臺灣博碩士論文加值系統

本研究主要探討錳鋁元素添加(21Mn、24Mn、24Mn-4Al)對冷軋TWIP鋼主要機械性質影響之研究。主要定義出拉伸速率於3.3×10-3s-1時三種不同成分鋼種其變形機制分別為TRIP及TWIP、TWIP、TWIP及差排滑移。此外，本研究也以(21Mn、24Mn、24Mn-4Al)為材料，進行三種不同拉伸速率(3.3×10-3s-1、3.3×10-2s-1、10-1s-1)，探討其對機械性質之影響。
根據熱力學方式計算，不同合金元素添加對疊差能之關係，由計算結果可發現，隨著錳、鋁元素添加對於疊差能皆有提升之作用，經熱力學計算後，21Mn、24Mn、24Mn-4Al之疊差能依序為21.9 mJ/m2 29.2 mJ/m2及58.7 mJ/m2。
拉伸速率於3.3×10-3s-1時，24Mn具有最大T.S.×El.為69645.03MPa%，24Mn-4Al其T.S.×El.則為最小43918.75 MPa%，21Mn則介於其兩者之間為54819.04 MPa，21Mn 具有最大T.S.值為907.6MPa，24Mn 具有最大El.值為78.9%，24Mn-4Al具有最大Y.S.值為352.9MPa，由XRD結果顯示24Mn及24Mn-4Al無論拉伸前後皆為穩定γ相，另外21Mn則於拉伸前為γ相為主並同時存在ε相，拉伸後則呈現以ε相為主要相，拉伸後TEM試片觀察，21Mn具有ε相以及雙晶存在，因此其機制主要有TRIP及部分TWIP主導，24Mn則皆為機械雙晶，因此其機制為TWIP主導，最後24Mn-4Al則具有差排糾結以及雙晶，因此其機制主要為差排滑移主導加上部分TWIP。
同成分下應變速率對機械性質探討中發現，21Mn隨著速率增加其El.值由60.4%增加至75.7%，T.S.×El.值則由54819.04 MPa%增加至68024.02 MPa%，24Mn其性質則不隨著速率有明顯變化T.S.×El.平均值約為69029 MPa%，24Mn-4Al其性質也不隨著速率有明顯變化T.S.×El.平均值約為41326 MPa%。

This study focused on the effect of Mn and Al alloys on the mechanical properties in cold-rolled TWIP steels, however, the effect of strain rate on mechanical properties was also investigated. In this study, steels were adopted as the test materials.
According to thermodynamic calculation, the stacking fault energy of the 21Mn、24Mn and 24Mn-4Al were 21.9 mJ/m2, 29.2 mJ/m2 and 58.7 mJ/m2, respectively. It reveals that stacking fault energy increased with addition of manganese and aluminum.
As the mechanical property, tensile test was carried out to investigate the TWIP steels tensile strength (T.S.), elongation (El.), and toughness (T.S.×El.) with various strain rates of 3.3×10-3s-1、3.3×10-2s-1、10-1s-1. The results showed that 21Mn possessed the maximum (T.S.) of 907.6MPa. and 24Mn possessed the maximum elongation (El.) of 78.9%. In addition, 24Mn-4Al possessed the maximum Y.S. of 352.9MPa. Summary the results of mechanical properties showed that 24Mn steel possessed the superior toughness of 69645.03MPa% (T.S.×El. value), while strain rate of 3.3×10-3s-1. 21Mn and 24Mn-4Al steels were 54819.04 MPa% and 43918.75 MPa%, respectively.
From XRD results, 24Mn and 24Mn-4Al steels possessed stableγphase, even though after deformed. It was noticed the 21Mn specimen possessed γ(F.C.C.) structure before tensile test and obtained the phase transformation fromγ transform to εafter tensile test. The TEM results revealed ε-martensite and twin co-exist in 21Mn, it supported that deformation mechanism is TRIP and TWIP under tensile test. Only mechanical twin structure was observed in 24Mn, resulting in obtaining TWIP deformation mechanism. Moreover 24Mn-4Al possessed dislocation entanglement phenomenon and twin structure; as a result its deformation mechanism was classified to dislocation slip and partly TWIP mode.
