WO2011129179A1 - ばねおよびその製造方法 - Google Patents
ばねおよびその製造方法 Download PDFInfo
- Publication number
- WO2011129179A1 WO2011129179A1 PCT/JP2011/056923 JP2011056923W WO2011129179A1 WO 2011129179 A1 WO2011129179 A1 WO 2011129179A1 JP 2011056923 W JP2011056923 W JP 2011056923W WO 2011129179 A1 WO2011129179 A1 WO 2011129179A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- residual stress
- compressive residual
- layer
- spring
- spring according
- Prior art date
Links
Classifications
-
- 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
- C23C8/06—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 gases
- C23C8/28—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 gases more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
-
- 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
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/18—Hardening; Quenching with or without subsequent tempering
- C21D1/25—Hardening, combined with annealing between 300 degrees Celsius and 600 degrees Celsius, i.e. heat refining ("Vergüten")
-
- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/04—Modifying the physical properties of iron or steel by deformation by cold working of the surface
- C21D7/06—Modifying the physical properties of iron or steel by deformation by cold working of the surface by shot-peening or the like
-
- 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
- C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
-
- 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
- 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
- C23C8/80—After-treatment
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- 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
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Definitions
- the present invention relates to a spring and a method for manufacturing the same, and more particularly to a technique for forming a layer of high compressive residual stress from the surface to the deep part.
- Automotive valve springs are designed to be smaller and lighter, and the strength of the wire tends to increase because the spring wire diameter is reduced and the design stress is increased. Therefore, springs are required to further improve fatigue strength in order to maintain fatigue resistance even under high working stresses.
- One means for this is to form high and deep compressive residual stresses on the wire surface layer. To do. Until now, springs have generally formed compressive residual stress on the surface layer of wire by shot peening. However, as the hardness of the wire increases in recent years, the amount of plastic strain on the surface layer has decreased and a deep compressive residual stress layer has been formed. It was difficult to get.
- the depth at which the distribution of the net stress (inside the material) is maximized in the radial direction is a region of about 200 to 600 ⁇ m from the surface, depending on the wire diameter and acting stress. If inclusions of about 20 ⁇ m are present in the range, stress concentration is generated in the inclusions so as to exceed the fatigue strength of the material and become a breakage starting point. In order to solve such problems, the following techniques have been proposed.
- Patent Document 1 discloses a spring that has improved durability with a nitride layer having a compressive residual stress of 1200 MPa or more at the surface portion by shot peening after gas nitriding and a depth of the compressive residual stress of 250 ⁇ m or more. Is disclosed. However, the spring described in Patent Document 1 has a maximum compressive residual stress depth of 290 ⁇ m as disclosed in the examples, and it is difficult to prevent breakage starting from a deeper region. Conceivable. Further, since the nitride layer is brittle with almost no ductility, the nitride layer promotes the generation of fatigue cracks and becomes a factor of reducing the fatigue strength.
- Patent Document 2 discloses a spring excellent in fatigue strength in which a compressive residual stress of 90 ⁇ 10 kgf / mm 2 is distributed from the surface layer to a depth of 150 ⁇ m.
- Patent Document 3 discloses a spring excellent in fatigue strength having a surface compressive residual stress of 1600 MPa or more subjected to shot peening after nitriding. However, the improvement of the fatigue strength is not sufficient by simply defining the surface compressive residual stress. Rather, there is no description regarding the internal compressive residual stress although it is important to suppress internal fracture due to the presence of inclusions.
- the composition of oxide inclusions in steel is in terms of% by weight SiO 2 : 30 to 60%, Al 2 O 3 : 10 to 30%, CaO: 10 to 30%, MgO: 3 to 15 %, And its size is 15 ⁇ m or less in terms of the equivalent circle diameter, spring steel excellent in fatigue characteristics is disclosed.
- Patent Document 5 discloses a spring having a maximum compressive residual stress of 1600 MPa or more by performing shot peening using amorphous particles after nitriding as a projection material.
- the maximum compressive stress on the surface is about 2500 MPa, but there is no description regarding the depth distribution of the compressive residual stress.
- the depth of the compressive residual stress is about 250 ⁇ m, and it is considered difficult to suppress internal fracture starting from a deeper region.
- Patent Document 6 discloses a nitrogen-quenched product that has a nitrogen diffusion layer in which nitrogen is solid-dissolved from the surface to a predetermined depth without having a nitrogen compound in the surface layer, and has been subjected to quenching treatment, and a method for manufacturing the same. Yes. According to this, since a brittle nitrogen compound that can become a fracture starting point is not formed even after nitrogen penetration, and the surface layer has high hardness, an improvement in fatigue strength can be expected. However, Patent Document 6 does not describe compressive residual stress, and the thickness of the surface high hardness layer is 60 ⁇ m at the maximum. Therefore, a significant increase in fatigue strength cannot be expected only with the content described in Patent Document 6. Further, under the production conditions of Patent Document 6, since the nitriding temperature is low, it is expected that the surface nitrogen concentration is low and the thickness of the concentrated layer is thin.
- JP 2009-52144 A Japanese Patent No. 3028438 JP 2005-139508 A JP-A-6-158226 JP 2003-170353 A JP 2007-46088 A
- the present invention has been made in view of the above circumstances, and it is possible to reduce the thickness of the surface nitrogen compound layer and the carbon compound layer as much as possible, and to increase the fatigue strength by forming a high compressive residual stress layer on the surface layer. It is an object of the present invention to provide a greatly improved spring and a method for manufacturing the same.
