| 학회 | 한국재료학회 |
| 학술대회 | 2016년 가을 (11/16 ~ 11/18, 경주 현대호텔) |
| 권호 | 22권 2호 |
| 발표분야 | H. 한-일 재료공학 워크샵 |
| 제목 | Micro-mechanical deformation mechanisms of Ti alloys |
| 초록 | Titanium alloys are highly attractive to many high value industrial applications, particularly in aeroengines (e.g. blade and disc forms), due to their high strength-to-weight ratio, corrosion resistance and excellent mechanical properties. In service, these alloys are subjected to significant cyclic loading, with high thrust (i.e. stress) excursions during take-off, a load-hold during flight and unloading on landing. However, in early 1970s unexpected fatigue failure was found in the load-hold cyclic loading, which consequently reduced the number of cycles by an order of magnitude or more when compared with normal load-unload fatigue cycle. This is known as cold dwell fatigue problem and still remains as unsolved engineering problem due to its complexity associated with chemical, structural or morphological effects. In practice dwell fatigue failure is mitigated by use of dwell insensitive alloys and careful maintenance schedules but this management approach costs the aerospace industry significantly (~£100M / year). It is therefore important to unravel the dwell process and develop new methodology to assess time sensitive material properties in real engineering alloys. This will therefore be significant to enable the most cost effective component management strategies, ultimately engineering new materials that are dwell insensitive, and safer structure design. To approach this dwell problem, we have investigated the local deformation mechanisms and strain rate sensitivity of Ti alloys by developing the state-of-the-art micro-mechanical testing methodology (i.e. in-situ micro-pillar compression tests with further high resolution techniques) [1-3] and computational crystal plasticity [4-5]. We have discovered different trends of structural rate sensitivity between dwell sensitive and insensitive Ti alloys, and strong morphological effects on local deformation behaviour. These data are key as a first step in developing appropriate hypotheses towards a full understanding on how local microstructure controls dwell fatigue and failure of in-service components. Our experimental approach presents new exciting insight into this important deformation mechanisms, as well as opening up further studies of new alloy design. [1] T-S. Jun, G. Sernicola, F.P.E. Dunne, T.B. Britton, “Local deformation mechanisms of two-phase Ti alloy,” MSEA, vol. 649, pp. 39-47, 2016 [2] T-S. Jun, D.E.J. Armstrong, T.B. Britton, “A nanoindentation investigation of local strain rate sensitivity in dual-phase Ti alloys,” J. Alloys Compd., vol. 672, pp. 282-291, 2016 [3] T-S. Jun, Z. Zhang, G. Sernicola, F.P.E. Dunne, T.B. Britton, “Local strain rate sensitivity of single alpha within a dual-phase Ti alloy,” Acta Mater., vol. 107, pp. 298-309, 2016 [4] Z. Zhang, T-S. Jun, T.B. Britton, F.P.E. Dunne, “Determination of Ti6242 alpha and beta slip properties using micro-pillar test and computational crystal plasticity,” JMPS, vol. 95, pp. 393-410, 2016 [5] Z. Zhang, T-S. Jun, T.B. Britton, F.P.E. Dunne, “Intrinsic anisotropy of strain rate sensitivity in single crystal alpha titanium,” Acta Mater., vol. 118, pp. 317-330, 2016 |
| 저자 | 전태성1, Fionn P.E. Dunne2, T. Ben Britton3 |
| 소속 | 1인천대, 2Department of Materials, 3Imperial College London |
| 키워드 | Micromechanics; Strain rate sensitivity; micropillar compression; Ti alloy; dwell fatigue |
