EP1847630B1 - High-concentration carburized/low-strain quenched member and process for producing the same - Google Patents

High-concentration carburized/low-strain quenched member and process for producing the same Download PDF

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Publication number
EP1847630B1
EP1847630B1 EP06713304.1A EP06713304A EP1847630B1 EP 1847630 B1 EP1847630 B1 EP 1847630B1 EP 06713304 A EP06713304 A EP 06713304A EP 1847630 B1 EP1847630 B1 EP 1847630B1
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European Patent Office
Prior art keywords
surface layer
carburizing
layer portion
treatment
carbide
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EP06713304.1A
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German (de)
English (en)
French (fr)
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EP1847630A4 (en
EP1847630A1 (en
Inventor
Isao Machida
Hisashi Abe
Toshio Fukushima
Koji Horikiri
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Parker Netsushori Kogyo KK
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Parker Netsushori Kogyo KK
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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
    • C23C8/06—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
    • C23C8/08—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 only one element being applied
    • C23C8/20—Carburising
    • C23C8/22—Carburising 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
    • 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
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • 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
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • C21D2211/003—Cementite

Definitions

  • This invention relates to a super carburized, quenched member featuring temper softening resistance, high strength, high contact pressure and the like, especially to a super carburized, low-distortion quenched member (which may hereinafter be referred to simply as "member") with mutually conflicting properties, that is, higher performance and heat-treatment distortion attained together and also describes its production process.
  • case hardened members Owing to excellent properties such as high fatigue strength and wear resistance, carburized and quenched members (hereafter referred to as "case hardened members") are widely used as various members in transport equipment, industrial machines and the like. From the viewpoint of dimensional reductions, weight reductions and/or the like through further improvements in the performance of such members, numerous developments have been made on case hardened members. Recently, the vacuum carburizing (low-pressure carburizing) process has been developed.
  • the vacuum carburizing process Compared with the conventional gas carburizing process, the vacuum carburizing process has excellent characteristic features such as environmental friendliness, the prevention of intergranular oxidation, the feasibility of high-temperature carburizing treatment, and easy control of carburizing and carbon diffusion, and therefore, is expected to find still broader utility from the standpoints of further improvements in the performance and quality of members and further improvements in their productivity.
  • Patent Document 1 discloses a carburizing treatment process for a member. According to Patent Document 1, it is proposed to form quasispheroidal or spheroidal carbide at a volume percentage of 30% or higher within a range up to a depth of 0.4 mm by conducting precarburizing to such a carbon content that spheroidal carbide is caused to precipitate in a surface layer portion of a steel member and the carbon concentration in the surface layer portion becomes not higher than Acm but not lower than a eutectoid concentration between steel and carbon, slowly cooling or quenching the thus-treated member to convert the surface layer portion into a bainite, pearlite or martensite structure, and then heating the member at a ramp rate of not greater than 20°C/min from the Ac1 point to a temperature in a range of from 750 to 950°C to effect carburizing and quenching.
  • the member can be improved in properties such as pitting properties owing to the precipitation of the carbide in the surface layer portion of the member. Nonetheless, the resulting member involves problems such as a deformation and distortion by heat treatment, because the process is super carburizing that causes the precipitation of the carbide as much as 30% in the surface layer portion.
  • Patent Document 1 As a method for causing carbide to precipitate in an ultrafine form in a surface layer portion_of a member by super carburizing, many heating and cooling methods have been investigated.
  • Patent Document 1 it is described to be desirable that subsequent to the precurburizing, air cooling (which forms a bainite or pearlite structure) or quenching (which forms a martensite structure) is conducted, and that in the carbide-forming treatment as the next step, the member is heated at a slow ramp rate of not greater than 20°C/min from the Ac1 transformation temperature to a temperature within the range of from 750 to 950°C, and after direct quenching or air cooling, the member is again heated and quenched.
