KR20000037732A - Method of heat treatment for letting steel in with high carbon which increases fitting resistance, abrasion resistance and friction resistance of steel - Google Patents

Method of heat treatment for letting steel in with high carbon which increases fitting resistance, abrasion resistance and friction resistance of steel Download PDF

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KR20000037732A
KR20000037732A KR1019980052464A KR19980052464A KR20000037732A KR 20000037732 A KR20000037732 A KR 20000037732A KR 1019980052464 A KR1019980052464 A KR 1019980052464A KR 19980052464 A KR19980052464 A KR 19980052464A KR 20000037732 A KR20000037732 A KR 20000037732A
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South Korea
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temperature
carburizing
steel
high carbon
carbon
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KR1019980052464A
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Korean (ko)
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안승균
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정몽규
현대자동차 주식회사
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Priority to KR1019980052464A priority Critical patent/KR20000037732A/en
Publication of KR20000037732A publication Critical patent/KR20000037732A/en

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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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

PURPOSE: A heating method for carbonizing a steel with high carbon is provided to increase fitting resistance, abrasion resistance and friction resistance of the steel by forming a fine carbide inside a carbonizing layer. CONSTITUTION: A heating cycle starts carbonization of a low carbon steel under the condition of 1.2 to 2.0 of carbon concentration in an alpha + gamma area which is an Ar1 to Ar3 section. Then temperature is increased to 850 to 930°C as a target carbonizing temperature and the temperature is decreased to 800 to 850°C. An alpha phase has small carbon employment in order to be applied as a carbide nuclear generating position and to make the carbide size fine with low crystallization. The heating time is changed depending on hardening depth that takes 30 minutes to 2 hours in the alpha + gamma area, 2 to 6hours in a temperature of 850 to 930°C and 30 minutes to 1 hour in a temperature of 800 to 850°C.

Description

강의 내피팅성, 내마모 특성 및 마찰저항 특성을 향상시키는 고탄소 침탄 열처리 방법High carbon carburizing heat treatment method to improve the fitting resistance, wear resistance and friction resistance of steel

본 발명은 강 (steel)의 내피팅성, 내마모 특성 및 마찰저항 특성을 향상시킬 수 있는 고탄소 침탄 열처리 방법에 관한 것으로, 보다 상세하게는 저탄소강을 Fe-C 상태도 상의 Ac1점 이상의 온도에서 Acm 선상의 탄소 농도 (carbon potential)를 초과하는 분위기 하에서 침탄을 개시하여 오스테나이트 (Austenite)상까지 온도를 상승시키면서 고탄소 침탄을 수행하여 침탄층 내에 미세한 탄화물을 형성시킴으로써 강의 내피팅성, 내마모 특성 및 마찰저항 특성을 향상시키는 고탄소 침탄 열처리 방법에 관한 것이다.The present invention relates to a high carbon carburizing heat treatment method which can improve the fitting resistance, abrasion resistance and friction resistance of steel, and more specifically, the low carbon steel has a temperature higher than Ac1 point on Fe-C state diagram. In the atmosphere above the Acm linear carbon potential, the carburizing process starts by carburizing, raising the temperature to the austenite phase, and performing high carbon carburization to form fine carbide in the carburized layer. A high carbon carburizing heat treatment method for improving abrasion resistance and frictional resistance characteristics.

