JP2007231323A - Method for reforming surface of iron alloy-made structural part - Google Patents

Method for reforming surface of iron alloy-made structural part Download PDF

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JP2007231323A
JP2007231323A JP2006051997A JP2006051997A JP2007231323A JP 2007231323 A JP2007231323 A JP 2007231323A JP 2006051997 A JP2006051997 A JP 2006051997A JP 2006051997 A JP2006051997 A JP 2006051997A JP 2007231323 A JP2007231323 A JP 2007231323A
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iron alloy
quenching
temperature
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surface modification
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Kazumasa Nishio
一政 西尾
Mitsuaki Ikeda
満昭 池田
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Kyushu Institute of Technology NUC
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/78—Combined heat-treatments not provided for above
    • C21D1/785—Thermocycling

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reforming the surface of an iron alloy-made structural part with which surface hardness, fatigue strength resistance, wear resistance and corrosion resistance of the part, are improved together with keeping the toughness, without needing the limitation of characteristics and the afterworking. <P>SOLUTION: This surface reforming method is quenched to the iron alloy-made structural part by applying the heat-treatment, in which the heating/cooling process for rapidly cooling to the temperature of austenitic zone or less, repeats at least at three times or more, after rapidly heating to the temperature of the austenitic zone. The heat-treatment is applied to adjust an average crystal grain diameter to 1-10 μm. The heat-treatment is performed with high frequency induction hardening, laser beam quenching, flame hardening, electrolytic quenching or electron beam quenching. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、表面硬度、耐疲労強度、耐磨耗性、耐食性あるいは靭性等を高度に求められる鉄合金製機構部品の表面改質法に関する。   The present invention relates to a method for modifying the surface of a mechanical part made of an iron alloy that is highly required to have surface hardness, fatigue resistance, wear resistance, corrosion resistance, toughness, and the like.

例えばパワーステアリング用ギヤハウジング、エンジンバルブガイド、シリンダライナー、鋳鋼製ライナあるいは船用タービンシャフト等の機構部品は、用途によって表面硬度、耐疲労強度、耐磨耗性、耐食性あるいは靭性等の特性が要求される。
このような要求特性を満たす材料としては、機械構造用炭素鋼、軸受鋼、マルテンサイト型ステンレス鋼、フェライト型ステンレス鋼、耐熱鋼、マルテンサイト鋳鉄またはバネ鋼、工具鋼、クロム・モリブデン鋼もしくはニッケル・クロム鋼等の合金鋼等の焼入れ硬化が可能な合金が使用されている。 For example, mechanical parts such as power steering gear housings, engine valve guides, cylinder liners, cast steel liners, and ship turbine shafts require characteristics such as surface hardness, fatigue resistance, wear resistance, corrosion resistance, and toughness depending on the application. The
Materials that satisfy these requirements include carbon steel for machine structures, bearing steel, martensitic stainless steel, ferritic stainless steel, heat resistant steel, martensitic cast iron or spring steel, tool steel, chromium / molybdenum steel or nickel • Alloys that can be hardened by hardening, such as alloy steels such as chrome steel, are used.

機構部品の表面硬度、耐疲労強度、耐磨耗性および耐食性を向上させるとともに靭性を併せ持たせる方法としては、機構部品の表面全体もしくは必要な個所の表面だけを改質により硬化する表面改質法が取られる。この表面改質法は、材料の表面だけを高周波、レーザ、火炎、電解または電子ビーム等によりオーステナイト領域の温度まで昇温した後、水冷等の急冷処理でマルテンサイトなどの焼入れ組織にする方法である。   As a method to improve the surface hardness, fatigue resistance, wear resistance and corrosion resistance of mechanical parts, and to combine toughness, surface modification can be performed by modifying the entire surface of the mechanical part or only the surface of the required part. The law is taken. This surface modification method is a method in which only the surface of a material is heated to the temperature of the austenite region by high frequency, laser, flame, electrolysis or electron beam, etc., and then quenched into a quenched structure such as martensite by water cooling or the like. is there.

