Effects of pre-rolling on mechanical properties and fatigue crack growth rate of 2195 Al-Li alloy

Abstract

While pre-deformation is often conducted before aging treatment to increase the strength and microhardness of 2195 Al-Li alloy, it often increases the fatigue crack growth (FCG) rate and thus reduces the fatigue life of the alloy. To determine the effects and causes of pre-deformation and heat treatment on the mechanical properties and FCG rate of 2195 Al-Li alloy, and to provide a suitable calculation model for the FCG rate under different pre-deformation conditions, 2195 Al-Li alloy specimens with different degrees of pre-rolling (0, 3%, 6%, and 9%) were investigated. The experimental results indicate that with the increase of pre-rolling, the density of the T₁ phase and the uniformity of the S′ distribution and the microhardness, tensile strength, and yield strength of the alloy increase and at the same time the FCG rate increases, and thus the fatigue life is reduced. It was also found that the normalized stress intensity factor of elastic modulus (E) can be applied to correlate the FCG rate of pre-rolled 2195 Al-Li alloy with constant C and K parameters.

Keywords

2195 Al-Li alloy / pre-rolling / over-aging / fatigue crack growth / mechanical properties

References

[1] XiomaraC, ThomasB, RiojaR JNew aluminum lithium alloys for aerospace applications [C], 2007, Canada, Saint-Saveur, 4146

[2] RiojaR J, LiuJ. The evolution of Al-Li base products for aerospace and space applications [J]. Metallurgical and Materials Transactions A, 2012, 43(9): 3325-3337

[3] WarnerT. Recently-developed aluminium solutions for aerospace applications [J]. Materials Science Forum, 2006, 519–521: 1271-1278

[4] MarshG. Composites and metals–A marriage of convenience? [J]. Reinforced Plastics, 2014, 58(2): 38-42

[5] YuanS, LiY, HuangM, et al.. Determination of key parameters of Al–Li alloy adhesively bonded joints using cohesive zone model [J]. Journal of Central South University, 2018, 25(9): 2049-2057

[6] RiojaR J. Fabrication methods to manufacture isotropic Al-Li alloys and products for space and aerospace applications [J]. Materials Science and Engineering A, 1998, 257(1): 100-107

[7] ZhouC, ZhanL H, ShenR L, et al.. Creep behavior and mechanical properties of Al-Li-S4 alloy at different aging temperatures [J]. Journal of Central South University, 2020, 27(4): 1168-1175

[8] WenT, ChenY, DuY, et al.. Effect of spinning-deformation on microstructure and mechanical properties in 2195 Al-Li alloy [J]. Manned Spaceflight, 2020, 26(6): 717-722

[9] DuanL, ZhanL, XuY, et al.. Effect of pre deformation on creep aging behavior and microstructure evolution of Al-Li alloy [J]. Journal of Plastic Engineering, 2020, 27(8): 106-115

[10] WangL, BhattaL, XiongH, et al.. Mechanical properties and microstructure evolution of an Al-Cu-Li alloy subjected to rolling and aging [J]. Journal of Central South University, 2021, 28: 3800-3817

[11] StarkeE A, StaleyJ T. Application of modern aluminum alloys to aircraft [J]. Progress in Aerospace Sciences, 1996, 32(23): 131-172

[12] SchijveJ. The effect of pre-strain on fatigue crack growth and crack closure [J]. Engineering Fracture Mechanics, 1975, 8(4): 575-581

[13] WangZ, LiH, WeiX, et al.. Effects of prior strain on static tensile properties and fatigue lives of 2E12 aluminum alloy [J]. Rare Metal Materials and Engineering, 2010, 39(S1): 138-141(in Chinese)

[14] LiuF, LiuZ, LiuM, et al.. Analysis of empirical relation between microstructure, texture evolution and fatigue properties of an Al-Cu-Li alloy during different pre-deformation processes [J]. Materials Science and Engineering A, 2018, 726: 309-319

[15] ShenK, TimkoM, LiY, et al.. The effect of temper, grain orientation, and composition on the fatigue properties of forged aluminum-lithium 2195 alloy [J]. Journal of Materials Engineering and Performance, 2019, 28(9): 5625-5638

