Statistical Analysis of High-Cycle Fatigue Behavior of Friction Stir Welded AA5083-H321

Abstract

A review of the literature revealed that high-cycle fatigue data associated with friction stir-welded (FSW) joints of AA5083-H321 (a solid-solution-strengthened and strain-hardened/stabilized Al-Mg-Mn alloy) are characterized by a relatively large statistical scatter. This scatter is closely related to the intrinsic variability of the FSW process and to the stochastic nature of the workpiece material microstructure/properties as well as to the surface condition of the weld. Consequently, the use of statistical methods and tools in the analysis of FSW joints is highly critical. A three-step FSW-joint fatigue-strength/life statistical-analysis procedure is proposed in this study. Within the first step, the type of the most appropriate probability distribution function is identified. The parameters of the selected probability distribution function, along with their confidence limits, are computed in the second step. In the third step, a procedure is developed for assessment of the statistical significance of the effect of the FSW process parameters and fatigue specimen surface conditions. The procedure is then applied to a set of stress-amplitude versus number of cycles to failure experimental data in which the tool translational speed was varied over four levels, while the fatigue specimen surface condition was varied over two levels. The results obtained showed that a two-parameter weibull distribution function with its scale factor being dependent on the stress amplitude is the most appropriate choice for the probability distribution function. In addition, it is found that, while the tool translational speed has a first-order effect on the AA5083-H321 FSW-joint fatigue strength/life, the effect of the fatigue specimen surface condition is less pronounced.

Through thickness property variations in friction stir welded AA6061 joint fatigued in very high cycle fatigue regime

“…Therefore, it is crucial to understand the fatigue strength and failure mechanism of FSW joint considering the heterogeneity influence in very high cycle fatigue (VHCF) regime. However, current studies on the fatigue properties of the FSW are focused primarily on the fatigue crack propagation resistance, low cycle fatigue behavior and high cycle fatigue property [4][5][6]. In particular, the investigations on the fatigue strength and failure mechanism considering the heterogeneity through-thickness of FSW joint are extremely limited, especially in the VHCF regime.…”

The influences of rotational and welding speeds on microstructures and mechanical properties of friction stir welded Al5083 and commercially pure copper sheets lap joints

“…AA5083 is a solid-solution-strengthened and strain-hardened/ stabilized Al-Mg-Mn alloy widely used in aerospace, marine and military industries mainly because of its special properties such as good strength to weight ratio, appropriate weldability and elite corrosion resistance [16]. Recently many researches have been performed on similar and dissimilar FSW joints of this aluminum alloy [17][18][19][20].…”

The Influence of Process Parameters on Microstructure and Mechanical Properties of Friction Stir Welded Al 5083 alloy Lap joint

“…AA5083 is a strain hardening structural alloy that is widely used in aerospace, marine and military industries mostly because of its light weight, admissible weld ability and elite corrosion resistance [8]. Some recent researches have studied friction stir welding of this aluminum alloy in similar or dissimilar joints [9][10][11][12].…”