  • Patent Document 2 and Patent Document 3 propose, as an optimal method, to conduct slow cooling (or 30°C/hr or less) after precurburizing or primary carburizing.
  • Patent Document 1 also discloses quenching with an aim directed toward forming a martensite structure by increasing the cooling rate of a member subsequenttoitsprecarburizing.
  • Thistechnique involves a potential problem that carbide nuclei in a surface layer portion may dissolve out. It is also concerned that the quenching may take place with supersaturated carbon, and due to high-carbon martensitic transformation, the member may develop a greater deformation or distortion through an expansion, shrinkage or the like.
  • Patent Document 4 discloses a production process of a case hardened member by low-pressure carburizing. There is a reference to the conversion of carbide into an ultrafine form such as the control of the carbon concentration at 0.5 to 0.7 wt.% in primary carburizing and at 0.7 to 1 wt. % in secondary carburizing and the control of primary cooling at a very slow rate of from 1 to 10°C/min. Concerning deformation strain, however, this production process is not expected to be preferred like the above-mentioned Patent Documents 1, 2 and 3.
  • US 2004/0182480 relates to high strength carburized part and a method of producing the same.
  • the present invention has resolved the above-described problem by developing an optimal process, which makes it possible to use a member under a higher contact pressure and also to provide the member with a lower strain while making use of low-pressure carburizing facilities that permit a variety of control promptly with higher accuracy as to the concentration of carbon in the member, the repetition of carburizing treatment/diffusion treatment, and diverse temperature conditions, heating conditions and cooling rate (quenching) conditions for heating, soaking, carburizing, quenching and the like of the member.
  • a super carburized, low-distortion quenched member comprising a surface layer portion of a structure composed primarily of martensite and containing a mixed structure of troostite and retained austenite or the like in parts thereof, wherein in the surface layer, an outermost surface layer (a portion A), a layer (a portion B) inner than the portion A and a layer (a portion C) inner than the portion B are in an order of A ⁇ C ⁇ B in terms of the fineness of austenite grain size, according to claim 1.
  • the process used for producing the member according to the present invention performs the treatment of a member in low-pressure carburizing facilities while making the combined use of the primary treatment of conducting adequate super carburizing and quenching at an optimal cooling rate and the secondary treatment of subsequently causing a fine carbide to simply and efficiently precipitate; and can minimize the deformation and strain of the member treated through the heat treatment.
  • the greatest concern about the conventional super carburizing for example, the cumbersome grinding, strain correction and the like of the member after the treatment, such as the bending of an axle or the deformation strain of a tooth profile, can be substantially relieved, thereby bringing about advantageous effects that significant improvements can be made in the productivity, quality and cost of the case hardened member.
  • additional carburizing treatment may be applied to the surface layer portion of the member in the secondary treatment.
  • This additional carburizing treatment makes it possible to achieve a high hardness of matrix and also to reduce the crystal grain size of an outermost surface layer portion of the member to an ultrafine grain size and, therefore, is also extremely effective for providing the member with higher strength and higher toughness.
  • the process used in the present invention it is possible to readily achieve higher strength, higher toughness, higher contact pressure and the like for members such as axles and gears to which super carburizing has heretofore been hardly applicable. Therefore, the process can be widely applied to fields where there is a high need for such properties, and has an advantageous effect that it can make significant contributions to improvements in the performance of a member and also to reductions in the size and weight of the member.
  • An aim was then set at the establishment of a novel process for super carburizing and low-strain quenching, which can achieve both of mutually-conflicting properties of providing a member with higher performance by super carburizing and minimizing a deformation, distortion or the like of the member while balancing them at high levels.
  • the deformation or strain of a member by the heat treatment can be minimized by controlling a range, in which the ultrafine carbide precipitate in a surface layer portion of the member, to 10 to 30% in terms of effective case depth percentage and further by converting an outermost surface layer portion into an ultrafine crystalline structure.