최근 엔진의 고성능화, 고출력화에 따른 부품의 내구성, 신뢰성에 대한 요구가 강력히 대두되고 있다. 통상 변속기 (transmission) 및 엔진 재료의 침탄품은 고면압 (高面壓)과 고RPM 하에서 마찰열로 인해 마르텐사이트 (Martensite) 조직이 소려 연화되어 내피팅성 (Pitting-proof) 및 스커핑 (Scuffing) 저항성이 떨어진다. 이러한 문제를 해결하기 위해 1960년 이후 여러 학자들에 의해 고탄소 침탄 열처리 기술개발 및 평가가 활발히 진행되어 1980년 중반에 이르러 자동차 엔진용 태핏 (tappet), 밸브 리프터 (valve lifter), 커넥팅 로드 (connecting rod), 베어링 (bearing), 구동축(drive shaft) 및 고부하(高負荷) 기어 등의 부품에 적용가능성이 검토되었으나 탄화물의 형상, 크기 (입경) 및 양 등의 제어기술이 안정적이지 못하고, 오스테나이트 입계에 위험한 망상탄화물이 용이하게 석출된다는 문제점이 있는데, 망상탄화물이 석출되면 표면 침탄층의 기계적 강도, 특히 접촉피로강도가 저하하여 박리를 유발하여 내피팅 측면에서 불리하다. 이러한 문제점 이외에 기존의 고탄소 침탄법은 합금강에 탄화물 생성 원소가 작고, 처리 패턴이 복잡하고 장시간이 요구될 뿐만 아니라 일반 침탄로에서 열처리하는 경우 입계산화층이 형성되고, 높은 분위기의 탄소농도 (carbon potential; C.P)에서 열처리함으로 인한 로벽 그을음 (Sooting)으로 인하여 생산성 및 품질의 안정적 확보가 곤란하여 양산화에는 실패하였다.Recently, there is a strong demand for durability and reliability of components due to high performance and high output of the engine. Usually, carburizing products of transmission and engine materials are softened by martensite structure due to frictional heat under high surface pressure and high RPM, resulting in pitting-proof and scuffing resistance. Falls. In order to solve this problem, since 1960, various scholars have been actively developing and evaluating high-carbon carburizing heat treatment technology. By mid-1980, tappet, valve lifter and connecting rod for automobile engine Applicability to parts such as rods, bearings, drive shafts and high-load gears has been examined, but control technologies such as carbide shape, size (particle size) and quantity are not stable and austenite There is a problem in that the reticular carbides which are dangerous at the grain boundaries are easily precipitated, but the precipitation of the reticular carbides is disadvantageous in terms of fitting resistance since the mechanical strength of the surface carburized layer, in particular, the contact fatigue strength, is reduced, causing peeling. In addition to these problems, the conventional high carbon carburizing method has a small carbide generation element in the alloy steel, a complicated processing pattern, a long time is required, a grain boundary oxide layer is formed when heat treatment is performed in a general carburizing furnace, and a high carbon concentration (carbon potential). ; Sooting due to heat treatment in CP) prevented mass production because it was difficult to secure stable productivity and quality.

이에 본 발명자는 상기 문제점을 해결하기 위하여 노력하여 오던 중 저압 진공침탄로를 이용하여 침탄층의 마르텐사이트 기지내에 미세한 유리탄화물을 석출시킬 수 있는 탄화물 제어기술 및 1공정으로 처리가 가능한 고탄소 침탄방법을 개발하여 본 발명을 완성하였다.The present inventors have been trying to solve the above problems by using a low pressure vacuum carburizing furnace carbide control technology that can precipitate fine glass carbide in the martensite base of the carburizing layer and a high carbon carburizing method that can be treated in one step It was developed to complete the present invention.

본 발명의 목적은 내피팅성, 내마모 특성 및 마찰저항 특성이 우수한 강을 얻기 위한 고탄소 침탄 열처리 방법을 제공하는 것이다.It is an object of the present invention to provide a high carbon carburizing heat treatment method for obtaining steel having excellent fitting resistance, abrasion resistance and friction resistance.

도 1은 본 발명의 고탄소 침탄 공정의 개략도이고, 1 is a schematic diagram of a high carbon carburizing process of the present invention,

도 2는 고탄소 침탄 전용강인 RK706 (대동특수강 제품)을 소재로 본 발명의 방법에 의해 처리된 시험편의 표면조직을 나타낸 사진이고, Figure 2 is a photograph showing the surface texture of the test piece treated by the method of the present invention based on RK706 (product of Daedong Special Steel), a high carbon carburized steel,

도 3은 상기 도 1의 시험편에 석출된 탄화물의 크기 분포를 나타낸 그래프 이고, 3 is a graph showing the size distribution of carbide deposited on the test piece of FIG.

