JP2008144200A - Method for producing soft-nitrided steel product - Google Patents

Method for producing soft-nitrided steel product Download PDF

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JP2008144200A
JP2008144200A JP2006330364A JP2006330364A JP2008144200A JP 2008144200 A JP2008144200 A JP 2008144200A JP 2006330364 A JP2006330364 A JP 2006330364A JP 2006330364 A JP2006330364 A JP 2006330364A JP 2008144200 A JP2008144200 A JP 2008144200A
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Shinsaku Fukuda
晋作 福田
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Isuzu Motors Ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/40—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions
    • C23C8/52—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using liquids, e.g. salt baths, liquid suspensions more than one element being applied in one step
    • C23C8/54—Carbo-nitriding
    • C23C8/56—Carbo-nitriding of ferrous surfaces
    • 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
    • C21D1/06—Surface hardening
    • 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
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/30—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for crankshafts; for camshafts
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Heat Treatment Of Articles (AREA)
  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a soft-nitrided steel product by which a high bending fatigue limit and an excellent unbending property is obtained only by a soft nitridation treatment without the need of any thermomechanical treatment. <P>SOLUTION: The method for producing the soft-nitirided steel product is characterized in that steel material containing, by mass%, 0.40-0.46% C, 0.15-0.35% Si, 1.30-1.70% Mn, ≤0.030% P, ≤0.030% S, ≤0.35% Cr, ≤0.25% Ni, ≤0.30% Cu and the balance Fe with impurities is subjected to hot-forging to form a crude product, and then subjecting the crude product to only the soft nitridation treatment without conducting any thermomechanical treatment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、軟窒化鋼製品の製造方法、特に、自動車のクランク軸製品の製造方法に関するものである。   The present invention relates to a method for producing a nitrocarburized steel product, and more particularly to a method for producing a crankshaft product of an automobile.

自動車のクランク軸は、処理の仕方により、軟窒化クランク軸と高周波クランク軸に大別される。   The crankshaft of an automobile is roughly classified into a soft nitrided crankshaft and a high-frequency crankshaft depending on how it is processed.

従来のクランク軸は、例えば、熱間鍛造→調質処理→軟窒化処理又は高周波焼入れ処理→曲り直しの工程を経て製造されている。曲り直しは、軟窒化処理によって生じた変形を、逆方向の曲げ変形を加えることによって矯正する曲げ矯正加工である。   A conventional crankshaft is manufactured through, for example, a process of hot forging → refining treatment → soft nitriding treatment or induction hardening treatment → rebending. Re-bending is a bending correction process that corrects deformation caused by soft nitriding by applying bending deformation in the opposite direction.

近年、クランク軸の製造コスト低減のため、調質処理無しでも従来と同等の機械的特性が得られる非調質鋼をクランク軸用鋼として採用することが実施されている（非調質鋼化）。この非調質鋼には、調質処理を実施しなくても良好な機械的特性が得られるように、Ｖなどの特殊元素が添加されている。   In recent years, in order to reduce the manufacturing cost of crankshafts, it has been implemented to use non-heat treated steel as crankshaft steel that can obtain the same mechanical characteristics as before without refining treatment. ). A special element such as V is added to the non-tempered steel so that good mechanical properties can be obtained without performing a tempering treatment.

非調質鋼を用いた軟窒化クランク軸の場合では、軟窒化処理後、Ｖの影響によって窒化層（化合物層）が硬くなり過ぎるため、その後に曲り直しなどを行うことができなくってしまう。つまり、非調質鋼を用いた軟窒化クランク軸の場合、軟窒化処理後の製造性が悪くなってしまう。   In the case of a nitrocarburized crankshaft using non-tempered steel, the nitrided layer (compound layer) becomes too hard due to the influence of V after the nitrocarburizing treatment, so that subsequent re-bending cannot be performed. That is, in the case of a nitrocarburized crankshaft using non-heat treated steel, the productivity after the nitrocarburizing process is deteriorated.

そこで、Ｖを含まない鋼で構成された非調質のクランク軸で、かつ、高い曲げ疲労限度及び優れた曲げ矯正性を確保した軟窒化非調質クランク軸が提案されている（特許文献１，２）。   Therefore, a non-tempered crankshaft composed of steel containing no V, and a soft nitrided non-tempered crankshaft that ensures a high bending fatigue limit and excellent bend straightening properties have been proposed (Patent Document 1). , 2).