ところが上記方法では改質効果に限界があるために、表面の必要な個所だけを融点以上の温度まで急速昇温した後、急速冷却する表面改質法が開発された（例えば、非特許文献１参照。）。この文献に記載されているとおり、この方法が適用されている機構部品は、上記のパワーステアリング用ギヤハウジング、エンジンバルブガイド、シリンダライナー、鋳鋼製ライナ、船用タービンシャフト等であり、加熱源としては高周波、レーザ、電子ビームが採用されている。この方法が優れた表面硬度等の特性を出現させる原因は、焼入れ組織の細粒化にある。   However, since the above-described method has a limit on the modification effect, a surface modification method has been developed in which only a necessary portion of the surface is rapidly heated to a temperature higher than the melting point and then rapidly cooled (for example, Non-Patent Document 1). reference.). As described in this document, the mechanical parts to which this method is applied are the power steering gear housing, engine valve guide, cylinder liner, cast steel liner, marine turbine shaft, etc. High frequency, laser and electron beam are used. The cause of the appearance of excellent characteristics such as surface hardness by this method is the refinement of the quenched structure.

ところで、鉄鋼材料の細粒化に関して、本出願人は、鉄基合金材料に材料表面が溶融しない条件下で１回乃至２０回レーザを照射して急速加熱および急速冷却を施す微細化方法を提案している（特許文献１参照。）。
この方法は、具体的には、炭素量が０．１％の低炭素鋼を対象として５００〜８００℃の範囲を急速加熱した後、急速冷却するものであり、オーステナイトとフェライト組織間の変態点（Ａｃ３またはＡｒ３）を超える温度まで加熱した後、冷却することで、低炭素鋼を対象とした溶接部のフェライト組織の細粒化を図るものである。これにより、鉄基合金の溶接継手部等所望の局部領域の結晶組織を数μｍオーダまで微細化することができ、疲労強度を高くすることができる。 By the way, regarding the refinement of steel materials, the present applicant has proposed a miniaturization method that performs rapid heating and cooling by irradiating a laser once to 20 times under the condition that the material surface of the iron-based alloy material does not melt. (See Patent Document 1).
Specifically, this method is a method in which a low-carbon steel having a carbon content of 0.1% is rapidly heated in a range of 500 to 800 ° C. and then rapidly cooled, and the transformation point between austenite and ferrite structure. By heating to a temperature exceeding (Ac3 or Ar3) and then cooling, the ferrite structure of the welded portion intended for low-carbon steel is refined. Thereby, the crystal structure of a desired local region such as a welded joint of an iron-base alloy can be refined to several μm order, and the fatigue strength can be increased.