도 4는 고탄소 침탄재의 마모특성을 나타낸 그래프이고, Figure 4 is a graph showing the wear characteristics of the high carbon carburizing material,

-●- : RK706 + 고탄소 침탄 -▲- : SCM722H + 고탄소 침탄-●-: RK706 + High Carbon Carburization-▲-: SCM722H + High Carbon Carburization

-▼- : SCM415H + 일반 침탄-▼-: SCM415H + General Carburization

도 5는 소려온도를 100∼500 ℃로 변화시켜 표면경도를 확인한 결과를 나타낸 그래프이고, 5 is a graph showing the results of confirming the surface hardness by changing the soaking temperature to 100 ~ 500 ℃,

-▼- : 기존 침탄 -●- : 고탄소 침탄-▼-: Conventional Carburization-●-: High Carbon Carburization

도 6은 고탄소 침탄재의 피팅 저항성을 나타낸 그래프이다. 6 is a graph showing the fitting resistance of the high carbon carburized material.

① : RK706 + 고탄소 침탄 ② : SCM318H1 + 진공 침탄①: RK706 + high carbon carburizing ②: SCM318H1 + vacuum carburizing

③ : SCM318H1 + 기존 침탄③: SCM318H1 + conventional carburization

상기 목적을 달성하기 위하여 본 발명에서는 저탄소강을 Fe-C 상태도 상의 Ac1점 이상의 온도에서 Acm 선상의 탄소 농도를 초과하는 분위기 하에서 침탄을 개시하여 오스테나이트 상까지 온도를 상승시키면서 고탄소 침탄을 수행하여 침탄층 내에 미세한 탄화물을 형성시킴으로써 강의 내피팅성, 내마모 특성 및 마찰저항 특성을 향상시키는 고탄소 침탄 열처리 방법을 제공한다.In order to achieve the above object, in the present invention, high carbon carburization is performed while low carbon steel is started carburizing in an atmosphere exceeding Acm linear carbon concentration at a temperature equal to or more than Ac1 point on Fe-C state diagram. By providing a fine carbide in the carburized layer to provide a high carbon carburizing heat treatment method for improving the fitting resistance, wear resistance and frictional resistance properties of the steel.

이하 본 발명을 상세히 설명한다.Hereinafter, the present invention will be described in detail.

본 발명에서는 저탄소강을 Fe-C 상태도 상의 Ac1점 이상의 온도에서 Acm 선상의 탄소 농도를 초과하는 분위기 하에서 침탄을 개시하여 오스테나이트 상까지 온도를 상승시키면서 고탄소 침탄을 수행하여 침탄층 내에 미세한 탄화물을 형성시키는 것을 특징으로 하는 고탄소 침탄 열처리 방법을 제공하는 것이다.In the present invention, the low carbon steel starts carburizing in an atmosphere exceeding the Acm linear carbon concentration at the temperature of Ac1 point or more on the Fe-C state diagram, and performs high carbon carburizing while raising the temperature to the austenite phase. It is to provide a high carbon carburizing heat treatment method characterized in that to form a.

본 발명의 열처리 방법은도 1과 같은 열처리 사이클로 이루어져 있는데, 이는 Ar1∼Ar3 구간인 α+γ 영역에서 탄소농도 1.2∼2.0의 분위기 하에서 저탄소강의 침탄을 개시하여 10 ℃/분의 승온속도로 목적 침탄온도인 850∼930 ℃로 승온시켜서 침탄하고 이를 다시 800∼850 ℃ 정도의 온도로 온도를 낮추는 과정으로 구성된다. 이 때 저탄소강을 Ar1∼Ar3 구간인 α+γ 영역에서 탄소농도 1.2∼2.0 분위기 하에서 침탄 개시시 α상은 탄소 고용도가 작아 탄화물 핵생성 위치로 작용함과 동시에 침탄온도가 낮으므로 결정립이 작아 탄화물 크기 또한 미세해지고 침탄온도 상승에 따른 γ 영역에서 탄소 고용량 증대에 따라 적절한 탄화물 깊이의 미세 탄화물이 생성되는 것이다.The heat treatment method of the present invention consists of a heat treatment cycle as shown in FIG . It is composed of a process of carburizing by raising the temperature to 850 ~ 930 ℃ and lowering the temperature to a temperature of about 800 ~ 850 ℃ again. At this time, when carburizing starts low carbon steel under the carbon concentration of 1.2 ~ 2.0 in the region of Ar1 ~ Ar3, the α phase acts as a carbide nucleation site due to its low carbon solubility and at the same time the carburizing temperature is low. In addition, as the size becomes finer and the higher carbon capacity increases in the gamma region due to the increase in the carburizing temperature, fine carbides having an appropriate carbide depth are produced.

