• 제목/요약/키워드: Surface Hardening Treatment

검색결과 172건 처리시간 0.025초

고강도 이온질화 기어의 개발 (Development of high-strength ion nitrided gear)

  • 김영훈;선철곤;김한군
    • 열처리공학회지
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    • 제7권3호
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    • pp.184-189
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    • 1994
  • The heat treatment charaterristic of SCM 440 and B 16 steels has been investigated in various condition(A, B and C) to the effect of heat treatment on mechanical properties, and the following results were obtained. 1. We are obtained a good nitriding characteristic in bainitic structure than other heat treatment cycle in our experiment. 2. Fatigue characteristic has shown in order of B)C)A condition as heat treatment cycle. 3. The effective hardening depth and fatigue characteristic has been excellented in B 16 than SCM 440 after the nitriding and Q. T for Band C condition. 4. Nitriding depth has been increased in addition of Cr, V and the nitriding efficiency is increased as easiness of banite formation to wide range of cooling rate by addition of Mo. 5. The depth of compound layer in parallel surface, notched slop plane and notched bottom has been varied to the nitriding depth of 5, 4 and 3 ${\mu}$ in relatively uniform pattern after 10h nitriding treatment for SCM 440 into A condition.

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질화포텐셜 제어 가스질화로 개발(III) : SCR420H 에널러스기어에 대한 제어질화 적용 및 내구성 평가 (Development of Controlled Gas Nitriding Furnace(III) : Application of Controlled Gas Nitriding Process and Evaluation of Durability for SCR420H Annulus gear)

  • 이원범;정민재;권민상;김태환;문철우
    • 열처리공학회지
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    • 제36권3호
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    • pp.161-173
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    • 2023
  • This study investigated the effects of KN and process time on the formation of a compound layer at a nitriding temperature of 540℃ for SCR420H material. As a result of controlled nitriding from 3 h to 20 h at KN 1.2 atm-1/2, compound layers were formed up to about 10 ㎛, and an effective hardening depth of about 460 ㎛ was obtained. Initially, an ε+γ' complex phase was formed, and the phase fraction changed over time, and finally, the fraction of ε phase decreased to less than 1%. With higher KN, the compound thickness increased, a pore layer was formed on the surface, and the surface hardness decreased. By applying the controlled nitriding process, it was possible to produce annulus gears with a compound thickness of 12.8 ㎛ and an ε phase of 5% or less. The annulus gears made through controlled nitriding were mounted on a 6-speed transmission and tested for durability. As a result, the durability test of 250,000 km was satisfied, and the transmission efficiency was also confirmed to be expected.

함안 도항리 마갑총출토 철제금은상감환두대도의 제작기법 및 보존처리 (Manufacture technique and conservation of a big iron-golden silver-inlaying sword excavated from Haman Tohang-ri tomb)

  • 위광철
    • 보존과학연구
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    • 통권19호
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    • pp.61-74
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    • 1998
  • Conservation Treatment Process 1. Inlaying is observed at the back and head of a sword to grasp the inner structure of relics by photographing X-ray. 2. After removing rust of surface, inlaying emerge. 3. After hardening, inlaying emerge to magnetite layer by standing Scapel and Vibrotool throught microscope. Charcterization 1. Most of domestic inlaying become designed to the head of a sword but this inlaying become designed to gold inlaying to the back of a sword. 2. Inlaying is the technique to groove V-shape on the surface of relice and to put gold thread in.

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60 kgf/$\textrm{mm}^2$급 자동차용 변태유기소성강화강 Zn-Ni 전기도금 특성 연구 (Characteristics of Zn-Ni Electrodeposition of 60 kgf/$\textrm{mm}^2$ Grade Transformation Induced Plastic Steel Sheets for Automotive Body)

  • 김동환;김병일;전유택;정연수
    • 한국표면공학회지
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    • 제37권5호
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    • pp.263-272
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    • 2004
  • High strength steels such as transformation induced plastic steel, dual phase and solid solution Hardening have been developed and continuously improved due to the intensified needs in the automotive industry. But silicon and manganese in transformation induced plastic steels were known to exhibit harmful effects on galvannealing reaction by oxide film formed during heat treatment. Therefore, in this work, the applicability of Zn-Ni electrodeposition instead of hot dip galvannealed coating to transformation induced plastic steels was evaluated and optimum electroplating condition was investigated. Based on these investigations optimized electroplating conditions were proposed and Zn-Ni electrogalvanized steel sheet was produced by EGL (electrogalvanized line). Its perfomance properties for automotive steel was evaluated.

유동상열처리로에 의해 BORIDING처리한 철강재료의 미끄럼마모특성연구 (Sliding Wear Properties of Borided Iron and Steel in Fluidized Bed Furnace)

  • 이한영;배석천
    • 열처리공학회지
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    • 제9권4호
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    • pp.261-270
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    • 1996
  • Boriding is one of the chemical methods to achieve the case hardening of steel as well as nitriding or carburizing. The surface layer of the borided steel shows higher hardness and exhibits better resistance to corrosion or fatigue than the nitrided or carburized steel. The great majority of previous studies were confined to mild steel or some alloy steel. To enlarge the application, ductile cast iron (DCI) as a material for boriding has been tried in this study. Thus, sliding wear test has conducted using a pin-on-disc machine to compare between borided DCI and mild steel in fluidized bed furnace. The results show that the wear resistance of borided DCI is improved. Especially it is more efficient in the case of occurence of the mechanical wear.

