Fatigue crack initiation behaviors throughout friction stir welded joints in AA7075-T6 in ultrasonic fatigue |
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Affiliation: | 1. Politecnico di Torino, Department of Mechanical and Aerospace Engineering, Corso Duca degli Abruzzi 24, Turin 10129, Italy |
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Abstract: | This paper presents the results of experimental investigation on fatigue behaviors of friction stir welded joints in AA7075-T6 with ultrasonic fatigue test system (20 kHz). Two kinds of particles, Fe-rich intermetallic compounds and Mg2Si-based particles, governed the fatigue crack initiation. The plastic deformation and recrystallization during welding process led to the changes in particle size and micro crack occurrence between thermo-mechanically affected zone (TMAZ) and nugget zone (NZ). Therefore, the fatigue crack initiation sites leaned to be located at the TMAZ in short fatigue life, or at the NZ in very high cycle fatigue regime. |
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Keywords: | Very high cycle fatigue Friction stir welding Aluminum alloy Fatigue crack initiation |
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