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2상 스테인리스강의 인장특성에 미치는 오스테나이트상의 함량 및 합금원소의 영향
주동원,성장현,이성근 동아대학교 공과대학부설 생산기술연구소 1997 生産技術硏究所硏究論文集 Vol.2 No.1
The effect of alloying elements addition, austenite content and distributions on the tensile properties and corrosion resistance of duplex and super duplex stainless steels has been investigated by changing heat treatment conditions. With the addition of N and Cu, the austenite content of duplex stainless steels increased. After heat treating the super duplex stainless steel, the austenite content increased above 1200℃ and the ferrite single phase temperature shifted to 50℃ high in comparison to duplex stainless steel. Due to the stored energy induced from cold rolling the super duplex stainless steel. the specimen with fibous structure showed to be increased in austenite content compared to the specimen with dispersed structure. Tensile strengths decreased and elongations increased with increasing austenite content. The super duplex stainless steel with fibrous structure showed superior tensile strengths and elongations to the fibrous duplex stainless steel and super duplex stainless steel with dispered structure. The effect of Cu and CU+W addition on tensile properties was small. The passive current density and critical current density of high alloyed super duplex stainless steel showed value in comparison to duplex stainless steel. The Cu+W added super duplex stainless steel appeared the highest corrosion resistance among all specimens.
목표출현(目標出現)의 불확실성(不確實性)이 추적작업(追跡作業)에 미치는 영향에 관한 연구(硏究)
주동원,박세진,이순요,Ju, Dong-Won,Park, Se-Jin,Lee, Sun-Yo 대한인간공학회 1984 大韓人間工學會誌 Vol.3 No.1
An experimental study was made to examine the effects of the uncertainty of objectives-presentation using two-handle and joystick on the predictive, precognitive and preview manual tracking systems (pursuit tracking system). The task had two factors of difficulty, a locational and a temporal uncertainty, chosen to be perceptibly more difficult having a high presentation rate. Six male subjects were required to perform the experiments. It was obtained from the results of the experiments that the preview manual tracking system is better than the other systems and the performance decrement doesn't appear.
고원변형과 열간노출에 따른 주조용 합금 738LC의 탄화물 분해거동 고찰
주동원,조창용,김두현,서성문,이영찬,Ju, Dong-Won,Jo, Chang-Yong,Kim, Du-Hyeon,Seo, Seong-Mun,Lee, Yeong-Chan 한국재료학회 2000 한국재료학회지 Vol.10 No.2
니켈기 주조용 합금 738LC를 816$^{\circ}C$와 982$^{\circ}C$에서 크리프 파단 시험과 열간 노출시험을 통해 온도와 응력 변화에 따른 파단양상, 탄화물과 $\sigma$상의 석출 거동에 대해 조사하였다. 816$^{\circ}C$/440MPa에서는 크리프 파단양상이 전단변형에 의한 입내파괴를 나타내었으나, 982$^{\circ}C$/152MPa에서는 표면과 접하는 결정입계에서 입계산화에 의해 표면에너지의 감소로 균열이 나타나 진행되는 입계파괴가 나타났다. M(sub)23C(sub)6 탄화물이 816$^{\circ}C$에서는 주로 결정입계에서와 전단변형에 의한 입내균열을 따라 석출하였으나, 982$^{\circ}C$에서는 결정입계 뿐만 아니라 입내에서는 석출하였으며 석출양은 증가하였다. $\sigma$상은 Cr(sub)23C(sub)6 탄화물에서 핵생성 후 기지로 성장하며, 온도가 높고 응력이 주어지면 Cr(sub)23C(sub)6 탄화물의 양이 증가하여 $\sigma$상의 석출도 많아졌다. Fracture mode and carbide reactions of cast alloy 738LC during thermal exposure and creep at 816$^{\circ}C$/440MPa and 982$^{\circ}C$/152MPa were investigated. Crystallographic transgranular failure was observed in the specimen crept at 816$^{\circ}C$ due to shearing on the slip plane. Because selective oxidation at the grainboundaries which was exposed at the surface leads reduction in surface energy, however, early initiation of crack at the grainboundaries and intergranular failure were observed in the specimen crept at 982$^{\circ}C$/152MPa. As a result of decomposition of MC carbide at the tested temperatures, M(sub)23C(sub)6 carbide precipitated either on the grainboundaries or on the deformation band. The applied stress enhanced decomposition of MC. $\sigma$phase nucleated from Cr(sub)23C(sub)6 then grew to the ${\gamma}$+${\gamma}$\\` matrix. Precipitation of $\sigma$was accelerated by increasing temperature and applied stress.
주조용 718합금의 고온 인장 성질에 미치는 석출물의 영향
주동원,조창용,김두현,류영수,김인수,조해용,최승주,Ju, Dong-Won,Jo, Chang-Yong,Kim, Du-Hyeon,Ryu, Yeong-Su,Kim, In-Su,Jo, Hae-Yong,Choe, Seung-Ju 한국재료학회 2000 한국재료학회지 Vol.10 No.7
주소용 718합금의 고온 인장 성질에 미치는 석축물의 영향을 상추출법과 미세조직관찰을 통해 고찰되었다. 고온 인장시험에서 $760^{\circ}C$까지는 인장강도와 연신율이 동시에 감소하였고, 그보다 높은 온도에서는 인장강도는 급격히 감소하고 연신율은 증가하였다. 고온 인장시험에의한 응력의 영향으로 인하여 ${\gamma}',{\gamma}"$석출물의 양은 $760^{\circ}C$에서 최대의 값을 나타내었다. 미세한 ${\gamma}',{\gamma}"$상의 석출이 최대로 일어나는 온도에서 석출물에의한 유동응력의 증가로 인해 항복강도의 저하폭이 작았으며, 연신율은 가장 낮은값을 나타내었다. $760^{\circ}C$보다 높은 온도에서는 전체적인 석출물의 양도 감소하였고, 특히 강화석출상의 양이 적어 연화현상이 급격히 나타났다. 급격히 나타났다. The effect of precipitates on the high temperature tensile properties of cast alloy 718 was investigated by phase extraction method and microstructural observation. The value of tensile strength and elongation gradually decreased with increasing testing temperature up to $760^{\circ}C$. Elongation of the alloy increased, while tensile strength decreased above 76$0^{\circ}C$. The amount of precipitates in the specimen that tensile tested at $760^{\circ}C$ showed maximum owing to stress assisted precipitation. Therefore, the alloy exhibited the lowest value of the elongation and the degree of decrease in yield strength at this temperature due to high flow stress of precipitates. Little amount of precipitate, especially $\gamma$' and $\gamma$", resulted in softening of the alloy at the temperature above $760^{\circ}C$.
주동원(Dong Won Joo),구광덕(Kwang Duk Koo),성장현(Jang Hyun Sung) 대한금속재료학회(구 대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.12
To investigate the applicability of a coarse powder to the metal injection molding, coarse iron podwers were combined up to 60% in weight fraction with fine iron powders in the injection molding process. With increasing relative fraction of a coarse powder, the green density of the compacts increased slowly up to 97% at 60 wt. % addition of coarse powder and it became possible to remove a binder completely out of the compact through the broader channels of binder flow during the debinding stage. The increase in the porosity of the compact owing to the increasing portion of a coarse powder resulted in the decrease in the sintered density and volume shrinkage. And then it brought the tensile strength and elongation of the final product down. In this experiment the maximum amount of a coarse powder replacing a fine powder with the equivalence in densification behavior, microstructure and tensile property to injection molded-fine carbonyl iron powder was found to be 20% in weight fraction.