しかしながら、熱処理技術は、鋼種によって適用条件および作用効果が異なると考えるのが一般的であり、本出願人も、上記方法を検討した当時、高炭素鋼への適用可能性については、考慮外であった。
なぜなら、焼入れ組織を有する炭素量０．１５％以上の鉄合金においては、オーステナイトと焼入れ組織(マルテンサイト，ソルバイト，トルースタイト)間の変態点が重要となるが、例えばマルテンサイト変態の場合この変態点は５０〜二百数十℃であり、上記オーステナイトとフェライト組織間の変態点とは大きく異なるためである。焼入れ組織においては、このマルテンサイト変態の変態点以下まで急冷して焼入れ組織でないフェライトやパーライトの析出を阻止する必要があり、また、焼入れが十分に行われるためには加熱後の組織を完全オーステナイトにする必要がある。
また、加熱の際に組織を完全オーステナイトにするためには炭素の拡散時間が必要となるが、短時間の加熱を行うレーザ照射よって拡散に必要な十分な加熱保持時間が得られるかという点については予測可能な範囲ではない。
したがって、上記レーザ照射技術は、炭素量０．１５％以上の鉄合金である機構部品の特性を改善するうえで、先行技術としての位置づけは実質的には乏しいといえる。
特開２００２−２５６３３５号公報 精密工学会 表面改質に関する調査研究分科会編，表面改質技術，１９８８年，ページ１４７，日刊工業新聞社 However, the heat treatment technology is generally considered to have different application conditions and operational effects depending on the steel type, and the applicant has not considered the applicability to high carbon steel at the time when the above method was studied. there were.
This is because, in an iron alloy having a quenching structure with a carbon content of 0.15% or more, the transformation point between austenite and the quenching structure (martensite, sorbite, troostite) is important. For example, in the case of martensite transformation, this transformation This is because the point is 50 to two hundred and several tens of degrees Celsius, which is greatly different from the transformation point between the austenite and the ferrite structure. In the quenched structure, it is necessary to rapidly cool to below the martensitic transformation point to prevent the precipitation of ferrite and pearlite that are not quenched, and in order for the quenching to be performed sufficiently, the structure after heating must be completely austenitic. It is necessary to.
Also, in order to make the structure completely austenite at the time of heating, it is necessary to diffuse the carbon, but whether sufficient heating and holding time necessary for diffusion can be obtained by laser irradiation that performs heating for a short time. Is not in a predictable range.
Therefore, it can be said that the laser irradiation technique is substantially poor in position as a prior art in improving the characteristics of mechanical parts that are iron alloys having a carbon content of 0.15% or more.
JP 2002-256335 A Japan Society for Precision Engineering, Research Subcommittee on Surface Modification, Surface Modification Technology, 1988, Page 147, Nikkan Kogyo Shimbun

先に説明した機構部品の表面改質技術は、材料を融点以上の温度に加熱するため、Ｃｒ等の合金元素の蒸発損失、融解材の飛散付着あるいは形状の乱れが生じるために、例えば蒸発し易いＣｒが表面部分だけ少なくなると耐食性が低下する等の特性の制限や仕上げ処理等の後加工の必要性が生じる。   In the mechanism part surface modification technology described above, the material is heated to a temperature equal to or higher than the melting point, which causes evaporation loss of alloy elements such as Cr, scattered adhesion of molten material, or disorder of shape. When easy Cr is reduced only on the surface portion, there is a need for post-processing such as limitation of properties such as deterioration of corrosion resistance and finishing treatment.

本発明は、上記の課題に鑑みてなされたものであり、特性の制限や後加工を要することなく、部品の表面の硬度、耐疲労強度、耐磨耗性、耐食性を向上させて靭性も併せ持たせる鉄合金製機構部品の表面改質法を提供することを目的とする。   The present invention has been made in view of the above-mentioned problems, and without increasing the properties and post-processing, the surface hardness, fatigue strength, wear resistance, and corrosion resistance of the parts are improved and the toughness is combined. It is an object of the present invention to provide a surface modification method for mechanical parts made of iron alloy.

上記目的を達成するために、本発明に係る鉄合金製機構部品の表面改質法は、鉄合金製機構部品をオーステナイト領域の温度に急速加熱した後、オーステナイト領域以下の温度まで急速冷却する加熱・冷却工程を少なくとも３回以上繰り返す熱処理を施して焼き入れすることを特徴とする。   In order to achieve the above object, the surface modification method for an iron alloy mechanical component according to the present invention is a method in which an iron alloy mechanical component is rapidly heated to a temperature in the austenite region and then rapidly cooled to a temperature below the austenite region. -It is characterized by quenching by applying a heat treatment in which the cooling step is repeated at least three times.

