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냉간압연에 의해 제조된 Ti-Ni계 합금 리본의 마르텐사이트 변태 및 형상기억 특성

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Author(s)
김록형
Issued Date
2016
Abstract
Recently, Ni-rich Ti-Ni binary alloy has been widely used as an actuator in automobile and medical industries. In this study, this binary alloy was cold-rolled and annealed at the temperatures, 250, 350, 450 and 550℃ to evaluate mechanical property, microstructural change, martensite transformation and shape memory effect.

(1) The hardness value of the ribbon rolled to 65% was 325.6 Hv, and the hardness value of the as-received wire was 211Hv. As the degree of processing increased, the hardness value increased. Also as the annealing temperature increased, the hardness value decreased.

(2) In the rolled ribbons, B2 → R-phase → B19' forward transformation during cooling and B19' → B2 reverse transformation during heating did not appear. But as the annealing temperature increased, B2 → R phase → B19' and B19' → B2 transformations appeared, and R-phase disappears and B2 ↔ B19 'transformations appeared.

(3) The as-received wire does not appear deformation band and the deformation band was most prominent at 65%. The shape of the deformation band was appeared to difference according to the degree of processing. Also as the annealing temperature increased, the deformation band disappeared and the ribbon with the 65% processing degree had a residual deformation band.

(4) The martensite plate of the processed ribbon was finer than the as-received wire martensite plate. The martensite structure with the degree of processing of 65% was the finest, and the martensite structure was observed as the annealing temperature increased.

(5) In as-received wire, R-phase → B19' martensite transformation occurred even without annealing. But phase transformation characteristic did not appear in the rolled ribbon. In Ribbon with the degree of processing 50 and 65%, R phase rearrangement → R phase → B19' martensite transformation was occurred at 350℃. As the annealing temperature increased, the R → B19' transformation appeared, and the elongation increased and the ultimate tensile strength decreased.

(6) As the degree of processing increases, the diffraction peaks of martensite and austenite become broad and the intensity of the peaks decreases. But as the annealing temperature increases, the intensity of the diffraction peaks of the R phase (112) and (330) and the (110) plane of B2 is increased and the diffraction peak having the degree of processing of 65% is the largest. Also at an annealing temperature of 550℃ diffraction appeared on all sides.

(7) As-received wire showed the best shape recovery rate of 100% when they were not annealed. 35% was appeared 100% shape recovery rate at 250℃. And as the degree of processing increased, the shape recovery rate of 100% was appeared at 350℃. But as the annealing temperature was increased, the shape recovery rate decreased.
Alternative Title
Martensitic transformation and shape memory characteristics of Ti-Ni based alloy ribbon fabricated by cold rolling
Alternative Author(s)
Kim, Rok Hyeong
Affiliation
조선대학교 일반대학원 첨단소재공학과
Department
일반대학원 첨단소재공학과
Advisor
장우양
Awarded Date
2017-02
Table Of Contents
목 차


LIST OF TABLES ⅲ
LIST OF FIGURES ⅳ
ABSTRACT ⅺ

제 1 장 서 론 1

제 2 장 이론적 배경 3
2. 1. Ti-Ni계 형상기억합금 3
2. 1. 1. Ti-Ni계 합금의 상태도 3
2. 1. 2. 변태온도에 미치는 합금조성의 영향 6
2. 1. 3. Ti-Ni계 합금의 결정구조와 마르텐사이트 변태 8
2. 1. 4. 형상기억 변태특성 12
2. 1. 5. 형상기억 특성 14
2. 1. 6. 반복 사용에 의한 특성변화 22
2. 1. 7. Ti-Ni계 합금의 형상기억효과 및 변태 의탄성의 온도 의존성 22
2. 1. 8. Ti-Ni 합금의 온도에 따른 변형특성 24
2. 2. 압연 26
2. 2. 1. 가공열처리 효과 26
2. 2. 2. 가공도에 따른 기계적 성질 변화 27
2. 2. 3. 압연이론 29
2. 2. 4. 변형저항과 마찰계수 31

제 3 장 실험 방법 36
3. 1. 시편 36
3. 2. 냉간압연 37
3. 3. 가공열처리(=어닐링) 39
3. 4. 시편절단 및 산세 40
3. 5. 마이크로비커스 경도시험 40
3. 6. DSC(Differential scanning calorimetry) 분석에 의한 변태온도 측정 40
3. 7. 인장시험 41
3. 8. 전해연마 41
3. 9. 미세조직 관찰 42
3. 10. X-선 회절분석 42
3. 11. 형상회복 특성평가 43

제 4 장 결과 및 고찰 44
4. 1. 원형선재의 냉간압연 44
4. 2. 어닐링온도에 따른 경도변화 61
4. 3. As-received 선재 및 리본의 열분석 64
4. 4. 어닐링 온도에 따른 상변태 특성 68
4. 5. 어닐링 온도에 따른 미세조직 변화 91
4. 6. 어닐링 온도에 따른 응력-변형률 곡선 110
4. 7. 가공도에 따른 X-선 회절분석 119
4. 8. 어닐링 온도에 따른 형상회복 특성평가 127


제 5 장 결 론 113

참 고 문 헌 136
Degree
Master
Publisher
조선대학교 일반대학원
Citation
김록형. (2016). 냉간압연에 의해 제조된 Ti-Ni계 합금 리본의 마르텐사이트 변태 및 형상기억 특성.
Type
Dissertation
URI
https://oak.chosun.ac.kr/handle/2020.oak/13070
http://chosun.dcollection.net/common/orgView/200000265964
Appears in Collections:
General Graduate School > 3. Theses(Master)
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