http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
높은 온도구배에 따른 GS-36NI 단결정 초내열 합금의 응고 특성
이종훈,최승주,이재현,염종택,최광진 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.6
Directional solidification have been studied on the GS-36Ni russian single crystal superalloy at various temperature gradients and solidification rates. A liquid metal cooling technique was employed to take advantage of its high temperature gradient capability in directional solidification which is essential for single crystal growth. The dendrite spacings(λ) with temperature gradients (G) and solidifiation rates(V) were satisfied by well known equation λ ∝ G^(-½) V^(-¼). The finer dendrite spacings in the single crystal superalloy were produced at the higher temperature gradients, which results in decreasing sharply the homogenization time. The solid/liquid interface instability was also investigated by quenching the solid/liquid interface during directional solidification.
김인수,박노광,염종택 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.10
The microstructural evolution during a hot forging of Alloy 718 has been studied using compression tests and FEM simulation. The microstructures developed during a hot forging varied depending on dynamic recrystallization. The Zener-Holloman parameter(Z) measured as a function of temperature(T) and strain rate(ε˙) was given by Z=ε˙exp(447.706/RT). The size of dynamically recrystallized grains decreased as Z increased. The critical strain(ε_0) for the initiation of dynamic recrystallization was obtained from compression test and FEM simulation. The detailed variation of microstructures due to dynamic recrystallization could effectively be predicted at various locations in a forged pancake.
Rene' 77 합금의 고온 응력- 파단에 따른 σ 상의 생성 및 미세조직의 변화
조창용,최승주,이재현,염종택,김상식 대한금속재료학회(대한금속학회) 1997 대한금속·재료학회지 Vol.35 No.10
The possibility of formation of the a phase in the Rene´ 77 superalloy, when exposed to high temperature: and under the applied stress, has been evaluated. The Phacomp calculations on the Rene´ 77 used in the present study indicates that an electron vacancy number of this alloy is 2.45, which is not immune to formation of the a phase. Among the four stress-rupture test conditions, the σ phase was observed when the sample was exposed at 871℃ under the applied stress of 276 ㎫. The shape of the σ phase observed in the present study was more-or-less close to blocky shape, and the detrimental effect on stress-rupture property of the Rene´ 77 was minimal. It was interesting to find that the fracture modes were different with stress conditions. While fracture initiated near the carbide in High stress condition, it appeared to grow near the grain boundary or triple point in low stress condition.