- the present inventors have intensively studied the distribution of compressive residual stress that affects the fatigue strength of high-strength springs. As a result, even if the compressive residual stress of the surface layer is increased to a certain extent, there is a limit to the increase in fatigue strength against the stress acting on the external load, and the surface is effective in suppressing fatigue fracture starting from the inside. From the results, it was found that the presence of compressive residual stress at a depth of 300 ⁇ m or more is extremely effective. Further, by increasing the nitriding temperature compared to the technique described in Patent Document 6 and forming a high concentration layer of nitrogen and carbon on the surface, residual austenite is actively generated, and then shot pinning or the like is performed. It was concluded that the use of processing-induced martensitic transformation of residual austenite (with volume expansion) is efficient in obtaining a layer of high hardness and high compressive residual stress.
- the spring of the present invention has been made on the basis of the above findings, and in terms of weight%, C: 0.27 to 0.48%, Si: 0.01 to 2.2%, Mn: 0.30 to 1. 0%, P: 0.035% or less, S: 0.035% or less, the balance is the entire composition composed of Fe and inevitable impurities, and the thickness of the surface nitrogen compound layer and carbon compound layer is 2 ⁇ m or less
- the hardness of the central portion in the cross section is 500 to 700 HV
- the compressive residual stress layer has a thickness of 0.30 mm to D / 4 when the equivalent circle diameter of the cross section is D (mm) on the surface layer. Formed, and its maximum compressive residual stress is 1400 to 2000 MPa.
- the equivalent cross-sectional diameter of the strand is preferably 1.5 to 5.0 mm.
- the “transverse section” is a cross section orthogonal to the longitudinal direction of the spring.
- the spring manufacturing method of the present invention is to manufacture the above-mentioned spring, and by weight, C: 0.27 to 0.48%, Si: 0.01 to 2.2%, Mn: 0.30.
- a steel material satisfying ⁇ 1.0%, P: 0.035% or less, S: 0.035% or less, and the balance being iron and inevitable impurities, is heated to 3 to 1100 ° C or less of steel A, 50
- a chemical surface treatment step for concentrating nitrogen and carbon in the surface layer by contacting with a mixed gas atmosphere consisting of ⁇ 90 vol% NH 3 and the balance consisting of inert gas and inevitable impurities, and then a rate of 20 ° C / second or more And a quenching step of cooling to room temperature, a tempering step of heating to 100 to 200 ° C., and a compressive residual stress applying step of applying compressive residual stress to the surface layer.
- C is an element necessary for ensuring the strength of steel that can withstand the load required for the spring by quenching and tempering.
- the hardness of the steel material tends to increase with an increase in the concentration of C.
- C it is necessary to make the concentration of 0.27% or more.
- the concentration of C is excessive, the hardness of the center portion after quenching exceeds 700 HV, and the toughness is significantly reduced.
- the hardness of the central part can be reduced by tempering at a high temperature exceeding 400 ° C., but at the same time, a nitrogen compound or a carbon compound is generated in a solid solution layer of nitrogen and carbon. Therefore, even if low temperature tempering that does not generate a nitrogen compound or a carbon compound is performed, the C concentration is set to 0.48% or less so that the hardness of the center portion of the steel material is 700 HV or less.
- Si 0.01-2.2%
- Si is a deoxidizing element useful in steel refining, and it is necessary to add 0.01% or more.
- Si is also a solid solution strengthening element and is an effective element for obtaining high strength.
- the Si concentration is excessive, the workability is deteriorated, so that it is set to 2.2% or less.
- Mn 0.3 to 1.0%
- Mn is added as a deoxidizing element, but 0.3% or more is added to contribute to solid solution strengthening and hardenability improvement.
- concentration of Mn is excessive, segregation occurs and the workability is liable to be lowered.
- P 0.035% or less
- S 0.035% or less
- the hardness of the spring center portion needs to be 500 HV or more in order to ensure the strength that can withstand the load required for the spring.
- the hardness is excessively high, the notch sensitivity of the steel material itself is increased and the fatigue strength is lowered, so that it is suppressed to 700 HV or less.
- the maximum value of the compressive residual stress of the surface layer is 1400 to 2000 MPa, and the thickness of the compressive residual stress layer (the distance from the surface to the position where the compressive residual stress becomes zero, hereinafter the same) is 0.30 mm to D / 4. is there. Since the compressive residual stress of the surface layer suppresses the occurrence and development of fatigue cracks, it is desirable that the maximum value of the compressive residual stress is large and the thickness of the compressive residual stress layer is thick.
- the thickness of the compressive residual stress layer when the maximum compressive residual stress is 1400 MPa is D / 4
- the thickness of the compressive residual stress layer when the maximum compressive residual stress is 2000 MPa is 0.30 mm.
- the compressive residual stress at a depth of 300 ⁇ m from the surface is 100 to 300 MPa.
- the combined stress with the action stress exceeds 1100 MPa (the strand diameter is 5 mm).
- the coil average diameter is assumed to be 15 mm or more), and there is a high risk of exceeding the fatigue limit assumed from the hardness of the wire, which is insufficient to suppress internal fracture.
- the compressive residual stress at a depth of 300 ⁇ m from the surface exceeds 300 MPa, the tensile residual stress on the inner side becomes too high and the fatigue strength is lowered.
- the manufacturing method of the spring of this invention is demonstrated.