また、本発明に係る鉄合金製機構部品の表面改質法は、前記熱処理により、前記鉄合金製機構部品の少なくとも表面付近の結晶粒の平均結晶粒径を１〜１０μｍに調製することを特徴とする。   The surface modification method for an iron alloy mechanical component according to the present invention is characterized in that an average crystal grain size of crystal grains at least near the surface of the iron alloy mechanical component is adjusted to 1 to 10 μm by the heat treatment. And

また、本発明に係る鉄合金製機構部品の表面改質法は、前記熱処理を、高周波焼入れ、レーザ焼入れ、火炎焼入れ、電解焼入れおよび電子ビーム焼入れのうちから選択されるいずれか１つの方法または２以上の方法を組み合わせて行うことを特徴とする。   Further, in the surface modification method for an iron alloy mechanical component according to the present invention, the heat treatment is any one method selected from induction hardening, laser hardening, flame hardening, electrolytic hardening, and electron beam hardening, or 2 A combination of the above methods is performed.

本発明の鉄合金製機構部品の表面改質法は、鉄合金製機構部品をオーステナイト領域の温度に急速加熱した後、オーステナイト領域以下の温度まで急速冷却する加熱・冷却工程を少なくとも３回以上繰り返す熱処理を施して焼入れし、融点以上の温度に加熱することがないので、特性の制限や後加工を要することなく、部品の表面の硬度、耐疲労強度、耐磨耗性、耐食性を向上させて靭性も併せ持たせることができる。   In the surface modification method for an iron alloy mechanical component according to the present invention, the heating / cooling step of rapidly heating the iron alloy mechanical component to the temperature of the austenite region and then rapidly cooling to the temperature below the austenite region is repeated at least three times. Since it is heat-treated and hardened and is not heated to a temperature higher than the melting point, it improves the surface hardness, fatigue resistance, wear resistance, and corrosion resistance of the parts without the need for property limitations or post-processing. It can also have toughness.

本発明の実施の形態について、以下に説明する。   Embodiments of the present invention will be described below.

金属材料の結晶粒径を小さくすれば硬度と靭性が共に向上することや、オーステナイト組織を微細化して得られた焼入れ組織の微細化が疲労強度、耐磨耗性、耐食性を改善することは古くから知られている。ここで、焼入れ組織とは、マルテンサイト、炭化物、ベイナイトなどの焼入れによって出現する組織のことである。しかしながら、従来の熱処理だけでは、焼入れ組織の微細化には限界がある。
本発明者等は、急速加熱急速冷却を伴う融点以下で行う熱処理を同じ個所に対して繰り返して施すことで、組織を従来よりもさらに微細化することができることを見出し、本発明に想達した。 If the crystal grain size of the metal material is reduced, both hardness and toughness will improve, and refinement of the hardened structure obtained by refining the austenite structure will improve fatigue strength, wear resistance, and corrosion resistance. Known from. Here, the quenching structure is a structure that appears by quenching of martensite, carbide, bainite and the like. However, there is a limit to refinement of the quenching structure only by the conventional heat treatment.
The present inventors have found that the structure can be made finer than before by repeatedly performing heat treatment performed at a temperature equal to or lower than the melting point with rapid heating and rapid cooling to the same portion, and have conceived the present invention. .

本発明の鉄合金製機構部品の表面改質法は、図１の急速加熱・急速冷却のパターン例に示すように、鉄合金製機構部品をオーステナイト領域の温度に急速加熱した後、オーステナイト領域以下の温度まで急速冷却する加熱・冷却工程を少なくとも３回以上繰り返す熱処理を施して焼入れする。
ここで、図１中、Ｔｓはオーステナイト領域の下限温度、Ｔｍは融点である。加熱温度はＴｓより１００〜３００℃高い条件が望ましい。Ｔｓより１００℃高い温度を下回るとオーステナイト変態が不十分となり、部品の特性が十分でない。また、Ｔｓより３００℃高い温度を上回ると酸化や合金元素の蒸発などによりやはり部品の特性が不十分となる。
加熱・冷却は、鉄合金製機構部品の全体の表面に対して繰り返し行ってもよく、また、特定の同一部位の表面に対して繰り返し行ってもよい。 The surface modification method for an iron alloy mechanical component according to the present invention is a method of rapidly heating an iron alloy mechanical component to the temperature of the austenite region, as shown in the rapid heating / rapid cooling pattern example of FIG. A heating and cooling process for rapidly cooling to a temperature of 5 is repeated for at least three times and quenched.
Here, in FIG. 1, Ts is the lower limit temperature of the austenite region, and Tm is the melting point. The heating temperature is preferably 100 to 300 ° C. higher than Ts. When the temperature is below 100 ° C. higher than Ts, the austenite transformation becomes insufficient and the characteristics of the parts are not sufficient. On the other hand, if the temperature exceeds 300 ° C. higher than Ts, the characteristics of the parts become insufficient due to oxidation or evaporation of alloy elements.
Heating / cooling may be repeated for the entire surface of the iron alloy mechanical component, or may be repeated for the surface of a specific same part.