  • effective case depth percentage means a ratio (t/T) of a precipitated depth (t) of ultrafine carbide existing in an outermost surface layer portion of a member to an effective case depth (T) of the member after completion of the secondary treatment (including the tempering treatment at 180°C).
  • effective case depth means a distance from a surface of a hardened layer, which is still in a quenched state or has been tempered at a temperature not exceeding 200°C, to the position of a critical depth of a Vickers hardness (HV) of 550 as measured by the Method of Measuring Case Depth Hardened by Carburizing Treatment for Steel (JIS G0557).
  • the term "precipitated depth of ultrafine carbide” means themaximumdepth, where the ultrafine carbide exists, from the outermost surface layer portion of the member as determined by an analysis under an optical microscope or an electron microscope.
  • the member is analyzed in a state of being etched with an etching solution such as 5% nital etching reagent.
  • the vacuum carburizing (low-pressure carburizing) facilities for use in the present invention are equipped with a carburizing and heating chamber including a treatment furnace which is sectionally controllable at different pressures of from 200 to 2,000 Pa, and are available on the market. Conventionally-available vacuum carburizing facilities are all usable in the present invention.
  • the primary treatment in the present invention the member is heated and soaked to a predetermined temperature in the furnace of the facilities, and to raise the concentration of carbon in the surface layer portion of the member to or higher than the eutectoid carbon concentration, the member is then quenched at an appropriate cooling rate.
  • the carbide is caused to precipitate in an ultrafine form in the surface layer portion of the member, optionally followed by additional carburizing treatment as needed.
  • steel to be treated (member) is heated and soaked to an austenite region of from 900 to 1,100°C, carburizing is conducted such that the carbon concentration of a surface layer portion becomes preferably 0.8 wt.% or higher, and from the thus-carburized state, quenching is then conducted at an optimal cooling rate.
  • Optimal cooling conditions are to evenly cool the member at a cooling rate of from 3 to 15°C/sec over a temperature range of from the carburizing temperature (the temperature in the austenite region) to the A 1 transformation temperature or lower, preferably to 400°C or lower.
  • ultrafine carbide is caused to precipitate in the surface layer portion of the member so that a structure composed primarily of martensite is formed in the surface layer portion.
  • the term "ultrafine carbide” means an M 23 C 6 type carbide formed as a result of bonding of carbide-forming elements such as Cr and Mo in Fe 3 C (cementite) or steel with carbon dissolved in supersaturation.
  • the non-carburized portion (interior) of the member is heated and soaked to a range of from an austenizing temperature to the austenizing temperature +80°C, preferably to a range of from 10 to 70°C above the austenizing temperature, and is then rapidly quenched to effect precipitation of ultrafine carbide such that the carbon concentration of the surface layer portion becomes preferably 0.8 wt. % or higher, more preferably 1.0 to 2.0 wt.%.
  • the temperature of the final quenching after the secondary treatment varies depending on the pretreatment conditions, that is, whether the final quenching is after the heating and soaking or after the heating, soaking and additional carburizing.
  • the rapid quenching can be conducted at the temperature after the pretreatment or at a temperature raised or lowered relative to the temperature of the pretreatment.
  • the temperature of the final quenching after the secondary treatment can be set at a level commensurate with the quality of heat treatment such as the hardness and microstructure required for the member.
  • the present inventors conducted a detailed investigation on the carbon concentrations upon heating, soaking and carburizing and diffusion and various cooling (quenching) conditions with respect to the primary treatment in which super carburizing is applied to a surface layer portion of a member in low-pressure carburizing facilities and the secondary treatment in which ultrafine grains of carbide are caused to precipitated in the surface layer portion.
  • a super carburized, quenched member having a carbon concentration of preferably.0.8 wt.% or higher, more preferably from 1.0 to 2.0 wt.% in a range of from 10 to 30% in terms of the percentage of an effective case depth (t/T) in an outermost surface layer portion and having a three-layer structure consisting of a superultrafine grain layer of No. 10 or greater austenite grain size, a fine grain layer and an ultrafine grain layer in this order from the outermost surface layer.