- the steel material having the above-mentioned chemical composition is heated to 3 to 1100 ° C. in the steel A, and in a mixed gas atmosphere consisting of 50 to 90% by volume of NH 3 and the balance of inert gas and inevitable impurities.
- a chemical surface treatment step of concentrating nitrogen and carbon on the surface layer by contact a quenching step of cooling to room temperature at a rate of 20 ° C./second or more, a tempering step of heating to 100 to 200 ° C., and It is manufactured by applying a compressive residual stress applying step for applying compressive residual stress to the surface layer.
- a The structure of the steel before heating to 3 points or more is not particularly limited, but the smaller the prior austenite crystal grain size, the better, and the average grain size is preferably 30 ⁇ m or less.
- a hot-forged or drawn steel strip can be used as the material. Below, the reason for limitation in each process is demonstrated.
- the chemical surface treatment step forms a compressive residual stress layer having a thickness of 0.30 mm to D / 4 by allowing nitrogen and carbon to penetrate into the material to be treated, and also actively retains austenite, and a predetermined amount after tempering. This is a step for obtaining a layer having a higher compressive residual stress in the compressive residual stress applying step described later in the presence of residual austenite.
- the compressive residual stress layer that has undergone the compressive residual stress applying step is referred to as a “high compressive residual stress layer”. For the same reason as conventional quenching treatment, first heating the steel material to more than three points A.
- the heating temperature is too high, NH 3 gas is immediately decomposed after introduction, and nitrogen and carbon intrusion into the material to be treated (carbon intrusion will be described later) is remarkably suppressed.
- the upper limit is 1100 ° C.
- the temperature is preferably 850 to 1000 ° C.
- the heating time is preferably 15 to 110 minutes. When the heating time is less than 15 minutes, the amount of residual austenite generated due to the small amount of nitrogen and carbon intrusion decreases, and it becomes difficult to obtain a desired high compressive residual stress layer in the compressive residual stress application step. When the heating time exceeds 110 minutes, brittle nitrogen compounds and carbon compounds exceeding 2 ⁇ m are easily formed on the surface layer, which promotes the generation of cracks.
- This heating time is for the case where the chemical surface treatment gas is at about 1 atm including an error that can be industrially managed.
- the heating time is inversely proportional to the pressure. It is desirable to adjust the pressurization time.
- the mixed gas that is brought into contact with the steel material in order to concentrate nitrogen and carbon to the surface layer supplies an amount that sufficiently enters the amount of nitrogen intruding into the product to be processed by the amount calculated from the concentration specified in the present invention.
- the NH 3 concentration in the state (1 atm, 20 ° C.) is 50 to 90% by volume.
- the NH 3 concentration in the mixed gas atmosphere is less than 50% by volume, the penetration amount of nitrogen and carbon is small, and a desired high compressive residual stress layer cannot be obtained.
- the NH 3 concentration exceeds 90% by volume the residual austenite ratio of the surface layer increases excessively, so the compressive residual stress does not increase, and 80 to 90% by volume is preferable. This will be described in detail in later sections [Residual austenite ratio] and [Nitrogen and carbon concentrations].
- the temperature and time of the chemical surface treatment process and the mixed gas composition in the standard state suppress the formation of nitrogen compounds and carbon compounds on the surface layer by quickly diffusing nitrogen and carbon entering the steel material surface.
- this is an important condition for forming a thick high compressive residual stress layer through a compressive stress applying step.
- the radical N maintains the radical state even if it penetrates into the steel for some reason and is dissolved, and an electron beam microanalyzer used for elemental analysis in the form for carrying out the invention (EPMA-1600 manufactured by Shimadzu Corporation) In this case, it is considered that some change occurs in the wavelength of the characteristic X-ray originally obtained from N, and this may be detected as carbon in the analysis.
- the cooling rate to room temperature is preferably 50 ° C./second or more.
- Tempering process In the martensitic structure after quenching at the center of the steel material, tempering is performed because defects such as set cracks are likely to occur due to strain caused by quenching, and the toughness is extremely low and breakage under low load stress may occur. Tempering needs to be performed at 100 ° C. or higher in order to reduce strain at the center of the steel material. On the other hand, when the tempering temperature exceeds 200 ° C., the hardness of the central portion of the steel material becomes low and cannot withstand the load required as a spring.
- the high and thick compressive residual stress on the surface layer is applied by utilizing the processing-induced martensite (with volume expansion) of the retained austenite.
- shot pinning is preferable.
- a shot used in shot pinning a cut wire, a steel ball, or the like can be used.
- the compression residual stress can be adjusted by a shot equivalent sphere diameter, a projection speed, a projection time, and a multi-stage projection method.
- the sphere equivalent diameter of the shot is preferably 0.7 to 1.3 mm.
- the shot diameter is less than 0.7 mm, a sufficiently large impact energy of the projected shot cannot be obtained, the plastic strain of the wire surface layer becomes small, and it becomes difficult to obtain a desired compressive residual stress distribution. Further, if the shot diameter is too large, the surface roughness of the strands becomes large, and this tends to cause premature breakage of the surface starting point. Further, if the hardness of the shot is higher than the hardness of the central portion of the material to be processed, the efficiency is good, and the Vickers hardness is preferably 600 HV or more.
- the average residual austenite ratio from the surface to the depth of 100 ⁇ m in the cross section of the spring strand is preferably 10 to 35% by volume.