상기에서 열처리 시간은 부품의 유효경화 깊이에 따라 변할 수 있으나, Ar1∼Ar3 구간인 α+γ 영역에서 30분∼2시간, 850∼930 ℃ 온도에서 2시간∼6시간, 800∼850 ℃ 정도의 온도에서 30분∼1시간 동안 수행하는 것이 바람직하다.The heat treatment time may vary depending on the effective hardening depth of the part, but 30 minutes to 2 hours in the α + γ region, Ar1 to Ar3, 2 hours to 6 hours at 850 to 930 ° C, and 800 to 850 ° C. Preference is given to performing at temperature for 30 minutes to 1 hour.

또한 본 발명의 고탄소 침탄 방법에서는 저압 진공 침탄로를 이용하는 것이 바람직한데, 이는 일반 침탄로에서 열처리를 수행할 경우 발생되는 입계 산화층 및 로벽 그을음이 나타나지 않기 때문이다.In addition, in the high carbon carburizing method of the present invention, it is preferable to use a low pressure vacuum carburizing furnace because the grain boundary oxide layer and the furnace wall soot generated when the heat treatment is performed in a general carburizing furnace do not appear.

본 발명의 방법은 자동차 엔진용 태핏심 (tappet shim), 밸브 리프터 (valve lifter), 커넥팅 로드 (connecting rod), 베어링 (bearing), 구동축 (drive shaft) 및 고부하 (高負何) 기어 등의 부품에 적용가능한 유용한 고탄소 침탄 열처리 방법이다. 엔진 저속에서의 기여율이 높은 밸브계의 마찰 저감은 실차 연비 향상에 매우 효과적인 수단인데, 본 발명의 방법으로 처리된 고탄소 침탄재는 마르텐사이트 침탄층 내에 아주 강한 탄소 알갱이가 골고루 분포된 형태이므로 자동차의 내마모 부품들에 특히 유용하게 적용될 수 있는 것이다.The method of the present invention is suitable for parts such as tappet shims, valve lifters, connecting rods, bearings, drive shafts and high load gears for automobile engines. It is a useful high carbon carburizing heat treatment method applicable to. The friction reduction of the valve system with high contribution rate at low engine speed is a very effective means to improve the fuel efficiency of the vehicle. The high carbon carburizing material treated by the method of the present invention has a very strong carbon grain evenly distributed in the martensite carburizing layer. Particularly useful for wear resistant parts.

이하 실시예 및 실험예에 의하여 본 발명을 상세히 설명하기로 한다. 하기 실시예 및 실험예는 본 발명을 예시하는 것일 뿐 본 발명이 이들에 의하여 한정되는 것은 아니다.Hereinafter, the present invention will be described in detail by Examples and Experimental Examples. The following Examples and Experimental Examples are only illustrative of the present invention and the present invention is not limited thereto.