特開２００１−２５４１４３号公報JP 2001-254143 A 特開平１０−０４６２８７号公報Japanese Patent Laid-Open No. 10-046287

特許文献１記載のクランク軸用窒化鋼は、Ｃｕ及びＮｉを比較的多く含有させると共に、数種類の微量元素を含有させることで、クランク軸としての強度を確保している。   The crankshaft nitrided steel described in Patent Document 1 contains a relatively large amount of Cu and Ni and also contains several kinds of trace elements to ensure the strength of the crankshaft.

しかしながら、特許文献１記載のクランク軸用窒化鋼は、これらの元素の含有量を細かく規定していることから、その調整に手間を要し、製造時間及び製造コストの上昇を招くという問題があった。   However, the crankshaft nitride steel described in Patent Document 1 has a problem that the adjustment of the content of these elements requires a lot of time and increases the manufacturing time and manufacturing cost. It was.

そこで本発明の目的は、調質処理を施すことなく、軟窒化処理のみで、高い曲げ疲労限度及び優れた曲げ矯正性が得られる軟窒化鋼製品の製造方法を提供することにある。   Accordingly, an object of the present invention is to provide a method for producing a nitrocarburized steel product that can obtain a high bending fatigue limit and excellent bend straightening property by only nitrocarburizing without performing tempering.

上記の目的を達成するために、請求項１の発明は、質量％で、
Ｃ：０．４０〜０．４６％、
Ｓｉ：０．１５〜０．３５％、
Ｍｎ：１．３０〜１．７０％、
Ｐ：０．０３０％以下、
Ｓ：０．０３０％以下、
Ｃｒ：０．３５％以下、
Ｎｉ：０．２５％以下、
Ｃｕ：０．３０％以下、
を含有し、
残部がＦｅ及び不純物である鋼材に、熱間で鍛造加工を施して製品粗材を鍛造形成した後、その製品粗材に調質処理を施すことなく軟窒化処理のみを施すことを特徴とする軟窒化鋼製品の製造方法である。 In order to achieve the above object, the invention of claim 1 is in mass%,
C: 0.40 to 0.46%,
Si: 0.15-0.35%,
Mn: 1.30 to 1.70%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 0.35% or less,
Ni: 0.25% or less,
Cu: 0.30% or less,
Containing
A steel material whose balance is Fe and impurities is forged by hot forging to form a product coarse material, and then only the soft nitriding treatment is performed without subjecting the product coarse material to a tempering treatment. This is a method for producing a nitrocarburized steel product.

請求項２の発明は、上記製品粗材がクランク軸粗材である請求項１記載の軟窒化鋼製品の製造方法である。   The invention according to claim 2 is the method for producing a nitrocarburized steel product according to claim 1, wherein the coarse product is a coarse crankshaft.

請求項３の発明は、上記軟窒化処理が、Ｎ2ガスとＮＨ3ガスの混合ガス雰囲気下で加熱処理を施すガス軟窒化処理である請求項１又は２記載の軟窒化鋼製品の製造方法である。 According to a third aspect of the invention, the soft nitriding treatment is a gas soft nitriding treatment in which heat treatment is performed in a mixed gas atmosphere of N 2 gas and NH 3 gas. It is.

請求項４の発明は、上記軟窒化処理後、曲げ矯正加工を施す請求項１から３いずれかに記載の軟窒化鋼製品の製造方法である。   A fourth aspect of the present invention is the method for producing a nitrocarburized steel product according to any one of the first to third aspects, wherein a bending correction process is performed after the soft nitriding treatment.

鋼材に、熱間鍛造加工を施した後、調質処理を行わずに、直接、軟窒化処理を施してなる軟窒化鋼製品は、従来の調質処理を行った軟窒化鋼製品と同等以上の高い曲げ疲労限度及び優れた曲げ矯正性を有する。   A nitrocarburized steel product that is directly subjected to nitrocarburizing treatment after hot forging after being subjected to hot forging is equivalent to or better than conventional nitrocarburized steel products that have been subjected to tempering treatment. It has a high bending fatigue limit and excellent bending straightness.