本発明の表面改質法により、鉄合金製機構部品の焼入れ組織の平均粒径を１〜１０μｍの範囲とすることで、部品の表面硬度、耐疲労強度、耐磨耗性、耐食性、耐脆性破壊（靭性）を向上させることができる。なお、平均粒径が１０μｍを超えるとこれらの特性が従来のものと変わらなくなる。
また、熱処理は、好適には、高周波焼入れ、レーザ焼入れ、火炎焼入れ、電解焼入れ、電子ビーム焼入れなどの処理法で得られるが、このときの細粒化の限界は、平均粒径１μｍである。この場合、高周波焼入れ、レーザ焼入れ、火炎焼入れ、電解焼入れ、電子ビーム焼入れなどの処理法のうちのいずれか１つの方法のみを用いて必要回数繰り返し熱処理を行ってもよく、あるいはまた、例えば、繰り返し回数４回のうち最初の３回は高周波焼入れ方法を用い最後の１回はレーザ焼入れ方法を用いる等、２以上の方法を適宜組み合わせて必要回数繰り返し熱処理を行ってもよい。 By using the surface modification method of the present invention, the average grain size of the hardened structure of iron alloy mechanical parts is in the range of 1 to 10 μm, so that the surface hardness, fatigue resistance, wear resistance, corrosion resistance, brittleness resistance of the parts Fracture (toughness) can be improved. When the average particle size exceeds 10 μm, these characteristics are not different from the conventional ones.
The heat treatment is preferably obtained by a treatment method such as induction quenching, laser quenching, flame quenching, electrolytic quenching, or electron beam quenching. The limit of fine graining at this time is an average particle size of 1 μm. In this case, the heat treatment may be repeated as many times as necessary using only one of the treatment methods such as induction hardening, laser hardening, flame hardening, electrolytic hardening, and electron beam hardening, or, for example, repeatedly. The heat treatment may be repeated as many times as necessary by appropriately combining two or more methods, such as using the induction hardening method for the first three times and using the laser hardening method for the last three times.

本発明が適用される鉄合金製機構部品としては、パワーステアリング用ギヤハウジング、エンジンバルブガイド、シリンダライナー、鋳鋼製ライナ、船用タービンシャフト、歯車、電車用車輪、圧延用ロール、モータ用シャフト、金型等を挙げることができる。また、これらに限らず、表面硬度、耐疲労強度、耐磨耗性、耐食性、耐脆性破壊等の特性が要求されるものであれば全て対象となる。また、マイクロマシン用機構部品等の肉厚の薄い部品では表面だけでなく内部まで適用する。   Iron alloy mechanism parts to which the present invention is applied include power steering gear housings, engine valve guides, cylinder liners, cast steel liners, marine turbine shafts, gears, train wheels, rolling rolls, motor shafts, gold Examples include molds. Further, not limited to these, all are required if properties such as surface hardness, fatigue resistance, wear resistance, corrosion resistance, brittle fracture resistance, etc. are required. In addition, in the case of a thin part such as a mechanical part for a micromachine, it is applied not only to the surface but also to the inside.