As the effect of strain rate on mechanical property with TWIP steels, the elongation (El.) of 21Mn was increased from 60.4% to 75.07% with strain rate increasing. In addition, the value of T.S.×El. was also increased to 68024.02 MPa%. However, 24Mn possessed the highest value of T.S.×El. reached to 69029 MPa%. But the strain rate was not affect the mechanical property of 24Mn-4Al significantly.

謝誌 Ⅰ
總目錄 III
表目錄 V
圖目錄 VI
中文摘要 1
英文摘要 2
第一章 前言 4
第二章 文獻回顧 6
2.1 TWIP鋼發展沿革 6
2.2變形過程中雙晶扮演角色 11
2.2.1雙晶類型 11
2.2.2變形雙晶與TWIP鋼機械性質之關係 17
2.3疊差對TWIP鋼之影響 21
2.3.1何謂疊差 21
2.3.2疊差種類 23
2.3.3影響疊差因素與雙晶形成之關係 23
2.4 PLC介紹 26
2.5 加工硬化率 27
第三章 研究目的 30
第四章 實驗流程與方法 31
4.1 實驗流程 31
4.2實驗方法 32
4.2.1合金設計 32
4.2.1.1理論疊差能之計算 33
4.2.2 熔煉 37
4.2.3熱軋延 38
4.2.4冷軋延 40
4.2.5退火 40
4.2.6顯微結構 41
4.2.6.1 光學顯微鏡(Optical Microscopy) 41
4.2.6.2背向電子繞射儀(Electron Backscatter Diffraction) 41
4.2.6.3穿透式電子顯微鏡(Transmission Electron Microscopy) 41
4.2.6.4 X光繞射儀 (X-Ray Diffraction) 42
4.2.6.5掃描式電子顯微鏡(Scanning Electron Microscopy) 42
4.2.7 機械性質 42
4.2.7.1拉伸試驗 42
第五章 結果與討論 44
5.1錳鋁元素對TWIP鋼顯微結構組織之影響 44
5.2錳鋁元素對TWIP鋼機械性質之影響 48
5.3 錳鋁元素對PLC現象之影響 67
5.4錳鋁元素於不同應變速率對其PLC現象之影響 76
5.5 PLC現象於不同應變量下顯微結構組織之差異 89
第六章 結論 92
第七章 參考文獻 93

[1]. WorldAutoSteel: Automotive Steel Performance Advantages
[2]. O. Grassel, L. Krueger, G. Frommeyer, L.W. Meyer, “High strength Fe-Mn-(Al, Si) TRIP/TWIP steels development-properties-application”, International Journal Plasticity. 16,1391-1409(2000).
[3]. ULSAB-AVC Consortium: Technical Transfer Dispatch #6, May 2001.
[4]. W. Bleck, K. Phiu-On, “Microalloying of Cold-Formable Multi Phase Steel Grades”, Materials Science Forum. 500-501 , 97-114(2005).
[5]. W. Bleck: International Conference on TRIP-Aided High Strength Ferrous Alloys, Ghent, Belgium 2002, pp. 13-23.
[6]. W. Bleck, A. Frehn and J. Ohlert: Proc. Inter. Symposium Niobium 2001, USA, pp. 727-752.
[7]. G. Frommeyer, U. Bruex, and P. Neumann, ISIJ International.43, 438-446(2003).
[8]. S. Allain, J.P. Chateau, D. Dahmoun , O. Bouaziz, Materials Science and Engineering A. 387-389, 272-276(2004).
[9]. C. Scott, P. Maugis, P. Barges and M. Goune, International Conference on Advanced High Strength.
[10].德國國科會特別研究報告資料, 2007
[11].S. Mahajan, C. S. Pande, M. A. Imam, B. B. Rath, Acta mater. 45, 2633 -2638(1997).
[12].Gertsman, V. Y., Tangri, K. , Valiev, R. Z., Acta metall. mater. 42, 1785(1994).
[13].Pande, C. S., Imam, M. A., Rath, B. B., Met. Trans.A. 21A, 2891(1990).
[14].B.B. Rath, M.A. Imam and C.S. Pande,“Nucleation and growth of twin interfaces in FCC metals and alloys”,Mater.Phys.Mech.1, 61-66(2000)
[15].李欣怡，國立台灣大學工學院材料工程學系博士論文，“黃銅退火雙晶與高碳麻田散鐵相變雙晶之奈米顯微組織研究”，99年7月
[16].F.D. Fischer, T. Schaden, F. Appel, H. Clemens, ”Mechanical twins, their development and growth”, Eur. J. of Mech. A/Solids 22, 709-726(2003).
