TY - JOUR
T1 - Very High Cycle Fatigue Crack Initiation Mechanism in Nugget Zone of AA 7075 Friction Stir Welded Joint
AU - He, Chao
AU - Kitamura, Kazuhiro
AU - Yang, Kun
AU - Liu, Yong Jie
AU - Wang, Qing Yuan
AU - Chen, Qiang
N1 - Funding Information:
Tis research was fnancially supported by the National Natural Science Foundation of China (no. 11572057 and no. 11602038), and the support of JSPS Postdoctoral Fellowship for Overseas Researchers (P16809) is very much appreciated.
Publisher Copyright:
© 2017 Chao He et al.
PY - 2017
Y1 - 2017
N2 - Very high cycle fatigue behavior of nugget zone in AA 7075 friction stir welded joint was experimentally investigated using ultrasonic fatigue testing system (20 kHz) to clarify the crack initiation mechanism. It was found that the fatigue strength of nugget zone decreased continuously even beyond 107 cycles with no traditional fatigue limits. Fatigue cracks initiated from the welding defects located at the bottom side of the friction stir weld. Moreover, a special semicircular zone could be characterized around the crack initiation site, of which the stress intensity factor approximately equaled the threshold of fatigue crack propagation rate. Finally, a simplified model was proposed to estimate the fatigue life by correlating the welding defect size and applied stress. The predicted results are in good agreement with the experimental results.
AB - Very high cycle fatigue behavior of nugget zone in AA 7075 friction stir welded joint was experimentally investigated using ultrasonic fatigue testing system (20 kHz) to clarify the crack initiation mechanism. It was found that the fatigue strength of nugget zone decreased continuously even beyond 107 cycles with no traditional fatigue limits. Fatigue cracks initiated from the welding defects located at the bottom side of the friction stir weld. Moreover, a special semicircular zone could be characterized around the crack initiation site, of which the stress intensity factor approximately equaled the threshold of fatigue crack propagation rate. Finally, a simplified model was proposed to estimate the fatigue life by correlating the welding defect size and applied stress. The predicted results are in good agreement with the experimental results.
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U2 - 10.1155/2017/7189369
DO - 10.1155/2017/7189369
M3 - Article
AN - SCOPUS:85042087242
SN - 1687-8434
VL - 2017
JO - Advances in Materials Science and Engineering
JF - Advances in Materials Science and Engineering
M1 - 7189369
ER -