以下、本発明の実施の形態を添付図面に基いて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

本発明者が鋭意研究した結果、Ｖを含む従来の非調質鋼を用いず、かつ、熱間鍛造後に調質処理を施すことなく軟窒化処理を施すのみで、十分な強度及び良好な製造性が得られ、かつ、安価な軟窒化鋼製品のための製造方法を見出した。   As a result of intensive studies by the inventor, sufficient strength and good production can be obtained only by applying soft nitriding treatment without using tempering treatment after hot forging without using conventional non-tempered steel containing V. The present inventors have found a production method for a soft nitrided steel product that has good properties and is inexpensive.

本実施の形態においては、軟窒化鋼製品、具体的には軟窒化クランク軸を構成するための鋼材として、自動車の足廻り部品に用いられている既存の鋼材、具体的には焼入れ性を保証した構造用鋼鋼材（Ｈ鋼）であるＳＭｎ４４３Ｈ（ＪＩＳ規格、ＡＳＭｎ４４３Ｈとも言う）を用いることに特徴がある。   In this embodiment, existing steel materials used for automobile undercarriage parts, specifically hardenability, are guaranteed as soft nitrided steel products, specifically steel materials for constituting a soft nitrided crankshaft. It is characterized by using SMn443H (JIS standard, also referred to as ASMn443H), which is a structural steel material (H steel).

本実施の形態に係る製造方法に用いる鋼材は、このＳＭｎ４４３Ｈで構成され、かつ、軟窒化処理を施してなる軟窒化鋼製品に用いられる鋼材であり、質量％で、
Ｃ：０．４０〜０．４６％、
Ｓｉ：０．１５〜０．３５％、
Ｍｎ：１．３０〜１．７０％、
Ｐ：０．０３０％以下、
Ｓ：０．０３０％以下、
Ｃｒ：０．３５％以下、
Ｎｉ：０．２５％以下、
Ｃｕ：０．３０％以下、
を含有し、
残部がＦｅ及び不純物のものである。ここで、ＳＭｎ４４３Ｈは、Ｖを含有しないことが規格で定められたものである。よって、当然のことながら、本実施の形態に係る製造方法に用いる鋼材においても、Ｖは含まない。 The steel material used in the manufacturing method according to the present embodiment is a steel material that is composed of this SMn443H and is used for a soft nitriding steel product that is subjected to soft nitriding treatment.
C: 0.40 to 0.46%,
Si: 0.15-0.35%,
Mn: 1.30 to 1.70%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 0.35% or less,
Ni: 0.25% or less,
Cu: 0.30% or less,
Containing
The balance is Fe and impurities. Here, it is defined in the standard that SMn443H does not contain V. Therefore, as a matter of course, V is not included in the steel material used in the manufacturing method according to the present embodiment.

一方、従来のＳＭｎ４４３Ｈで構成される足廻り部品は、ＳＭｎ４４３Ｈの鋼材に、熱間で鍛造加工を施して足廻り部品粗材を鍛造形成した後、その足廻り部品粗材に調質処理（焼入れ・焼戻し処理）を施し、その後、高周波焼入れ処理を施すことで製造される高周波鋼製品であった。   On the other hand, the suspension parts made of conventional SMn443H are forged into hot parts by forging the steel material of SMn443H and then tempering (quenching) the rough parts of the suspension parts. -It was a high-frequency steel product manufactured by performing a tempering process and then performing an induction hardening process.

これに対して、本実施の形態に係る軟窒化鋼製品は、ＳＭｎ４４３Ｈで構成される鋼材に、熱間で鍛造加工を施して製品粗材を鍛造形成した後、その製品粗材に調質処理（焼入れ・焼戻し処理）を施すことなく、直接、軟窒化処理を施すことで製造されるものである。軟窒化処理後の軟窒化鋼製品には、順次、曲げ矯正加工としての曲り直し、仕上げ加工が施され、最終製品が得られる。また、熱間鍛造処理と軟窒化処理の間に粗加工を施してもよい。   On the other hand, the soft nitrided steel product according to the present embodiment is forged to a steel material composed of SMn443H by hot forging and then tempering the product material. It is manufactured by performing soft nitriding directly without applying (quenching / tempering). The nitrocarburized steel product after the nitrocarburizing treatment is successively subjected to re-bending and finishing as a bending correction process to obtain a final product. Further, roughing may be performed between the hot forging process and the soft nitriding process.