[17].Jinkyung Kim, S.J. Lee, B.C. De Cooman, “Effect of Al on the Stacking Fault Energy of Fe-18Mn-0.6C Twinning-Induced Plasticity”, Scripta Materialia,2010
[18].O. Bouaziz, S. Allain and C. Scott，“Effect of grain and twin boundaries on the hardening mechanisms of twinning-induced plasticity steels”, Scripta Materialia. 58, 484–487 (2008).
[19].Robert D. Boyer, “Shear-Induced Homogeneous Deformation Twinning in FCC Aluminum and Copper via Atomistic Simulation”, B.S. Materials Science and Engineering Case Western Reserve University.
[20].Bo Qin, “Crystallography of TWIP Steel”, A dissertation submitted for the degree of Master of Engineering at Pohang University of Science and Technology July 2007.
[21].S. Curtze, V.T. Kuokkala, A. Oikari, J. Talonen, H. Hanninen, “Thermodynamic modeling of the stacking fault energy of austenitic steels”, Acta Materialia. 59, 1068–1076 (2011).
[22].J. W. Christian, S. Mahajan, “Deformation twinning”, Progress in Materials Science, 39, 1-157(1995).
[23].S. Vercammen, “Processing and Tensile Behavior of TWIP steels Microstructure and Texture Analysis”. Ph. D. thesis, Katholieke Universitieit, Leuven, Belgium, (2004).
[24].G. Frommeyer, U. Brux, P. Neumann, “Supra-ductile and high-strength manganese-TRIP/TWIP steels for high energy absorption purposes”, ISIJ International.43, 438-446(2003).
[25].Y. S. Han, S. H. Hong, “The effect of Al on mechanical properties and microstructures of Fe-32Mn-12Cr-xAl-0.4C cryogenic alloys”, Material Science and Engineering. A 222, 76-83(1997).
[26].M. Melchior, “Modelling of texture and hardening of TWIP steel-Advanced finite element representation of polycrystalline aggregates”, PH. D. thesis, Université catholique de Louvain.
[27].S. Takaki, T. Furuya, Y. Tokunaga, ISIJ International.30, 632-638(1990).
[28].F.C. Chen, C.P. Chou, P. Li, S.L. Chu, Materials Science and Engineering A.A160, 261-270 (1993).
[29].E.I. Poliak, F. Siciliano, Proceeding of Materials Science & Technology conference, edition by M.A. Baker, AIST & TMS, Warrendale, PA, 2004, p.39.
[30].A.S. Hamada, M.C. Somani, L.P. Karjalainen, ISIJ International. 47, 907-912 (2007).
[31].O. Vohringer. Zur Zwilingsbidung bei vielkristallinen a-CuSn legierungen Mater, Sci. Eng. 1968, 3, pp.299-302.
[32].L. Bracke, L. Kestens and J. Penning, “Direct observation of the twinning mechanism in an austenitic Fe–Mn–C steel”, Scripta Materialia. 61, 220–222 (2009).
[33].L. Chen, H.S. Kim, S.K. Kim, B.C. De Cooman, “Localized Deformation due to Portevin-Lechatelier Effect in 18Mn-0.6C TWIP Austenitic Steel”, ISIJ International. 47, 1804-1812 (2007).
[34].K.S. Ragharam, A.S. Sastri, M.J. Marcinkowksi, “Nature of work hardening behavior in hadfield's manganese steel”, Transactions of the Metallurgical Society of AIME. 245, 1569-1975 (1969).
[35].O. Bouaziz, N. Guelton, “Modelling of TWIP effect on work-hardening”, Material Science and Engineering. A319-321, 246-249 (2001).
[36].Y.G. Kim, J.M. Han, J.S. Lee, “ Effect of Aluminum content on low temperature tensile properties in cryogenic Fe/Mn/Al/Nb/C steels”, Metallurgical Transactions A. 17, 2097-2098 (1986).
