先進高強度鋼竟近年 因汽車發展來受到注目，本實驗藉由 Fe-5.3Mn-2.3Al-1.1Si-0.35C之中錳鋼在 175°C的固定拉伸溫度及 1x10-5/s的 低應變速率 利用不同拉伸應變量 (15%、 20%、 30%、 50%、 69%)來觀察次微米細晶中應變誘發變韌鐵相變化之顯微組織演化過程。 變韌鐵需一定的沃斯田鐵應變量才會誘發其相變化的發生，且不是每個晶粒的相變化都是同時開始的，變韌鐵會傾向在較細長的晶粒中誘發相變化。透過 TEM觀察到應變誘發變韌鐵的子單元與傳統變韌鐵不太一樣，其形貌偏向變形的板狀結構 ，而沃斯田鐵母相與變韌鐵之間有特定之晶向關係。

Advanced high-strength medium Mn steel has attracted great attention in the recent years due to the development of light weight application in car industries. In this research, a submicro-grained Fe-5.3Mn-2.3Al-1.1Si-0.35C (in wt%) medium Mn steel was deformed at 175°C under a strain rate of 10-5s-1 , to different tensile elongations(15%, 20%, 30%, 50%, 69%), in order to observe the microstructure evolution of strain-induced bainitic transformation. Our results showed that bainite requires a certain amount of strain in austenite to be induced by strain. Deformation-induced bainitic transformation did not start at the same time in every austenite grain. The short axis of elongated grains which inclined to the tensile axis were often found easier to have bainite grains nucleated at austenite grain boundaries. Under TEM, the subunit shape of strain-induced bainite is different from that of bainite subunit in steels with conventional grain size. Subunits shape of strain-induced bainite is more like deformed plate-like structure. In submicron-grained austenite, K-S, N-W and Pitch orientation relationships between deformation-induced bainite and austenite have been found.

論文審定書 i
中文摘要 ii
Abstract iii
目錄 iv
圖目錄 vi
表目錄 xx
一、前言 1
二、文獻回顧 2
2-1 Transformation Induced Plasticity (TRIP) 2
2-1-1 TRIP鋼的沃斯田鐵穩定性 2
2-2 變韌鐵 3
2-2-1 變韌鐵成核與成長 4
2-2-2 變韌鐵結構 5
2-2-3 應力對變韌鐵相變化之影響 6
2-2-4 應變對變韌鐵相變化之影響 9
2-2-5 變形溫度對中猛鋼機械性質的影響 11
2-2-6 變韌鐵之晶向關係 13
三、研究目的 14
四、實驗方法 15
4-1實驗材料 15
4-2實驗步驟 15
4-3 SEM顯微組織分析 15
4-4 X-ray繞射分析(X-ray diffraction, XRD) 16
4-5 TEM顯微組織分析 16
4-6 EPMA成分分析 16
五、實驗結果 17
5-1 拉伸前後顯微組織觀察 17
5-2 拉伸前後顯微組織觀察 17
5-3 SEM之顯微結構觀察 18
5-4 TEM之顯微結構觀察 20
5-4-1 應變誘發變韌鐵sub unit之形貌 20
5-4-2 變韌鐵sub unit之成核成長 21
5-5 應變誘發變韌鐵與沃斯田鐵母相之晶向關係 25
5-6 EPMA之元素成分分析 27
六、討論 28
七、結論 35
八、參考文獻 36