〈실시예〉<Example>

대동특수강(일) 제품인 고탄소 침탄 전용강인 RK7060 (0.18C-0.4Si-2.15Cr- 0.4Mo)을 진공침탄로에 넣고 탄소농도 1.6의 분위기에서 780 ℃온도에서 침탄을 개시한 다음 1시간이 경과한 다음 10 ℃/분의 승온속도로 900 ℃정도가 될 때까지 온도를 높여 이 온도에서 4시간 동안 처리한 다음 역시 10 ℃/분의 속도로 830 ℃가 될 때까지 온도를 낮추어 30분 동안 처리하여 본 발명의 고탄소 침탄 열처리 방법으로 표면처리된 강을 얻어 이를 후술하는 실험예에 시험편으로 사용하였다.RK7060 (0.18C-0.4Si-2.15Cr-0.4Mo), a high carbon carburizing steel made from Daedong Special Steel (Japan), was placed in a vacuum carburizing furnace, and carburization was started at 780 ° C under a carbon concentration of 1.6 Then, increase the temperature until it reaches 900 ℃ at a temperature increase rate of 10 ℃ / min, and then treat at this temperature for 4 hours, and then lower the temperature until it reaches 830 ℃ at the rate of 10 ℃ / min for 30 minutes. To obtain a steel surface-treated by the high carbon carburizing heat treatment method of the present invention was used as a test piece in the experimental example described later.

[실험예]Experimental Example

우선 상기 실시예에서 제조한 시험편의 표면조직으로 마르텐사이트 침탄층 내에 미세한 구상탄화물이 석출된 형태를도 2에 나타냈다.도 2에서 볼 수 있는 탄화물 형상 및 기지조직을 분석한 결과는 하기표 1과 같고 탄화물 크기 분포는도 3에 나타내었다.First, the form in which the fine spherical carbide precipitated in the martensite carburized layer as the surface structure of the test piece prepared in the above example is shown in FIG. 2 . The results of analyzing the carbide shape and matrix structure as shown in FIG. 2 are shown in Table 1 below , and the carbide size distribution is shown in FIG. 3 .

탄화물량(%)Carbide amount (%) 탄화물 두께(mm)Carbide thickness (mm) 탄화물 크기(㎛)Carbide size (μm) 탄화물 형상Carbide shape 표면경도(Hv)Surface Hardness (Hv) 잔류 오스테나이트량(%)Residual Austenite Content (%) 목표치Target 20∼2520-25 0.10.1 5 이하5 or less 미세구상탄화물Fine Spherical Carbide 850 이상850 or more 10 이하below 10 실시예의 시험편Test piece of the example 25.225.2 0.10.1 4 이하4 or less 미세구상탄화물Fine Spherical Carbide 870∼890870-890 5.695.69

한편도 4는 고탄소 침탄재의 마모특성을 핀 온 디스크 타입 (Pin on Disc Type)으로 시험한 결과를 나타낸 것으로 기존 침탄재 (-▼- : SCM415H + 일반 침탄)의 마찰계수는 0.101∼0.125 수준이나 본 발명의 방법으로 처리한 고탄소 침탄재 (-●- : RK706 + 고탄소 침탄)의 경우 0.064∼0.072로 기존 침탄재에 비해 약 40%의 마찰계수 저감효과를 나타냈다. 고탄소 침탄 전용강이 아닌 일반 침탄강 (SCM722H)에 고탄소 침탄 처리한 시험편 (-▲- : SCM722H + 고탄소 침탄) 또한 0.069∼0.072로 뛰어난 마찰특성 효과가 있었다. 핀 (Pin) 마모량 또한 고탄소 침탄재가 기존 침탄재에 비해 1/2 수준으로 내마모저항이 우수함을 보였다.On the other hand, Figure 4 shows the results of testing the wear characteristics of the high carbon carburizing material (Pin on Disc Type), the friction coefficient of the existing carburizing material (-▼-: SCM415H + general carburizing) is 0.101 ~ 0.125 In the case of the high carbon carburized material (-●-: RK706 + high carbon carburized) treated by the method of the present invention, 0.064 to 0.072 exhibited a friction coefficient reduction effect of about 40% compared to the existing carburized material. High carbon carburized specimens (-▲-: SCM722H + high carbon carburized) in general carburized steel (SCM722H), not high carbon carburized steel, also had excellent friction characteristics. Pin wear also showed that the high carbon carburized material had abrasion resistance superior to that of the existing carburized materials at 1/2 level.