- Residual austenite is induced by plastic deformation and transformed into martensite, which is accompanied by volume expansion. Therefore, by allowing the residual austenite to exist in the surface layer of the spring wire in advance after the tempering step, a thick high compressive residual stress layer can be formed on the surface layer in the subsequent compressive residual stress applying step. If the retained austenite ratio is less than 10%, the volume expansion due to the work-induced martensitic transformation is small, and it becomes difficult to obtain a desired compressive residual stress distribution.
- the retained austenite increases in stability against external force as the concentration of nitrogen and carbon contained in the austenite increases, and the processing-induced martensite transformation is less likely to occur.
- the residual austenite ratio exceeds 35%, the concentrations of nitrogen and carbon exceed the allowable values, and as a result, it becomes difficult to obtain a desired compressive residual stress distribution.
- the reason why the range defining the retained austenite ratio is from the surface to a depth of 100 ⁇ m is that the surface has the highest degree of processing in processing in the compressive residual stress application step, and becomes smaller as the depth increases.
- the degree of workability that austenite transforms into martensite can be imparted to a depth of about 100 ⁇ m from the surface, and the residual austenite martensite transformation (with volume expansion) in this region has a deeper compressive residual stress. Form. Therefore, the retained austenite ratio from the surface to a depth of 100 ⁇ m is an important factor for obtaining a desired compressive residual stress distribution.
- the total concentration of nitrogen and carbon from the surface in the cross section of the spring wire to a depth of 100 ⁇ m is 0.8 to 1.2% by weight. It is desirable. When the total concentration of nitrogen and carbon is less than 0.8% by weight, it is difficult to obtain a residual austenite ratio of 10% or more. When the total concentration exceeds 1.2% by weight, the residual austenite is stabilized as described above. Compressive residual stress distribution cannot be obtained.
- the reason for defining the nitrogen and carbon concentrations from the surface to a depth of 100 ⁇ m is that, as described above, the total concentration of these elements and the production ratio of residual austenite are closely related.
- the thickness of the surface nitrogen compound layer and the carbon compound layer is made as thin as possible, and the fatigue strength can be remarkably improved by having a thick high compressive residual stress layer on the surface layer. can get.
- a chemical surface treatment was performed under the conditions shown in Table 2 on a round steel bar having a diameter of 4 mm made of the representative chemical components shown in Table 1.
- the secondary treatment was held at 860 ° C. for 15 minutes. Thereafter, it was cooled to room temperature at a rate of 20 ° C./second or more, quenched, and then tempered for 60 minutes.
- shot peening was performed on the round bar steel that had been tempered.
- a round cut wire (630HV) with a sphere equivalent diameter of 0.8 mm is used as the first stage
- a round cut wire (630 HV) with a sphere equivalent diameter of 0.45 mm is used as the second stage.
- Sand grains having a sphere equivalent diameter of 0.1 mm were used.