[16] GableB M, ZhuA W, CsontosA A, et al.. The role of plastic deformation on the competitive microstructural evolution and mechanical properties of a novel Al-Li-Cu-X alloy [J]. Journal of Light Metals, 2001, 1(1): 1-14

[17] CassadaW A, ShifletG J, StarkeE A. The effect of plastic deformation on Al₂CuLi (T₁) precipitation [J]. Metallurgical Transactions A, 1991, 22(2): 299-306

[18] ZhangJ, LiZ, XuF, et al.. Regulating effect of pre-stretching degree on the creep aging process of Al-Cu-Li alloy [J]. Materials Science and Engineering A, 2019, 763: 138157

[19] LiJ, YeZ, LiuD, et al.. Influence of pre-deformation on aging precipitation behavior of three Al-Cu-Li alloys [J]. Acta Metallurgica Sinica (English Letters), 2017, 30(2): 133-145

[20] PearsonS. Fatigue crack propagation in metals [J]. Nature, 1966, 211(5053): 1077-1078

[21] LalD N. On the combined influences of Young’s modulus and stress ratio on the LEFM fatigue crack growth process: A new mechanistic approach [J]. Engineering Fracture Mechanics, 1996, 54(6): 761-790

[22] MatchaN B, SasikalaG. Effect of temperature on the fatigue crack growth behaviour of SS316L(N) [J]. International Journal of Fatigue, 2020, 40105815

[23] MurayamaM, HonoK, SagaandM, et al.. Atom probe studies on the early stages of precipitation in Al-Mg-Si alloys [J]. Materials Science and Engineering A, 1998, 250(1): 127

[24] RitchieR O. Near-threshold fatigue-crack propagation in steels [J]. International Metals Reviews, 1979, 241205-230

[25] RodgersB I, PrangnellP B. Quantification of the influence of increased pre-stretching on microstructure-strength relationships in the Al-Cu-Li alloy AA2195 [J]. Acta Materialia, 2016, 10855-67

[26] AnL, CaiY, LiuW, et al.. Effect of pre-deformation on microstructure and mechanical properties of 2219 aluminum alloy sheet by thermomechanical treatment [J]. Transactions of Nonferrous Metals Society of China, 2012, 22: s370-s375

[27] DorinT, de GeuserF, LefebvreW, et al.. Strengthening mechanisms of T₁ precipitates and their influence on the plasticity of an Al-Cu-Li alloy [J]. Materials Science and Engineering A, 2014, 605: 119-126

[28] ZhaoQ, LiuZ, LiS, et al.. Evolution of the Brass texture in an Al-Cu-Mg alloy during hot rolling [J]. Journal of Alloys and Compounds, 2017, 691: 786-799

[29] ZhaoQ, LiuZ, HuangT, et al.. Enhanced fracture toughness in an annealed Al-Cu-Mg alloy by increasing Goss/Brass texture ratio [J]. Materials Characterization, 2016, 119: 47-54

[30] WangZ C, PrangnellP B. Microstructure refinement and mechanical properties of severely deformed Al-Mg-Li alloys [J]. Materials Science and Engineering A, 2002, 328(12): 87-97

[31] LiF, LiuZ, WuW, et al.. Enhanced fatigue crack propagation resistance of Al-Cu-Mg alloy by intensifying Goss texture and refining Goss grains [J]. Materials Science and Engineering A, 2017, 679: 204-214

[32] LiF, LiuZ, WuW, et al.. Slip band formation in plastic deformation zone at crack tip in fatigue stage II of 2xxx aluminum alloys [J]. International Journal of Fatigue, 2016, 91: 68-78

[33] LiF, LiuZ, WuW, et al.. On the role of texture in governing fatigue crack propagation behavior of 2524 aluminum alloy [J]. Materials Science and Engineering A, 2016, 669: 367-378

[34] WuW, LiuZ, HuY, et al.. Goss texture intensity effect on fatigue crack propagation resistance in an Al-Cu-Mg alloy [J]. Journal of Alloys and Compounds, 2018, 730: 318-326