이러한 이유는 기존 침탄재의 경우 자기재와 상대재와의 마찰열로 인해 발열, 표면연화로의 급진적마모의 과정을 겪게 되나 고탄소 침탄재는 침탄층 내에 미세한 탄화물이 발열로 인한 매크로 (Macro)적 응착마모를 최소화시켜 급진적 마모를 저지시키기 때문이다.The reason for this is that existing carburizing materials undergo radical wear to heat generation and surface softening due to frictional heat between magnetic materials and counterpart materials.However, high carbon carburizing materials suffer from macro-adhesive wear due to the generation of fine carbides in the carburizing layer. This minimizes radical wear and prevents wear.

도 5는 침탄층의 열적안정성을 확인하기 위해 소려온도를 100∼500 ℃로 변화시켜 표면경도를 확인한 결과로 기존 침탄재 (▼)는 200 ℃로 마모면의 발열에 의한 온도상승시 일반적인 침탄층의 물성을 잃어 버리나 고탄소 침탄재 (●)의 경우 450 ℃에서도 표면경도 Hv 650 이상을 유지하고 있어 우수한 고온 연화저항 특성을 나타냈다. Figure 5 shows the surface hardness by changing the soaking temperature to 100 ~ 500 ℃ to check the thermal stability of the carburizing layer, the existing carburizing material (▼) is 200 ℃ general carburizing layer when the temperature rise due to heat generation of the wear surface However, the high carbon carburizing material (●) retained its surface hardness of Hv 650 or higher even at 450 ° C, showing excellent high temperature softening resistance.

도 6에 로울러 타입 (Roller type) 접촉피로시험기를 이용하여 미끄럼율 (Slip ratio) 40%, 오일온도 50±3 ℃, 오일분사속도 1.21/분, 샤프트 (Shaft) 회전속도 1000 rpm, 헤르쯔 접촉 압력 332 kgf/mm2조건으로 고탄소 침탄재의 내피팅성을 시험한 결과이다. 고탄소 침탄재 (① : RK706 + 고탄소 침탄)는 1.1 × 107Cycle 이상에서도 피팅이 발생되지 않았으며, 기존 침탄재 (③ : SCM318H1 + 기존 침탄) 및 진공 침탄재 (② : SCM318H1 + 진공 침탄)에 비해서 우수한 내피팅 저항성을 나타내었다. Figure 6 using a roller type contact fatigue tester (Slip ratio) 40%, oil temperature 50 ± 3 ℃, oil spray rate 1.21 / min, shaft rotation speed 1000 rpm, Hertz contact pressure The test results of the fitting resistance of high carbon carburized material under 332 kgf / mm 2 condition. High carbon carburizing materials (①: RK706 + high carbon carburizing) did not produce fittings even over 1.1 × 10 7 Cycle, and existing carburizing materials (③: SCM318H1 + conventional carburizing) and vacuum carburizing materials (②: SCM318H1 + vacuum carburizing) It showed excellent fitting resistance compared to).

이상에서 살펴본 바와 같이, 본 발명의 고탄소 침탄 열처리 방법은 1공정으로 처리가 가능하여 신속하게 저탄소강을 침탄 처리할 수 있을 뿐만 아니라 탄화물의 형상, 양 및 크기를 안정적으로 제어할 수 있는 공정으로서 침탄층 내에 미세한 탄화물을 형성시킴으로써 강의 내피팅성, 내마모 특성 및 마찰저항 특성을 크게 향상시킬 수 있는 방법이다. 또한 본 발명의 방법은 고출력화에 대응하는 자동차 엔진용 태핏심, 밸브 리프터, 커넥팅 로드, 베어링, 구동축 및 고부하 기어 등의 자동차의 내마모 부품에 효과적으로 적용될 수 있다.As described above, the high-carbon carburization heat treatment method of the present invention can be processed in one step, and not only can quickly carburize low-carbon steel, but also stably control the shape, quantity and size of carbides. By forming fine carbide in the carburized layer, it is a method that can greatly improve the fitting resistance, wear resistance and frictional resistance characteristics of steel. In addition, the method of the present invention can be effectively applied to wear-resistant parts of automobiles such as tappet shims, valve lifters, connecting rods, bearings, drive shafts, and high load gears for automobile engines corresponding to high output.