なお、本発明の表面改質法を施した鉄合金製機構部品に浸炭窒化などの表面硬化処理をさらに行えば、用途によってはより良い結果が得られる。
また、本発明の表面改質法を３％Ｃｒ鋼、６％Ｗ鋼、３％Ｃｏ鋼、ＫＳ鋼などの焼入れ磁石鋼に適用した場合、焼入れ組織の微細化で保磁力が向上し磁石特性が高くなることも当然のことである。 In addition, if a surface hardening process such as carbonitriding is further performed on an iron alloy mechanical component subjected to the surface modification method of the present invention, better results can be obtained depending on the application.
Also, when the surface modification method of the present invention is applied to hardened magnetic steels such as 3% Cr steel, 6% W steel, 3% Co steel, KS steel, etc., the coercive force is improved due to the refined hardened structure and the magnet characteristics. It goes without saying that the price increases.

（実施例１）
図２に示すフェライト可鍛鋳鉄製パワーステアリング用ギヤハウジング１０の内面硬化処理を焼入れ部１２に対してレーザビームで行った。レーザは炭酸ガスレーザ（出力２ｋＷ）を使用して、幅１．５ｍｍの部分に対して３００ｍｍ／ｓの速度で照射した。冷却は施さなかったが、部品の質量効果が大きいので急冷されていた。このときのオーステナイト変態点からマルテンサイト変態点以下までの冷却速度は２５０℃／ｓであった。以下の実施例も同様である。
レーザビームの照射回数を変えたときの耐磨耗性の結果を表1に示す。表１の比較例のうち、照射回数を示していないものは従来技術の項で説明した、部品を融点以上に昇温した例であり、処理後に仕上げ加工を施して摩耗試験をした。その他の比較例はレーザビームの照射回数が２回以下の例である。実施例は、比較例より優れた結果が得られており、そのときの焼入れ組織の平均粒径は１〜１０μｍの範囲であった。 Example 1
The inner surface hardening treatment of the power steering gear housing 10 made of ferrite malleable cast iron shown in FIG. As the laser, a carbon dioxide laser (output 2 kW) was used, and a portion having a width of 1.5 mm was irradiated at a speed of 300 mm / s. Although it was not cooled, it was rapidly cooled because of the large mass effect of the parts. The cooling rate from the austenite transformation point to the martensite transformation point or less at this time was 250 ° C./s. The same applies to the following embodiments.
Table 1 shows the results of wear resistance when the number of times of laser beam irradiation is changed. Of the comparative examples in Table 1, those that do not indicate the number of times of irradiation are examples in which the temperature of the component is raised to the melting point or higher, as described in the section of the prior art, and a wear test was performed after finishing processing. Another comparative example is an example in which the number of times of laser beam irradiation is two or less. In the examples, results superior to the comparative examples were obtained, and the average particle size of the quenched structure at that time was in the range of 1 to 10 μm.

Figure 2007231323
Figure 2007231323

（実施例２）
図３に示すＳＵＭ４３製バルブカムフォロア１４のボールシート１６部分を電子ビームで焼入れた。電子ビームのスキャンは電磁コイルに流す電流制御で行い照射部の冷却は自然冷却とした。
電子ビームの照射回数を変えたときのロックウェル硬度の結果を表２に示す。表２の比較例のうち、照射回数を示していないものは従来技術の項で説明した、部品を融点以上に昇温した場合であり、処理後に仕上げ加工を施して硬度を測定した。その他の比較例はレーザビームの照射回数が２回以下の例である。実施例は比較例より優れた結果が得られており、そのときの焼入れ組織の平均粒径は１〜１０μｍの範囲であった。 (Example 2)
The ball seat 16 portion of the SUM43 valve cam follower 14 shown in FIG. 3 was quenched with an electron beam. The scanning of the electron beam was performed by controlling the current flowing through the electromagnetic coil, and the cooling of the irradiated part was natural cooling.
Table 2 shows the results of Rockwell hardness when the number of electron beam irradiations was changed. Of the comparative examples in Table 2, the number of irradiations not shown is the case described in the section of the prior art when the temperature of the part is raised to the melting point or higher, and finishing is performed after the treatment to measure the hardness. Another comparative example is an example in which the number of times of laser beam irradiation is two or less. In the examples, results superior to the comparative examples were obtained, and the average particle size of the quenched structure at that time was in the range of 1 to 10 μm.

