Assessment of improvement techniques effect on fatigue behaviour of friction stir welded aerospace aluminium alloys

Abstract

This research work is based on analysis of the improvement of friction stir welded joints of the aerospace aluminium alloy AA2024-T351. Therefore, initially, the Taguchi method was used to obtain the optimal FSW parameters for improvement its mechanical behaviour. Then the fatigue resistance of base material, joints in as-welded condition and sound and defective FSW welded joints improved by grinding were detailed investigated. The influence of process parameters was addressed via statistical analysis of weld bead appearance parameters, mechanical tensile and bending resistance, metallurgical features and hardness field characterization. Validation tests demonstrate the Taguchi design's feasibility in the optimization of the FSW parameters and fatigue results show the resistance of improved welded joints overcoming base material.

Friction stir welds in aluminium: Design S‐N curves from statistical analysis of literature data

“…However, the work of James et al confirms that there is a significant increase in fatigue strength by surface finishing. The same comments apply to data in categories B0 and B0M taken from references …”

Fatigue behavior of friction spot welds in lap shear specimens of AA5754 and Ti6Al4V alloys

“…(6) for the evaluation of fatigue test data [10,17,18]. This equation is valid for fatigue lives that are within the range of 1 Â 10 3 -5 Â 10 8 cycles for non-ferrous metals such as aluminum and titanium [18]. Based on the results, a fatigue limit of 25 MPa (15% of the maximum average static fracture load) was determined for the AA5754/Ti6Al4V joints produced by FSpW.…”

Aluminum friction stir welds: Review of fatigue parameter data and probabilistic fracture mechanics analysis

“…Zhou et al [66] have already shown, for instance, that the fatigue life of flawed welds can be on the order of 33-80 times shorter than that of ''flaw-free" welds. In this context, initial cracks and flaw were obtained from several authors from the literature [6,29,[69][70][71][72]14,73,74,68,75,76]. The results are shown in Fig.…”