[1] 邱孟婷,"拉伸溫度對多相中錳鋼拉伸性質及顯微組織的影響" 國立中山大學材料與光電科學所 碩士論文, 2017.
[2] 彭子庭,"低應變速率下拉伸溫度對中錳鋼之拉伸性質與顯微組織的影響" 國立中山大學材料與光電科學所 碩士論文, 2017.
[3] B. De Cooman, "Structure–properties relationship in TRIP steels containing carbide-free bainite, " Current Opinion in Solid State and Materials Science, vol. 8 ,pp. 285-303, 2004.
[4] K. Sugimoto, T. Hojo, S. Ikeda , " Ductility of 0.1-0.6 C-1.5 Si-1.5 Mn ultra high-strength TRIP-aided sheet steels with bainitic ferrite matrix," ISIJ International, Vol. 44, pp. 1608–1614, 2004.
[5] P.J. Gibbs, "Design considerations for the third generation advanced high strength steel ," Colorado School of Mines. Arthur Lakes Library, 2012.
[6] S. Lee, S.-J. Lee, B.C. De Cooman," Austenite stability of ultrafine-grained transformation-induced plasticity steel with Mn partitioning ," Scripta Materialia, Vol. 65,pp. 225-228, 2011
[7] Y. K. Lee and J. Han, "Current opinion in medium manganese steel," Materials Science and Technology, vol. 31, pp. 843-856, 2014.
[8] S. Lee, S.-J. Lee, B.C. De Cooman" Work hardening behavior of ultrafine-grained Mn transformation-induced plasticity steel," Acta Materialia, vol. 59, pp.7546-7553, 2011
[9] P. Maxwell, A. Goldberg, J. Shyne, "Stress-assisted and strain-induced martensites in Fe-Ni-C alloys, " Metallurgical and Materials Transactions B , vol. 5, pp.1305-1318, 1974.
[10] H. Bhadeshia, R. Honeycombe, "Steels: microstructure and properties, " Elsevier Science, 2011.
[11] P.H. Shipway, H. Bhadeshia, "Mechanical stabilisation of bainite, " Materials Science and Technology , vol.11, pp.1116-1128, 1995.
[12] K. Tsuzaki, T. Ueda, K. Fujiwara and T. Maki, "Increase in retained austenite by ausforming in an austempered silicon steel " New Materials & Processes for the Future ,pp. 799–804, 1989.
[13] E. Swallow, H. J. M. S. Bhadeshia, "High resolution observations of displacements caused by bainitic transformation," Materials Science and Technology ,vol. 12, pp. 121-125, 1996.
[14] R. F. J. A. Mehl, Metals Park, OH, "Hardenability of alloy steels," vol. 1, 1939.
[15] H. Ohtani, S. Okaguchi, Y. Fujishiro, and Y. Ohmori, "Morphology and properties of low-carbon bainite," Metallurgical Transactions A, vol. 21, pp. 877-888, 1990.
[16] J. Yin, M. Hillert, and A. Borgenstam, "Morphology of Upper and Lower Bainite with 0.7 Mass Pct C," Metallurgical and Materials Transactions A, vol. 48, pp. 4006-4024, 2017.
[17] K. Hase, C. Garcia Mateo , H.K.D.H. Bhadeshia " Bainite formation influenced by large stress, " Materials Science and Technology , vol. 20, pp.1499-1505, 2004.
[18] H. Bhadeshia, S. David, J. Vitek, and R. Reed, "Stress induced transformation to bainite in Fe–Cr–Mo–C pressure vessel steel," Materials Science and Technology, vol. 7, pp. 686-698, 1991.
[19] A. Matsuzaki, H. Bhadeshia, and H. Harada, "Stress affected bainitic transformation in a Fe-C-Si-Mn alloy," Acta metallurgica et materialia, vol. 42, pp. 1081-1090, 1994.
[20] R. Freiwillig, J. Kudrman, P. Chraska, " Bainite transformation in deformed austenite " Metall.Trans A ,vol. 7 ,pp. 1091–1097, 1976
[21] X.J. Jin, N. Min, K.Y. Zheng, T.Y. Hsu, " The effect of austenite deformation on bainite formation in an alloyed eutectoid steel, " Mater. Sci. Eng. A , vol. 438–440 pp. 170–172, 2006
[22] K. Fujiwara, S. Okaguchi, H. Ohtani " Effect of Hot Deformation on Bainite Structure in Low Carbon Steels , " ISIJ International, vol. 35 pp. 1006-1012. 1995
[23] J. Min, J. Lin, and Y. a. Min, "Effect of thermo-mechanical process on the microstructure and secondary-deformation behavior of 22MnB5 steels," Journal of Materials Processing Technology, vol. 213, pp. 818-825, 2013.
[24] K. Sugimoto, N. Usui, M. Kobayashi, and S. J. I Hashimoto, "Effects of volume fraction and stability of retained austenite on ductility of TRIP-aided dual-phase steels," ISIJ International,vol. 32, pp. 1311-1318, 1992.
[25] K. Sugimoto, M. Tsunezawa, T. Hojo, S. Ikeda, "Ductility of 0.1-0.6C-1.5Si-1.5Mn Ultra High-strength TRIP-aided Sheet Steels with Bainitic Ferrite Matrix, "ISIJ International, Vol. 44, pp. 1608–1614, 2004.
[26] R. H. Larn, and J. R. Yang, " The effect of compressive deformation of austenite on the bainitic ferrite transformation in Fe-Mn-Si-C steels," Materials Science and Engineering A, vol. 278 pp.278–291, 2000.
[27] H.C.Yang, and W.H. Hsieh , "Mechanical stabilization of austenite against bainitic reaction in Fe–Mn–Si–C bainitic steel," Materials Trans, vol. 37 pp. 579-85, 1996.
[28] Z. Shi, K. Liu, M. Wang, J. Shi, H. Dong, J. Pu, B. Chi ," Effect of non-isothermal deformation of austenite on phase transformation and microstructure of 22SiMn2TiB steel, "Materials Science and Engineering A, vol. 535 ,pp. 290– 296, 2012
[29] C.Y. Huang, J.R.Yang, S.C.Wang ,"Effect of Compressive Deformation on the Transformation Behavior of an Ultra-Low-Carbon Bainitic Steel"Materials Trans . JIM ,vol.34,pp.685,1993
[30] J.R.Yang, C.Y. Huang, W.H.Hsieh ," Mechanical Stabilization of Austenite against Bainitic Reaction in Fe-Mn-Si-C Bainitic Steel " Materials Trans. JIM, vol.37,pp.579,1996
[31] Y. He, S. Godet, J. J. Jonas, "Observations of the Gibeon meteorite and the inverse Greninger-Troiano orientation relationship"J. Appl. Cryst. , vol. 39,pp. 72-81, 2006