軟窒化処理（ガス軟窒化処理）は、例えば、Ｎ2ガス雰囲気下又はＲＸガス（吸熱型変成ガス）とＮＨ3ガスの比（ＮＨ3ガス／ＲＸガス）が０．８〜１．２の雰囲気下、５８０〜６００℃×１〜５ｈｒ（好ましくは５７０℃×３ｈｒ）の加熱処理を施した後、油冷するという条件で行われる。例えば、ＲＸガスは、ＣＯ２０％、Ｈ2４０％、Ｎ2４０％という組成のガスである。また、熱間鍛造は、加熱温度１１５０〜１２５０℃の範囲、好ましくは１２５０℃で行われる。 Soft nitriding treatment (gas soft nitriding treatment) is, for example, in an N 2 gas atmosphere or a ratio of RX gas (endothermic metamorphic gas) to NH 3 gas (NH 3 gas / RX gas) is 0.8 to 1.2. In the atmosphere, the heat treatment is performed at 580 to 600 ° C. × 1 to 5 hours (preferably 570 ° C. × 3 hours), and then the oil cooling is performed. For example, the RX gas is a gas having a composition of CO 20%, H 2 40%, and N 2 40%. The hot forging is performed at a heating temperature in the range of 1150 to 1250 ° C, preferably 1250 ° C.

次に、本実施の形態の作用を説明する。   Next, the operation of the present embodiment will be described.

本実施の形態の製造方法で得られた軟窒化鋼製品（以下、本軟窒化鋼製品という）は、既存のＨ鋼（ＳＭｎ４４３Ｈ）で構成されるものであるが、調質処理（焼入れ・焼戻し処理）を施さないものであるから、軟窒化処理前の段階では、従来の調質軟窒化鋼製品（以下、従来軟窒化鋼製品という）よりも機械的特性が劣っている。ここで言う本軟窒化鋼製品は、ＳＭｎ４４３Ｈで構成される鋼材に、順に、鍛造加工（１２５０℃加熱）→粗加工→軟窒化処理（５７０℃×３ｈｒ）→曲り直し→仕上げ加工を施したものであり、また、従来軟窒化鋼製品は、既存の軟窒化処理用の調質鋼（Ｓ５０Ｃ）で構成される鋼材に、順に、鍛造加工（１２５０℃加熱）→調質処理（８５０℃加熱→水焼入れ，６００℃焼戻し）→粗加工→軟窒化処理（５７０℃×３ｈｒ）→曲り直し→仕上げ加工を施したものである。   The soft nitrided steel product (hereinafter referred to as the present soft nitrided steel product) obtained by the manufacturing method of the present embodiment is composed of existing H steel (SMn443H), but is tempered (quenched / tempered). Therefore, mechanical properties are inferior to those of conventional tempered nitrocarburized steel products (hereinafter referred to as conventional nitrocarburized steel products) before the nitrocarburizing treatment. This soft-nitrided steel product here is a steel material composed of SMn443H, which has been subjected to forging (1250 ° C heating) → roughing → soft nitriding (570 ° C x 3hr) → re-bending → finishing In addition, the conventional nitrocarburized steel products are forged (1250 ° C. heating) → temper treatment (850 ° C. heating → Water quenching, tempering at 600 ° C.) → roughing → soft nitriding (570 ° C. × 3 hr) → rebending → finishing.

ところが、本実施の形態に係る製造方法に用いる鋼材に軟窒化処理を施すことで、本軟窒化鋼製品は製品表面に窒化層が形成され、焼入れ・焼戻し処理を施さなくても製品の強度が改善され、従来軟窒化鋼製品と同等以上の機械的特性、すなわち高い曲げ疲労限度及び優れた曲げ矯正性が得られるようになる。例えば、高い曲げ疲労限度としては、小野回転式曲げ試験において±３７５ＭＰａが±５５０ＭＰａ以上となる。   However, by subjecting the steel material used in the manufacturing method according to the present embodiment to soft nitriding treatment, a nitrided layer is formed on the product surface of the soft nitriding steel product, so that the strength of the product can be improved without performing quenching / tempering treatment. As a result, mechanical properties equivalent to or better than those of conventional nitrocarburized steel products, that is, a high bending fatigue limit and excellent bend straightening can be obtained. For example, as a high bending fatigue limit, ± 375 MPa becomes ± 550 MPa or more in the Ono rotary bending test.