Claims (5)

저탄소강을 Fe-C 상태도 상의 Ac1점 이상의 온도에서 Acm 선상의 탄소 농도 (carbon potential)를 초과하는 분위기 하에서 침탄을 개시하여 오스테나이트 (Austenite)상까지 온도를 상승시키면서 고탄소 침탄을 수행하여 침탄층 내에 미세한 탄화물을 형성시키는 것을 특징으로 하는 고탄소 침탄 열처리 방법Carburizing the low carbon steel by initiating carburization in the atmosphere exceeding the carbon potential on the Acm line at a temperature above Ac1 point on the Fe-C state diagram and carrying out high carbon carburization while raising the temperature to the austenite phase High carbon carburizing heat treatment method characterized in that to form fine carbide in the layer 제 1항에 있어서, Ar1∼Ar3 구간인 α+γ 영역에서 탄소농도 1.2∼2.0의 분위기 하에서 저탄소강의 침탄을 개시하여 10 ℃/분의 승온속도로 목적 침탄온도인 850∼930 ℃로 승온시켜서 침탄하고 이를 다시 800∼850 ℃ 정도의 온도로 온도를 낮추는 과정으로 이루어지는 것을 특징으로 하는 고탄소 침탄 열처리 방법The carburizing process of claim 1, wherein in the α + γ region of Ar1 to Ar3, carburization of low carbon steel is started under an atmosphere of carbon concentration of 1.2 to 2.0, and the temperature is raised to a target carburizing temperature of 850 to 930 ° C at a heating rate of 10 ° C / min. High carbon carburizing heat treatment method comprising the process of lowering the temperature to a temperature of about 800 ~ 850 ℃ again 제 2항에 있어서, 침탄은 Ar1∼Ar3 구간인 α+γ 영역에서 30분∼2시간, 850 ∼930 ℃ 온도에서 2시간∼6시간, 800∼850 ℃ 정도의 온도에서 30분∼1시간 동안 수행하는 것을 특징으로 하는 고탄소 침탄 열처리 방법3. The carburizing method according to claim 2, wherein the carburization is carried out for 30 minutes to 2 hours at an α + γ region in the Ar1 to Ar3 section, for 2 to 6 hours at a temperature of 850 to 930 ° C, and for 30 minutes to 1 hour at a temperature of about 800 to 850 ° C. High carbon carburizing heat treatment method characterized in that 제 1항에 있어서, 침탄은 저압 진공 침탄로를 이용하는 것을 특징으로 하는 고탄소 침탄 열처리 방법The high carbon carburization heat treatment method according to claim 1, wherein the carburization is performed using a low pressure vacuum carburizing furnace. 제 1항에 있어서, 저탄소강은 자동차 엔진용 태핏심 (tappet shim), 밸브 리프터 (valve lifter), 커넥팅 로드 (connecting rod), 베어링 (bearing), 구동축 (drive shaft) 및 고부하 (高負何) 기어를 포함하는 자동차의 내마모 부품인 것을 특징으로 하는 고탄소 침탄 열처리 방법The low carbon steel of claim 1, wherein the low carbon steel is a tappet shim, a valve lifter, a connecting rod, a bearing, a drive shaft, and a high load for an automotive engine. High carbon carburizing heat treatment method characterized in that the wear-resistant parts of the automobile including the gear
KR1019980052464A 1998-12-02 1998-12-02 Method of heat treatment for letting steel in with high carbon which increases fitting resistance, abrasion resistance and friction resistance of steel KR20000037732A (en)

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WO2015037897A1 (en) * 2013-09-11 2015-03-19 한국델파이주식회사 Hollow drive shaft and method for manufacturing same

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2015037897A1 (en) * 2013-09-11 2015-03-19 한국델파이주식회사 Hollow drive shaft and method for manufacturing same
US10018219B2 (en) 2013-09-11 2018-07-10 Erae Ams Co., Ltd. Hollow drive shaft and method for manufacturing same

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