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摘要: 研究不同含量的上貝氏體對ER8車輪鋼裂紋擴展行為的影響。利用激光共聚焦顯微鏡（LSCM）和掃描電鏡（SEM）對ER8車輪鋼的顯微組織和裂紋擴展路徑進行了研究。實驗結果表明：ER8車輪鋼中的組織除了有鐵素體和珠光體，還存在上貝氏體；裂紋穿過上貝氏體和珠光體擴展，最終停止在珠光體區域；與珠光體組織相比，裂紋在上貝氏體中的擴展路徑更曲折。利用掃描電鏡（SEM）對ER8車輪鋼的裂紋擴展變形進行原位觀察。實驗結果表明：含有80%上貝氏體的ER8車輪鋼拉伸時，組織變形過程主要以鐵素體和上貝氏體為主，裂紋在上貝氏體和珠光體中連續擴展，伴隨著珠光體的變形；而含有50%上貝氏體的ER8車輪鋼拉伸時，組織變形過程主要以鐵素體和珠光體為主，并且上貝氏體對鐵素體和珠光體的變形起到阻礙作用。上貝氏體能夠有效地阻止裂紋擴展，在偏轉裂紋路徑和延緩裂紋擴展方面起著重要作用；并且對鐵素體和珠光體的變形起到阻礙作用。Abstract: In recently years, high-speed and heavy-haul railway technology has been rapidly developed and widely used in China. Pearlite steel is usually used in railway wheels, and its structure is composed of pearlite and ferrite. Pearlite has properties, including mechanical properties, that combine those of ferrite and cementite, and it also has acceptable strength and toughness. The comprehensive mechanical properties of pearlite are better than those of ferrite or cementite alone. When upper bainite is produced after the heat-treatment of ER8 wheel steel, the upper bainite may become the channel of crack development because of the large carbide particles and the weak strengthening effect and especially because of the presence of flake ferrites. In this study, the influence of different contents of upper bainite on the crack propagation behavior of ER8 wheel steel was investigated. The microstructure and crack growth path of ER8 wheel steel were studied by laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). The experimental results show that ER8 wheel steels not only have ferrite and pearlite but also upper bainite. The crack propagates through the upper bainite and pearlite and finally stops in the pearlite region. Compared with the pearlite microstructure, the crack propagation path in the upper bainite is more tortuous. The crack propagation and deformation of ER8 wheel steels were observed in situ by scanning electron microscopy. The experimental results show that when ER8 iron wheel steel containing 80% upper bainite is stretched, the microstructure deformation process is mainly ferrite and upper bainite. The crack in the upper bainite and the pearlite continues to expand with the pearlite deformation. However, when ER8 iron wheel steel containing 50% upper bainite is stretched, the deformation process mainly involves ferrite and pearlite, and the upper bainite retards the ferrite and pearlite deformation. The upper bainite can effectively prevent crack growth and plays an important role in deflecting crack path and delaying crack growth. Moreover, it hinders the deformation of ferrite and pearlite.
