Al: 0.020 to 0.050%, N: 0.0100% or less, O: 0.0015% or less, and Al and N satisfy the formula: Al> 2.5N, and the balance Fe and Made of inevitable impurities, the proeutectoid ferrite area ratio in the microstructure before spheroidizing annealing is 2% or less, the hardness after spheroidizing annealing is 85 HRB or less, and the spheroidized carbide in the microstructure after spheroidizing annealing A steel for induction hardening excellent in cold workability, characterized in that the ratio is set to 80% or more, and hardness of 62 HRC or more can be secured in subsequent induction hardening.
Incidentally, spheroidized carbides ratio divided by the total number B of (major axis / minor axis) ratio of 2 or less carbide the test area 0.1mm 2 carbides the number A of which is in the test area 0.1mm 2 This is a value indicating the number ratio A / B as a percentage.
なお、球状化炭化物比率は、被検面積０．１ｍｍ2中の（長径／短径）の比が２以下である炭化物の個数Ａを被検面積０．１ｍｍ2炭化物の総個数Ｂで除した個数比Ａ／Ｂを百分率で示す値である。 In addition to the steel components according to claim 1, as elements for further improving the hardenability, Ni: 0.07 to 1.0%, Cr: 0.15 to 0.8%, Mo: It contains one or more selected from 0.002 to 0.20%, B: 0.0005 to 0.0030%, consists of the remainder Fe and inevitable impurities, and is the first in the microstructure before spheroidizing annealing. The precipitation ferrite area ratio is 2% or less, the hardness after spheroidizing annealing is 85HRB or less, and the spheroidizing carbide ratio in the microstructure after spheroidizing annealing is 80% or more. Induction hardening steel with excellent cold workability, characterized by ensuring hardness.
Incidentally, spheroidized carbides ratio divided by the total number B of (major axis / minor axis) ratio of 2 or less carbide the test area 0.1mm 2 carbides the number A of which is in the test area 0.1mm 2 This is a value indicating the number ratio A / B as a percentage.
なお、球状化炭化物比率は、被検面積０．１ｍｍ2中の（長径／短径）の比が２以下である炭化物の個数Ａを被検面積０．１ｍｍ2炭化物の総個数Ｂで除した個数比Ａ／Ｂを百分率で示す値である。 In addition to the steel components according to claim 1 or 2, as elements for further improving the cold workability, Ti: 0.02-0.05%, V: 0.01-0.10% 1 or 2 selected from the above, consisting of the remainder Fe and inevitable impurities, the area ratio of proeutectoid ferrite in the microstructure before spheroidizing annealing is 2% or less, and the hardness after spheroidizing annealing is 85 HRB or less And a spheroidizing carbide ratio in the microstructure after spheroidizing annealing is 80% or more, and a hardness of 62 HRC or more can be secured in the subsequent induction hardening. Hardening steel.
Incidentally, spheroidized carbides ratio divided by the total number B of (major axis / minor axis) ratio of 2 or less carbide the test area 0.1mm 2 carbides the number A of which is in the test area 0.1mm 2 This is a value indicating the number ratio A / B as a percentage.
なお、球状化炭化物比率は、被検面積０．１ｍｍ2中の（長径／短径）の比が２以下である炭化物の個数Ａを被検面積０．１ｍｍ2炭化物の総個数Ｂで除した個数比Ａ／Ｂを百分率で示す値である。 In addition to the steel component according to any one of claims 1 to 3, as elements for further improving the machinability, Pb: 0.001 to 0.30%, Se: 0.001 in mass%. 0.30%, Te: 0.001 to 0.30%, Bi: Any one or two or more selected from 0.001 to 0.30%, containing the remainder Fe and inevitable impurities, spherical The pro-eutectoid ferrite area ratio in the microstructure before annealing is 2% or less, the hardness after spheroidizing annealing is 85 HRB or less, and the spheroidizing carbide ratio in the microstructure after spheroidizing annealing is 80% or more. And the steel for induction hardening excellent in cold workability characterized by making it possible to ensure hardness of 62HRC or more in the subsequent induction hardening.