また、本実施の形態に係る製造方法に用いる鋼材（既存のＨ鋼）は、Ｖを含まないことから、軟窒化処理を施しても、窒化層（及び／又は窒化層直下の拡散層の表面硬さ）が硬くなり過ぎるおそれはなく、その後、容易に曲り直しを行うことができる。さらに、本実施の形態に係る製造方法に用いる鋼材は、前述した特許文献１，２記載のクランク軸用鋼（軟窒化用鋼）と比較して多量のＭｎ（Ｍｎ含有量：１．３０〜１．７０ｍａｓｓ％）を含ませており、これによって疲労強度の向上が図れる。また、本実施の形態に係る製造方法に用いる鋼材は、既存のＨ鋼、すなわち汎用品を軟窒化処理用の非調質鋼として用いるものであるため、前述した特許文献１，２記載のクランク軸用鋼（軟窒化用鋼）と比較して、原料コストを大幅に低減することができる。   In addition, since the steel material (existing H steel) used in the manufacturing method according to the present embodiment does not contain V, the surface of the nitrided layer (and / or the diffusion layer immediately below the nitrided layer) even when soft nitriding is performed. (Hardness) is not likely to be too hard, and thereafter it can be easily bent again. Furthermore, the steel material used for the manufacturing method according to the present embodiment is a large amount of Mn (Mn content: 1.30 compared with the crankshaft steel (soft nitriding steel) described in Patent Documents 1 and 2 described above. 1.70 mass%) is included, and this can improve the fatigue strength. In addition, the steel material used in the manufacturing method according to the present embodiment is an existing H steel, that is, a general-purpose product used as a non-tempered steel for soft nitriding treatment. Compared to shaft steel (soft nitriding steel), raw material costs can be greatly reduced.

更に、図１に本軟窒化鋼製品の曲り直し試験結果の一例を示すように、線１で示す本軟窒化鋼製品は、発生歪み１７２００μまで亀裂が発生せず、従来と同等以上の曲がり直し性を有している。   Further, as shown in FIG. 1 as an example of the results of the re-bending test of the nitrocarburized steel product, the nitrocarburized steel product indicated by line 1 does not crack up to a strain of 17200 μm, and is refracted at the same level or higher. It has sex.

また、図２に本軟窒化鋼製品及び従来軟窒化鋼製品の小野回転式曲げ労試験結果の一例を示すように、線１で示す本軟窒化鋼製品及び線２で示す従来軟窒化鋼製品の疲労回数が１．０×１０7回となる応力振幅はそれぞれ５５０ＭＰａ、３７５ＭＰａである。このことからわかるように、本軟窒化鋼製品１は、従来軟窒化鋼製品２と比較して疲労強度が約４５％も向上していた。よって、本軟窒化鋼製品１でクランク軸を製造する際、クランク軸サイズを従来と同サイズにした場合はエンジン出力の向上を図ることが可能となり、クランク軸の疲労強度を従来と同レベルにした場合はクランク軸の軽量化を図ることが可能となる。 In addition, as shown in FIG. 2 as an example of the Ono rotary bending labor test results of the present soft nitrided steel product and conventional soft nitrided steel product, the present soft nitrided steel product indicated by line 1 and the conventional soft nitrided steel product indicated by line 2. The stress amplitude at which the number of fatigue times becomes 1.0 × 10 7 times is 550 MPa and 375 MPa, respectively. As can be seen from this, the nitrocarburized steel product 1 was improved in fatigue strength by about 45% compared with the conventional nitrocarburized steel product 2. Therefore, when manufacturing the crankshaft with this soft nitrided steel product 1, if the crankshaft size is the same as the conventional size, the engine output can be improved, and the fatigue strength of the crankshaft is kept at the same level as before. In this case, it is possible to reduce the weight of the crankshaft.