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Key words:
- ER8 wheel steel /
- upper bainite /
- crack /
- in situ stretching /
- plastic deformation
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圖 1 ER8車輪鋼輪輞踏面區域取樣示意圖(單位：mm)
Figure 1. Schematic diagram of sampling area of steel rim tread of ER8 wheel steel (unit: mm)
圖 3 ER8車輪鋼微觀組織圖. （a）1#光鏡組織；（b）2#光鏡組織；（c）1#掃描組織；（d）2#掃描組織；（e）1#透射組織；（f）2#透射組織
Figure 3. Microstructure of ER8 wheel steel: (a) 1# microstructure; (b) 2# microstructure; (c) 1# scanning structure; (d) 2# scanning structure; (e) 1# transmission structure; (f) 2# transmission structure
圖 4 ER8車輪鋼輪輞踏面的裂紋形成與擴展顯微圖. （a）1#車輪鋼表面剝離坑；（b）1#車輪鋼裂紋擴展；（c,d）2#車輪鋼裂紋擴展
Figure 4. Micrograph of crack formation and propagation on rim tread of ER8 wheel steel: (a) 1# wheel steel surface peel pit; (b) crack growth of 1# wheel steel; (c, d) crack growth of 2# wheel steel
圖 5 ER8車輪鋼裂紋擴展示意圖. （a）裂紋萌生處；（b~d）裂紋在上貝氏體中擴展；（e~f）裂紋在珠光體中擴展（這些顯微照片不是在車輪鋼的同一區域拍攝）
Figure 5. ER8 wheel steel crack propagation diagram: (a) crack initiation; (b–d) crack propagation in upper bainite; (e–f) crack propagation in pearlite (Note that these micrographs were not taken at the same region of the wheel steels)
圖 6 1#車輪鋼原位拉伸掃描組織圖. （a）變形初期形成的主裂紋；（b）圖（a）的局部放大；（c）拉力增大，主裂紋擴展；（d）主裂紋進一步擴展；（e）拉伸斷裂后，主裂紋旁邊組織變形；（f）拉伸斷裂后，主裂紋附近的組織變形
Figure 6. In situ tensile scanning microstructure of 1# wheel steel: (a) main cracks formed in the early deformation stage; (b) partial enlargement of Fig.(a); (c) image showing main crack growth with tension increasing; (d) further expansion of the main crack; (e) microstructure adjacent to the main crack after tensile fracture; (f) microstructure around the main crack after tensile fracture
圖 7 2#車輪鋼原位拉伸掃描組織圖. （a）變形初期形成的主裂紋；（b）圖（a）的局部放大；（c）拉力增大，主裂紋穿過上貝氏體擴展；（d~f）拉伸斷裂后，主裂紋附近的組織變形
Figure 7. In situ tensile scanning microstructure of 2# wheel steel: (a) main cracks formed in the early deformation stage; (b) partial enlargement of Fig.(a); (c) image showing main crack growth with tension increasing; (d–f) deformation of the microstructure near the main crack after tensile fracture
表 1 ER8車輪鋼化學成分（質量分數）
Table 1. ER8 wheel steel chemical composition
% Sample C Si Mn S P Cr Mo Ni V Fe 1# 0.50 0.34 0.74 0.002 0.007 0.19 0.03 0.17 0.02 Bal. 2# 0.49 0.35 0.74 0.001 0.007 0.19 0.03 0.15 0.04 Bal. 
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參考文獻
[1] Duan G H, Zhang P, Li J X, et al. In situ studies on the effect of ferrite and pearlite contents on the deformation process. J Univ Sci Technol Beijing, 2014, 36(8): 1032段桂花, 張平, 李金許, 等. 鐵素體和珠光體含量影響變形過程的原位研究. 北京科技大學學報, 2014, 36(8):1032 [2] Zeng D F, Lu L T, Gong Y H, et al. Optimization of strength and toughness of railway wheel steel by alloy design. Mater Des, 2016, 92: 998 doi: 10.1016/j.matdes.2015.12.096 [3] Liu Z X, Gu H C. The in-situ fatigue crack observation of wheel steels. Prakt Metallogr, 2002, 39(4): 21 [4] Xie Y J, Hu X Z, Wang X H, et al. A theoretical note on mode-I crack branching and kinking. Eng Fract Mech, 2011, 78(6): 919 doi: 10.1016/j.engfracmech.2011.01.023 [5] Hamada S, Sasaki D, Ueda M, et al. Fatigue limit evaluation considering crack initiation for lamellar pearlitic steel. Procedia Eng, 2011, 10: 1467 