- Thickness of nitrogen compound and carbon compound on surface layer X-ray diffraction profile was measured on the outer peripheral side surface of the round bar, and the presence or absence of the compound was determined from the presence or absence of peaks corresponding to the nitrogen compound and carbon compound.
- the thickness was measured from the elemental distribution of nitrogen and carbon using an electron beam microanalyzer (EPMA).
- Residual stress distribution and residual austenite distribution Residual stress and residual austenite were measured on the outer peripheral surface of the steel using an X-ray diffraction method. Further, after the steel material was entirely chemically polished, each of the above measurements was performed and repeated to determine the residual stress and residual austenite distribution in the depth direction.
- the present invention can be widely applied to valve springs and suspension springs for automobiles or springs for uses other than automobiles.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Crystallography & Structural Chemistry (AREA)
- Thermal Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Heat Treatment Of Articles (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
Description
Cは焼入れ焼戻しによりばねに必要な荷重に耐え得る鋼の強度を確保するために必要な元素である。鋼材の硬さはCの濃度の増加に伴って高くなる傾向があるが、本発明の表面処理方法において400℃の焼戻し後でも鋼材の中心部の硬さを500HV以上とするためには、Cの濃度を0.27%以上とすることが必要である。一方、Cの濃度が過剰になると、焼入れ後の中心部の硬さが700HVを超え、靭性が著しく低下する。これに対し400℃を超える高温の焼戻しにより中心部の硬さを低下させることはできるが、同時に窒素および炭素の固溶層において窒素化合物や炭素化合物が生じてしまう。そこで、窒素化合物や炭素化合物を生じさせない程度の低温焼戻しを行っても鋼材の中心部の硬さを700HV以下とするためにCの濃度は0.48%以下とする。
Siは鋼の精錬において有用な脱酸元素であり0.01%以上を添加する必要がある。また、Siは固溶強化元素でもあり、高強度を得るために有効な元素であるが、Siの濃度が過剰であると加工性の低下を招くため2.2%以下とする。
Mnは脱酸元素として添加されるが、固溶強化や焼入れ性の向上にも寄与するため、0.3%以上を添加する。一方、Mnの濃度が過剰であると偏析が生じ加工性が低下し易くなるため、1.0%以下とする。
PおよびSは、粒界偏析による粒界破壊を助長する元素であるため、濃度は低いほうが望ましく、上限は0.035%とする。PおよびSの濃度は、ともに0.01%以下であることが好ましい。
[表面の窒素化合物層および炭素化合物層の厚さ]
窒素化合物や炭素化合物は脆く靭性が乏しいため、それらを表面に形成すると亀裂の発生を促進する。したがって、窒素化合物および炭素化合物はある程度許容されるものの、それらの厚さの上限は2μmであり、1μm以下が好ましい。
ばね中心部の硬さは、ばねに必要な荷重に耐え得る強度を確保するために500HV以上必要である。一方、硬さが過剰に高い場合は鋼材自体の切欠き感受性が増加し、疲労強度が低下するため、700HV以下に抑える。
表層の圧縮残留応力の最大値は1400~2000MPaであり、圧縮残留応力層の厚さ(表面から圧縮残留応力がゼロとなる位置までの距離、以下、同様)は0.30mm~D/4である。表層の圧縮残留応力は疲労亀裂の発生および進展を抑制するため、圧縮残留応力の最大値は大きく、圧縮残留応力層の厚さは厚い方が望ましい。しかしながら、表層の圧縮残留応力の最大値が高すぎるか、または圧縮残留応力層の厚さが厚過ぎると、鋼材全体で残留応力をバランスするために内側に存在する引張残留応力が著しく高くなり、この引張残留応力が外部負荷によりばね素線に発生する引張応力と合成され、亀裂の発生を促進する。したがって、最大圧縮残留応力が1400MPaの場合の圧縮残留応力層の厚さはD/4とし、最大圧縮残留応力が2000MPaの場合の圧縮残留応力層の厚さは0.30mmとするのが望ましい。
化学的表面処理工程は、被処理材に窒素および炭素を侵入させることにより0.30mm~D/4の厚さの圧縮残留応力層を形成するとともに積極的にオーステナイトを残留させ、焼戻し後に所定量の残留オーステナイトを存在させて後述する圧縮残留応力付与工程でさらに高い圧縮残留応力の層を得るための工程である。なお、以下の説明においては、圧縮残留応力付与工程を経た圧縮残留応力層を「高圧縮残留応力層」と称する。通常の焼入れ処理と同じ理由により、まず鋼材をA3点以上に加熱する。この場合において、加熱温度が高すぎると、NH3ガスが導入後に直ちに分解され、被処理材への窒素および炭素の侵入(炭素の侵入については後述する)が著しく抑制されるため、加熱温度は1100℃を上限とする。望ましくは850~1000℃が良い。加熱時間は15~110分とすることが望ましい。加熱時間が15分未満では、窒素および炭素の侵入量が少ないことにより生成する残留オ-ステナイト量が少なくなり、圧縮残留応力付与工程で所望の高圧縮残留応力層を得ることが困難となる。また、加熱時間が110分を超えると、表層に2μmを超える脆い窒素化合物や炭素化合物が形成し易くなり、これが亀裂の発生を促す。なお、本加熱時間は、化学的表面処理用ガスが工業的に管理できる誤差を含むほぼ1気圧の場合のものであり、減圧または加圧ガス雰囲気での処理では、その圧力に逆比例して加圧時間を調整することが望ましい。
化学的表面処理後の焼入れでは、室温までの冷却速度は速いほど良く、20℃/秒以上の冷却速度で行う必要がある。冷却速度が20℃/秒未満では冷却途中でパ-ライトが生成し、焼入れが不完全となり所望の硬さを得ることができない。室温までの冷却速度は、50℃/秒以上であることが好ましい。
鋼材の中心部が焼入れ後のマルテンサイト組織では、焼入れによって生じたひずみにより置き割れなどの不具合が生じやすくなるとともに、靭性が著しく低く低負荷応力下での折損も起こり得るため焼戻しを行う。焼戻しは、鋼材の中心部のひずみを低減するため100℃以上で行う必要がある。一方、焼戻し温度が200℃を超えると、鋼材の中心部の硬さが低くなりばねとして求められる荷重に耐えられない。
