Abstract
Effects of surface condition on fatigue properties of a medium-strength γ-TiAl alloy Ti–45Al–5Nb–1W (at%) were investigated. It is found that the maximum stresses of fatigue samples are lower than the yield stresses of the medium-strength γ-TiAl alloy. Meanwhile, the local plastic deformation is unconspicuous to occur at the crack tip. In this case, the fatigue strength is mainly decided by surface conditions of maximum-stressed surface, but compressive stress and deformation especially resulted from shot peening play an important role in the improvement of the condition fatigue strength. The affecting depth of shot peening is about 250 μm. As a result, the relatively weak microstructures and phases become the preferential initiation sites and propagation routes. They are observed to be equiaxed γ grains, B2 + ω grains, and α2-γ lamellar interface in soft orientations. The existence of V-notch can significantly reduce the fatigue properties of the samples.
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References
Dimiduk DM. Gamma titanium aluminide alloys-an assessment within the competition of aerospace structural materials. Mater Sci Eng A. 1999;263(2):282.
Khan AN, Usman A. Effect of silver addition in gamma titanium aluminide. J Alloys Compd. 2010;491(1):210.
Qu HP, Li P, Zhang SQ, Li A, Wang HM. The effects of heat treatment on the microstructure and mechanical property of laser melting deposition γ-TiAl intermetallic alloys. Mater Des. 2010;31(4):2210.
Huang ZW, Cong T. Microstructural instability and embrittlement behaviour of an Al-lean, high-Nb γ-TiAl-based alloy subjected to a long-term thermal exposure in air. Intermetallics. 2010;18(1):170.
Bowen P, Chave RA, James AW. Cyclic crack growth in titanium aluminides. Mater Sci Eng A. 1995;192(1):450.
Jha SK, Larsen JM, Rosenberger AH. The role of competing mechanisms in the fatigue life variability of a nearly fully-lamellar γ-TiAl based alloy. Acta Mater. 2005;53(5):1301.
Wu X, Hu D, Botten R, Loretto MH. The significance of acoustic emission during stressing of TiAl-based alloys. Part II: influence of cracks induced by pre-stressing on the fatigue life. Acta Mater. 2001;49(10):1693.
Botten R, Wu X, Hu D, Loretto MH. The significance of acoustic emission during stressing of TiAl-based alloys. Part I: detection of cracking during loading up in tension. Acta Mater. 2001;49(10):1689.
Hénaff G, Gloanec AL. Fatigue properties of TiAl alloys. Intermetallics. 2005;13(5):553.
Novovic D, Dewes RC, Aspinwall DK, Voice W, Bowen P. The effect of machined topography and integrity on fatigue life. Int J Mach Tools Manuf. 2004;44(2):131.
Bolz S, Oehring M, Lindemann J, Pyczak F, Paul J, Stark A, Weiß S. Microstructure and mechanical properties of a forged β-solidifying γ TiAl alloy in different heat treatment conditions. Intermetallics. 2015;58(1):79.
Namjoshi SA, Mall S, Jain VK, Jin O. Fretting fatigue crack initiation mechanism in Ti–6Al–4V. Fatigue Fract Eng Mater Struct. 2002;25(10):962.
Huang ZW. Ordered ω phases in a 4Zr–4Nb-containing TiAl-based alloy. Acta Mater. 2008;56(8):1693.
Trail SJ, Bowen P. Effects of stress concentrations on the fatigue life of a gamma-based titanium aluminide. Mater Sci Eng A. 1995;192(1):431.
Hu ZZ, Cao SZ. Relationship between fatigue notch factor and strength. Eng Fract Mech. 1994;48(1):134.
Ohta A, Kosuge M, Sasaki E. Fatigue crack closure over the range of stress ratios from −1 to 0.8 down to stress intensity threshold level in HT80 steel and SUS304 stainless steel. Int J Fract. 1978;14(3):262.
Huang ZW, Sun C. On the role of thermal exposure on the stress controlled fatigue behaviour of a high strength titanium–aluminum alloy. Mater Sci Eng A. 2014;615:35.
Guagliano M, Vergani L. An approach for prediction of fatigue strength of shot peened components. Eng Fract Mech. 2004;71(4):508.
Wang YL, Hui SX, Liu R, Ye WJ, Yu Y, Kayumov R. Dynamic response and plastic deformation behavior of Ti–5Al–2.5 Sn ELI and Ti–8Al–1Mo–1V alloys under high-strain rate. Rare Met. 2014;33(2):127.
Sun C, Huang ZW. Effects of varied surface condition on the fatigue behavior of a high-strength gamma-based titanium aluminide alloy. Rare Met Mater Eng. 2014;43(3):589.
Acknowledgments
This research was financially supported by the National Natural Science Foundation of China (Nos. 50971106 and 50211141) and the National Higher-Education Institution General Research and Development Fund (No. 2682014CX005). The author is also grateful to the School of Metallurgy and Materials, The University of Birmingham, UK, for some experimental support.
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Yang, ZJ., Sun, HL., Huang, ZW. et al. Fatigue properties of a medium-strength γ-TiAl alloy with different surface conditions. Rare Met. 35, 93–99 (2016). https://doi.org/10.1007/s12598-015-0625-z
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DOI: https://doi.org/10.1007/s12598-015-0625-z