Silicon-Iron 의 기계적 가공및 열처리에 따르는 불순물의 분포상태와 2 차 재결정 기구에 관한 연구

김상주 대한금속재료학회(대한금속학회) 1970 대한금속·재료학회지 Vol.8 No.2

무유황 규소철 탁판을 중성분위기 속에서 고추파 용해하여 여기에 0.25w/o의 S^(35) 동위원소를 첨가하고 이것을 60∼80%의 가공률로 압연하였다. 이것을 800°∼1,100℃의 각온도에서 H₂가스 capsule에서 시간을 變化시켜 열처리하고 급냉한 후 AR-10 autoradiographic stripping film을 사용하여 이미 확립한 autoradiograph 방법에 의하여 주조상태, 열간압연 상태, 냉간압연 후, 열처리 후의 강상태에서 S^(35)의 분포상태를 검토하였다. 이와 같이 하여 얻은 분포 조직도와 그의 현미경 및 전자 현미경 조직과 Mn-free 규소철의 그것과 비교하여 일차 재결정에서 이차 재결정으로 이행될때의 정체 기구에 대하여 고찰하였다.

강유전체에서 분극이 반전될 때 발생하는 열에 대한 모델링

김상주 서울시립대학교 산업기술연구소 1999 산업기술연구소논문집 Vol.7 No.-

Ferroelectric materials such as PZT, PLZT change their polarization directions when they are subject to external electrical loadings. The change in polarization direction is usually accompanied by mechanical deformation and this property enables them to be used widely as sensors, actuators, MEMS, smart structures, etc. A one-dimensional continuum model for ferroelectric domain switching has been proposed by [1]. According to [1], a certain amount of heat is generated from a moving domain boundary mainly due to both nonreversible processes occurring at the domain boundary and latent heat. In this paper we study a one-dimensional model for domain switching and its thermal effects by using a finite difference algorithm which was developed by (2).

Ni-Ti 합금의 저온 성질과 변태에 관한 연구 (1) : CO 첨가에 따른 마르텐사이트 변태 온도의 변화 Effects of Co Addition on the Martensitic Transformation Temperature

김상주,선우현 대한금속재료학회(대한금속학회) 1977 대한금속·재료학회지 Vol.15 No.2

NiTi 금속간 화합물의 Ni을 Co로 치환시켜 Co의 농도가 증가할수록 그 합금의 martensite 변태 온도가 저하된다고 하였다. 따라서 Ni 대신 소량의 Co를 첨가함으로써 NiTi합금의 성질에 영향을 주지않고 변태 온도를 저하시킬 수 있을 것이다. 이 변태 온도 저하의 정도를 구하기 위해 NiTi와 Ni 대신 Co를 3%, 5% 첨가시킨 시편을 Ar 분위기에서 고주파 용해하여 그 시편의 열팽창과 전기 저항을 -100°∼+150℃의 온도 범위에서 측정함으로써 변태 온도의 변화를 구하고 그 원인을 고찰하였다. 그 결과 Co 첨가에 의해 변태 온도는 저하하며 Co 소량 첨가시 Co 농도가 1% 증가함에 따라 변태온도는 약 20℃ 정도씩 저하하였으며 그 변태는 중간성을 거치는 2단계 변태인 것으로 보여진다. The martensitic transformation temperature is believed to be lowered when Co is substituted for Ni in NiTi intermetallic compound. Therefore the transformation temperature can be lowered without change in its good properties by substituting a small amount of Co for Ni. To obtain the extent of decrease in transformation temperature caused by Co addition, NiTi and those with 3% and 5% Co were prepared by induction melting in Ar atmosphere. After machining, they were studied by means of, dilatation and electrical resistivity measurement through a temperature range of -100 to +150℃. It is certain that the martensitic transformation temperature is lowered by a small amount of Co addition and it is lowered by 20℃ with the increase of 1% of Co concentration. It is also believed that there exits an intermediate phase when Co is added.

전기-기계적으로 연성된 재료의 분극역전 거동에 대한 유한요소 모델링

김상주,Kim, Sang-Ju 대한기계학회 2001 大韓機械學會論文集A Vol.25 No.11

A finite element model for polarization switching in electro-mechanically coupled materials is proposed and applied to predict the switching behavior of a two-dimensional ferroelectric ceramic. A complicated micro-structure existing in the material is modeled as il continuum body and a simple 3 node triangle finite element with nodal displacement and voltage degrees of freedom is used for a finite element analysis. The elements use nonlinear constitutive equations, switching criterion and kinetic relation, fur representation of material response at strong electric and stress fields. The polarization state of the material is represented by internal variables in each element, which are updated at each simulation step based on the proposed constitutive equations. The model reproduces strain and electric displacement hysteresis loops observed in the material.

이종 알루미늄 합금 KS5J32/AA6K31 겹치기 마찰교반 접합부의 인장성질에 미치는 접합조건의 영향

김상주,윤태진,송상우,강정윤,Kim, Sang-Ju,Yoon, Tae-Jin,Song, Sang-Woo,Kang, Chung-Yun 대한용접접합학회 2012 대한용접·접합학회지 Vol.30 No.6

The focus of this investigation is to evaluate the effect of joining parameter on the microstructure and mechanical properties of welds produced by friction stir lap welding. The dissimilar Al alloys, KS5J32 and AA6K31, were joined by friction stir lap welding technique under several welding conditions, and KS5J32 alloy was placed on the top of AA6K31 alloy. The tool rotation speeds were 1000, 1250, and 1500rpm, and the welding speeds were 100, 300, 500, 700mm/min, respectively. The results showed that two shapes of nugget, such as onion ring and irregular vortex type, were observed with various revolutionary pitch. In all welding conditions, fracture occurred at the soften region of bottom sheet(AA6K31) and the strengths were 64~78% of those of base metal. Fractured positions were classified into three types : HAZ, triple point, void depending on the revolutionary pitch. The actual thickness of specimen at the fractured location was decreased with decreasing heat input. A linear relationship exists between the effective thickness of fractured position and peak load.