表層の高くかつ厚い圧縮残留応力は、残留オ-ステナイトの加工誘起マルテンサイト(体積膨張を伴う)を利用して付与するものであり、その加工方法は、実操業上の生産性と経済性の制約を考慮し、ショットピ-ニングが好ましい。ショットピ-ニングで使用するショットとしては、カットワイヤやスチ-ルボ-ル等を用いることできる。また、圧縮残留応力の調整は、ショットの球相当直径や投射速度、投射時間、および多段階の投射方式で調整することができる。ここで、ショットの球相当直径は0.7~1.3mmが望ましい。ショットの直径が0.7mm未満では、十分に大きな投射ショットの衝突エネルギ-が得られず、素線表層の塑性ひずみが小さくなり、所望の圧縮残留応力分布を得ることが困難となる。また、ショットの直径は、大き過ぎると素線の表面粗さが大きくなり、これにより表面起点の早期折損を招きやすくなるため1.3mm以下が望ましい。また、ショットの硬度は被処理材の中心部の硬度より高いと効率が良く、ビッカース硬さ600HV以上が好ましい。
焼戻し工程後であって圧縮残留応力付与工程前においては、ばねの素線の横断面における表面から深さ100μmまでの平均残留オ-ステナイト比率は、体積比で10~35%であることが望ましい。残留オ-ステナイトは塑性変形に誘起されてマルテンサイトに変態するが、この際体積膨張を伴う。したがって、焼戻し工程後にばね素線の表層に予め残留オ-ステナイトを存在させておくことで、その後の圧縮残留応力付与工程において表層に厚い高圧縮残留応力層を形成することができる。残留オ-ステナイト比率が10%未満では加工誘起マルテンサイト変態による体積膨張が小さく、所望の圧縮残留応力分布を得ることが困難となる。
前記焼戻し工程後であって圧縮残留応力付与工程前においては、ばねの素線の横断面における表面から深さ100μmまでの窒素および炭素の合計濃度は、0.8~1.2重量%であることが望ましい。窒素および炭素の合計濃度が0.8重量%未満では10%以上の残留オ-ステナイト比率を得ることが困難となり、1.2重量%を超えると前述の通り残留オ-ステナイトが安定化し、所望の圧縮残留応力分布を得ることができない。窒素および炭素の濃度を規定する範囲を表面から深さ100μmまでとしたのは、前述の通りこれら元素の合計濃度と残留オ-ステナイトの生成比率は密接に関連しているためである。
丸棒の外周側面に対しX線回折プロファイルを測定し、窒素化合物および炭素化合物に相当するピ-クの有無から化合物の有無を判定した。また、その厚さは、電子線マイクロアナライザ-(EPMA)を用いた窒素および炭素の元素分布から測定した。
横断面において、鋼材の中心から0mm、0.1mm、0.2mmの各位置でのビッカ-ス硬さを測定しその平均値を求めた。
鋼材の外周表面に対しX線回折法を用いて残留応力、残留オ-ステナイトをそれぞれ測定した。また、鋼材を全面化学研磨後、上記の各測定を行い、これを繰返すことで深さ方向の残留応力および残留オ-ステナイトの分布を求めた。
丸棒の横断面に対し、前述の電子線マイクロアナライザ-(EPMA)を用いて表面から深さ100μmまでの窒素および炭素の濃度を求めた。
本発明の条件を全て満足する本発明例No.4~9は、表面に窒素化合物層および炭素化合物層が存在せず、しかも表層に厚い高圧縮残留応力層を有する。これに対し、比較例No.1~3では、化学的表面処理工程における雰囲気ガス中のNH3濃度が高いため、焼戻し工程後であってショットピ-ニング前における表層の窒素および炭素の濃度が高い。その結果、残留オ-ステナイト量が過多となり、表層の最大圧縮応力が低くなった。比較例No.10では、化学的表面処理工程における温度が高いため、窒素および炭素の侵入量が少なく残留オ-ステナイト量が少ない。その結果、圧縮残留応力層の厚さが浅く、かつ最大値が小さくなった。比較例No.11では、化学的表面処理工程における雰囲気ガス中のNH3濃度がゼロであり、窒素および炭素が侵入しないため、圧縮残留応力層の厚さが浅く、かつ最大値が小さくなった。
Claims (10)
- 重量%で、C:0.27~0.48%、Si:0.01~2.2%、Mn:0.30~1.0%、P:0.035%以下、S:0.035%以下、残部がFe及び不可避不純物からなる全体組成を有し、表面の窒素化合物層および炭素化合物層の厚さが2μm以下であり、かつ横断面において中心部の硬さが500~700HVであり、表層に横断面の円相当直径をD(mm)としたときに圧縮残留応力層が0.30mm~D/4の厚さで形成され、その最大圧縮残留応力が1400~2000MPaであることを特徴とするばね。
- 表面から深さ300μmの位置における圧縮残留応力が100~300MPaであることを特徴とする請求項1に記載のばね。
- 素線の横断面円相当直径が1.5~5.0mmであることを特徴とする請求項1または2に記載のばね。
- 重量%で、C:0.27~0.48%、Si:0.01~2.2%、Mn:0.30~1.0%、P:0.035%以下、S:0.035%以下を満たし、残部が鉄及び不可避不純物からなる鋼材に対し、鋼のA3点以上1100℃以下に加熱し、標準状態(1気圧、20℃)における濃度が50~90体積%のNH3と残部が不活性ガスおよび不可避不純物からなる混合ガス雰囲気に接触させることで窒素および炭素を表層に濃化させる化学的表面処理工程と、次いで20℃/秒以上の速度で室温まで冷却する焼入れ工程と、次いで100~200℃に加熱する焼戻し工程と、次いで表層に圧縮残留応力を付与する圧縮残留応力付与工程を有することを特徴とするばねの製造方法。
- 前記化学的表面処理工程において、加熱温度が850~1000℃であり、かつ加熱時間が15分~110分であることを特徴とする請求項4に記載のばねの製造方法。
- 前記化学的表面処理工程において、混合ガス雰囲気のNH3濃度が80~90体積%であることを特徴とする請求項4または5に記載のばねの製造方法。
- 前記圧縮残留応力付与工程において、ショットピ-ニングを用いることを特徴とする請求項4~6のいずれかに記載のばねの製造方法。
- 前記圧縮残留応力付与工程のショットピ-ニングにおいて、ショットの球相当直径が0.7~1.3mmであることを特徴とする請求項4~7のいずれかに記載のばねの製造方法。
- 前記焼戻し工程後かつ圧縮残留応力付与工程前であって、ばねの素線の横断面において表面から深さ100μmまでの平均残留オ-ステナイト比率が体積比で10~35%であることを特徴とする請求項4~8のいずれかに記載のばねの製造方法。
- 前記焼戻し工程後であって前記圧縮残留応力付与工程前において、ばねの素線の横断面における表面から深さ100μmまでのCとNの合計濃度が0.8~1.2重量%であることを特徴とする請求項4~9のいずれかに記載のばねの製造方法。
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201180018770.3A CN102834540B (zh) | 2010-04-14 | 2011-03-23 | 弹簧及其制造方法 |
US13/635,533 US9080233B2 (en) | 2010-04-14 | 2011-03-23 | Spring and method for producing same |
EP11768700.4A EP2559781A4 (en) | 2010-04-14 | 2011-03-23 | SPRING AND METHOD FOR MANUFACTURING THE SAME |
KR20127029498A KR20130092968A (ko) | 2010-04-14 | 2011-03-23 | 스프링 및 그 제조 방법 |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010093543A JP5631044B2 (ja) | 2010-04-14 | 2010-04-14 | ばねおよびその製造方法 |
