EFFECTS OF PRE-FATIGUE DEFORMATION ON THE  UNIAXIAL TENSILE BEHAVIOR OF COARSEGRAINED PURE Al

  • YAN Ying ,
  • LU Meng ,
  • LI Xiaowu
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  • 1) Institute of Materials Physics and Chemistry, College of Sciences, Northeastern University, Shenyang 110819
    2) Key Laboratory for Anisotropy and Texture of Materials, Ministry of Education, Northeastern University, Shenyang 110819

Received date: 2012-11-15

  Revised date: 2013-03-25

  Online published: 2013-06-11

Abstract

The coarse-grained pure Al was first pre-fatigued to different fatigue life fractions D(D=2%-75 {%}) at a constant stress amplitude, and then the effect of pre-fatigue deformation on its uniaxial tensile behavior, fracture surface deformation features and dislocation structures were investigated. The results show that with increasing D, the extrusion/intrusion phenomenon on the surfaces of the pre-fatigued coarse-grained pure Al becomes more serious, and the non-uniform deformation in grain interiors is also enhanced, leading to the nucleation of micro-cracks and micro-voids along slip bands (SBs) or at grain boundaries (GBs) as well as their subsequent propagation. As D is as high as 75%, the longer intergranular cracks are produced at triple grain boundary nodes. With increasing D, the fatigue dislocation structures transform from loose cellular structures under annealing state into regular cellular structures and sub-grains, but the size of sub-grains nearly does not change. After the pre-fatigued coarse-grained pure Al specimens were subjected to the uniaxial tension, the yield strengthσYS obviously increases, but the change inσYS is not so obvious as D increases. Meanwhile, the ultimate tensile strengthσUTS first decreases and then increases, and finally sharply re-decreases. However, the pre-fatigued coarse-grained pure Al has poor ability to work hardening. The tensile fracture surface consists of fibrous and shear lip zones, and the number of dimples in fibrous zones increases and the size reduces with increasing D; as D reaches 50%, the number of dimples re-reduces and the size raises, and the fracture surface exhibits tearing characteristics. The sub-structures after the uniaxial tension are mainly composed of sub-grains and cellular dislocation structures inside sub-grains, and with increasing D, the size of sub-grains first reduces and then increases. The formation of fine sub-grains and cellular dislocation structures inside sub-grains results in the fact that the pre-fatigued coarse-grained pure Al has higher maximum uniform percent elongation.

Cite this article

YAN Ying , LU Meng , LI Xiaowu . EFFECTS OF PRE-FATIGUE DEFORMATION ON THE  UNIAXIAL TENSILE BEHAVIOR OF COARSEGRAINED PURE Al[J]. Acta Metall Sin, 2013 , 49(6) : 658 -666 . DOI: 10.3724/SP.J.1037.2012.00684

References

[1] Torres M A S, Voorwald H J C.  Int J Fatigue, 2002; 24: 877

[2] Williams J J, Deng X, Chawla N.  Int J Fatigue, 2007; 29: 1978
[3] Al-Rubaie K S, Del Grande M A, Travessa D N, Cardoso K R.  Mater Sci Eng, 2007; A464: 141
[4] Niendorf T, Lotze C, Canadinc D, Frehn A, Maier H J.  Mater Sci Eng, 2009; A499: 518
[5] Mocilnik V, Gubeljak N, Predan J, Flasker J.  Eng Fract Mech, 2010; 77: 3132
[6] Valiev R Z, Langdon T G.  Prog  Mater Sci, 2006; 51: 881
[7] Estrin Y, Vinogradov A.  Int J Fatigue, 2010; 32: 898
 [8] Galan Lopez J, Verleysen P, De Baere I, Degrieck J.  Procedia Eng,2011; 10: 1961
[9] Froustey C, Lataillade J L.  Mater Sci Eng, 2009; A500: 155
[10] Sanchez-Santana U, Rubio-Gonzalez C, Mesmacque G, Amrouche A. Int J Fatigue, 2009; 31: 1928
[11] Sanchez-Santana U, Rubio-Gonz alez C, Mesmacque G, Amrouche A,Decoopman X.  Int J Fatigue, 2008; 30: 1708
[12] Sanchez-Santana U, Rubio-Gonzalez C, Mesmacque G, Amrouche A,Decoopman X.  Mater Sci Eng, 2008; A497: 51
[13] Ye D Y, Xu Y D, Xiao L, Cha H B.  Mater Sci Eng, 2010; A527: 4092
[14] Verleysen P, Vanduyslager P, Van Slycken J, Vermeulen M, Degrieck J.  J Phy IV,2006; 134: 1307
[15] Li X W, Wang X M, Guo W W, Qi C J, Yan Y.  Metall Mater Trans, 2013; 44A: 1631
[16] Xia Y B, Wang Z G.  Acta Metall Sin, 1992; 28: A51
 (夏月波, 王中光. 金属学报, 1992; 28: A51)
[17] Liu G D, Zhu Z G, Wang J.  Acta Metall Sin, 1996; 5: 510
 (刘国东, 朱振刚, 王静. 金属学报, 1996; 5: 510)
[18] Videm M, Ryum N.  Mater Sci Eng, 1996; A219: 1
[19] Giese A, Estrin Y.  Scr Metall, 1993; 28: 803
[20] Fujii T, Sawatari N, Onaka S, Kato M.  Mater Sci Eng, 2004; A387--389: 486
[21] Vorren O, Ryum N.  Acta Metall, 1987; 35: 855
[22] Videm M, Ryum N.  Mater Sci Eng, 1996; A219: 11
[23] Xia Y B, Wang Z G, Ai S H.  Acta Metall Sin, 1982; 18: 606
 (夏月波, 王中光, 艾素华. 金属学报, 1982: 18: 606)
[24] Wang H, Xu Y L, Sun Q Y, Xiao L, Sun J.  Acta Metall Sin, 2009; 45: 434
 (王航, 徐燕灵, 孙巧艳, 肖林, 孙军. 金属学报, 2009; 45: 434)
[25] Li C.  Metallography Theory. Harbin: Harbin Industry University Press, 1996: 274
 (李超. 金属学原理. 哈尔滨: 哈尔滨工业大学出版社, 1996: 274)
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