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플라즈마 침질탄화처리시 처리시간이 화합물층의 특성에 미치는 영향
박율민(Y. M. Park),신평우(P. W. Shin),조효석(H. S. Cho),남기석(K. S Nam),이구현(K. H. Lee) 한국진공학회(ASCT) 2000 Applied Science and Convergence Technology Vol.9 No.4
플라즈마 침질탄화처리는 보통탄소강, 저합금강 등에 내마모성, 내식성 및 내피로성 향상에 사용되어 있으며 자동차 부품, 기계류 부품, 공업용 공구 등에 적용할 수 있는 표면경화열처리이지만 내마모성 및 내식성을 향상시키는 단상의 ε 화합물층을 생성시키기는 어려운 문제점으로 남아 있다. 따라서 본 연구에서는 탄소강과 저합금강에 대해 질소와 CH₄ 가스농도를 변화시켜 플라즈마 침질탄화처리를 실시하여 단상의 ε 화합물층 생성가능성과 시간을 변화시켜 화합물층의 생성과정을 고찰하였다. ε 화합물층은 질소농도가 증가할수록 형성이 용이하였고 CH₄ 가스농도가 증가할수록 ε 화합물층의 형성이 용이하였지만 시멘타이트상이 생성되었다. 화합물층은 10분이 경과한 후 생성되었고 γ’상으로부터 시작되었으며 처리시간이 10시간 이상이 되면 화합물층내에 시멘타이트상이 생성되어 화합물층의 두께가 감소하였다. Plasma nitrocarburising is a thermochemical heat treatment, and can be used for plain carbon steels and low alloy steels to improve wear, corrosion and fatigue resistance. The process is performed on automotive parts, machinery parts and engineering tools. However, it is still facing problems in obtaining a mono ε phased compound layer. Therefore, the aim of this research is to investigate the possibility of forming a mono ε phased compound layer using a gas mixture of nitrogen and methane. ε was found that high nitrogen contents were essential for the production of ε phase compound layer and with increasing methane content in the gas mixture, ε phase compound layer was favoured. In addition, when the methane content was further increased, cementite was observed in the compound layer. γ' phase was produced after 10 minutes treatment time and cementite was formed in the compound layer resulting in decreasing the thickness of the compound layer.
이구현(K . H . Lee),남기석(K . S . Nam),이상로(S . R . Lee),조효석(H . S . Cho),신평우(P . W . Shin),박율민(Y . M . Park) 한국열처리공학회 2001 熱處理工學會誌 Vol.14 No.2
N/A Plasma nitrocarburising and post oxidation were performed on SM45C steel using a plasma nitriding unit. Nitrocarburising was carried out with various methane gas compositions with 4 torr gas pressure at 570℃ for 3hours and post oxidation was carried out with 100% oxygen gas atmosphere with 4 torr at different temperatures for various times. It was found that the compound layer produced by plasma nitrocarburising consisted of predominantly ε-Fe_(2-3)(N,C) and a small proportion of γ-Fe₄(N,C). With increasing methane content in the gas mixture, a phase compound layer was favoured. In addition, when the methane content was further increased, cementite was observed in the compound layer. The very thin oxide layer on top of the compound layer was obtained by post oxidation. The formation of oxide phase was initially started from the magnetite(Fe₃O₄) and with increasing oxidation time, the oxide phase was increased. With increasing oxidation temperature, oxide phase was increased. However the oxide layer was split from the compound layer at high temperature. Corrosion resistance was slightly influenced by oxidation times and temperatures.
반응고 성형된 A357 Al 합금 성형품의 후열처리 특성
최원호 ( W. H. Choi ),신평우 ( P. W. Shin ),이상용 ( S. Y. Lee ) 한국열처리공학회 2003 熱處理工學會誌 Vol.16 No.1
N/A Recently, semi-solid forming (SSF) process has been applied in many automobile parts for improved weight reduction, better environmental protection and energy savings. SSF process was well developed for high volume production of light weight aluminum components. In this paper, knuckle has been manufactured by SSF and then the microstructures and mechanical properties were investigated followed by various heat-treatment conditions, It was found that the examined microstructure was equiaxed at the whole cross-section area.
P. C 강선에서 Patenting 열처리에 미치는 인장응력의 영향
이찬규,신평우,홍종휘 고려대학교 공학기술연구소 1982 고려대학교 생산기술연구소 연구보고 Vol.17 No.1
Optimum heat treatment producing P.C. wire is the most important for the further drawing. Drawability depends on the metallic microstructure and mechanical properties. Mechanical properties depend on the amount of pro-eutctoid ferrite and the fineness of pearlite. The amount of ferrite and the fineness of pearlite are dominated by the solid solution treatment and the cooling velocity from the sutenitizing temperature to the patenting temperature. Basides the above, the tension stress is very effective for ausenitizing and eutectoid reaction. The results obtained from this investigation could be summarized as follows. 1. Drawabdity was lowered by the precipitation of pro-eutectoid ferrite as the solid solution treating time was longer. 2. Slow cooling velocity from solid solution treating temperature to the isothermal transformation temperature made the drawability poor. 3. Solid solution treatment under tension stress was very effective for reducing the solid solution treating time and for refining the pearlite. 4. Solid solution treatment under tension stress and rapid cooling from 950 % to 540 % made the pearlite fine and increased drawability.
Ni-Cr-Mo 구조용강의 열처리에 따른 기계적 성질과 절삭성에 관한 연구
이용호,홍종휘,김기주,이우엽,신평우 대한금속재료학회(대한금속학회) 1980 대한금속·재료학회지 Vol.18 No.6
Ni-Cr-Mo 鋼에 있어서 機械的性質과 切削性에 미치는 熱處理條件과 初期組織의 影響을 硏究檢討한 바 다음과 같은 結論을 얻었다. 1. 硬化能에 미치는 初期組織의 影響은 顯著하였다. 臨界直經은 球狀化處理, 恒溫處理 및 燒準處理된 初期組織 順序로 增加되었다. 2. 燒入溫度가 높을수록 機植的性質에 미치는 初期組織의 影響은 컸다. 3. 燒入溫度가 높고 소려온도가 낮을때 切削性은 增加하였다. 4. 燒入溫度가 높을때에는 燒準處理, 球狀化處理 및 恒溫處理된 初期組織順으로 切制性이 增加하였다. 5. 燒入溫度가 낮을때에는 燒入溫度가 높을때와 같은 初期組織順으로 切削性이 增加하였다. The general mechanical properties, the influence of heat treatment condition and the initial microstructure on machinability of Ni-Cr-Mo steel has been studied. The results from the study were as follows 1. The influence of an initial microstructure on hardenability was pronounced. The critical diameter of a hardenability increased as the initial microstructure changed from the spheroidized, patented and to normalized. 2. The influence of an initial microstructure on the mechanical properties increased as the quenching temperature increased. 3. The machinability increases as the quenching temperature increased and the tempering temperature decreased. 4. When the quenching temperature was high, the machinability increased as the initial microstructure changed in a sequence from the normalized, spheroidized and to patented one. 5. However, when the quenching temperature was low, the sequence of improving machinability was the same as when quenching temperature was high.