更に、本実施の形態に係る製造方法に用いる鋼材は、その用途をクランク軸だけに限定するものではなく、軟窒化処理を施した後に曲げ矯正加工が施されることが多い部品の素材としても適用可能である。   Furthermore, the steel material used in the manufacturing method according to the present embodiment is not limited to the crankshaft, but can be used as a material for parts that are often subjected to bending straightening after soft nitriding. Applicable.

本発明の好適一実施の形態に係る軟窒化鋼製品の曲り直し試験結果の一例を示す図である。It is a figure which shows an example of the re-bending test result of the nitrocarburized steel product which concerns on suitable one embodiment of this invention. 本発明の好適一実施の形態に係る軟窒化鋼製品の疲労試験結果の一例を示す図である。It is a figure which shows an example of the fatigue test result of the nitrocarburized steel product which concerns on suitable one embodiment of this invention.

符号の説明Explanation of symbols

１ 本軟窒化鋼製品（軟窒化鋼製品）   1 Soft nitriding steel product (soft nitriding steel product)

Claims (4)

質量％で、
Ｃ：０．４０〜０．４６％、
Ｓｉ：０．１５〜０．３５％、
Ｍｎ：１．３０〜１．７０％、
Ｐ：０．０３０％以下、
Ｓ：０．０３０％以下、
Ｃｒ：０．３５％以下、
Ｎｉ：０．２５％以下、
Ｃｕ：０．３０％以下、
を含有し、
残部がＦｅ及び不純物である鋼材に、熱間で鍛造加工を施して製品粗材を鍛造形成した後、その製品粗材に調質処理を施すことなく軟窒化処理のみを施すことを特徴とする軟窒化鋼製品の製造方法。 % By mass
C: 0.40 to 0.46%,
Si: 0.15-0.35%,
Mn: 1.30 to 1.70%,
P: 0.030% or less,
S: 0.030% or less,
Cr: 0.35% or less,
Ni: 0.25% or less,
Cu: 0.30% or less,
Containing
A steel material whose balance is Fe and impurities is forged by hot forging to form a product coarse material, and then only the soft nitriding treatment is performed without subjecting the product coarse material to a tempering treatment. A method for producing nitrocarburized steel products. 上記製品粗材がクランク軸粗材である請求項１記載の軟窒化鋼製品の製造方法。   The method for producing a nitrocarburized steel product according to claim 1, wherein the product coarse material is a crankshaft coarse material. 上記軟窒化処理が、Ｎ2ガスとＮＨ3ガスの混合ガス雰囲気下で加熱処理を施すガス軟窒化処理である請求項１又は２記載の軟窒化鋼製品の製造方法。 The method for producing a soft nitrided steel product according to claim 1 or 2, wherein the soft nitriding treatment is a gas soft nitriding treatment in which heat treatment is performed in a mixed gas atmosphere of N 2 gas and NH 3 gas. 上記軟窒化処理後、曲げ矯正加工を施す請求項１から３いずれかに記載の軟窒化鋼製品の製造方法。   The method for producing a nitrocarburized steel product according to any one of claims 1 to 3, wherein a bending straightening process is performed after the nitrocarburizing treatment.
JP2006330364A 2006-12-07 2006-12-07 Method for producing soft-nitrided steel product Pending JP2008144200A (en)

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WO2017056896A1 (en) * 2015-10-01 2017-04-06 新日鐵住金株式会社 Preform for crankshaft, nitride crankshaft, and manufacturing method for same

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JP4230794B2 (en) * 2002-09-25 2009-02-25 大同特殊鋼株式会社 Machine parts and manufacturing method thereof
JP2004292915A (en) * 2003-03-27 2004-10-21 Daido Steel Co Ltd Machine component and manufacturing method therefor

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017056896A1 (en) * 2015-10-01 2017-04-06 新日鐵住金株式会社 Preform for crankshaft, nitride crankshaft, and manufacturing method for same
JPWO2017056896A1 (en) * 2015-10-01 2018-03-01 新日鐵住金株式会社 Crankshaft rough profile, nitrided crankshaft, and method of manufacturing the same

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