JP2010-093543 | 2010-04-14 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2011129179A1 true WO2011129179A1 (ja) | 2011-10-20 |
Family
ID=44798558
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2011/056923 WO2011129179A1 (ja) | 2010-04-14 | 2011-03-23 | ばねおよびその製造方法 |
Country Status (6)
Country | Link |
---|---|
US (1) | US9080233B2 (ja) |
EP (1) | EP2559781A4 (ja) |
JP (1) | JP5631044B2 (ja) |
KR (1) | KR20130092968A (ja) |
CN (1) | CN102834540B (ja) |
WO (1) | WO2011129179A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015098182A1 (ja) * | 2013-12-24 | 2015-07-02 | 中央発條株式会社 | 懸架ばね及び懸架ばねの製造方法 |
WO2016158408A1 (ja) * | 2015-03-31 | 2016-10-06 | 日本発條株式会社 | 懸架装置用ばねの製造方法及び懸架装置用ばね |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8328169B2 (en) * | 2009-09-29 | 2012-12-11 | Chuo Hatsujo Kabushiki Kaisha | Spring steel and spring having superior corrosion fatigue strength |
JP5711539B2 (ja) | 2011-01-06 | 2015-05-07 | 中央発條株式会社 | 腐食疲労強度に優れるばね |
JP5361098B1 (ja) * | 2012-09-14 | 2013-12-04 | 日本発條株式会社 | 圧縮コイルばねおよびその製造方法 |
JP6357042B2 (ja) * | 2014-07-18 | 2018-07-11 | 株式会社日本テクノ | ガス軟窒化方法およびガス軟窒化装置 |
US10043903B2 (en) | 2015-12-21 | 2018-08-07 | Samsung Electronics Co., Ltd. | Semiconductor devices with source/drain stress liner |
KR102142894B1 (ko) * | 2016-09-20 | 2020-08-10 | 닛폰세이테츠 가부시키가이샤 | 샤프트 부품 |
JP6251830B1 (ja) * | 2017-04-11 | 2017-12-20 | 日本発條株式会社 | 圧縮コイルばね |
CN110205451A (zh) * | 2017-07-05 | 2019-09-06 | 凌伯勇 | 一种弹簧合金钢工件调质方法 |
JP2021042398A (ja) * | 2017-12-27 | 2021-03-18 | パーカー熱処理工業株式会社 | 窒化鋼部材並びに窒化鋼部材の製造方法及び製造装置 |
Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS58193323A (ja) * | 1982-05-06 | 1983-11-11 | Nippon Steel Corp | 高強度ばねの製造法 |
JPS62137133A (ja) * | 1985-12-11 | 1987-06-20 | Sumitomo Electric Ind Ltd | 耐疲れ性に優れたコイルばねおよびその製造方法 |
JPH0328438B2 (ja) | 1982-02-05 | 1991-04-19 | Chugai Pharmaceutical Co Ltd | |
JPH06158226A (ja) | 1992-11-24 | 1994-06-07 | Nippon Steel Corp | 疲労特性に優れたばね用鋼 |
JPH11241143A (ja) * | 1997-11-17 | 1999-09-07 | Chuo Spring Co Ltd | 耐腐食疲労強度を向上させたばね |
JP2003170353A (ja) | 2001-12-06 | 2003-06-17 | Sintokogio Ltd | 弁ばねの製造方法及びその弁ばね |
JP2005139508A (ja) | 2003-11-06 | 2005-06-02 | Chuo Spring Co Ltd | 弁ばねの製造方法 |
JP2007046088A (ja) | 2005-08-09 | 2007-02-22 | Yuki Koshuha:Kk | 浸窒焼入品及びその製造方法 |
JP2009052144A (ja) | 2008-09-29 | 2009-03-12 | Togo Seisakusho Corp | 高強度ばね |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH07179985A (ja) * | 1993-12-24 | 1995-07-18 | Kobe Steel Ltd | 耐食性に優れた高強度懸架ばねおよびその製法 |
DE19852734B4 (de) * | 1997-11-17 | 2005-02-24 | Chuo Hatsujo K.K., Nagoya | Feder mit verbesserter Korrosionsermüdungsbeständigkeit |
KR20010060753A (ko) * | 1999-12-28 | 2001-07-07 | 이구택 | 저합금형 고응력 스프링의 제조방법 |
US20040079067A1 (en) * | 2002-03-18 | 2004-04-29 | Chuo Hatsujo Kabushiki Kaisha | Oil tempered wire for cold forming coil springs |
KR101286948B1 (ko) * | 2008-03-31 | 2013-07-17 | 신닛테츠스미킨 카부시키카이샤 | 강재, 강재의 제조방법 및 강재의 제조장치 |
JP2009270150A (ja) * | 2008-05-07 | 2009-11-19 | Togo Seisakusho Corp | コイルばねの製造方法 |
CN101665892B (zh) | 2009-08-28 | 2011-06-22 | 莱芜钢铁股份有限公司 | 一种硅合金钢及其制造方法 |
WO2011115255A1 (ja) | 2010-03-18 | 2011-09-22 | 日本発條株式会社 | ばね用鋼および鋼材の表面処理方法 |
-
2010
- 2010-04-14 JP JP2010093543A patent/JP5631044B2/ja not_active Expired - Fee Related
-
2011
- 2011-03-23 WO PCT/JP2011/056923 patent/WO2011129179A1/ja active Application Filing
- 2011-03-23 KR KR20127029498A patent/KR20130092968A/ko not_active Application Discontinuation
- 2011-03-23 US US13/635,533 patent/US9080233B2/en not_active Expired - Fee Related