  • Machine structural steels (materials) shown in Table 1 were provided. Those materials were subj ected beforehand to normalizing treatment at 900°C and were then machined to prepare stepped round-bar test pieces of ⁇ 30/ ⁇ 25/ ⁇ 20 ⁇ L300 mm, respectively. As carburizing and quenching of each test piece, the primary treatment of the super carburizing step in the present invention was conducted using facilities which permitted heating and carburizing at a low pressure and also permitted oil hardening and high pressure gas cooling.
  • steel grades 1 and 2 are carburizing, quenching steels as specified under the JIS
  • steel grade 1 is SCM420
  • steel grade 2 is SCr415
  • MAC14 as steel grade 3 is a grade for a commercial product developed by a steel maker, and is steel developed by increasing the Cr content in comparison with the above-described two steel grades and further adding Mo element with a view to causing M 23 C 6 type ultrafine carbide to precipitate upon super carburizing (the primary and secondary treatments).
  • Table 1 Used Steels and Their Chemical Components (wt.%) Steel grade C Si Mn P S Cr Mo 1 SCM420 0.20 0.30 0.75 0.019 0.025 1.10 0.20 2 SCr415 0.16 0.35 0.78 0.021 0.019 1.05 0.02 3 MAC14 0.15 0.27 0.53 0.020 0.022 2.50 0.38
  • Table 2 summarizes the results obtained by experimenting in various ways effects of the cooling rate on the states of carbide to be precipitated in surface layer portions of test pieces and the deformations of the test pieces by heat treatment through the primary treatment in the present invention.
  • super carburizing of each test piece was conducted by the heat cycle shown in FIG. 1 such that subsequent to heating and soaking, an effective case depth of 0.5 mm would be achieved.
  • super carburizing and diffusion treatment of each test piece were alternately conducted at 950°C for about 70 minutes, respectively, such that the carbon concentration of the surface layer portion of the test piece in its final state would be controlled at about 1.5wt.%.
  • the cooling rate during the cooling was as low as 1°C/sec so that the carbide precipitated in the surface layer portion consisted primarily of a network of carbide formed of carbide flakes bonded together and the matrix was in the form of an slack quenching structure of ferrite, pearlite and bainite.
  • the comparative example shown as Test Piece No. 3 was subjected to rapid cooling equivalent to conventional oil quenching (20°C/sec). Its surface layer portion contained a very small amount of precipitated carbide, and had a structure quenched from a high carbon state that carbon was in supersaturation. That comparative example was large in radial runout and deformation.
  • Table 3 shows the results obtained by using representative ones of the test pieces subjected to the primary treatment shown in Table 2, applying the secondary treatment in various ways to the representative test pieces to cause ultrafine carbide to finally precipitate in their surface layer portions, and investigating the carbon concentrations, states of precipitated carbide, microstructures, crystal grain sizes, etc. in their surface layer portions and the radial runouts of the test pieces.
  • the soaking temperature was selectively set at three levels of 800°C, 850°C and 900°C, all above the A 1 transformation temperature, and subsequent to the heating and soaking, additional carburizing was also conducted at the same time to achieve a carbon concentration higher than the eutectoid carbon concentration as a technique for further raising the carbon concentrations in the surface layer portions and also increasing the amounts of precipitated ultrafine carbide through the secondary treatment.
  • test pieces ⁇ 30/ ⁇ 25/ ⁇ 20 ⁇ L300 mm
  • chips were collected by lathe turning from the surface layer portion to the 0.05 mm depth of its ⁇ 25 mm portion, and the carbon concentration of the surface layer portion was determined by a chemical analysis.
  • Test Piece No. 2 series indicate effects on the precipitation form of carbide and others when the secondary treatment temperature was varied
  • Test Pieces No. 5 and No. 7 series indicate effects on the precipitation of ultrafine carbide and the final carbon concentrations in the surface layer portions depending on whether or not the additional carburizing was applied in the secondary treatment.
  • the temperature of 900°C employed for Test Piece No. 2-1 involves a problem in that the carbide in a surface layer portion dissolves to lead to a reduction in the overall precipitation of carbide grains and also to an increase in the radial runout of the test piece.
  • the secondary treatment temperature of 800°C employed for Test Piece No. 2-3 carbide flakes precipitate at grain boundaries in the surface layer portion, and the core portion of the member is quenched incomplete. Test pieces, therefore, develop variations in radial runout.
  • the optimal temperature for the treatment that causes ultrafine carbide to precipitate in a surface layer portion by the secondary treatment can preferably be a temperature equivalent to the A 3 transformation temperature + 10-70°C, which is determined by the composition of the member (before the carburizing treatment).