[37].X. Tian, R. Tian, X. Wei , Y. Zhang, “Effect of Al on work hardening in Austenitic Fe-Mn-Al-C alloys”, Canadian Metallurgical Quarterly. 43, 183-192 (2004).
[38].Surya R. Kalidindi, “Modeling the strain hardening response of low SFE FCC alloys”, International Journal of Plasticity. 14, 1265-1277 (1998).
[39].P. J. Ferreira, J. B. Vander Sande, M. Fortes, A. A. Kyrolainen, “Microstructure development during high-velocity deformation”, Metallurgical and Materials Transactions A.35, 3091-3101( 2004).
[40].A. S. Hamada, L. P. Karjalainen, M. C. Somani, “The influence of aluminum on hot deformation behavior and tensile properties of high-Mn TWIP steels”. Materials Science and Engineering A.A467, 114-124 (2007).
[41].Ding Hao, Ding Hua, Song Dan, Tang Zhengyou,Yang Ping, “Strain hardening behavior of a TRIP/TWIP steel with 18.8% Mn”, Materials Science and Engineering A.(2010)
[42].A. Haldar, S. Suwas, D. Bhattacharjee, “Microstructure and texture in steels”, Springer Book, (2009)
[43].B. Jiang, X. Oi, S. Yang, W. Zhou, T. Y. Hsu, “Effect of stacking fault probability on γ-ε martensitic transformation and shape memory effect in Fe-Mn-Si based alloys”, Acta Materialia.46, 501-510 (1998).
[44].Y. K. Lee and C. S. Choi, “Driving force for γ→ε martensitic transformation and stacking fault energy of γ in Fe-Mn binary system, ”Metallurgical and Materials Transaction A.31A, 355-360 (2000).
[45].H. K. D. H. Bhadeshia,“worked examples in the geometry of crystals”,The Institute of metals,(1987),p.56
[46].G. Frommeyer, U. Brux, P. Neumann, “Supra-ductile and high-strength manganese-TRIP/TWIP steels for high energy absorption purposes”, ISIJ International. 43, 438-446 (2003).
[47].S. Vercammen, “Processing and tensile behavior of TWIP steels microstructure and texture analysis”, Ph. D. thesis, Katholieke Universitieit, 2004.
[48].G.B. Olson and M. Cohen, Metall. Trans. 7A, 1897 (1976).
[49].P. J. Ferreira and P. Müllner, “A thermodynamic model for the stacking fault energy”, Acta mater., 46, 4479-4484 (1998).
[50].S. Cotes, M. Sade, A. Fernàndez Guillermet,” Fcc/Hcp Martensitic Transformation in the Fe-Mn System: Experimental Study and Thermodynamic Analysis of Phase Stability”, Metall. Mater. Trans. A, 26A , 1957-1969 (1995).
[51].O. Redlich and A.T. Kister, Ind. Eng. Chem., 40 , 345-348 (1948).
[52].M. Hillert and M. Jarl, CALPHAD, 2 , 227-238 (1978).
[53].G. Inden, Phys. B, 103,82-100 (1981).
[54].A. T. Dinsdale, SGTE data for pure elements, CALPHAD, 4, 317-425 (1991).
[55].A. Dumay, J.-P. Chateau, S. Allain, S. Migot and O. Bouaziz, “Influence of addition elements on the stacking-fault energy and mechanical properties of an austenitic Fe-Mn-C steel”, Mater. Sci. Eng. A, 483-484, 184-187 (2008).
[56].S. Allain, Ph.D. Thesis, INPL, Nancy, 2004.
[57].W. S. Yang and C. M. Wan, “The influence of aluminum content to the stacking fault energy in Fe-Mn-Al-C alloy system”, Journal of Materials Science, 25 , 1821-1823 (1990).
[58].W. Huang, CALPHAD, 13, 243-252 (1989).
[59].S. Curtze, Characterization of the Dynamic Behavior and Microstructure Evolution of High Strength Sheet Steels, PhD thesis, Tampere University of Technology.
[60].G. F. Bolling, R. H. Richman, Continual mechanical twinning, Acta Met. 13,709-722 (1965).
[61].Arunansu Haldar, Dr. , Debashish Bhattacharjee, Dr. , Satyam Suwas, Asst. Prof. ,“Microstructure and Texture in Steels and Other Materials”,pp.175-192, Springer, London New York.(2008).