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유도 표면 경화의 야금학적 고찰 (The Metallurgy of Induction Surface Hardening)

  • 장우양
    • 열처리공학회지
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    • 제14권4호
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    • pp.235-239
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    • 2001
  • 급속 표면가열과 기존의 전기로 열처리에서 얻어지는 경화의 가장 중요한 차이점은 전자가 불균질한 오스테나이트를 생성할 수도 있다는 것이다. 즉, 오스테나이트에 미용해 탄화물이 존재할 수도 있고 탄소와 합금원소의 농도 구배가 존재할 수도 있다. 합금강에서, 이러한 탄화물은 합금성분이 비교적 높기 때문에 철 탄화물에 비해서는 좀 더 천천히 기지에 용해된다. 또한 망간, 크롬, 니켈 및 몰리브덴과 같은 치환형 합금원소는 천천히 확산한다. 따라서, 균일한 오스테나이트를 생성하기 위해서는 더 많은 시간과 더 높은 온도가 요구된다. 그러나 표면 구역의 낮은 경화능에도 불구하고 냉각속도가 마르텐사이트의 체적분율이 큰 미세조직을 확보할 만큼 충분히 크기 때문에 경도는 높게 된다.

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GC250D의 가스분위기 제어질화 공정에서 화합물층의 형성에 따른 표면조도의 변화 (Surface Roughness and Formation of Compound Layer in the Controlled Gaseous Nitriding Process on Cast Iron GC250D)

  • 정민재;손석원;위재용;이영국;이원범
    • 열처리공학회지
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    • 제37권2호
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    • pp.49-57
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    • 2024
  • We investigated the changes in microstructure and surface roughness of the compound layer of GC250D gray cast iron, commonly used in brake discs, during gas nitriding. The gas atmosphere of the nitriding process was controlled with a hydrogen partial pressure of 49.5%, and the process was conducted at a nitriding temperature of 520℃ with various process times. As the nitriding process time of the GC250D material increased, both the depth of hardening and the thickness of the compound layer increased, with a maximum surface hardness of approximately 1265 HV0.1 was measured. Additionally, the surface roughness increased with the process time. Phase analysis of the compound layer revealed an increase in the proportion of the γ' phase as the nitriding process time increased. Changes in the formation of the compound layer were observed depending on the orientation of graphite within the material, leading to the formation of wedges. Therefore, the increase in surface roughness appears to be attributed to the uneven compounds, the expansion of the compound layer and wedges formed on the surface during the nitriding process.

Effects of Alloying Element and Heat Treatment on Properties of Cu-Ti Alloys

  • Suk, Han-Gil;Hong, Hyun-Seon
    • 한국표면공학회지
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    • 제42권5호
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    • pp.246-249
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    • 2009
  • Cu-Ti alloys with titanium in the range of 0.5-6.0 wt% were developed to evaluate the effect of the titanium content and heat treatment on microstructure, hardness, and electrical conductivity. The hardness of the Ti-added copper alloys generally increased with the increase in titanium content and hardening was effective up to the 2.5 wt%-Ti addition. Microstructural examination showed that the second phase of $Cu_4Ti$ started to precipitate out from the 3.0 wt% Ti-addition, and the precipitate size and volume fraction increased with further Ti addition. Aging of the present Cu-Ti alloys at $450^{\circ}C$ for 1 h increased the hardness; however, the further aging up to 10 h did not much change the hardness. In the present study, it was inferred that in optimal Ti addition and aging condition Cu-Ti alloy could have the hardness and electrical conductivity values which are comparable to those of commercial Cu-Be alloy.

마이크로 펄스 플라즈마 질화에 의해 생성된 금형 공구강의 표면층에 관한 연구 -공정 변수의 영향- (The Microstructures and Properties of Surface Layer on the Tool Steel Formed by Ion Nitriding -Effects of Process Parameter-)

  • 이재식;김한군;유용주
    • 열처리공학회지
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    • 제14권1호
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    • pp.8-16
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    • 2001
  • The effects of gas composition, pressure, temperature and time on the case thickness, hardness and nitride formation in the surface of tool steels(STD11 and STD61) have been studied by micro-pulse plasma nitriding. External compound layer and internal diffusion layer and the diffusion layer were observed in the nitrided case of tool steels. The relative amounts and kind of phases formed in the nitrided case changed with the change of nitriding conditions. Generally, only nitride phases such as ${\gamma}(Fe_4N)$, ${\varepsilon}(Fe_{2-3}N)$, or $Cr_{1.75}V_{0.25}N_2$ phases were detected in the compound layer, while nitride and carbide phases such as ${\varepsilon}-nitride(Fe_{2-3}N)$, $(Cr,Fe)_{\gamma}C_3$ or $Fe_3C$ were detected in the diffusion layer by XRD analysis. The thickness of compound layer increased with the increase of nitrogen content in the gas composition. Maximum case depth was obtained at gas pressure of 200Pa.

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유압 피스톤 펌프 소재의 마모 특성에 관한 연구 (A Study on Wear Property of Oil Hydraulic Piston Pump Material)

  • 김남석;김현수;성기용;안석환;남기우
    • 한국해양공학회지
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    • 제23권3호
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    • pp.30-34
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    • 2009
  • Oil hydraulic piston pumps are being extensively used in the world, because of simple design, light weight and effective cost etc. An oil hydraulic pump is likely to have serious problems of high leakage, friction and low energy efficiency according to large time use. In the oil hydraulic piston pumps the clearance between the valve block and piston plays an important role for volumetric and overall efficiency. In this paper, the wear property of the SACM645 material used the hydraulic piston pump has been work out by experimentation with variable heat treatment. To investigate the effect according to the piston surface condition, seven different types specimen were prepared. From the wear test results, induction hardening and nitration were definitely superior to the others. On the whole, nitration was estimated for high strength material to wear resistance.