Figure 2007231323
Figure 2007231323

（実施例３）
図４に示すＳ４５Ｃ製モータ用シャフト１８の表面に高周波コイル２０を配置して焼入れした。高周波コイル２０の電圧は５ｋＶ、周波数は２００ｋＨｚとした。
高周波コイルによる熱処理回数を変えたときの回転曲げによる疲労試験（疲労特性）の結果を表３に示す。表３の比較例のうち、照射回数を示していないものは従来技術の項で説明した、部品を融点以上に昇温した場合であり、処理後に仕上げ加工を施して疲労試験を行った。その他の比較例はレーザビームの照射回数が２回以下の例である。実施例はと比較例より優れた結果が得られており、そのときの焼入れ組織の平均粒径は１〜１０μｍの範囲であった。 (Example 3)
The high frequency coil 20 was placed on the surface of the S45C motor shaft 18 shown in FIG. The voltage of the high frequency coil 20 was 5 kV, and the frequency was 200 kHz.
Table 3 shows the results of fatigue tests (fatigue characteristics) by rotational bending when the number of heat treatments by the high frequency coil was changed. Of the comparative examples in Table 3, the number of times of irradiation is not shown in the case of raising the temperature of the part to the melting point or more as described in the section of the prior art, and a fatigue test was performed after finishing processing. Another comparative example is an example in which the number of times of laser beam irradiation is two or less. In the examples, results superior to those of the comparative examples were obtained, and the average particle size of the quenched structure at that time was in the range of 1 to 10 μm.

Figure 2007231323
Figure 2007231323

（実施例４）
炭素工具鋼（ＳＫ３）に対してＹＡＧレーザ(出力４００Ｗ)を移動速度１００ｍｍ／ｓで照射して焼入れした。
ＹＡＧレーザの照射回数を変えたときのヌープ硬度およびｐＨ８のホウ酸塩液中で電解腐食を行った結果を表４に示す。表４の比較例のうち、照射回数を示していないものは従来技術の項で説明した、部品を融点以上に昇温した場合であり、処理後に仕上げ加工を施してヌープ硬度等を測定した。その他の比較例はレーザビームの照射回数が２回以下の例である。実施例は比較例より優れた結果が得られており、そのときの焼入れ組織の平均粒径は１〜１０μｍの範囲であった。 Example 4
Carbon tool steel (SK3) was quenched by irradiation with a YAG laser (output 400 W) at a moving speed of 100 mm / s.
Table 4 shows the results of electrolytic corrosion in a Knoop hardness and pH 8 borate solution when the number of YAG laser irradiations was changed. Of the comparative examples shown in Table 4, the number of times of irradiation is not shown in the case of raising the temperature of the part to the melting point or more described in the section of the prior art. Another comparative example is an example in which the number of times of laser beam irradiation is two or less. In the examples, results superior to the comparative examples were obtained, and the average particle size of the quenched structure at that time was in the range of 1 to 10 μm.

Figure 2007231323
Figure 2007231323

本発明の鉄合金製機構部品の表面改質法における、急速加熱急速冷却の温度パターン例を示す図である。It is a figure which shows the temperature pattern example of rapid heating rapid cooling in the surface modification method of the iron alloy mechanism components of this invention. 本発明を適用したパワーステアリング用ギヤハウジングの概略断面構成図である。It is a schematic sectional block diagram of the gear housing for power steering to which this invention is applied. 本発明を適用したバルブカムフォロアの概略断面構成図である。1 is a schematic cross-sectional configuration diagram of a valve cam follower to which the present invention is applied. 本発明を適用したモータ用シャフトの概略断面構成図である。It is a schematic sectional block diagram of the shaft for motors to which this invention is applied.

