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Fe-X%Mn-6%Si-9%Cr-5%Ni 합금의 형상기억효과에 미치는 가공열처리의 영향
백승한,전중환,최종술,한중호 연세대학교 산업기술연구소 1994 논문집 Vol.26 No.1
The effect of thermomechanical treatment on the SME(Shape Memory Effect) of Fe-(10∼16)%Mn-6%Si-9%Cr-5%Ni alloys was investigated. The corrosion behaviors of these alloys were also investigated compared with SUS 304 stainless steel and Fe-30%Mn-6%Si shape memory alloy. Through the investigation the Fe-2%Mn-6%Si-9%Cr-5%Ni alloy showed the best SME in as-solution treated state. Training treatment consisting of repetition of cold rolling by 2% at room temperature and subsequent annealing at 650℃ for 10 minutes was performed to improve the SME. The remarkable improvement of SME was obtained at two cycles of training, and then the SME was decreased with further training. This suggests that the extra lattice defects of dislocation and stacking faults introduced by training treatment deteriorates the SME. The Fe-X%Mn-6%Si-9%Cr-5%Ni alloys showed the passive behavior similar to that of SUS 304 stainless steel in 30℃-5% H₂SO₄solution and great improvement in corrosion resistance compared with the Fe-30%Mn-6%Si shape memory alloy.
Fe-23% Mn 합금의 진동감쇠능에 미치는 냉간압연의 영향
최종술,이영국,전중환 대한금속재료학회(대한금속학회) 1995 대한금속·재료학회지 Vol.33 No.12
Damping capacity and mechanical properties were investigated with respect to the amount of cold rolling for an Fe-23%Mn alloy. Maximum damping capacity was observed around 10% reduction at strain amplitude range of 2×10^(-4)∼4×10^(-4). The internal stacking faults in ε martensite plates are considered the most important damping source in this strain range. However, the strain amplitude range of 5×10^(-4)_∼6×10^(-4) higher than that showed the maximum damping capacity around 2% reduction. This means that γ/ε interface is the principal damping source in this strain range. Hardness increased continuously with the amount of deformation. Especially, when deformed at the range of 10%∼20%, the hardness increased steeply due to the work hardening as well as the stress-induced martensitic transformation. Mechanical properties such as yield strength and tensile strength were increased with the increase of cold work, but elongation showed reverse tendency. The 10% cold rolling showed the best combination of damping capacity and tensile strength.
Al-Zn 합금의 진동감쇠능에 미치는 조성 및 열처리 조건의 영향
최종술,한기우 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.2
Variation of damping capacity with cooling rate and aging condition was investigated in Al-40% Zn, Al-60% Zn and Al-78% Zn alloys. Additional investigation for structural changes due to different cooling rate was made in those alloys. The Al-Zn alloys were found to show constant values in damping capacity regardless of maximum surface strain, The damping capacities of the Al-40% Zn and Al-60% Zn alloys were increased with decreasing cooling rate. This may be due to increase in βphase precipitation in accordance with decrease in cooling rate. However, the Al -78% Zn alloy showed high damping capacity with increasing cooling rate. This was because at the rapid cooling rate the two phases(α+β) were decomposed into homogeneous and fine grain structure by spinodal decomposition, while at the slow cooling rate the coarse lamella structure was formed by discontinuous precipitation. The damping capacities of the water-quenched Al-40% Zn, Al-60% Zn and Al-78% Zn alloys were increased with aging time at i50℃ and 250℃. However, the damping capacity of the Al-60% Zn alloy was decreased on further aging above critical times at 150℃ and 250℃, because coarsening in the lamellar structure of the alloy occurred on aging above the critical time at each temperature.
Fe-X% Mn 합금의 형상기억효과에 미치는 굽힘변형온도와 반복열처리의 영향
최종술,진원 대한금속재료학회(대한금속학회) 1991 대한금속·재료학회지 Vol.29 No.5
Effects of bending temperature and thermal cycle on SME in Fe-X%Mn alloy were studied. As the bending temperature was decreased from room temperature to-196℃, the SME of Fe-17%Mn, Fe-21%Mn, and Fe-24%Mn alloys were increased. The reason is considered that the mechanical driving force required for stress induced a martensite transformation is lowered due to the increase in chemical driving force for the martensite transformation in accordance with decrease in the bending temperature. However, since Fe-28%Mn alloy is stable, the SME of the alloy was very small regardless of the bending temperature up to-196℃. The SME was increased with increase in number of thermal cycle, showing a peak value at around 5 cycles, and then decreased with further thermal cycle. This effect of thermal cycle on the SME became greater with decrease in Mn content. After the 17%Mn alloy was controlled to have various a martensite contents by holding at temperatures below Ms temperature, the SME of the alloy was measured with respect to a martensite content after bending at 170℃ and heating to 350℃. The measured SME of the alloy showed tendency to increase with increase in a martensite content. From this result, it is concluded that the presence of more or less a martensite content improves the SME at high bending temperature such as 170℃, because the yield strength of γ is increased with the presence of some ε martensite content and the usual slip off {111} $lt;110$gt;γ is γ estrained during bending.