- 2011-03-23 CN CN201180018770.3A patent/CN102834540B/zh not_active Expired - Fee Related
- 2011-03-23 EP EP11768700.4A patent/EP2559781A4/en not_active Withdrawn
Patent Citations (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0328438B2 (ja) | 1982-02-05 | 1991-04-19 | Chugai Pharmaceutical Co Ltd | |
JPS58193323A (ja) * | 1982-05-06 | 1983-11-11 | Nippon Steel Corp | 高強度ばねの製造法 |
JPS62137133A (ja) * | 1985-12-11 | 1987-06-20 | Sumitomo Electric Ind Ltd | 耐疲れ性に優れたコイルばねおよびその製造方法 |
JPH06158226A (ja) | 1992-11-24 | 1994-06-07 | Nippon Steel Corp | 疲労特性に優れたばね用鋼 |
JPH11241143A (ja) * | 1997-11-17 | 1999-09-07 | Chuo Spring Co Ltd | 耐腐食疲労強度を向上させたばね |
JP2003170353A (ja) | 2001-12-06 | 2003-06-17 | Sintokogio Ltd | 弁ばねの製造方法及びその弁ばね |
JP2005139508A (ja) | 2003-11-06 | 2005-06-02 | Chuo Spring Co Ltd | 弁ばねの製造方法 |
JP2007046088A (ja) | 2005-08-09 | 2007-02-22 | Yuki Koshuha:Kk | 浸窒焼入品及びその製造方法 |
JP2009052144A (ja) | 2008-09-29 | 2009-03-12 | Togo Seisakusho Corp | 高強度ばね |
Non-Patent Citations (1)
Title |
---|
See also references of EP2559781A4 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2015098182A1 (ja) * | 2013-12-24 | 2015-07-02 | 中央発條株式会社 | 懸架ばね及び懸架ばねの製造方法 |
WO2016158408A1 (ja) * | 2015-03-31 | 2016-10-06 | 日本発條株式会社 | 懸架装置用ばねの製造方法及び懸架装置用ばね |
Also Published As
Publication number | Publication date |
---|---|
CN102834540A (zh) | 2012-12-19 |
JP5631044B2 (ja) | 2014-11-26 |
US9080233B2 (en) | 2015-07-14 |
US20130008566A1 (en) | 2013-01-10 |
EP2559781A4 (en) | 2014-12-10 |
JP2011219851A (ja) | 2011-11-04 |
EP2559781A1 (en) | 2013-02-20 |
KR20130092968A (ko) | 2013-08-21 |
CN102834540B (zh) | 2015-05-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5631044B2 (ja) | ばねおよびその製造方法 | |
EP2682493B2 (en) | Spring and manufacturing method thereof | |
JP5378512B2 (ja) | 浸炭部品およびその製造方法 | |
EP2692888B1 (en) | Case hardening steel, method for producing same, and mechanical structural part using case hardening steel | |
EP1728883A1 (en) | High strength bolt excellent in characteristics of resistance to delayed fracture and resistance to relaxation | |
EP2765213A1 (en) | Steel wire for bolt, bolt, and manufacturing processes therefor | |
EP2530178A1 (en) | Case-hardened steel and carburized material | |
KR20130004307A (ko) | 템퍼링 연화 저항성이 우수한 강 부품 | |
WO2012018144A1 (ja) | ばねおよびその製造方法 | |
US9469895B2 (en) | Spring steel and surface treatment method for steel material | |
WO2012133885A1 (ja) | ばねおよびその製造方法 | |
JP4097151B2 (ja) | 加工性に優れた高強度ばね用鋼線および高強度ばね | |
KR101789944B1 (ko) | 코일 스프링 및 그 제조 방법 | |
JP5141332B2 (ja) | 耐遅れ破壊性に優れた内部高硬度型パーライト鋼レールおよびその製造方法 | |
JP2008266782A (ja) | 耐水素脆性、腐食疲労強度の優れたばね用鋼及びそれを用いた高強度ばね部品 | |
EP3748027B1 (en) | Bolt | |
CN107641771A (zh) | 耐延迟断裂特性优异的线材及其制造方法 | |
WO2013115404A1 (ja) | コイルばねおよびその製造方法 | |
WO2023120475A1 (ja) | 圧縮コイルばねおよびその製造方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 201180018770.3 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 11768700 Country of ref document: EP Kind code of ref document: A1 |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13635533 Country of ref document: US |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2689/KOLNP/2012 Country of ref document: IN |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2011768700 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1201005408 Country of ref document: TH |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
ENP | Entry into the national phase |
Ref document number: 20127029498 Country of ref document: KR Kind code of ref document: A |