符号の説明Explanation of symbols

１０ パワーステアリング用ギヤハウジング
１２ 焼入れ部
１４ バルブカムフォロア
１６ ボールシート
１８ モータ用シャフト
２０ 高周波コイル
DESCRIPTION OF SYMBOLS 10 Power steering gear housing 12 Hardened part 14 Valve cam follower 16 Ball seat 18 Motor shaft 20 High frequency coil

Claims (3)

鉄合金製機構部品をオーステナイト領域の温度に急速加熱した後、オーステナイト領域以下の温度まで急速冷却する加熱・冷却工程を少なくとも３回以上繰り返す熱処理を施して焼き入れすることを特徴とする鉄合金製機構部品の表面改質法。   An iron alloy product characterized in that after the iron alloy mechanical component is rapidly heated to a temperature in the austenite region, it is quenched by performing a heat treatment that repeats at least three times the heating and cooling process for rapidly cooling to a temperature in the austenite region or lower. Surface modification method for mechanical parts. 前記熱処理により、前記鉄合金製機構部品の少なくとも表面付近の結晶粒の平均結晶粒径を１〜１０μｍに調製することを特徴とする請求項１記載の鉄合金製機構部品の表面改質法。   2. The surface modification method for an iron alloy mechanical component according to claim 1, wherein an average crystal grain size of crystal grains in the vicinity of at least the surface of the iron alloy mechanical component is adjusted to 1 to 10 [mu] m by the heat treatment. 前記熱処理を、高周波焼入れ、レーザ焼入れ、火炎焼入れ、電解焼入れおよび電子ビーム焼入れのうちから選択されるいずれか１つの方法または２以上の方法を組み合わせて行うことを特徴とする請求項１または２に記載の鉄合金製機構部品の表面改質法。
3. The method according to claim 1, wherein the heat treatment is performed by any one method selected from induction quenching, laser quenching, flame quenching, electrolytic quenching, and electron beam quenching, or a combination of two or more methods. The surface modification method of the iron alloy mechanism components as described.
JP2006051997A 2006-02-28 2006-02-28 Method for reforming surface of iron alloy-made structural part Pending JP2007231323A (en)

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JP2009153230A (en) * 2007-12-18 2009-07-09 Yaskawa Electric Corp Method of manufacturing rotor core, rotor core manufactured by the manufacturing method, rotor core, embedded magnet type dynamo-electric machine having the rotor, vehicle, lift and working machine each using the dynamo-electric machine
CN101798619A (en) * 2010-03-25 2010-08-11 黄山市精锐输送机械有限公司 Local quenching process for link plate hole surface
WO2010098292A1 (en) * 2009-02-24 2010-09-02 株式会社デルタツーリング Manufacturing method and heat-treatment device for high-strength, highly-tough thin steel
EP2772555A4 (en) * 2011-10-28 2016-04-20 Ntn Toyo Bearing Co Ltd Ring-shaped member heat treatment method and ring-shaped member manufacturing method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009153230A (en) * 2007-12-18 2009-07-09 Yaskawa Electric Corp Method of manufacturing rotor core, rotor core manufactured by the manufacturing method, rotor core, embedded magnet type dynamo-electric machine having the rotor, vehicle, lift and working machine each using the dynamo-electric machine
WO2010098292A1 (en) * 2009-02-24 2010-09-02 株式会社デルタツーリング Manufacturing method and heat-treatment device for high-strength, highly-tough thin steel
JP2010196106A (en) * 2009-02-24 2010-09-09 Delta Tooling Co Ltd Method for manufacturing high-strength high-toughness thin-walled steel and thermal treatment apparatus
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EP2772555A4 (en) * 2011-10-28 2016-04-20 Ntn Toyo Bearing Co Ltd Ring-shaped member heat treatment method and ring-shaped member manufacturing method

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