  • the application of the additional carburizing treatment has been recognized, as evident from the results of Test Piece Nos. . 5-1 and 7-1, to bring about the advantageous effect that carbide precipitates in an ultrafine form, to say nothing of an improvement in the concentration of carbon in the surface layer portion.
  • the replenishment of carbon to the surface layer portion by the additional carburizing could promote the new formation of ultrafine carbide, such as Fe 3 C and M 23 C 6 , and nuclei thereof.
  • the austenite grain size of the outermost surface layer portion is reduced to an ultrafine grain size.
  • the term "ultrafine grain size” corresponds to an austenite grain size of No. 10 or greater as measured by the carburized grain-size testing method in JIS-G0551, "Method of Testing Austenite Grain Size for Steel".
  • the grain sizes of the outermost surface layer portion greatest in the amount of precipitated ultrafine carbide, the carburized layer portion (fine grain portion) located inside the outermost surface layer portion and the ultrafine grain portion located still inside the fine grain portion are in a relationship of A ⁇ C ⁇ B, in which "A", "C” and "B” stand for the outermost surface layer portion, the ultrafine grain portion and the fine grain portion, respectively.
  • the austenite grain size of a surface layer portion in conventional carburizing is generally equivalent to No. 7 or 8.
  • the surface layer portion has a grain structure of the characteristic three-layer structure which does not appear in the conventional carburizing treatment.
  • Table 4 shows effects of the percentage of an effective case depth of a carbide layer precipitated in super carburizing according to the present invention on various properties.
  • Various test pieces were prepared by providing SCM420, JIS steel for machine structure, as a material, subjecting the material to normalizing treatment at 900°C beforehand, and then machining the resultant material.
  • the super carburizing of each test piece was conducted by the heat cycle of primary treatment and secondary treatment shown in FIG. 3 .
  • Each treated test piece was analyzed and investigated for pitting life, impact strength, distortion by heat treatment, etc. Concerning effects of the carbon concentration of the outermost surface layer portion of each test piece shown in Table 5, the test piece was treated by the heat cycle shown in FIG. 3 in a similar manner as the various test pieces in Table 4, and the carbon concentration and the like of the treated test piece were investigated.
  • the adjustment of the precipitation depth of carbide in Table 4 was effected primarily by the control or the like of the carburizing time and carbon concentration, and the adjustment of the carbon concentration of the outermost surface layer portion in Table 5 was effected by controlling the process gas flow, treatment time and the like upon repeating carburizing and diffusion in the primary treatment and secondary treatment in accordance with a program calculated beforehand.
  • Process gases for low-pressure carburizing include propane, acetylene, ethylene and the like. Among these, most popular and economical propane was used.
  • nitrogen gas was used as an inert gas upon diffusion. Further, the rapid quenching in the secondary treatment was conducted by oil.
  • the rapid quenching can also be conducted by high pressure gas which makes sole or mixed use of gases such as N 2 , He and H 2 .
  • Table 4 Effects of the Percentage of Effective Case Depth on Strength, Durability and Distortion by Heat Treatment Ex./Comp.Ex. Sign Percentage of effective case depth, t/T (%) Carburizing time (min) Carbon concentration of the outermost surface layer portion (%) Rolling fatigue life (number of rotations) Impact strength ( J ) Roundness ( ⁇ ) Comp.Ex. A 5 80 1.0 6.5 ⁇ 10 6 118 29 Ex. B 10 104 1.5 1.1 ⁇ 10 7 110 31 Ex. C 20 119 1.7 2.1 ⁇ 10 7 105 39 Ex.
  • the carbon concentration of super carburizing can be set preferably at 0.8 wt. % or higher in the present invention.
  • the additional carburizing treatment may stabilize the carbon concentration of the matrix and may also promote the formation of ultrafine carbide in the outermost surface layer portion, the carburized layer itself may be converted into a dense and well-balanced structure, and the quality available through the heat treatment may be thoroughly stabilized.
  • the present invention can provide an absolutely novel, super carburized, low-distortion quenched member and its production process.
  • machine structural members such as gears and axle members can be provided with higher strength and can be used under higher contact pressure, thereby making it possible to materialize with low distortion the needs for various members of higher strength, higher performance, lighter weight and smaller size, such as members required to have low distortion, rotary sliding or reciprocal sliding members equipped with bearing structures, and members required to have high contact fatigue resistance and high abrasion resistance under high contact pressure.
EP06713304.1A 2005-02-08 2006-02-08 High-concentration carburized/low-strain quenched member and process for producing the same Expired - Fee Related EP1847630B1 (en)