Incidentally, spheroidized carbides ratio divided by the total number B of (major axis / minor axis) ratio of 2 or less carbide the test area 0.1mm 2 carbides the number A of which is in the test area 0.1mm 2 This is a value indicating the number ratio A / B as a percentage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005325480A JP4632931B2 (en) | 2005-11-09 | 2005-11-09 | Induction hardening steel excellent in cold workability and its manufacturing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005325480A JP4632931B2 (en) | 2005-11-09 | 2005-11-09 | Induction hardening steel excellent in cold workability and its manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2007131907A true JP2007131907A (en) | 2007-05-31 |
| JP4632931B2 JP4632931B2 (en) | 2011-02-16 |
Family
ID=38153801
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2005325480A Expired - Fee Related JP4632931B2 (en) | 2005-11-09 | 2005-11-09 | Induction hardening steel excellent in cold workability and its manufacturing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4632931B2 (en) |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008248282A (en) * | 2007-03-29 | 2008-10-16 | Nippon Steel Corp | Induction hardened component and manufacturing method thereof |
| JP2009242918A (en) * | 2008-03-31 | 2009-10-22 | Jfe Steel Corp | Component for machine structure having excellent rolling fatigue property, and method for producing the same |
| WO2012160675A1 (en) * | 2011-05-25 | 2012-11-29 | 株式会社神戸製鋼所 | Steel with excellent rolling fatigue characteristics |
| WO2012160676A1 (en) * | 2011-05-25 | 2012-11-29 | 株式会社神戸製鋼所 | Steel with constant rolling fatigue life |
| WO2012160677A1 (en) * | 2011-05-25 | 2012-11-29 | 株式会社神戸製鋼所 | Bearing steel with excellent cold workability |
| JP2015143377A (en) * | 2014-01-31 | 2015-08-06 | 株式会社神戸製鋼所 | SPHEROIDIZING HEAT TREATMENT METHOD OF HIGH CARBON LOW Cr STEEL MATERIAL FOR COLD FORGING |
| CN110747397A (en) * | 2019-11-05 | 2020-02-04 | 宝钢特钢韶关有限公司 | Round steel for gear and preparation method thereof, gear part and preparation method thereof |
| CN110777303A (en) * | 2019-12-04 | 2020-02-11 | 宝钢特钢韶关有限公司 | Round steel for gear and preparation method thereof |
| CN112080687A (en) * | 2020-08-10 | 2020-12-15 | 大冶特殊钢有限公司 | Fine-grain high-carbon steel and rolling production method thereof |
| CN112941279A (en) * | 2021-01-26 | 2021-06-11 | 青海西钢特殊钢科技开发有限公司 | Heat treatment process for improving hardenability hardness of 20MnCr5+ HH steel tail end |
| WO2021125765A1 (en) * | 2019-12-20 | 2021-06-24 | 주식회사 포스코 | Steel sheet having excellent processability, and method for manufacturing same |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1180884A (en) * | 1997-09-08 | 1999-03-26 | Nisshin Steel Co Ltd | Medium-or high-carbon steel sheet excellent in local ductility and hardenabiltiy |
| JP2000319725A (en) * | 1999-04-30 | 2000-11-21 | Sanyo Special Steel Co Ltd | Manufacture of steel excellent in workability and induction hardenability |
| JP2005002366A (en) * | 2003-06-09 | 2005-01-06 | Sanyo Special Steel Co Ltd | High hardness steel for induction hardening having excellent cold work properties |
-
2005
- 2005-11-09 JP JP2005325480A patent/JP4632931B2/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1180884A (en) * | 1997-09-08 | 1999-03-26 | Nisshin Steel Co Ltd | Medium-or high-carbon steel sheet excellent in local ductility and hardenabiltiy |
| JP2000319725A (en) * | 1999-04-30 | 2000-11-21 | Sanyo Special Steel Co Ltd | Manufacture of steel excellent in workability and induction hardenability |
| JP2005002366A (en) * | 2003-06-09 | 2005-01-06 | Sanyo Special Steel Co Ltd | High hardness steel for induction hardening having excellent cold work properties |
Cited By (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008248282A (en) * | 2007-03-29 | 2008-10-16 | Nippon Steel Corp | Induction hardened component and manufacturing method thereof |
| JP4757831B2 (en) * | 2007-03-29 | 2011-08-24 | 新日本製鐵株式会社 | Induction hardening part and manufacturing method thereof |
| JP2009242918A (en) * | 2008-03-31 | 2009-10-22 | Jfe Steel Corp | Component for machine structure having excellent rolling fatigue property, and method for producing the same |
| US9303302B2 (en) | 2011-05-25 | 2016-04-05 | Kobe Steel, Ltd. | Steel with excellent rolling-contact fatigue properties |
| WO2012160676A1 (en) * | 2011-05-25 | 2012-11-29 | 株式会社神戸製鋼所 | Steel with constant rolling fatigue life |