doi: 10.1016/j.proeng.2011.04.245 [6] Mutoh Y, Korda A A, Miyashita Y, et al. Stress shielding and fatigue crack growth resistance in ferritic–pearlitic steel. Mater Sci Eng A, 2007, 468-470: 114 doi: 10.1016/j.msea.2006.07.171 [7] Zhang W, Liu Y M. Investigation of incremental fatigue crack growth mechanisms using in situ SEM testing. Int J Fatigue, 2012, 42: 14 doi: 10.1016/j.ijfatigue.2011.03.004 [8] Toribio J, González B, Matos J C. Micro-and macro-analysis of the fatigue crack growth in pearlitic steels. Ciênc Tecnol Mater, 2008, 20(1-2): 68 [9] Maya-Johnson S, Ramirez A J, Toro A. Fatigue crack growth rate of two pearlitic rail steels. Eng Fract Mech, 2015, 138: 63 doi: 10.1016/j.engfracmech.2015.03.023 [10] Guan M F, Yu H. Fatigue crack growth behaviors in hot-rolled low carbon steels: a comparison between ferrite–pearlite and ferrite–bainite microstructures. Mater Sci Eng A, 2013, 559: 875 doi: 10.1016/j.msea.2012.09.036 [11] Chen L, Guo F X, Wang H J, et al. Effect of microstructure on fatigue crack propagation behavior of U20Mn bainite steel. Trans Mater Heat Treat, 2018, 39(2): 119陳林, 郭飛翔, 王慧軍, 等. 微觀組織對U20Mn貝氏體鋼疲勞裂紋擴展行為的影響. 材料熱處理學報, 2018, 39(2):119 [12] Sun Z Y, Zhou H, Cheng X H. Impact toughness of low-carbon bainite steel with initial cracks. J Shanghai Jiaotong Univ, 2016, 50(7): 1000孫志永, 周華, 程先華. 含有初始裂紋的低碳貝氏體鋼的沖擊韌性. 上海交通大學學報, 2016, 50(7):1000 [13] Teshima T, Kosaka M, Ushioda K, et al. Local cementite cracking induced by heterogeneous plastic deformation in lamellar pearlite. Mater Sci Eng A, 2017, 679: 223 doi: 10.1016/j.msea.2016.10.018 [14] Masoumi M, Sinatora A, Goldenstein H. Role of microstructure and crystallographic orientation in fatigue crack failure analysis of a heavy haul railway rail. Eng Fail Anal, 2019, 96: 320 doi: 10.1016/j.engfailanal.2018.10.022 [15] Korda A A, Mutoh Y, Miyashita Y, et al. In situ observation of fatigue crack retardation in banded ferrite–pearlite microstructure due to crack branching. Scripta Mater, 2006, 54(11): 1835 doi: 10.1016/j.scriptamat.2006.02.025 [16] Eden H C, Garnham J E, Davis C L. Influential microstructural changes on rolling contact fatigue crack initiation in pearlitic rail steels. Mater Sci Technol, 2005, 21(6): 623 doi: 10.1179/174328405X43207 [17] Garnham J E, Davis C L. The role of deformed rail microstructure on rolling contact fatigue initiation. Wear, 2008, 265(9-10): 1363 doi: 10.1016/j.wear.2008.02.042 [18] Tomota Y, Watanabe O, Kanie A, et al. Effect of carbon concentration on tensile behaviour of pearlitic steels. Mater Sci Technol, 2003, 19(12): 1715 doi: 10.1179/026708303225008310 [19] Pardoen T, Dumont D, Deschamps A, et al. Grain boundary versus transgranular ductile failure. J Mech Phys Solids, 2003, 51(4): 637 doi: 10.1016/S0022-5096(02)00102-3 [20] Wang J Y, Sun C X, Zhang J. Wheel-rail contact mechanics analysis of internal cracks. J Dalian Jiaotong Univ, 2017, 38(6): 50汪金余, 孫傳喜, 張軍. 內部存在裂紋的輪軌接觸力學分析. 大連交通大學學報, 2017, 38(6):50 [21] Maya-Johnson S, Santa J F, Toro A. Dry and lubricated wear of rail steel under rolling contact fatigue-Wear mechanisms and crack growth. Wear, 2017, 380-381: 240 doi: 10.1016/j.wear.2017.03.025 -
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