건국 초 공학교육의 초석을 다진 석천 '김동일'

김상주,Kim, Sang-Ju 한국대학교육협의회 2001 大學敎育 Vol.112 No.-

고장력 저합금 실리콘강의 열처리에 따른 마르텐사이트 조직변화와 기계적 성질에 관한 연구

김상주,이후철,지충수 대한금속재료학회(대한금속학회) 1979 대한금속·재료학회지 Vol.17 No.6

저합금 실리콘강에서 규소가 martensite강의 조직에 미치는 영향을 연구하기 위하여 prior austenite 입도를 조절하여 martensite조직을 얻고 소입 및 소려에 따라 강도, 인성 등 기계적 성질과의 관계를 주로 전자현미경을 이용하여 조사하였다. 소입한 상태의 조직은 주로 lath martensite이며 auto-tempered ε-탄화물의 석출이 있었고 300℃의 소려까지 성장이 뚜렷하였으나 400℃부근에서부터 소멸되기 시작했고 세멘타이트의 석출이 시작되었다. 강도와 인성은 packet size와 밀접한 관계가 있으며, 규소가 소려에 따른 강도의 연화현상을 억제하는 것이 분명하였다. Tempered martensite embrittlement는 400℃부근의 소려에서 발생되었고, 이러한 현상은 lath사이의 잔류 austenite가 열적 불안정으로 film형상의 세멘타이트를 석출시키므로써 inter cleavage fracture의 원인이 되는 것 같았다. In the present work, mechanical properties (strength and toughness, etc) of medium carbon silicon steel according to the prior austenite grain size and the change of structures tempered at various temperatures were studied, using primarily electron microscopy. As-quenched martensitic structure consits mainly of packets of laths, and auto-tempered precipitate (ε-carbide) could be also observed within some of laths. ε-carbide was precipitated within laths when tempered at below 300℃, while cementite begins to form first along lath boundaries tempered at 400℃ and develop in spheroidized shape at higher tempering temperature. Packet size was related to yield stress and toughness. And it was apparent for silicon to retard the softening of tempered carbon steel. Tempered martensite embrittlement occurred at around 400℃ tempering and resulted in interlath cleavage of fracture mode. Such a considerable decrease in toughness is thought to be attributed to the formation of cementite in interlath boundaries, since retained austenite in lath boundaries is thermally unstable with respect to tempering temperature.

종심정맥압?-중심정맥압측정의 이유와 방법

김상주 대한간호협회 1978 대한간호 Vol.17 No.1

5086 알루미늄 합금의 해수에서의 갈바닉부식에 미치는 이종금속의 영향

김상주,이학열,손운택 대한금속재료학회(대한금속학회) 1982 대한금속·재료학회지 Vol.20 No.3

The effect of dissimilar metal (1100-0 Al, 6061-T6, 5083-H32, SM15C, SCM2, SCM21, SNCM8, SNCM21, STS304, DIN x10CrNiMoTi1810, Cu, brass, bronze) on the galvanic corrosion of 5086-H116 Al alloy in the synthetic sea water was studied by the galvanic current method and corrosion product morphologies on the 5086-H116 Al alloy exposed in the salt spray test chamber were observed by the metallurgical microscope and scanning electron microscope. Results show that the potential difference of uncoupled dissimilar metals is a poor indicator of the extent(rate) of galvanic corrosion of coupled dissimilar metals. Galvanic series for 5086-H116 Al alloy in synthetic sea water based on the galvanic current density was Cu≥brass>SM15C≥SNCM21≥bronze>SNCM8>SCM2≥SCM21>STS304≥DIN x10CrNiMoTi1810≥6061-T6>1100-0≥5083-H32. Corrosion product morphologies on the 5086-H116 Al alloy exposed in the salt spray test chamber agreed with the galvanic current data. When coupled with other Al alloy there was no galvanic effect but when coupled with Cu, brass, SM15C, pitting and intergranular corrosion occurred on the surface of the 5086-H116 Al alloy near the interface of the dissimilar metal.

급냉응고된 Al-Co 합금의 미세구조

김상주,배기광 대한금속재료학회(대한금속학회) 1986 대한금속·재료학회지 Vol.24 No.8

Microstructures of rapidly quenched Al-Co alloys made by a melt spinner were investigated and in-situ decomposition behavior of the solidified microstructures were also studied. Two regions of microstructures were observed in the as-quenched strips; one was a chilled structure formed on the side facing the copper substrate and the other was a free surface structure on the opposite side The chill structure consisted of micrograins and fine precipitates, i.e. B phase, which are metastable and have (001)_(At),//[001]_B and (130)_(At)//[110]_B orientation relationship with Al matrix. The free surface structure was composed of large and stable Al_9Co₂ precipitates surrounded by microdendritic, eutectic and cell structures. Upon annealing it was found that the finer the micro-structure, the faster the decomposition accompanied by nucleation of the slowly growing precipitates. The microhardness of the as-quenched structure increased with increasing Co contents and with addition of the third elements, and the value decreased monotonically with aging time and temperature. Among the various third elements tried, Mn showed the most effective results in hardness increase.