| 연속냉각 중 산소함량이 Ti-5Al-2.5Fe 합금의 상변태 거동에 미치는 영향 |
| 김도헌1,2, 원종우1, 정대원1, 이학성1, 윤석영2, 현용택1 |
1한국기계연구원부설 재료연구소
2부산대학교 재료공학과 |
| Effect of Oxygen Content on the Phase Transformation of Ti-5Al-2.5Fe Alloy During Continuous Cooling |
| Do-Heon Kim1,2, Jong Woo Won1, Dae-Won Jeong1, Hak-Sung Lee1, Seog-Young Yoon2, Yong-Taek Hyun1 |
1Metal Materials Division, Korea Institute of Materials Science, Changwon 51508, Republic of Korea
2School of Meterials Science and Engineering, Pusan National University, Pusan 46241, Republic of Korea |
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Received: 2 March 2017; Accepted: 8 May 2017. Published online: 30 August 2017. |
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| ABSTRACT |
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The effects of oxygen content on the β to α phase transformation of the Ti-5Al-2.5Fe alloy during continuous cooling were investigated by varying the oxygen content between 0.08 – 0.41 wt%. Dilatometer tests were performed at cooling rates of 0.05 – 100 ℃/s combined with microstructure observation to examine phase transformation mechanisms and resulting microstructure. Our results showed that oxygen acted as a strong α phase stabilizer by increasing β-transus temperature, and promoted diffuse-controlled α phase transformation with hindering martensitic transformation. Depending on the oxygen content, the different transformation mechanism led to a distinct difference in microstructure evolution. As an oxygen content increased, α phase was developed in thicker lath forms and was globularized at a slow cooling rate, whereas the formation of acicular-shaped α phase was significantly reduced. Hardness behavior after cooling was discussed in the light of microstructure morphology and possible precipitation formation. Based on the analysis results, continuous cooling transformation diagrams of the investigated alloys were established. |
| Keywords:
metals, phase transformation, microstructure, dilatometry, continuous cooling transformation diagram |
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