Fatigue Crack Growth Behavior of U20Mn Bainite Rail

Abstract

a-N curves of fatigue crack growth of U20Mn bainite rail after different heat treatment process were studied (The temperature is cooled from 900 to 20 °C, the cooling rate was 0.5 °C/s, 1 °C/s and salt bath isothermal respectively), the Paris formula of fatigue crack growth was fitted linearly, and the material parameters C and n were measured. The results show that the sample with cooling rate of 0.5 °C/s has the fastest crack growth rate, and the sample with salt bath isothermal has the slowest crack growth rate. The coarse M/A islands with irregular shape in bainite structure with cooling rate of 0.5 °C/s has poor resistance to fatigue crack propagation, which is not conducive to improving the fatigue performance. However, the sample with salt bath isothermal has longer fatigue life. Due to the combination of bainitie lamellar and retained austenite distributed between them, the salt bath isothermal sample can effectively improve the strength and toughness of bainite steel. The sample with cooling rate of 0.5 °C/s is mainly composed of granular bainitie structure, and the fatigue crack growth trajectory is generally gentle without large angle deflection, the sample with salt bath isothermal is mainly composed of bainite lamellar structure, and the fatigue crack growth trajectory is not straight, with a large number of Z-shaped deflection. The fatigue cracks are prone to produce branch cracks at the stress concentration of propagation deflection, and the branch crack consumes the energy of the main fatigue cracks, thus reducing the fatigue crack growth rate and improving fatigue life.

References

[1] LiJ P, WengZ Y, ZhouY, et al.. Prediction Model of Rail Head Check Initiation Considering Wear and Nonlinear Fatigue Damage Accumulation[J]. Fatigue Fract. Eng. M., 2023, 46(12): 4591-4605

[2] CenY D, ChenL, DongR, et al.. Effect of Quenching Rate on Fatigue Crack Growth of Hypereutectoid Rail Steel[J]. J. Mater. Sci., 2020, 55(30): 15033-15042

[3] CenY D, ChenL, JiC J, et al.. Fatigue Crack Growth Behavior of Eutectoid Steel Rail[J]. J. Wuhan Univ. Technol.-Mater. Sci.Ed., 2022, 37(3): 507-512

[4] LiY G, KangG Z, WangC A, et al.. Vertical Short-Crack Behavior and Its Application in Rolling Contact Fatigue[J]. Int. J. Fatigue, 2006, 28(7): 804-811

[5] HasanS M, ChakrabartiD, SinghS B. Dry Rolling/Sliding Wear Behaviour of Pearlitic Rail and Newly Developed Carbide-Free Bainitic Rail Steels[J]. Wear, 2018, 408: 151-159

[6] LiuJ P, DuH Q, LiY Q, et al.. Effect of Typical Production Process on Microstructure and Properties of Carbide-Free Bainitic Rail Steels[J]. China Railw. Sci., 2022, 43(1): 29-37

[7] LiQ G, ZhangY A, LuoH. Impact Abrasive Wear Behaviour of the Multiphase Microstructure in a Medium Carbon Quenched and Partitioned Bainitic Steel[J]. Wear, 2023, 518: 204 644

[8] LiQ G, HuangX F, HuangW G. Fatigue Property and Microstructure Deformation Behavior of Multiphase Microstructure in a Medium-Carbon Bainite Steel Under Rolling Contact Condition[J]. Int. J. Fatigue, 2019, 125: 381-393

[9] DouP, SuoS F, BaiB Z, et al.. Vertical Short Crack Initiation in Medium Carbon Bainitic Steel under Mild Tractive Rolling Contact[J]. J. Iron. Steel Res., 2008, 15(3): 37-41

[10] WangK, HuF, ZhouS B, et al.. Effect of Microstructure Transformation Below MS Temperature in Bainitic Steels on the Impact-Abrasive Wear Behavior[J]. Wear, 2023, 514: 204 589

[11] GaoX L, BaW Y, ZhangF C, et al.. Study of the Solute Micro-Segregation Behaviour of Bainite Rail Steel in the Continuous Casting Process[J]. J. Mater. Res. Technol., 2024, 29: 751-763

[12] ZhangR, ZhengC, LvB, et al.. Effect of Non-Uniform Microstructure on Rolling Contact Fatigue Performance of Bainitic Rail Steel[J]. Int. J. Fatigue, 2022, 159: 106 795

[13] GaoG H, XuQ Z, GuoH R, et al.. Effect of Inclusion and Microstructure on the Very High Cycle Fatigue Behaviors of High Strength Bainite/Martensite Multiphase Steels[J]. Mat. Sci. Eng. A-Struct., 2019, 739: 404-414

[14] BaoX R, WangJ N. Effects of Lanthanum on Bainite Transformation Behavior in Mn-Cr-Mo rail Steel[J]. J. Mater. Res., 2021, 36(6): 1400-1412

[15] ZhangR J, ZhengC L, ZhangP J, et al.. Effect of Segregation and Contact Stress on Fatigue Wear Behavior of Bainitic Rail Steel[J]. J. Mech. Eng., 2023, 59(12): 253-263

[16] MirandaR S, RezendeA B, FonsecaS T, et al.. Fatigue and Wear Behavior of Pearlitic and Bainitic Microstructures with the Same Chemical Composition and Hardness Using Twin-Disc Tests[J]. Wear, 2022, 494: 204 253

[17] GaoG H, LiuR, FanY S, et al.. Mechanism of Subsurface Microstructural Fatigue Crack Initiation During High and Very-High Cycle Fatigue of Advanced Bainitic Steels[J]. J. Mater. Sci. Technol., 2022, 108: 142-157

[18] ZhengC L, ZhangF C, LuB, et al.. Rolling Contact Fatigue Wear Behavior of Carbide Bainite Steel[J]. J. Mech. Eng., 2018, 54(4): 176-185

[19] GuiX L, ZhangB X, GaoG H. Fatigue Behavior of Bainite/Martensite Multiphase High Strength Steel Treated by Quenching-Partitioning-Tempering Process[J]. Acta Metall. Sin., 2016, 52(9): 1036-1044

[20] BaekM S, KimK S, ParkT W, et al.. Quantitative Phase Analysis of Martensite-Bainite Steel Using EBSD and Its Microstructure, Tensile and High-Cycle Fatigue Behaviors[J]. Mat. Sci. Eng. A-Struct., 2020, 785: 139 375

[21] LiuX Y, ZhangD, SuH, et al.. Numerical Simulation and Experimental Study on Heat Treatment Process of U20Mn Bainite Rail[J]. Metallogr. Microstruc., 2022, 11(1): 119-131

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