| WO2012160677A1 (en) * | 2011-05-25 | 2012-11-29 | 株式会社神戸製鋼所 | Bearing steel with excellent cold workability |
| CN103562423A (en) * | 2011-05-25 | 2014-02-05 | 株式会社神户制钢所 | Steel with excellent rolling fatigue characteristics |
| WO2012160675A1 (en) * | 2011-05-25 | 2012-11-29 | 株式会社神戸製鋼所 | Steel with excellent rolling fatigue characteristics |
| JP2015143377A (en) * | 2014-01-31 | 2015-08-06 | 株式会社神戸製鋼所 | SPHEROIDIZING HEAT TREATMENT METHOD OF HIGH CARBON LOW Cr STEEL MATERIAL FOR COLD FORGING |
| CN110747397A (en) * | 2019-11-05 | 2020-02-04 | 宝钢特钢韶关有限公司 | Round steel for gear and preparation method thereof, gear part and preparation method thereof |
| CN110777303A (en) * | 2019-12-04 | 2020-02-11 | 宝钢特钢韶关有限公司 | Round steel for gear and preparation method thereof |
| WO2021125765A1 (en) * | 2019-12-20 | 2021-06-24 | 주식회사 포스코 | Steel sheet having excellent processability, and method for manufacturing same |
| CN114846169A (en) * | 2019-12-20 | 2022-08-02 | Posco公司 | Steel material having excellent workability and method for producing same |
| CN114846169B (en) * | 2019-12-20 | 2023-12-22 | Posco公司 | Steel material having excellent workability and method for producing same |
| CN112080687A (en) * | 2020-08-10 | 2020-12-15 | 大冶特殊钢有限公司 | Fine-grain high-carbon steel and rolling production method thereof |
| CN112080687B (en) * | 2020-08-10 | 2021-10-08 | 大冶特殊钢有限公司 | Fine-grain high-carbon steel and rolling production method thereof |
| CN112941279A (en) * | 2021-01-26 | 2021-06-11 | 青海西钢特殊钢科技开发有限公司 | Heat treatment process for improving hardenability hardness of 20MnCr5+ HH steel tail end |
Also Published As
| Publication number | Publication date |
|---|---|
| JP4632931B2 (en) | 2011-02-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP4632931B2 (en) | Induction hardening steel excellent in cold workability and its manufacturing method | |
| JP5927868B2 (en) | Carburizing steel excellent in cold forgeability and method for producing the same | |
| JP5332646B2 (en) | Manufacturing method of carburizing steel with excellent cold forgeability | |
| US9200354B2 (en) | Rolled steel bar or wire for hot forging | |
| JP2001240940A (en) | Bar wire rod for cold forging and its production method | |
| JP2007146232A (en) | Method for producing soft-nitrided machine part made of steel | |
| JP2011256456A (en) | Method for manufacturing steel for cold forging | |
| JPWO2017115842A1 (en) | Case-hardened steel, carburized parts and method for producing case-hardened steel | |
| JP6693206B2 (en) | Crankshaft, manufacturing method thereof, and crankshaft steel | |
| US20140182414A1 (en) | Steel for induction hardening and crankshaft manufactured by using the same | |
| JP2001123244A (en) | Steel for large-sized bearing and large-sized bearing parts | |
| JP4328924B2 (en) | Manufacturing method of high-strength shaft parts | |
| JP2018024909A (en) | Steel for machine structural use for cold working and production method thereof | |
| JP2007119865A (en) | Steel tube for machine structural member, and production method therefor | |
| JP4488228B2 (en) | Induction hardening steel | |
| JP2018165403A (en) | Steel for carburizing having excellent low cycle fatigue strength and machinability, and carburized component | |
| JP5365477B2 (en) | Steel for surface hardening treatment | |
| JPH10147814A (en) | Production of case hardening steel product small in heat treating strain | |
| JP5976581B2 (en) | Steel material for bearings and bearing parts with excellent rolling fatigue characteristics | |
| JP4393344B2 (en) | Manufacturing method of case hardening steel with excellent cold workability and grain coarsening resistance | |
| TWI630278B (en) | Surface hardened steel | |
| JP2005002366A (en) | High hardness steel for induction hardening having excellent cold work properties | |
| JP6085210B2 (en) | Case-hardened steel with excellent rolling fatigue characteristics and method for producing the same | |
| JP7140274B2 (en) | steel shaft parts | |
| JP3242336B2 (en) | Cold forging steel excellent in cold forgeability and fatigue strength and method for producing cold forged member |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20080916 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20101028 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20101116 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20101116 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20131126 Year of fee payment: 3 |
|
| LAPS | Cancellation because of no payment of annual fees |