Applications Claiming Priority (2)

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JP2005032302 2005-02-08
PCT/JP2006/302161 WO2006085549A1 (ja) 2005-02-08 2006-02-08 高濃度浸炭・低歪焼入れ部材およびその製造方法

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EP1847630A1 EP1847630A1 (en) 2007-10-24
EP1847630A4 EP1847630A4 (en) 2011-01-12
EP1847630B1 true EP1847630B1 (en) 2014-07-09

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US (1) US20080156399A1 (ja)
EP (1) EP1847630B1 (ja)
JP (1) JP4627776B2 (ja)
KR (1) KR100898679B1 (ja)
CN (1) CN101115859B (ja)
CA (1) CA2594838C (ja)
WO (1) WO2006085549A1 (ja)

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Publication number Priority date Publication date Assignee Title
US9212416B2 (en) 2009-08-07 2015-12-15 Swagelok Company Low temperature carburization under soft vacuum

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2008124239A1 (en) * 2007-04-06 2008-10-16 Swagelok Company Hybrid carburization with intermediate rapid quench
BR112013012641B1 (pt) * 2010-12-13 2018-06-05 Nippon Steel & Sumitomo Metal Corporation Aço de rolamento de cromo de alto carbono e método de produção do mesmo
AU2013210034A1 (en) 2012-01-20 2014-09-11 Swagelok Company Concurrent flow of activating gas in low temperature carburization
EP3000910A4 (en) * 2013-05-10 2017-01-25 Hitachi, Ltd. Software and method for calculating carbon concentration distribution
KR101575435B1 (ko) 2013-12-24 2015-12-07 현대자동차주식회사 고탄소침탄강 소재 및 이를 이용한 기어 제조방법
JP6414385B2 (ja) * 2014-02-27 2018-10-31 新日鐵住金株式会社 浸炭部品
CN104726819B (zh) * 2015-03-20 2017-09-19 上海人本集团有限公司 渗碳钢的热处理渗碳工艺
JP6922759B2 (ja) * 2018-01-25 2021-08-18 トヨタ自動車株式会社 鋼部材の製造方法
CN110184561A (zh) * 2019-07-05 2019-08-30 晋江鹏发机械有限公司 一种合金钢铸件的渗碳热处理工艺
CN110541139B (zh) * 2019-10-18 2020-11-10 浙江丰安齿轮股份有限公司 一种半轴齿轮内花键渗碳淬火方法及渗碳淬火设备
CN116065005B (zh) * 2023-03-07 2023-07-25 中国机械总院集团北京机电研究所有限公司 一种真空热处理复合工艺开发设备及处理工艺

Family Cites Families (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2260249A (en) * 1939-08-31 1941-10-21 Battelle Memorial Institute Case carburizing
JPS5569252A (en) * 1978-11-20 1980-05-24 Komatsu Ltd Carburizing method for steel
US4202710A (en) * 1978-12-01 1980-05-13 Kabushiki Kaisha Komatsu Seisakusho Carburization of ferrous alloys
EP0033403A1 (en) * 1980-01-31 1981-08-12 Ford Motor Company Method of treating the surfaces of high carbon steel bodies and bodies of high carbon steel
JP2808621B2 (ja) 1988-11-28 1998-10-08 大同特殊鋼株式会社 鋼の浸炭処理方法
JP2787455B2 (ja) 1988-12-08 1998-08-20 マツダ株式会社 浸炭焼入れ方法
JPH083720A (ja) * 1994-06-16 1996-01-09 Sumitomo Metal Ind Ltd 転動疲労寿命に優れた鋼製部品とその製造方法
JPH0881737A (ja) * 1994-09-14 1996-03-26 Daido Steel Co Ltd 摺動特性に優れるロッカーアームおよびその製造方法
JP3410947B2 (ja) * 1998-01-09 2003-05-26 日産自動車株式会社 無段変速機の転動体およびその製造方法
US6537390B1 (en) * 1999-11-11 2003-03-25 Koyo Seiko Co., Ltd. Antifriction bearing
JP2002212642A (ja) * 2001-01-10 2002-07-31 Ntn Corp 転動部品のガス浸炭焼入れ方法およびそれにより得られる転動部品
JP2002348615A (ja) 2001-05-18 2002-12-04 Daido Steel Co Ltd 耐高面圧部材およびその製造方法
JP2004285384A (ja) * 2003-03-20 2004-10-14 Daido Steel Co Ltd 高強度浸炭部品

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9212416B2 (en) 2009-08-07 2015-12-15 Swagelok Company Low temperature carburization under soft vacuum

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EP1847630A4 (en) 2011-01-12
US20080156399A1 (en) 2008-07-03
CA2594838A1 (en) 2006-08-17
CN101115859B (zh) 2011-05-18
EP1847630A1 (en) 2007-10-24
JPWO2006085549A1 (ja) 2008-06-26
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KR20070095390A (ko) 2007-09-28
CN101115859A (zh) 2008-01-30

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